U.S. patent application number 10/362273 was filed with the patent office on 2004-05-06 for catheter locator apparatus and method of use.
Invention is credited to Besz, William John, Brasted, Stuart, Chorley, Donald Philip, Walker, Kathleen Maria, Walker, Robert Anthony.
Application Number | 20040087877 10/362273 |
Document ID | / |
Family ID | 25646417 |
Filed Date | 2004-05-06 |
United States Patent
Application |
20040087877 |
Kind Code |
A1 |
Besz, William John ; et
al. |
May 6, 2004 |
Catheter locator apparatus and method of use
Abstract
This invention relates to a method of catheter and radiating
coil location in a human body and in particular to the
determination over time of the location of the tip of a catheter as
it is inserted and during its use in the body. In particular when a
radiating coil is used in conjunction with a catheter, a coil
locating device can be used to determine the distance the coil is
from the device and hence its depth in the body of a patient. To
assist a clinician using the coil-locating device, a display is
provided that shows both a reference image of a part or portion of
a body (non-subject body) and an image of the coil located on the
display with reference to the reference image. This is achieved by
locating the coil-locating device on or over a predetermined
landmark on the patient's body. The coil and its associated signal
wires can be incorporated into a stylet, guide wire or a catheter.
The coil locating device has a preferable triangular shape in plan
view that allows it uppermost apex to be orientated towards the
head of the patient and for an axis of the device to be aligned
with the mid sagittal plane of the patient. Preferable landmarks on
a human body include the xiphoid sternal junction and the
caudal/mid sagittal aspect of the jugular sternal notch.
Inventors: |
Besz, William John; (South
Australia, AU) ; Chorley, Donald Philip; (South
Australia, AU) ; Brasted, Stuart; (South Australia,
AU) ; Walker, Robert Anthony; (Parkside, AU) ;
Walker, Kathleen Maria; (Parkside, AU) |
Correspondence
Address: |
BELL, BOYD & LLOYD, LLC
PO BOX 1135
CHICAGO
IL
60690-1135
US
|
Family ID: |
25646417 |
Appl. No.: |
10/362273 |
Filed: |
February 21, 2003 |
PCT Filed: |
August 23, 2001 |
PCT NO: |
PCT/AU01/01051 |
Current U.S.
Class: |
600/585 |
Current CPC
Class: |
A61B 2090/3983 20160201;
A61B 5/6852 20130101; A61J 15/0069 20130101; A61B 5/742 20130101;
A61B 5/062 20130101; A61B 34/20 20160201; A61B 5/06 20130101; A61B
5/6851 20130101; A61B 2034/2051 20160201; A61B 2034/107 20160201;
A61J 15/0007 20130101; A61B 5/061 20130101; A61B 5/065 20130101;
A61M 25/0105 20130101; A61M 2025/0166 20130101; A61B 2090/363
20160201; A61B 5/743 20130101; A61M 25/09 20130101; A61B 90/36
20160201 |
Class at
Publication: |
600/585 |
International
Class: |
A61B 005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 23, 2000 |
AU |
PQ 9592 |
May 24, 2001 |
AU |
PR 5250 |
Claims
1. A method of guiding a coil used in relation to a catheter to be
inserted into a subject body wherein said coil radiates signal
energy; the method including the steps of: a) using a coil
detection means having at least two signal energy detectors wherein
said detection means is located with reference to a predetermined
location on or part of said subject body and generating a signal
based on a spatial separation of a said radiating coil from said
detection means; b) displaying a predetermined symbol
representative of an area on or part of a non-subject body wherein
said signal generated by said detection means is used to display a
predetermined coil symbol representative of said coil at a position
on a display device relative to said predetermined body symbol for
use by a clinician to guide a positioning of said coil and said
catheter into said subject body.
2. The method according to claim 1 wherein said coil detection
means is located with reference to a predetermined location being
on or over the xiphoid sternal junction of a human body for use
with a catheter inserted into the alimentary canal.
3. The method according to claim 2 wherein a predetermined body
symbol representative of an area on or part of a non-subject body
is displayed that is representative of the diaphragm of a
non-subject human body thus delineating on said display the upper
and lower chest cavities of a human body.
4. The method according to claim 1 wherein said coil detection
means is located with reference to a predetermined location being
on or over the caudal/mid sagittal aspect of the jugular sternal
notch of a human body for use with a catheter inserted into the
cardiovascular or respiratory system.
5. The method according to claim 5 wherein a predetermined body
symbol representative of an area on or part of a non-subject body
is displayed that is representative of the sternum of a non-subject
human body thus delineating on said display a portion of the upper
skeleton of a human body.
6. The method according to claim 1 includes the further step of: c)
displaying a predetermined coil symbol representative of said coil
at predetermined intervals of time.
7. The method according to claim 1 wherein said coil is
incorporated into a stylet or guide wire adapted for use with a
catheter.
8. The method according to claim 7 includes the further step of: d)
displaying a predetermined coil symbol representative of said coil
at predetermined intervals of time while said stylet or guide wire
is inserted or retracted from a catheter located over a said stylet
or guide wire so that the path of said coil and thus said catheter
can be tracked and displayed.
9. The method according to claim 8 wherein said track is
constructed for display by calculating a line of best fit from two
or more signals generated by said coil detection means.
10. The method according to claim 1 wherein a coil is incorporated
into a catheter for use in a body.
11. The method according to claim 10 includes the further step of:
e) displaying a predetermined coil symbol representative of said
coil at predetermined intervals of time while said catheter is
inserted into or retracted from said body and thus said catheter
can be tracked and displayed.
12. The method according to claim 11 wherein said track is
constructed for display by calculating a line of best fit from two
or more signals generated by said coil detection means.
13. A catheter locator apparatus for assisting a user's placement
of a catheter into a subject body, the catheter locator apparatus
comprising: a pair of wires usable with the catheter, the wires
having a first end and a second end; a processor in electronic
communication with the first end of the wires; a radiating coil
connected to the second end of the wires, the radiating coil having
various locations in the subject body; a detector device in
electronic communication with the processor, the detector device
adapted to be positioned in relation to a predetermined portion of
the subject body; reference data retrieved by the processor which
specifies at least one reference image which represents at least
one predetermined image; indicator data generated by the processor
which specifies at least one indicator image which provides
information related to at least one location of the radiating coil
in the subject body; and a monitor in electronic communication with
the processor which displays the indicator image and the reference
image.
14. The catheter locator apparatus of claim 13, wherein the
radiating coil transmits electromagnetic signals.
15. The catheter locator apparatus of claim 13, wherein the pair of
wires is a stylet or guide wire or is incorporated into a stylet or
guide wire or the catheter.
16. The catheter locator apparatus of claim 13, wherein the
detector device includes at least two receiving coils, which
receive electromagnetic signals from, said radiating coil.
17. The catheter locator apparatus of claim 16, wherein the
processor receives at least one indicator signal from the detector
device representative of the received electromagnetic signals after
said detector device is located in relation to a predetermined
portion of the subject body.
18. The catheter locator apparatus of claim 13, wherein the
predetermined portion of the subject body is the caudal/mid
sagittal aspect of the jugular sternal notch when the catheter is
used in the cardiovascular or respiratory system.
19. The catheter locator apparatus of claim 13, wherein the
processor receives at least one indicator signal from the detector
device while the radiating coil is in the catheter that is within
the subject body.
20. The catheter locator apparatus of claim 13, wherein the
predetermined portion of the subject body is the xiphoid sternal
junction of the subject body when the catheter is used in the
gastrointestinal tract or alimentary canal.
21. The catheter locator apparatus of claim 13, wherein the display
provides a user with information related to the catheter's location
when the radiating coil is used with the catheter and the catheter
is in the subject body.
22. The catheter locator apparatus of claim 21, wherein the
indicator image and reference image provide a user with information
related to depth of the catheter in the subject body.
23. The catheter locator apparatus of claim 21, wherein the display
provides a user with information related to X-Y location of the
catheter in the subject body.
24. The catheter locator apparatus of claim 21, wherein the
catheter's location is relative to the detector device.
25. The catheter locator apparatus of claim 21, wherein the monitor
provides users with information related to direction of travel of
the catheter in the subject body.
26. The catheter locator apparatus of claim 25, wherein information
related to the direction of travel results from a change in the
indicator data.
27. The catheter locator apparatus of claim 13, which includes a
data storage device in electronic communication with the
processor.
28. The catheter locator apparatus of claim 27, wherein the data
storage device includes data which specifies a reference image of
at least a portion of a non-subject body.
29. The catheter locator apparatus of claim 28, wherein the
non-subject body is a theoretical body.
30. The catheter locator apparatus of claim 27, wherein the data
storage device includes data that specifies a reference image
comprising a symbol.
31. The catheter locator apparatus of claim 13, wherein the
catheter is used in a gastrointestial tract of the subject
body.
32. A catheter locator apparatus of claim 13, wherein the catheter
is used in an alimentary canal of the subject body.
33. A catheter locator apparatus of claim 13, wherein the catheter
is used in a cardiovascular system of the subject body.
34. A catheter locator apparatus of claim 13, wherein the catheter
is used in a respiratory system of the subject body.
35. An apparatus for use in conjunction with a medical instrument,
the medical instrument having a first end and a second end, the
first end movable between a plurality of anatomical locations
within a subject body, the apparatus comprising: at least one
energy radiating member operatively coupled to the first end of the
medical instrument, the energy radiating member producing a
plurality of signals; at least one energy receiving member
receiving energy from the energy radiating member; at least one
processor in communication with the energy receiving member, the
processor producing signal data based on the signals; at least one
data storage device in communication with the processor, the data
storage device storing the signal data and image data in
association with the signal data, the image data representing a
plurality of images, each of the images indicating one of the
anatomical locations; and at least one display device communicating
with the processor, the display device displaying the images.
36. The apparatus of claim 35, wherein the medical device includes
a catheter.
37. The apparatus of claim 35, wherein the signal data includes
data related to movement of the first end along an X-axis.
38. The apparatus of claim 37, wherein the signal data includes
data related to movement of the first end along a Y-axis.
39. The apparatus of claim 38, wherein the signal data includes
data related to movement of the first end along a Z-axis.
40. The apparatus of claim 35, wherein the anatomical locations are
selected from the group consisting of a location in an alimentary
canal of the patient, a location in a cardiovascular system of the
patient, a location in a respiratory system of the patient and a
location in a reproduction system of the subject body.
41. The apparatus of claim 35, wherein at least one of the images
includes a graphical representation of an anatomical portion of the
subject body.
42. The apparatus of claim 35, wherein at least one of the images
includes a textual description of an anatomical portion of the
subject body.
43. The apparatus of claim 35, wherein at least one of the images
includes a symbolic message related to an anatomical portion of the
patient.
44. The apparatus of claim 35, which includes at least one printing
device in communication with the processor, the printing device
adapted to print the images.
45. The apparatus of claim 35, wherein the at least one energy
receiving member is positioned with reference to a predetermined
location on or part of said subject body.
46. The apparatus of claim 45, wherein said predetermined location
is a caudal/mid sagittal portion of a jugular sternal notch of the
subject body.
47. The apparatus of claim 45, wherein said predetermined location
is a xiphoid sternal junction of the subject body.
48. An apparatus for use in conjunction with a medical instrument,
the medical instrument having a first end and a second end, the
first end movable within a subject body along a path having a
shape, the apparatus comprising: at least one energy radiating
member operatively coupled to the first end of the medical
instrument; at least one energy receiving member receiving energy
from the energy radiating member; at least one processor in
communication with the energy receiving member; and at least one
display device communicating with the processor, the display device
displaying an image which indicates information related to the
shape of the path.
49. The apparatus of claim 48, wherein the medical device includes
a catheter.
50. The apparatus of claim 48, wherein the shape of the path has at
least one curve.
51. The apparatus of claim 50, wherein the image has at least one
curve.
52. The apparatus of claim 51, wherein the image includes a
graphical representation of at least part of the path, the
representation based on a correspondence of the curve of the image
to the curve of the shape of the path.
53. The apparatus of claim 48, wherein the image includes a
graphical representation of the path.
54. The apparatus of claim 48, which includes at least one data
storage device in communication with the processor, the data
storage device storing a program having instructions which direct
the processor to produce the image.
55. The guidance apparatus of claim 54, wherein the program has
instructions which direct the processor to produce data related to
at least one position of the first end of the medical instrument,
the position selected from the group consisting of a position on an
X-axis, a position on a Y-axis and a position on a Z-axis relative
to a predetermined location on or part of said subject body.
56. The apparatus of claim 48, which includes a signal generator in
communication with the energy radiating member and a plurality of
signals produced by the energy radiating member being received by
the energy receiving member.
57. The apparatus of claim 56, wherein the shape of the path is
determined from information calculated based on the signals.
58. The apparatus of claim 48, wherein the medical instrument is
for use in insertion into an alimentary canal of subject body.
59. The apparatus of claim 48, wherein the medical instrument is
for use in insertion into a cardiovascular system of the
patient.
60. The apparatus of claim 48, wherein the medical instrument is
for use in insertion into a respiratory system of the patient.
61. The apparatus of claim 48, wherein an energy receiving member
has a position referenced to a xiphoid sternal junction of the
subject body.
62. The apparatus of claim 48, wherein the energy receiving member
has a position referenced to a caudal/mid sagittal aspect of a
jugular sternal notch of the subject body.
63. The apparatus of claim 48, which includes an image displayed on
the visual display device, the image representing a portion of a
non-subject body.
64. The apparatus of claim 48, which includes at least one printing
device for receiving data to print the image.
65. An apparatus for graphically depicting data regarding catheter
movement during placement of a catheter within a subject body, the
catheter having a first end and a second end moveable along a
placement path, comprising: an energy radiating member adapted to
cooperate with the second end of the catheter; an energy receiving
member external to the patient, the energy receiving member
receiving energy from the energy radiating member; a data processor
communicating with the energy receiving member, the data processor
capable of producing data indicative of position changes of the
second end of the catheter along the placement path; and a visual
display device communicating with the data processor, the visual
display device displaying graphically the position change data of
the second end of the catheter along the placement path.
66. The apparatus of claim 65, which further comprises a signal
generator in communication with the energy radiating member and a
plurality of signals produced by the energy radiating member being
received by the energy receiving member.
67. The apparatus of claim 66, wherein the data includes
information calculated based on the signals.
68. The apparatus of claim 65, wherein the catheter is for use in
insertion into an alimentary canal of the subject body.
69. The apparatus of claim 65, wherein the catheter is for use in
insertion into a cardiovascular system of the patient.
70. The apparatus of claim 65, wherein the catheter is for use in
insertion into a respiratory system of the patient.
71. The apparatus of claim 65, wherein the energy receiving member
has a position referenced to a xiphoid sternal junction of the
subject body.
72. The apparatus of claim 65, wherein the energy receiving member
has a position referenced to a caudal/mid sagittal aspect of a
jugular sternal notch of the patient.
73. The apparatus of claim 65, which includes an image displayed on
the visual display device, the image representing a portion of a
non-subject body.
74. The apparatus of claim 65, which includes at least one printing
device in communication with the data processor, the printing
device adapted to print a graphical representation of the position
change data.
75. A method for aiding a user in positioning a medical instrument
in a portion of a subject body, said method comprising the steps
of: (a) coupling at least one energy radiating member to a first
end of the medical instrument; (b) positioning at least one energy
receiving member with reference to a predetermined location on or
part of said subject body; (c) the user to insert a predetermined
length of the first end into the subject body; (d) causing the
energy radiating member to produce a plurality of signals while the
length of the medical instrument is being moved inside the subject
body; (e) transforming received signals into signals for
communication to a processor; (f) performing at least one
calculation based on the transformed signals; (g) producing data
based on the calculation; and (h) graphically representing the
data.
76. The method of claim 75, wherein the step of positioning at
least one energy receiving member adjacent to an exterior portion
of the patient includes the step of positioning the receiving
member referenced to a xiphoid sternal junction of the patient.
77. The method of claim 75, wherein the step of positioning at
least one energy receiving member adjacent to an exterior portion
of the patient includes the step of positioning the receiving
member referenced to a caudal/mid sagittal aspect of a jugular
sternal notch of the patient.
78. The method of claim 75, wherein the step of enabling the user
to insert a predetermined length of the first end of the medical
instrument into the patient includes the step of enabling the user
to retract a desired length of the first end of the medical
instrument.
79. The method of claim 75, wherein steps (d) through (h) are
performed in real time.
80. The method of claim 75, wherein the step of graphically
representing the data includes the step of displaying an image,
which provides information related to a shape of a movement path of
the first end in the subject body.
81. The method of claim 75, which includes the step of repeating
steps (c) through (h) as the first end is past through the subject
body.
82. A wire bundle for use with a catheter locator apparatus which
includes: (a) a processor in electronic communication with a
predetermined portion of a proximal end of the wire bundle, (b) a
radiating coil connected to a predetermined portion of a distal end
of the wire bundle, the radiating coil having various locations in
a subject body; (c) a detector device in electronic communication
with the processor, the detector device is located with reference
to a predetermined location on or part of said subject body; (d)
reference data retrieved by the processor which specifies at least
one reference image which represents at least one predetermined
image; (e) indicator data generated by the processor which
specifies at least one indicator image which provides information
related to at least one location of the radiating coil in the
subject body; and (f) a monitor in electronic communication with
the processor which displays the indicator image and the reference
image, said wire bundle comprising: a first wire having a
predetermined stiffness adapted to control positioning of a
flexible tube; a second wire adapted to transmit signals between
the radiating coil and the processor; and means for binding the
second wire to the first wire.
83. The wire bundle of claim 82, wherein the binding means includes
winding of the second wire around a circumference of the first
wire.
84. The wire bundle of claim 82, wherein the binding means includes
a wrapping material.
85. The wire bundle of claim 82, wherein the binding means includes
an adhesive.
86. The wire bundle of claim 82, wherein the binding means includes
a predetermined fastener.
Description
BACKGROUND
[0001] For ease of explanation, the guidance and placement and
ongoing maintenance of a catheter for enteral nutrition will be
described in one example in this specification. It will however be
clear to the person skilled in the art that the techniques and
equipment described are useful for similar placement requirements
in other parts of the human body and animal bodies as well.
Catheters are used for many different purposes and there exist many
different catheter types. An example of the use of the invention in
a human body will also be provided in the field of Central Venous
Catheter location.
[0002] Enteral nutrition includes both the ingestion of food orally
and the non-volitional delivery of nutrients by tube into the
gastrointestinal tract. Patients are candidates for enteral tube
feeding that will not, should not, or cannot eat but who have a
functional gastrointestinal tract. Benefits of enteral tube feeding
are the maintenance of gastrointestinal structure and functional
integrity, enhanced utilization of nutrients, ease and safety of
administration.
[0003] Enteral tube feeding is contraindicated for patients with
diffuse peritonitis, intestinal obstruction that prohibits use of
the bowel, intractable vomiting, paralytic ileus, and/or severe
diarrhoea that makes metabolic management typical. Other potential
contraindications that depend on the clinical circumstances include
severe pancreatitis, enterocutaneous fistulae, and gastrointestinal
ischemia. Enteral tube feeding is not recommended during the early
stages of short-bowel syndrome or in the presence of severe
malabsorption.
[0004] The route selected for tube feeding depends upon the
anticipated duration of feeding, the condition of the
gastrointestinal tract (e.g. esophageal obstruction, prior gastric
or small-bowel resections), and the potential for aspiration. The
intestine can be accessed at the bedside (naso intestinal tube,
naso endoscopic gastrostomy) or in the operating room (gastrostomy
and jejunostomy).
[0005] Nasal intubation for gastric feeding is the simplest and
most often used method for tube feeding. This technique is
preferred for patients who are expected to eventually resume oral
feeding. Maximal patient comfort and acceptance is more likely when
a soft feeding tube with a small external diameter is used. Access
to the duodenum and jejunum is possible with longer tubes but
placement of the tip into the duodenum and jejunum is more
difficult and time consuming and has added risk factors.
[0006] Enteral tube feeding is considered safer than parenteral
nourishment because mechanical, infection, and metabolic
complications are usually less severe than those encountered with
parenteral nutrition. However, enteral feeding is not problem free,
and significant complications can occur when the tube and feeding
is managed by unskilled or untrained individuals or if monitoring
is absent or inappropriate.
[0007] Incorrect placement of the feeding tube is one of a number
of major complications. Most serious is the unintended placement of
the catheter during nasal intubation into the cardiovascular system
or into the lungs. Both of these situations are possible when
inexperienced medical staff perform intubation. A stylet
(relatively stiff small gauge wire) is used to stiffen and support
the otherwise flaccid catheter tube during its intubation.
[0008] It is also prudent to check that the exit aperture of the
feeding tube (typically located at the distal end/tip of the tube)
remains in its desired location over the period of feeding.
Protocols that address this requirement include frequent monitoring
for the appropriate pH of fluids extracted from the feeding tube
while not carrying nutritional liquids and careful patient
monitoring to ensure that nutritional uptake is as expected.
[0009] X-rays are often used to determine the location of the
caudal/distal end of the tube. However, even X-rays are not
necessarily conclusive as to its location. The natural and
continuous movement of the internal organs can make it difficult
for the physician interpreting the X-ray to be sure of the actual
location of the caudal/distal end of the tube because the movement
described can change the position of the catheter over time.
[0010] There exist a large variety of catheters, their names
sometimes indicating their use, the part of the body they enter or
treat and sometimes they are named after the physician or
physicians who developed methodologies for their use.
[0011] This invention also relates to catheter location methods and
means for central venous catheters.
[0012] Intravenous catheters are those that access the interior of
a patient via an opening in the skin passed down one or more of the
many branches of the venous system to the region requiring medical
attention. These types of catheters are also referred to as Venous
Access Catheters (VAC) and Central Venous Catheters (CVCs) and are
used generally in the cardiovascular system.
[0013] A sub-category of intravenous catheters is those that fall
under the heading of Peripherally Inserted Central Catheter (PICC).
These catheters have been used by clinicians for many years and
many different techniques exist for their insertion.
[0014] One such insertion technique is the Seldinger technique and
along with advances in devices and materials there now exists a
modified Seldinger technique, useful particularly for small or poor
veins.
[0015] There exist a large selection of intravenous catheters such
as for example peripheral catheters which are used for insertion
into the body that are from one half to three inches in length;
midline catheters which are used for insertion being greater than
three inches in length; mid-clavicular and non-tunneled
sub-clavian, tunneled Groshong, Hickman and Broviac or subcutaneous
implanted ports for longer lengths.
[0016] Common to intravenous catheters is the use of a guide wire
that is passed into the body and into a vein and then directed by
the skill of the clinician to the desired location. Once the guide
wire is in place a catheter is slid over its external free end and
pushed till the distal end of the catheter reaches the end of the
guide wire.
[0017] The location of the tip of these types of catheters or the
recordal of the advancement of the guide wire into the body is
achieved in a number of ways.
[0018] Return checks are used to expire types of liquids expected
to be at or near the tip of the catheter and the checking of length
markings on the wires used within catheters are two methods used by
clinicians who do not have ready access to alternatives. Ultrasound
guidance, fluoroscopy and X-ray methodologies are preferred even
though they do not always provide an exact determination of the
location of the tip or path of the guide wire or catheter.
[0019] More expensive and more time-consuming CT examinations
provide the best means of locating not only the tip but also the
path of any of the types of catheter described above and others
that are located in the body of a patient.
[0020] The final location of the caudal/distal end of any catheter
is critical to the efficacy of the purpose for the use of the
catheter. In one example, the delivery of drugs directly into the
heart can be best achieved by the location of the caudal/distal end
of the catheter in the superior vena cava (CVC). Studies show that
it is preferable to locate the caudal/distal end of the catheter in
the upper portion of the superior vena cava (typically recognised
as being more than 4.5 cm above the cavoatrial junction). Studies
indicate that these preferable locations appear to minimise
catheter malfunction.
[0021] More critical however, is to ensure that the catheter is in
the superior vena cava itself, as there exist studies indicating
that there is a significant association between catheter
malfunction and catheter tip location in the venous system adjacent
to the superior vena cava.
[0022] FIG. 7 depicts the various veins in the vicinity of and
including the superior vena cava.
[0023] Where for example, the catheter tip is in either of the
brachiocephilac veins or near the junction of a brachiocephilac
vein there is a greater likelihood of the unwanted development of a
fibrin sheath or the presence of thrombus around or at the tip of
the catheter as compared to catheter tips located in the superior
vena cava. Greater likelihood of unwanted developments can occur
when a catheter tip is located in the sub-clavian vein or the
cavoatrial junction or in the right atrium.
[0024] The effect of inappropriate or less than ideal catheter tip
location is shortened survival which clearly is manageable but more
serious effects may include thrombosis and phlebitis infections
more, particularly pheumothorax infections and, in more serious
situations, occlusions.
[0025] When catheter tips suffer thrombosis, these studies
demonstrate significantly shorter survival than those catheters
that are not subject to this unwanted development.
[0026] Appropriate patient care requires consideration of a large
number of factors when considering the need for intravenous
catheter usage. Sometimes the benefit of drug delivery has to be
carefully weighed against the likelihood of adverse effects of
intravascular device related infections as mentioned
previously.
[0027] Catheter selection is not a simple matter and factors to be
considered include the following:
[0028] type of medication
[0029] osmolarity and pH of the solution to be infused
[0030] duration of therapy required
[0031] secondary risk factors and chronic diseases
[0032] patient age, activities, work and lifestyle
[0033] future intravenous needs and long term prognosis
[0034] current availability and status of access veins (typically
peripheral veins of the limbs)
[0035] patient history of neurologic impairments, surgeries
affecting veins or lymphatic system, bloods dyscrasias, thrombosis
and previous intravenous use history
[0036] current patient diagnosis and preferences for treatment
[0037] The anticipated duration of therapy can readily suggest
short peripheral catheters for periods of less than five days, and
for periods of less than four weeks a midline catheter is generally
suitable.
[0038] Midclavicular lines are an option and becoming more popular
as the occurrence of thrombosis resulting from sub-optimal
placement in sub-clavian regions other than the superior vena cava
increase.
[0039] In fact mid-clavicular lines are often used in home care
situations to avoid the time and cost of confirmatory X-rays.
However, even mid-clavicular lines need to be optimally placed in
the lower one third of the superior vena cava, dose to the junction
of the superior vena cava and the right atrium but should not
advance into the right atrium itself.
[0040] The previously mentioned Peripherally Inserted Central
Catheters (PICCs) having a tip location in the superior vena cava
can be used for long term therapy (five days to one year). However,
they should be critically checked by X-ray to determine appropriate
tip placement even though this is neither a totally satisfactory
nor certain method of location checking.
[0041] It is thus a real need for physicians to be able to increase
their confidence that the catheter has been placed at the desired
location and remain there in the body of their patient. This is so
whether that is for the purpose of enteral and parenteral
nutrition, receiving vesicant chemotherapeutic agents, antibiotics
and blood sampling or for other purposes.
BRIEF DESCRIPTION OF THE INVENTION
[0042] A broad form of the invention is a method of locating a coil
used in relation to a catheter to be inserted into a subject body
wherein said coil radiates signal energy; the method including the
steps of: using a coil position measuring means having at least two
signal energy detectors wherein said measuring means is located
with reference to a predetermined location on or part of said
subject human body; and displaying a position measurement made by
said coil position measuring means wherein said position
measurement is relative to said position measuring means for use by
a clinician in determining the position of said coil and said
catheter in said subject human body relative to said predetermined
location on or part of said subject human body.
[0043] In a further aspect of the invention, the method includes
the further step of also displaying with said position measurement
a representation of a point or region of a non-subject body
referenced to said displayed position measurement for use by the
clinician in determining the position of said coil and said
catheter in said subject human body.
[0044] 3. In another aspect of the invention, the position
measuring means is located with reference to a predetermined
location being on or over the xiphoid sternal junction of said
human body for use with a catheter inserted into the alimentary
canal.
[0045] In another aspect of the invention, a region or delineation
of a body part is displayed that is representative of the diaphragm
of a non-subject human body thus delineating on said display the
upper and lower chest cavities of a human body.
[0046] In another aspect of the invention, the position measuring
means is located with reference to a predetermined location being
on or over the caudal/mid sagital aspect of the jugular sternal
notch of said human body use with a catheter inserted into the
cardiovascular or respiratory system.
[0047] In yet a further aspect of the invention, a region or
delineation of a body part is displayed that is representative of
the sternum of the said human body thus delineating on said display
a portion of the upper skeleton of a human body.
[0048] In a yet further aspect of the invention, the method
includes the further step of displaying a position measurement of
said coil at predetermined intervals of time.
[0049] In a further aspect of the invention, the coil is
incorporated into a stylet or guide wire adapted for use with a
catheter.
[0050] In yet a further aspect of the invention, the method
includes the further step of displaying the position of said coil
at predetermined intervals of time while said stylet or guide wire
is retracted from a catheter so that the path of said coil and thus
said catheter can be tracked and displayed.
[0051] In an aspect of the invention, a coil is incorporated into a
catheter and usable for locating the position of said catheter in a
human body.
[0052] In another aspect of the invention a catheter locator
apparatus for assisting a user's placement of a catheter into a
subject body comprises: a pair of wires usable with the catheter,
the wires having a first end and a second end; a processor in
electronic communication with the first end of the wires; a
radiating coil connected to the second end of the wires, the
radiating coil having various locations in the subject body; a
detector device in electronic communication with the processor, the
detector device adapted to be positioned in relation to a
predetermined portion of the subject body; reference data retrieved
by the processor which specifies at least one reference image which
represents at least one predetermined image; indicator data
generated by the processor which specifies at least one indicator
image which provides information related to at least one location
of the radiating coil in the subject body; and a monitor in
electronic communication with the processor which displays the
indicator image and the reference image.
[0053] In yet a further aspect of the invention a catheter adapted
for use with a catheter locator apparatus includes: (a) a processor
in electronic communication with a coil; (b) the coil radiating and
incorporated into a coil positioning device, stylet, guide wire or
into said catheter, the radiating coil having various locations in
a subject body; (c) a detector device in electronic communication
with the processor; (d) reference data generated by the processor
which specifies at least one reference image which represents at
least one predetermined portion of the subject body; (e) indicator
data generated by the processor which specifies at least one
indicator image which provides information related to at least one
location of the radiating coil in the subject body; and (f) a
monitor in electronic communication with the processor which
displays the indicator image and the reference image, said catheter
comprising: a tube which is adapted to receive the stylet or guide
wire or having a coil incorporated thereto, the tube having a
proximal end and a distal end; and a tip included at the distal
end.
[0054] A yet further aspect of the invention is a catheter locator
apparatus comprising: a multi stranded wire insertable into a
catheter, the wire having a proximal end and a distal end; a
radiating coil connected to the distal end of two of the strands in
said wire; at least two receiving coils; a monitor; a processor, in
electronic communication with the wire, the receiving coils and the
monitor, which: the processor receives at least one reference
signal from at least two of the receiving coils after the receiving
coil is positioned with reference to at least one predetermined
bony landmark on the subject body; and retrieves reference data;
and drives the monitor in order to graphically represent the
reference data; and receives at least one indicator signal from the
at least two receiving coils that receive a signal from the
radiating coil after the radiating coil is inserted into the
subject body; as well as generates indicator data; and drives the
monitor in order to graphically represent the indicator data.
[0055] Another method of facilitating proper placement of a
catheter into a subject body, the method comprises the steps
of:
[0056] (a) receiving at least one reference signal indicative of a
location of at least one receiving coil positioned with reference
to a predetermined landmark on the subject body;
[0057] (b) receiving at least one indicator signal from a radiating
coil inserted into the subject body;
[0058] (c) retrieving reference data associated with the
predetermined landmark;
[0059] (d) displaying a reference image derived from the reference
data;
[0060] (e) generating data represented by an indicator signal
indicative of the relative position of the at least two receiving
coil positions on or over the subject body;
[0061] (f) displaying graphics represented by the indicator data;
and
[0062] (g) repeating steps (e) and (f) after a change in the
indicator signal is received.
[0063] A further method of operating a catheter locator apparatus,
comprises the steps of:
[0064] (a) placing a predetermined area of a detector device over a
predetermined landmark on a subject body;
[0065] (b) inserting a catheter, stylet, guide wire or coil
locating device, embedded with a radiating coil, into the subject
body;
[0066] (c) viewing a graphical representation of a predetermined
part or portion or a representation of a reference image on a
monitor;
[0067] (d) viewing a graphical representation of the radiating coil
on a monitor; and
[0068] (e) manipulating the catheter in the subject body with aid
of the display of the relative positions of the graphical
representations.
[0069] A yet further aspect of the invention comprises a wire
bundle for use with a catheter locator apparatus that includes: (a)
a processor in electronic communication with a predetermined
portion of a proximal end of the wire bundle; (b) a radiating coil
connected to a predetermined portion of a distal end of the wire
bundle, the radiating coil having various locations in a subject
body; (c) a detector device in electronic communication with the
processor, the detector device adapted to be positioned in relation
to a predetermined portion of the subject body; (d) reference data
retrieved by the processor which specifies at least one reference
image which represents at least one predetermined image; (e)
indicator data generated by the processor which specifies at least
one indicator image which provides information related to at least
one location of the radiating coil in the subject body; and (f) a
monitor in electronic communication with the processor which
displays the indicator image and the reference image, said wire
bundle comprising:
[0070] a first wire having a predetermined stiffness adapted to
control positioning of a flexible tube;
[0071] a second wire adapted to transmit signals between the
radiating coil and the processor; and
[0072] means for binding the second wire to the first wire.
[0073] Specific embodiments of the invention will now be described
in some further detail with reference to and as illustrated in the
accompanying figures. These embodiments are illustrative, and are
not meant to be restrictive of the scope of the invention.
[0074] Suggestions and descriptions of other embodiments may be
included within the description of the invention but may not be
illustrated in the accompanying figures or alternatively features
of the invention may be shown in the figures but not described in
the specification.
BRIEF DESCRIPTION OF THE FIGURES
[0075] FIG. 1 depicts a catheter having a coil and exit aperture
located near its caudal/distal end;
[0076] FIG. 2 depicts a stylet having a coil located near its
caudal/distal end;
[0077] FIG. 3 depicts a detector apparatus positioned appropriately
on a patient and an outline of a display that delineates regions of
the body;
[0078] FIG. 4 depicts a display of the location and depth of a coil
on the tip of a catheter or stylet superimposed over a
representation of a patient;
[0079] FIG. 5 depicts a typical display only of the coil position
located in the stomach of a patient over time even while it is not
being moved into a desired location;
[0080] FIG. 6 depicts the recorded path and the current location of
a catheter in a patient as would be displayed;
[0081] FIG. 7 depicts the venous system of the upper torso;
[0082] FIG. 8 depicts an outline of a coil location device located
in a preferred manner over the caudal/mid sagital aspect of the
jugular sternal notch of a patient;
[0083] FIG. 9 depicts a pictorial representation of a correctly
placed Central Venous Catheter (CVC) in the superior vena cava of a
patient; and
[0084] FIG. 10 depicts a pictorial representation of the upper
torso of a patient showing the path of a CVC and its tip in the
region of the superior vena cava.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0085] FIG. 1 depicts a single lumen catheter having located near
its caudal/distal end, a coil, which is used to emit a signal that
can be detected by an apparatus not unlike that described in U.S.
Pat. No. 5,099,845. That patent is in the name of Micronix Pty Ltd
and is hereby incorporated into this specification by reference.
The incorporation of the above-mentioned patent does not and should
not be construed as an admission of the content of the
specification having entered the common general knowledge of those
skilled in the art.
[0086] The apparatus of the invention described in the
above-mentioned patent provides a means to determine both the depth
and position of a coil located on the end of a catheter as well as
its orientation. The type of catheter is of no great importance to
the principle and method of the invention.
[0087] The depth and position determining apparatus, also referred
to herein as the detector apparatus, is generally of the type
disclosed in the above-mentioned specification and can be used in
the method described herein but is not the only such device that
will provide the required features.
[0088] The catheter 10 depicted in FIG. 1 is suitable for use in
parenteral nutrition in particular as it has a suitable tip shape
12 designed so that the exit aperture 14 is less likely to become
blocked. The catheter shown has a single lumen (single passageway
from proximal to caudal/distal end) but other catheters may have
multiple lumens.
[0089] A coil 16 is located near the tip 12 and the two ends of the
pair of wires, which will run the length of the catheter. The pair
of wires terminates at connector 18 near the proximal end of the
catheter. The entry aperture 20 to the catheter is located at the
extreme proximal end of the catheter. It is into this aperture that
nutrients are pumped at the desired times and rates once the
caudal/distal end of the catheter has been appropriately located
within the patient.
[0090] It is intended that the connectors for catheters used for
different uses will each be different sizes, connection types and
colors so as to make their use as safe as possible. By making the
interconnection of catheters for different applications difficult
if not impossible, it is intended to minimize accidental
administration of the incorrect or inappropriate fluids
particularly drugs to the patent via catheters not intended for
such use.
[0091] When the catheter 10 is being intubated into the
gastrointestinal tract of the patient, a metal stylet is used
within the catheter.
[0092] The stylet can comprise the pair of wires described
previously or can comprise the typical stylet wire or wires having
a pair of wires incorporated therein. The stylet may be
encapsulated in material know to be suitable for its intended use.
The stylet itself is typically made of stainless steel but it could
also be made of plastic or other suitable material as shown in FIG.
2.
[0093] In one embodiment, the processor is connected to a proximal
end of a wire bundle, and the coil is connected to the distal end
of the wire bundle. The wire bundle includes a guide wire suitably
bound to a signal-carrying wire/s. The bundle is preferably bound
together at its ends and along its length and may also be
encapsulated in material know to be suitable for its intended use.
The bundle may for example be wrapped together or wrapped with a
suitable material, it may be maintained by a suitable adhesive or
fastener or suitable size and shape. See FIG. 2
[0094] Intubation can be via the mouth or preferably via a nasal
passageway of the patient. The stylet stiffens the otherwise
formless catheter and is able to be manipulated along its length as
well as at its proximal end, so that its caudal/distal end
navigates an appropriate route through the patient under the
control of the health professional or trained staff performing the
intubation.
[0095] In this specification, mention is made of clinicians
performing intubations but it is possible for trained health
professionals to insert catheters into patients for a variety of
uses. It is also possible to use a suitably stiff catheter having a
coil incorporated into the wall of the catheter typically at or
near the caudal/distal end of the catheter that has a single lumen
used to deliver the appropriate fluids.
[0096] The inventors have identified that there are economic and
practical reasons why the arrangement of a coil integrated into a
catheter is usable. However, it is less desirable than an
alternative arrangement to be described herein which uses the
stylet to carry the radiating coil.
[0097] The above is so, because the catheter/coil combination is
expensive to manufacture to the high standards required of medical
equipment. Catheter manufacturers provide a specialist product and
it is not always in their interest to incorporate changes that will
markedly increase the cost of their product.
[0098] Furthermore, a catheter/coil combination is a single use
item, thus the added value of the coil is not recoverable and
therefore needs to compete with current detection techniques which
involve X-rays, even though they are more time consuming.
[0099] Thus it has been identified that it is possible to
incorporate a coil into the caudal/distal end of a stylet.
[0100] The stylet is used not only to manipulate the caudal/distal
end of the catheter to a desired location but it can be retracted
and is also capable of being reused after appropriate
decontamination and cleaning according to a required protocol. The
inventors do not recommend such reuse unless a relevant protocol is
in place.
[0101] The depth and position of the coil can be determined during
the process of intubation. Furthermore, when used to locate the tip
of a catheter and following appropriate positioning of the
caudal/distal end of the catheter the route of the catheter can be
determined while the stylet is retracted from the catheter. An
example of the trace displayed after a retraction of the stylet is
provided by FIG. 6 the details of which will be described later in
the specification. A stylet with a coil incorporated thereon can
also be used to determine the location in the patient of particular
locations along the length of the catheter. Thus for multiple lumen
catheters that have a plurality of ports along its length the
location in the patient of each of those ports can be
determined.
[0102] The manufacture of a coil on the end of a stylet is not
trivial but it can be automated and will involve only a few
different materials, not the many different material and processes
involved in the manufacture of a catheter/coil combination as
described above.
[0103] As described previously a particularly advantageous feature
of a coil being incorporated into a stylet is that while the stylet
and coil is being retracted from the catheter, it is possible for
the location apparatus to record the route through the patient
taken by the catheter. The route can be recorded, including its X-Y
location and its depth with respect to the detection apparatus.
Most conveniently, the route of the catheter can be displayed in a
manner, which directly relates it to the anatomy of a patient.
Appropriate positioning of the detection apparatus on the patient
in the manner described later in this specification provides an
ability to reference the position of the trace on the monitor with
the position of internal parts of a patient.
[0104] Consequently, the procedure of re-checking the position of
the caudal/distal end of the catheter and retracing the route of
the catheter at future times can be easily conducted and the
results compared with earlier records of the catheter tip
position.
[0105] Furthermore, the route displayed will have characteristics
that are likely to reassure a clinician that a desired route of the
catheter has in fact been taken.
[0106] Over time, displays including depth information will
correlate with other clinical observations as to the correctness of
the placement and therefore increase the confidence of the
clinician that the route and final placements are as they should
be.
[0107] The route displayed will, within expected anatomical
variation, confirm that the caudal/distal end of the catheter or
other portions of the catheter are located in the desired area of
the patient. For example, when locating enteral feeding catheters,
the region desired is that which is in the vicinity of the jejunum,
as is pictorially represented in FIG. 6.
[0108] It is also possible for these techniques to be used during
the intubation process and thus provide immediate feedback as to
the route being taken by the catheter.
[0109] The techniques described herein, which assist the placement
of a catheter, are particularly applicable when tube enterostomies
are necessary to provide long-term nutritional feeding or when
obstruction makes nasal intubation impossible. A conventional
gastrostomy or jejunostomy requires a surgical procedure and that
is obviously preferably avoided.
[0110] Percutaneous endoscopic placement of gastric feeding tubes
can be performed at the bedside or in the endoscopy suite without
general anesthesia. Jejunal extensions may also be noted through a
percutaneous placed gastric port into patients who require
post-pyloric intestinal feeding. Needle catheter or Witzel
jejunostomy placed at the time of the laparotomy allows early
postoperative feeding because the small bowel is less affected than
is the stomach and colon by postoperative ileus. Jejunal feedings
minimize the risk of vomiting and aspiration compared with gastric
feedings.
[0111] However, the techniques described herein are not a
substitute for controlled administration and careful monitoring to
check for residual gastric fluids. Clinical observation of the
patient must be continued. The technique however, does lessen or
eliminate the costly and time consuming use of X-ray facilities and
expertise or other even more expensive and time consuming catheter
location procedures.
[0112] FIG. 2 depicts a stylet 22 which has a coil 24 at its
caudal/distal end and the proximal ends of the wires which form the
coil are located in a connector base 26 and a manipulation block 28
is provided at the extreme proximal end of the stylet. The shape of
the stylet is typically long and straight but shown in FIG. 2
conforms with the shape of the catheter 10 shown in FIG. 1, for
illustrative purposes only. The clinician is capable of twisting
the stylet, so that its caudal/distal end when placed inside and to
the internal end of the catheter, turns the caudal/distal end of
the catheter to navigate various passages and apertures within the
patient body. This twisting of the stylet is not recommended but
recognises a clinical practice noted in the literature.
[0113] FIG. 3 depicts an anterior view of the skeleton 28 of a
patient and marked in overlay are three circles representative of
the preferred location of the three detector coils of the detector
apparatus over the patient's body.
[0114] The external shape of the detector apparatus is of little
consequence to the way in which the actual detector works but it is
considered advantageous by the inventors that the external shape
helps the clinician to appropriately locate the detector device on
or over a predetermined location of the patient. For example a
triangular shape places the upper apex of the apparatus towards the
head of the patient and the longitudinal axis of the apparatus can
be made to lie coincident with the mid-sagittal line of the patient
32.
[0115] Circle 30 can be the most important of the three detector
coil portions as in this embodiment for the placement of the
catheter in the alimentary canal (being that portion of the
digestive system of the body, including without limitation, the
mucus membrane-lined tube extending from the mouth to the anus
including the pharynx, esophagus, stomach and the intestines) or in
particular in the intestinal tract, it is positioned directly over
the xiphoid sternal junction. This will also place the longitudinal
axis of the three detector coils coincident with the median
antero-posterior plane 32 of the body (mid-sagittal line). The
longitudinal axis of the three detector coils is engraved on to the
case of the detector housing for the convenience of the clinician
to facilitate ease of positioning particularly since the xiphoid
sternal junction is typically easily palpitated.
[0116] The xiphoid sternal junction is the point at which the
diaphragm is connected to the human skeleton. The two arched lines
(34 and 36) shown on the figure, are representative of the upper
limits of the quite complex domes of the musculo-membranous
partition (diaphragm) separating the abdominal and thoracic
cavities and which serves as a major thoracic muscle.
[0117] It is of assistance to the clinician that these two arched
lines, 34 and 36, are displayed on the monitor along with the
mid-sagittal line 32 as is depicted in FIGS. 5 and 6, while the
catheter is being located.
[0118] The display of the arched lines, 34 and 36 is a tangible
consequence of the correct positioning of the detector coils in the
manner described. The correlation of the position of the coil in
circle 30 with the xiphoid sternal junction allows the monitor to
depict the position and depth of the coil with reference to a
position of the body that can be found on all patients. It is not
imperative that the coil be coincident with that particular bony
landmark since the detector apparatus can accommodate any
predetermined offset created by having the outer housing of the
apparatus located in a particular way that places the coil 30 other
than on or over the xiphoid sternal junction.
[0119] The device is relatively effective even if the specific coil
30 is not placed precisely in the manner described. It is more
important that the two or more signal detector elements are located
on or over a part of the human body with reference to a
predetermined part or position of the human body. Thus when the
position of the coil on the end of the guide wire or catheter is
displayed it can be displayed with reference to the approximate
position of a known body part or portion so as to assist the
clinician during the placement process.
[0120] Clearly, the two arched lines 34 and 36 are only
representations of the quite complex shape of the diaphragm. Since
there is coincidence of at least a portion of the representations
with the attachment point of the diaphragm at the xiphoid sternal
junction, the lines will be sufficiently accurately depicted on the
monitor to assist the clinician. With reference to the measurements
taken by the sensor, the representation is an acceptable guide so
as to provide confidence to the clinician that at least the
caudal/distal end of the catheter is either below or above the
diaphragm. Similar representations of parts or portions of the
human body could be represented on a monitor referenced to the
predetermined positioning of the detector coils.
[0121] As in most cases of intestinal intubation, once the
caudal/distal end of the catheter/stylet is displayed as passing
below the two arches that represent the shape of the diaphragm, the
clinician can be sure that the catheter is in the gastrointestinal
tract rather than in the airways and/or lung of the patient.
Indeed, if the caudal/distal end of the catheter were to be
mistakenly routed into the lung, the path of the catheter's
caudal/distal end would be shown on the monitor to deviate from
that expected.
[0122] The first noticeable deviation from the expected route would
occur some 10-cm above the two arches. That is, above the xiphoid
sternal junction, at the level of the bifurcation of the trachea.
This would also be measured as being deeper in the body from that
which is expected of the correct route. Since the route shown in
FIG. 4 is as expected for an intestinal intubation, it is on track
to enter the stomach shown, in general, as region 38. The catheter
will then move medially and cross the mid-sagittal line again at 40
entering the first part of the duodenum region 42 through the
pylorus orifice. Once through the duodenum region 42, the catheter
passes into the jejunum region 44 that is the portion of the small
intestine, which extends from the duodenum to the ileum.
[0123] It is also possible for the detection method and apparatus
to be used to locate particular portions of the catheter. For
example, a dual cavity catheter that is used for enteral feeding at
its distal end and decompression of gasses in the stomach along it
length should ideally have the caudal/distal end located in the
jejunum and the decompression cavity extend no further that the
pylorus orifice. If the decompression cavity of the catheter begins
a known distance from the distal end of the catheter then a stylet
having a coil on its end can be drawn back from the distal end of
the catheter that known distance. The position of the radiating
coil can then be detected and compared with expected position
measurements that will indicate whether the catheter is correctly
positioned in the patient.
[0124] In another example, it will be advantageous to determine
whether aspiration or pressure measurement ports located along the
length of a catheter are located at the desired position within the
body of the patient. This is the case not only at the time of
intubation but also during the time the catheter is being used.
[0125] The advantage of having a reference point or points on the
monitor, which correlates with an actual point, region or structure
of the patient, is dearly apparent. This feature is useful during
intestinal intubation but it is just as useful when locating a
Venous Access Catheter (VAC) which is a generic expression for the
better known Central Venous Catheters (CVCs) some of which and
their placement will be described in detail later in this
specification.
[0126] The monitoring of the passage of the catheter through the
body and rechecking of correct location during treatment is enabled
by means of the catheter locating apparatus described herein.
Advantageously, there is less erratic movement of the caudal/distal
end of a VAC/CVC as it is placed into location in the upper
thoracic region because it is not directly in contact with internal
organs of the body that move. Movement caused by the breathing of
the patient also affects the display of the position of the
catheter tip, much less in this application.
[0127] A monitor display that provides lines or a symbol
(representative of let us say, the diaphragm) assists the clinician
and increases their confidence that the correct path and final
position of the caudal/distal end of the catheter has been
achieved. However, the positioning of the detector coils in
relation to a predetermined reference point is important so that
the lines or symbol displayed are correctly positioned relative to
the trace and properly reflect the position of the catheter in the
body of the patient.
[0128] In the case of inserting CVCs with any of the catheter types
or methods previously described, it is preferable to position the
detector apparatus over a well-defined, preferably bony landmark.
In this example, a predetermined one of the three detector coils of
the detector apparatus is located over such a landmark. In the
particular case of locating the caudal/distal end of a Central
Venous Catheter into the superior vena cava of a patient, it is
preferable to locate coil 30, as depicted in FIG. 8, on the
caudal/mid sagittal aspect of the jugular sternal notch that lies
along the mid sagittal line.
[0129] A possible detector apparatus shape 31 is also shown in FIG.
8. The shape of the apparatus is of triangular form in plan view
and is preferable for its use on the chest of a patient as
described previously. This shape is convenient for the clinician to
use because its apex 33 can be located on the caudal/mid sagital
aspect of the jugular sternal notch and its longitudinal axis made
coincident with the midsagittal line 32 of the patient.
[0130] As an aid to the preferable positioning of the detector
apparatus, the external casing of the apparatus is preferably
marked near its lower corners "LEFT" and "RIGHT" respectively (not
shown) ensuring a preferred orientation of this particular shape of
apparatus in relation to the patient. Additionally, it is useful to
have a line marked or engraved on the apparatus that runs along its
longitudinal axis for assisting the visual alignment of that line
with the mid sagital line of the patient. However, it would be
possible to have a differently shaped detector housing to suit
other locations of use on the human body, whether that is for
general use or adapted for patient specific reasons.
[0131] The caudal/mid sagital aspect of the jugular sternal notch
appears to be an ideal point on the body for positioning of the
detector apparatus by clinicians as it is common to all humans and
readily located visually or palpitated regardless of the physical
presentation of the patient. However, the use of the jugular
sternal notch as a bony anatomy landmark is not the only bony point
or region of the body that could be used for this purpose. There
may be other points of the body to which the measuring equipment
can be reliably co-located or located with a predetermined offset.
Such an arrangement allows the monitor to be used to display a
reference point or object, preferably shaped the same as a part of
the body that will be useful to the clinician. Such as when
intubating a catheter or guide wire or checking the location of a
previously located catheter into which a stylet is located and
retracted from.
[0132] The paths of the catheter/guide wire for enteral or CVC
applications are shown in FIGS. 4, 6 as well as 9 and 10
respectively. These paths are ideally represented paths. They are
not what is necessarily seen by the clinician while using the
locator apparatus during the process of intubation of a catheter
for enteral feeding or CVC positioning.
[0133] In practice the current position and depth of the signal
emitting coil is displayed in a manner more like that shown in FIG.
5.
[0134] The coil at the caudal/distal end of the enteral feeding
catheter when used in certain body regions of a living patient will
be subjected to continual movement due to the involuntary movement
of the internal organs of the patient. This can be due to the
simple act of breathing (movement of the diaphragm). It can also be
due to peristalsis (movement by the tubular organs such as the
stomach, duodenum and jejunum in which both longitudinal and
circular muscle fibres of those organs propel their contents).
Furthermore there are other unavoidable movements that occur during
the intubation procedure, although the extent of movement is much
less for intubation into organs of the upper thoracic cavity
[0135] Clearly, to provide the most useful form of display there
needs to be a balance between the delay between drawing successive
arrows (which represent the current position, depth and orientation
of the coil) and the need to display the movement of the coil to
the clinician. Too long an interval may allow the coil to traverse
an unacceptable distance along an incorrect path before it is
recorded on the screen and displayed to the clinician. Too short an
interval merely fills the screen with arrows that appear to jump
about due to the movement factors described above. Either of these
cases may confuse or mislead the clinician rather than being of
assistance.
[0136] The ideal delay is ultimately a matter of clinical
preference and the apparatus can be adjusted by the clinician to
deliver/provide a desired display characteristics. Such a delay may
be different when CVC catheters are being inserted or being
inserted into other regions of the body.
[0137] The quantity of successively displayed location indicia is
also a matter for clinical preference and in the example shown in
FIG. 5 there are 14 successive positions shown at any one time. The
tail of the display disappears as the route of the coil progresses
through the internal organs of a patient so as to keep to a minimum
the number of indicia on the screen at any one time. The monitor
would otherwise become cluttered with symbols, which would make it
difficult to discern the relevant movement and location of the
current position of the caudal/distal end of the catheter/guide
wire. Use of different colours to represent the newest versus the
last and intermediate indicators is also contemplated to be
advantageous to the clinician.
[0138] With regard to an enteral feeding catheter, once the
caudal/distal end of the catheter is located in the area of the
jejunum, a location most suitable for enteral tube feeding, the
guide wire can be retracted. At this point the location and depth
detection equipment can be used in a recording mode.
[0139] If the guide wire is retracted over a period of say three
seconds, the monitor will be used to trace the path (X-Y and depth)
of the coil as it passes back through the route of the then
properly located catheter. The detector apparatus is arranged to
record the radial distance of the radiating coil from the two or
more detector coils at predetermined intervals suitable for
providing enough measurements to calculate a line of best fit.
Clearly the more measurements the better the line of best fit will
be. There are however, many techniques for transforming such
measurements into a visual indicator of the route of the coil as it
is retracted from the catheter. Those skilled in the electronic and
computing arts would readily be able to provide such
functionality.
[0140] The change in the signal detected can be used to determine
the path being taken by the radiating coil and there exist many
other ways in which the activity of the coil can be detected and
processed to be displayed. A further way would be to display the
coil position each time there is a predetermined change. The actual
change required would be controllable by the user to suit the type
of use the radiating coil was being put to at the time.
[0141] A processor having computer functions would be one of many
ways of performing the comparisons of various signals received by
the detector device, that as is disclosed in the referred to US
patent by the applicants, comprises three coils set in a particular
spatial relationship.
[0142] The processor would produce indicator data based on the
signals received and processed by the processor. The processor can
then also produce indicator data representative of the position of
the radiating coil in the form most useful to the user of the
apparatus. One such form is an indicator image. The figures display
an arrow symbol that is an indication to the user of the position
and direction of the coil being detected. This particular indicator
image is useful but there will be many as useful alternatives.
[0143] The processor will also be capable of producing reference
data that specifies a predetermined reference image. The reference
image could be that of any line, curve or object. Preferably, the
reference image is that of an appropriate part or portion of a
body. That part or portion is not the actual part or portion of the
patient being intubated but rather a created pictorial
representation of such. In particular it could be of a non-subject
body (that is not the patient). As stated previously, it is
intended that different types of catheter locating apparatus be
made to be incompatible it may be possible to use a common detector
device. However, in the case of there being different devices it
may not be necessary for them to provide any indication to the
processor of their type. Since the two would be made for each other
it may be possible for a data storage device containing one or more
predetermined reference images to be available. Thus the data
storage device can be used to provide an appropriate image of say a
sternum for the type of detector device and its location being
used. The data storage device can also provide storage for symbols
and other images useful in displaying information on a display
relating to the position of a radiating coil (indicator data) used
with a catheter and a reference image (an appropriately located
symbol of a point or part of a body).
[0144] The display shown in FIG. 6 is a typical result, which shows
a trace in a particular patient. Other patients may display a
slightly different path and depth. The depth measurements shown is
a relative measure and not an absolute, but used in the appropriate
way it can greatly assist trained and experienced personnel
intubating a catheter into a patient.
[0145] Thus the relative depths of the tip of the catheter are
taken greatest note of since the ratio of change from person to
person will very likely be small.
[0146] In an example of an enteral feeding catheter intubation the
display shown in FIG. 6 shows that when the catheter passes below
the xiphoid sternal junction 30 it is very deep (say 17 cms below
the location of the detector device). While the catheter passes
through the stomach, its tip lies closer and less deep (say 14 cms)
and when passing under the mid sagital line 32 it is very shallow
and closest to the surface of the patient (say 8 cms). In the first
part of the duodenum it is relatively shallow (say 10 cms) and
finally becomes very deep (say 17 cms) when in the
duodenum/jejunum.
[0147] After long term clinical use, an acceptable and reliable
range of depths and ratios at the points or regions described above
(or others) will be developed and most useful for assisting
clinical assessment of the correctness of the route taken by the
catheter.
[0148] Again, it can be seen that although not proof of the exact
location of the caudal/distal end of the stylet mounted coil and
hence the tip of the catheter, the displayed characteristics
provide yet another aid to improving clinical decision making in
respect of the location of a catheter.
[0149] A stylet is capable of being reused in a catheter (after
decontamination and cleaning). Thus, it can be cheaper to use in a
clinical environment and encourages more frequent checking of the
catheter location than would otherwise be the case because the
expense and time consuming nature of X-ray or other detection
methods. Stylet reuse, although common in the clinical environment,
is not recommended by the authors of this document, until there is
regulatory approval under a code of practice governing re-use of
such devices.
[0150] It should not of course be forgotten that other clinical
monitoring techniques should continue to be used thereby increasing
the confidence of the clinician that the catheter is appropriately
located, whether that be for enteral/parenteral nutrition or other
purposes.
[0151] Patients are often intubated with VAC/CVCs using image
guidance by means of X-rays, fluoroscopy and ultrasonography.
Percutaneous central venous access is achieved when the tip of a
catheter is located in the caval atrial region. Tunneled catheters
travel through a subcutaneous tract prior to exiting the body via
an incision in the skin. Such catheters are used for medicament
delivery and dialysis. Image-guided techniques, although expensive,
are less fraught with early complications than blind or external
landmark intubation techniques.
[0152] VAC/CVCs are now used for long-term intravenous antibiotic
support as well as parenteral nutritional support and blood
sampling.
[0153] A selection from the many types of VAC/CVC in the
marketplace can include single or multi-lumen short-term "central
lines", tunneled catheters, such as Hickman.TM. or Groshong.TM.,
and implanted catheters, such as Port-A-Cath.TM. or InfusaPort.TM..
In addition, Peripherally Inserted Central Catheters (PICCs) are
also available.
[0154] The invention described herein can assist in the correct
placement of most catheters and most advantageously can be used to
check and confirm their correct placement at any time following
initial placement.
[0155] FIG. 7 depicts an anterior view of the venous system of the
upper torso showing the right subdavian vein 46 and the left
subclavian vein 48 which meet medially with corresponding right and
left brachiocephalic veins 50 and 52 respectively.
[0156] The junction of the brachiocephalic veins occurs at the
upper region of the superior vena cava 54, which descends towards
the cavoatrial junction 56 prior to entering the right atrium 60 of
the heart 62.
[0157] FIG. 9 depicts, as would be seen on a screen visible to the
clinician, a constructed trace 64 of the path of a Peripherally
Inserted Central Catheter (PICC) which has its tip ideally located
in the central region of the superior vena cava 54. FIG. 9 also
depicts an outline of a sternum 66 thus providing a region of
reference for the clinician between what is shown on screen and a
known landmark of the patient's body. Clearly, the outline is a
pictorial representation of a generic sternum and not the sternum
of the patient. This representation is, in any event, useful to the
clinician for the task at hand.
[0158] During placement of the PICC, because of the relative
stability of the organs above the diaphragm of the patient, the
feed in trace provided on a monitor will be similar to the pull
back trace described in respect of enteral feeding catheters. It
will be clear that the tip of the catheter has entered the superior
vena cava from not only the two dimensional route displayed on the
monitor, but also confirmed by its depth as it wends its way
through the various branches of the venous system in the upper
torso of the patient while being feed over the previously inserted
guide wire.
[0159] Most obvious to the clinician from the monitor will be the
sharp change in direction and relevant depth of the catheter as it
transitions from the subdavian vein into the brachiocephalic vein
(68 of FIG. 9).
[0160] As described previously, an independently identified measure
of the most preferred location of the tip of the catheter occurs
when, in an adult, there is about 9 cm of linear distance between
the catheter tip and the appropriately located measuring
instrument. This is with reference to when a detector apparatus has
been placed on the caudal/mid sagital aspect of the jugular sternal
notch along the midsagittal line of the patient.
[0161] Such an explicit measurement is used herein as an example
only, of the practical methodology associated with the use of the
device but it may well not be totally accurate for all
circumstances. Such measurements though, are likely as described
previously, to become clinically acceptable as an indicator of the
appropriate location of the tip of the catheter as the number of
patients measured increases and verification by other methods occur
and further data is gathered and analyzed in the future.
[0162] The display is particularly useful to the clinician as the
progress of the tip of the catheter is continuous and always
displayed with reference to, in this embodiment, the position of
the patient's sternum as is indicated by the shape 66 on the
monitor display.
[0163] FIG. 10 depicts some of the venous system of the upper
thoracic cavity and in particular the placement of a PICC 70
terminating in the superior vena cava.
[0164] It should be apparent from the foregoing that the part or
portion of the body displayed is not used to explicitly locate the
signal radiating coil with reference to it but is used more as a
guide.
[0165] The clinician will learn from their observations over time
that the position of the inserted coil as determined by the signal
detectors indicates a radial distance of X cms relative to a
predetermined location on the signal detector apparatus and not the
displayed symbol. The processor will be capable of providing the
coordinates, in say X and Y in the horizontal plane (assuming a
supine patient) of the location of the coil both as an image on the
screen but also in figures.
[0166] When the signal detector apparatus itself is consistently
located with reference to a predetermined body part or portion
thereof, each measurement displayed will be referenced to the
displayed reference image. However, this is not meant to be an
absolute and what the clinician experiences and assesses as the
actual position in say a particular organ or channel in the body is
a matter of acquired expertise.
[0167] Thus the display is used on two levels. One is to provide
accurate radial distance X or (X,Y) from a predetermined point on
the detector apparatus. The other is to reference that position
measurement to a known body part or portion thereof (that might be
a different one to that displayed).
[0168] The body part or portion displayed is only pictorial. It is
only used as an indicator of a region.
[0169] The arched lines (depicted in FIGS. 3, 4 and 5) represent as
discussed previously the complex shape on a vertical cross-section
of the diaphragm of a typical human. Since the electronics used in
the detector apparatus and the display expect that the upper coil
of the detector coils has been placed on a particular bony
landmark, the display can show the position the junction of the two
curved lines and reference the measurements of the position of the
catheter coil accordingly.
[0170] It is thus possible, even recognizing that the display is
only an indicator, to provide prompts additional to the obvious
visual ones. These prompts may inform the clinician that the
signal-radiating coil is above or below the arched line indicative
of the diaphragm of the patient. These prompts could be in the form
of audible signals.
[0171] Say for example, audible tones may increase in frequency as
the depicted coil position gets closer from above the arched lines
assuming that the head end of the patient is correctly determined
by correct placement of the detector device. Furthermore, as the
coil position displayed moves below and a way from the displayed
arched lines an audible tone may pluses less quickly the further it
moves away.
[0172] The audible signals could be of a type that is preferable to
the user of the apparatus.
[0173] It is also possible for the measured position to be used to
indicate the possibility of an incorrect placement. This requires
the equivalent of an expert system information database to be
programmed into the display device. Ideally, for a predetermined
location of the signal detector apparatus on the body, there are
defined regions in the body consisting of certain radial distances
from the signal detector, that if measured during an intubation
would indicate that the signal radiating coil is in or approaching
an undesirable region or part of the body.
[0174] Thus not only does the clinician form over time a feel for
the expected position measurements but the expert system can be
used as a backup to warn the clinician of the progression of the
radiating coil and thus the catheter into an inappropriate region
of the patient. This further indication can be by way of visual
indicators on the monitor screen or by additional audible signals.
Recognizing that there are variations in the anatomy of the human
body from patient to patient, it is important to note that the
method described provides guidance and is no substitute for
clinical experience.
[0175] As clinical experience accumulates with the placement of
catheters in other parts of the body, it will be possible to
overlay on a monitor other reference images such as representations
of static points, regions, or structures of the anatomy that may
assist the clinician. Additional visual and audible information can
also provide guidance to the skilled clinician or registered nurse
authorised to locate catheters into patients.
[0176] It will be appreciated by those skilled in the art, that the
invention is not restricted in its use to the particular
application described. Neither is the present invention restricted
in its preferred embodiment with regard to the particular elements
and/or features described or depicted herein. It will be
appreciated that various modifications can be made without
departing from the principles of the invention. Therefore, the
invention should be understood to include all such modifications
within its scope.
* * * * *