U.S. patent application number 13/961661 was filed with the patent office on 2013-12-05 for infiltration cannula.
The applicant listed for this patent is Jeffrey A. Klein. Invention is credited to Jeffrey A. Klein.
Application Number | 20130324968 13/961661 |
Document ID | / |
Family ID | 39944317 |
Filed Date | 2013-12-05 |
United States Patent
Application |
20130324968 |
Kind Code |
A1 |
Klein; Jeffrey A. |
December 5, 2013 |
INFILTRATION CANNULA
Abstract
An infiltration cannula and method of using the infiltration
cannula during a tumescent infiltration procedure are disclosed
herein. The infiltration cannula may have an outwardly flaring hub
which may be wedged into an adit of a patient to minimize leakage
of fluid being infiltrated into the patient. Also, the infiltration
cannula may be utilized to hydrate a dehydrated patient by a
medically untrained person. The infiltration cannula may also be
used to deliver an antibiotic/vasoconstrictive drug solution to
minimize surgical site infections.
Inventors: |
Klein; Jeffrey A.; (San Juan
Capistrano, CA) |
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Applicant: |
Name |
City |
State |
Country |
Type |
Klein; Jeffrey A. |
San Juan Capistrano |
CA |
US |
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Family ID: |
39944317 |
Appl. No.: |
13/961661 |
Filed: |
August 7, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13330961 |
Dec 20, 2011 |
8529541 |
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13961661 |
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11800355 |
May 4, 2007 |
8105310 |
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13330961 |
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10877566 |
Jun 25, 2004 |
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11800355 |
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10442370 |
May 21, 2003 |
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10877566 |
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Current U.S.
Class: |
604/511 ;
604/272; 604/506; 604/513 |
Current CPC
Class: |
A61M 25/007 20130101;
A61M 5/3291 20130101; A61M 5/158 20130101; A61M 25/0097 20130101;
A61M 37/00 20130101 |
Class at
Publication: |
604/511 ;
604/272; 604/506; 604/513 |
International
Class: |
A61M 5/158 20060101
A61M005/158 |
Claims
1. An infiltration cannula insertable into an adit of a patient for
infiltrating fluid into the patient, the infiltration cannula
comprising: a tubular needle defining a proximal end, the needle
comprising a plurality of apertures disposed in a pattern between
about 33% to about 100% of the distal end portion, the apertures
configured to infiltrate fluid into subcutaneous tissue or muscle
of a patient; and a hub configured to be held by a person
infiltrating the fluid into the patient, the hub having a first end
and an opposing second end, the hub flaring outwardly from the
first end to the opposing second end, the first end being attached
to the proximal end of the tubular needle, the second end
comprising a connector configured to connect to an input source for
receiving the fluid to be infiltrated into the subcutaneous tissue
of the patient, the fluid flowing from the connector, through the
hub, into the cannula, through the plurality of apertures and into
the patient; wherein the outward flared portion of the hub is
wedgeable into the adit to minimize leakage of the fluid flowing
out of the proximal apertures and out of the adit.
2. The infiltration cannula of claim 1 wherein the hub from the
first end to the opposing second end has a conical shape.
3. The infiltration cannula of claim 1, wherein the distal end of
the cannula is closed.
4. The infiltration cannula of claim 1, wherein the distal end of
the cannula is open with a hole allowing a tip of a rigid stylet to
protrude through.
5. The infiltration cannula of claim 1, wherein the apertures are
round or oval.
6. The infiltration cannula of claim 1 wherein the tubular needle
is flexible or rigid.
7. The infiltration cannula of claim 1 further comprising a solid
stylet for guiding the tubular needle into subcutaneous tissue or
muscle of the patient.
8. A method of infiltrating fluid into subcutaneous tissue or
muscle of a patient, the method comprising: a) providing a first
cannula having a tubular needle with apertures disposed about a
distal 33% to 100% end of the needle; b) inserting the tubular
needle into an adit of the patient; c) inserting all of the
apertures disposed on the needle into the patient; d) wedging an
outwardly flaring hub into the adit for forming a seal between the
hub and an inner periphery of the adit to minimize leakage of fluid
to be flowed through apertures of the first cannula; e) flowing
fluid through the hub, apertures and into the subcutaneous tissue
of the patient; f) blocking fluid flow out of the adit between the
needle and the skin of the patient due to flow of fluid through
proximal apertures disposed on the needle.
9. The method of claim 8 further comprising repeating steps of
a)-f) with a second cannula by inserting the second cannula into
the patient adjacent to the first cannula.
10. The method of claim 9 further comprising the step of removing
the first cannula after performing steps a)-f) with the second
cannula.
11. The method of claim 9 wherein the steps a)-f) are performed
with the second cannula after performing step e) with the first
cannula for about one and a half minute.
12. The method of claim 8 further comprising the steps of stopping
fluid flow through the hub and apertures of the first cannula;
removing the first cannula; inserting the first cannula into a
second site; and repeating steps a)-f) while the first cannula is
disposed at the second site.
13. A method of minimizing infections at a surgical site, the
method comprising the steps of: providing a solution containing an
antibiotic and a vasoconstrictive drug; inserting a tubular needle
having apertures into an adit of the patient such that the tubular
needle is adjacent the surgical site to infiltrate the solution at
the surgical site; flowing the antibiotic/vasoconstrictive drug
solution through the tubular needle and out of the apertures to
constrict the blood vessels and delay systemic absorption of the
antibiotic for prolonging a length of time that the antibiotic
remains at the surgical site; and performing surgery at the
surgical site.
14. The method of claim 13 further comprising the step of mixing
lidocaine into the antibiotic/vasoconstrictive drug solution for
providing an antibacterial effect.
15. The method of claim 13 wherein the performing surgery step
occurs after the flowing step.
16. A method of hydrating a dehydrated patient, the method
comprising the steps of: providing a hydrating solution in a
container; inserting a flexible tubular needle connected to the
container of hydrating solution into the patient; flowing the
hydrating solution through the flexible tubular needle, out of
apertures disposed on the flexible tubular needle and into the
patient for hydrating the dehydrated patient.
17. The method of claim 16 wherein the inserting step is performed
by a person untrained in establishing intravenous access.
18. The method of claim 16 wherein the inserting step is performed
by inserting the flexible tubular needle into the subcutaneous
tissue of a thigh of a person.
19. An infiltration cannula insertable into an adit of a patient
for infiltrating fluid into the patient, the infiltration cannula
comprising: a flexible tubular needle defining a hollow center, the
needle comprising a plurality of needle apertures disposed in a
pattern between about 33% to about 100% of the distal end portion,
the needle apertures configured to infiltrate fluid into
subcutaneous tissue or muscle of a patient; and a rigid stylet
having a plurality of stylet apertures disposed in a pattern
between about 33% to about 100% of the distal end portion, the
stylet apertures configured to infiltrate fluid into subcutaneous
tissue or muscle of a patient, the stylet being sized and
configured to be removeably insertable within the hollow center of
the tubular needle.
20. The infiltration cannula of claim 19 wherein the pattern of the
needle apertures is identical to the pattern of the stylet
apertures.
21. The infiltration cannula of claim 19 wherein the pattern of the
needle apertures is dissimilar to the pattern of the stylet
apertures.
22. The infiltration cannula of claim 19 wherein the stylet is
sized and configured to the hollow center of the tubular needle
such that the stylet is rotateable within the tubular needle to
align or misalign the patterns of needle apertures and stylet
apertures.
23. The infiltration cannula of claim 19 wherein the stylet has a
blunt tip or a sharp tip.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation-in-part
application of pending U.S. Ser. No. 10/877,566, filed Jun. 21,
2004, which is a continuation-in-part application of Applicant's
prior U.S. Ser. No. 10/442,370 filed May 21, 2003 entitled
INFILTRATION CANNULA, and is related to pending U.S. patent
application Ser. No. 10/877,337, filed Jun. 25, 2004, the
disclosures of which are expressly incorporated herein by
reference.
STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT
[0002] Not Applicable
BACKGROUND OF THE INVENTION
[0003] The present invention relates in general to an infiltration
cannula permitting the infiltration of very large volumes of
tumescent fluid in a safe and painless manner.
[0004] Definitions:
[0005] infiltration: an injection that causes a fluid to permeate
or percolate through pores or interstices. Thus an infiltration
refers to an injection directly into tissue.
[0006] infusion: an injection that pours a fluid into a place or
into (the lumen of a blood) vessel. Thus an infusion refers to an
intravascular injection.
[0007] injection: The action of forcing a fluid, etc. into tissue
or cavity, as by means of a syringe, or by some impulsive
force.
[0008] Tumescent Technique, Tumescent Infiltration: The tumescent
technique is a method of subcutaneous drug delivery of large
volumes of very dilute medication together with dilute epinephrine
in isotonic solution of crystalloid (e.g. physiologic saline,
lactated Ringer's solution, Hartman's solution, etc) infiltrated
directly into subcutaneous fat or muscle or along the exterior
length of a vein to produce swelling and firmness, or tumescence,
of the targeted tissues, and thus produce very slow systemic
absorption as a result of intense subcutaneous vasoconstriction, as
well as direct hydrostatic compression of capillaries and
veins.
[0009] Tumescent Drug Delivery, Tumescent Delivery: Tumescent drug
delivery and synonyms refer to the tumescent technique for
delivering a drug into the subcutaneous space. In other words,
tumescent delivery is a process of infiltration of very large
volumes of very dilute solutions of therapeutic substances
dissolved in a crystalloid solution into subcutaneous tissue to the
point of producing tumescence of the targeted tissue. Drugs other
than lidocaine can be administered by means of tumescent delivery,
that is, by subcutaneous infiltration of extremely dilute drug,
with or without a vasoconstrictor such as epinephrine.
[0010] Tumescent Local Anesthesia (TLA) is local anesthesia
produced by direct infiltration into subcutaneous tissue of large
volumes of very dilute lidocaine (e.g., less than or equal to 1
gram/liter) and epinephrine (e.g., less than or equal to 1
milligram/liter) with sodium bicarbonate (e.g., 10
milliequivalents/liter) in a crystaloid solution such as
physiologic saline (NaCl) or lactated Ringer's solution. Although
higher concentrations can be used and still qualify as TLA, it is
generally safer to use the least (lowest) effective
concentration.
[0011] Tumescent Local Anesthetic Solution (TLA Solution) is the
local anesthetic solution used to produce TLA. Typically, a TLA
Solution consists of a 10 to 20 fold dilution of commercially
available concentration of lidocaine and epinephrine. Thus, a
commercial solution of lidocaine and epinephrine contains 10 grams
of lidocaine per liter (10 gm/L) and 10 milligrams of epinephrine
per liter. In contrast TLA Solution typically contains very dilute
lidocaine (<1 gram/liter) and epinephrine (.ltoreq.1
milligram/liter) with sodium bicarbonate (10
milliequivalents/liter) in a crystalloid solution such as
physiologic saline or lactated Ringer's solution. Typically the
volume of infiltrated TLA Solution is so large that the skin and
subcutaneous tissue becomes tumescent, in other words swollen and
firm.
[0012] tumescent, tumescence: swollen and firm
[0013] tumescent liposuction: liposuction performed totally by
local anesthesia using tumescent local anesthesia.
[0014] tumescent fluid, tumescent solution: dilute solutions of
therapeutic substances dissolved in a crystalloid solution intended
for tumescent delivery into subcutaneous tissue.
[0015] tumescent "drug": the "drug" in the context as an ingredient
in a tumescent solution and its pharmacokinetic behavior as a
result of the pharmacokinetics of a tumescent solution; for example
tumescent lidocaine, tumescent epinephrine, tumescent
antibiotic.
[0016] Tumescent Pharmacokinetics: The absorption pharmacokinetics
(the pharmacologic and physiologic factors associated with the
systemic absorption of a drug) after tumescent infiltration of a
drug is dramatically slower than the rate of systemic absorption of
routine injection of the drug. The intense vasoconstriction induced
by epinephrine, slows the rate of drug absorption into the central
circulation and prolongs the local effects of the drug. For
example, the duration of routine local anesthesia with lidocaine is
typically 2 hours, in contrast the duration of local anesthesia
with tumescent local anesthesia may be 12 to 18 hours or more. A
similar prolonged effect of tumescent antibiotic infiltration
significantly improves the prophylactic effect of preoperative
antibiotic therapy in the prevention of surgical site
infections.
[0017] adit: a small round hole in the skin (typically 1 mm, 1.5 mm
or 2 mm diameter) made by a skin-biopsy punch, and intended to be
an access port for percutaneous entry into the subcutaneous fat by
a tumescent infiltration cannula and/or a liposuction cannula.
[0018] Many medical procedures require infiltration of fluids, such
as a local anesthetic. For example, liposuction may be performed
entirely by tumescent local anesthesia which was invented by
Jeffrey A. Klein. Dr. Klein first published the description of
tumescent local anesthesia to perform liposuction in 1987 (Klein J
A. The tumescent technique for liposuction surgery. J Am Acad
Cosmetic Surg 4:263-267, 1987). The tumescent technique was
invented in order to eliminate the dangers of liposuction surgery
under general anesthesia and the associated excessive bleeding.
With proper technique, tumescent infiltration permits liposuction
totally by local anesthesia with virtually no surgical blood
loss.
[0019] One method of infiltration of local anesthetic is via a
blunt tipped infiltration cannula. Infiltrators are known as
sprinkler-tip or Klein.TM. (the present applicant) needle
infiltrators. These cannulas are constructed out of a rigid
stainless steel and have one or more apertures, which are typically
round or oval, and are distributed about the distal end of the
cannula. The apertures are distributed over about 15% to 25% or
less than 5.0 cm. of the distal end of the cannula needle. These
traditional infiltration cannulas are intended to be inserted
through a small incision in the patient's skin and then moved in
and out through the subcutaneous tissue while a dilute solution of
local anesthetic (or other pharmaceutical solution) is ejected
through the distal apertures. Since the cannula needle is moved in
and out, only the distal end (e.g., about 15% to 25%) of the
cannula needle may have apertures. Otherwise, fluid may squirt out
of the apertures and onto medical professionals when the cannula
needle is moved out too much. Such infiltrators typically have a
blunt tip and require the placement of a small hole (made by a one
mm skin-biopsy punch or a small surgical blade) through which the
blunt tipped cannula can be passed. Unfortunately, the piston-like
in and out motion of the cannula causes the patient discomfort.
[0020] Another type of infiltration cannula is the sharp tipped
tumescent infiltration cannula which is available as 1) a single
long sharp needle similar to a spinal needle and 2) a group of
short sharp hypodermic needles each connected by separate plastic
tube to a manifold that distributes TLA solution. The first type of
needle is inserted into subcutaneous fat and infiltration proceeds
while the needle is continuously moved in and out along paths that
radiate from the skin puncture site. A targeted area is eventually
anesthetized after multiple skin punctures. The second type, the
group of short sharp needles, consists of a group of individual
hypodermic needles each attached to an individual IV extension
tube, which are in turn connected to a multi port manifold which
connected to a reservoir (IV bag) of tumescent fluid. These
sharp-tipped tumescent infiltration devices have been associated
with puncture-injury to deeper tissues such as the lungs causing
pneumothorax or intra-abdominal viscera causing peritonitis.
[0021] In summary, there are two causes of pain associated with the
blunt and sharp tipped infiltration cannulas. One significant cause
of pain is a continuous in and out motion of the cannula as it
moves through non-anesthetized tissue. In order to deliver
tumescent anesthetic solution throughout an entire compartment of
subcutaneous fat, the anesthetist must move the cannula with a
continuous to and fro reciprocating motion, and repeatedly change
directions. Each advance of the cannula through fat causes
discomfort and pain. The second cause of pain is associated with an
excessively rapid distention of tissue resulting from a high rate
of fluid injection into a relatively small volume of tissue via
limited number of holes on the distal tip of the infiltration
cannula. Ironically, the pain associated with each of these two
factors often necessitates the use of narcotic analgesia, IV
sedation, or general anesthesia in order to infiltrate local
anesthesia. The present invention eliminates or greatly reduces
these two sources of pain.
[0022] Another method of fluid insertion is via a peripherally
inserted central catheter, also called a PICC line comprising an
elongate plastic tube that is placed inside a vein of the patient.
PICC lines are typically used for procedures requiring delivery of
fluids over a prolonged period of time. For example, a PICC line
may be used when a patient needs to receive intravenous (IV)
fluids, such as medication or nutrients over a prolonged period of
time, such as a week or more.
[0023] The On-Q.RTM. Pain Management System marketed by I-Flow.RTM.
Corporation employs a flexible plastic or silicone catheter system
for continuously providing local anesthetic. This system provides
prolonged local anesthesia by means of an elastomeric (elastic
container) device that continuously infiltrates a solution of local
anesthesia over many hours. The On-Q.RTM. device comprises a long
soft flexible tube with many small holes arranged along a
significant portion of the tube. The On-Q.RTM. device is designed
to be initially positioned within a surgical wound at the time of
surgery. After the surgical wound is closed, the On-Q.RTM. device
permits slow steady infiltration of a local anesthetic solution
into the wound, thereby attenuating post-operative pain. The
On-Q.RTM. device cannot be inserted through a tiny hole in the skin
into subcutaneous tissue. Therefore the On-Q device cannot achieve
infiltration of local anesthesia and prevent post-operative pain in
a preemptive fashion. It has been shown that preemptive local
anesthesia in the form of peripheral nerve blocks, can prevent
nocioception by the central nervous system (CNS) during general
anesthesia, and thereby prevent chronic post-operative pain
syndromes similar to "phantom-limb syndrome." Thus there is a need
for a simple device that can permit the direct percutaneous
insertion of a multi-holed infiltration cannula into subcutaneous
tissue for the localized delivery of medications such as local
anesthetics, chemotherapeutic agents, or crystalloids for
parenteral hydration.
[0024] Traditional techniques for subcutaneous injection of local
anesthetic solutions (e.g. peripheral nerve blocks) use a
high-concentration/low-volume of local anesthetic. This is
associated with a rapid systemic absorption of the local
anesthetic. In order to achieve a prolonged local anesthetic
effect, the traditional techniques for using local anesthetics
necessitate either frequent repeated injections or slow continuous
subcutaneous infusion of the local anesthetic. As described above,
repeated injections or piston-like movement of the cannula causes
patient discomfort. Slow continuous infiltration may not be
desirable in certain situations. Furthermore, continuous
infiltrations restrict patient movement for extended periods of
time which also cause the patient discomfort. Thus, there is a need
for a system for infiltration of a local anesthetic into intact
subcutaneous tissue (not necessarily into peri-incisional tissue)
which decreases patient discomfort pre-emptively, and allows
prolonged local anesthesia either by rapid (less than 10 to 15
minutes) bolus injections, extended infiltration (e.g. over
intervals ranging from 15 minutes to several hours) or continuous
slow infiltration over many hours to days. Furthermore there is a
need for a devise that can provide pre-emptive local anesthesia
before a surgical wound is created. There is also a need for a
percutaneously-insertable infiltration cannula, with applications
that are unrelated to the delivery of local anesthesia, which can
be easily inserted by rescuers with minimal clinical skill or
training. One example is the need for a cannula that permits
emergency fluid resuscitation in situations where an IV cannot be
established such as nighttime military combat conditions where
using a flash light to establish an IV access would be extremely
dangerous. Another example is the need to provide emergency fluid
resuscitation to large numbers of patients in acute epidemic
diarrhea (dehydration) associated with biological warfare, or
mass-trauma situations such as a natural disaster (earth quake) or
terrorist attack. There is also a need for a device that can easily
provide localized fluid resuscitation to burn victims whereby fluid
is infiltrated into the subcutaneous tissue directly subjacent to
burned skin.
[0025] Other types of devices for delivering fluid to a patient
exist in the prior art. For example, U.S. Pat. Pub. No.
2003/0009132 (Schwartz et al.) is directed to a micro-intravascular
(never extra-vascular) catheter for infusing milliliter quantities
of drugs for the lysis of intravascular blood clots (i.e., a micro
target). Another embodiment of the Schwartz device is intended to
improve the precision and safety of intra-myocardial delivery of
micro-liter volumes of fluid for biologic gene therapy based
angiogenesis.
[0026] Unfortunately, the Schwartz device requires a sterile high
tech hospital environment and demands fluoroscopy and ultrasound
guidance. The Schwartz device requires a highly trained,
experienced and skilled medical professional to operate. In
particular, the Schwartz infiltration catheter is defined by its
obligatory guidewire and intravascular target. The intravascular
insertion of the catheter via the guidewire is a complex procedure
that requires significant clinical training, experience and skill
Specifically, it involves 1) preparation with a sterile surgical
field, 2) making a skin incision and inserting an introducing
catheter having coaxial stylet into the targeted vessel, 3)
removing the stylet, 4) inserting the guidewire through the
introducing catheter and into the vessel, 5) withdrawing the
introducing catheter from the vessel without disturbing the
intravascular location of the guidewire, 6) slipping the distal tip
of the infiltration catheter over the proximal end of the
guidewire, and advancing the infiltration catheter over the
considerable length of the guidewire through the skin and into the
intraluminal space of the targeted vessel, 7) withdrawing the
guidewire and attaching the proximal end of the infiltration
catheter to a source of the therapeutic fluid to be delivered into
the targeted vessel. This insertion procedure is so specialized
that a majority of physicians do not have the requisite expertise
to qualify for hospital privileges for inserting an intravascular
catheter using a guidewire. Locating a clotted blood vessel and
inserting the Schwartz catheter into the vessel requires the
ultrasound guidance.
[0027] As understood, an important feature of the Schwartz device
is the shape, size, direction and pattern of the holes on the
infiltration cannula. As stated in paragraph 15 of the Schwartz
disclosure, "there is a need for an injection device that gives
control over the concentration, pattern, and location of the
deposition of an injectate." The Schwartz device is intended to
improve directional control over the direction of injection of
minute volumes of injectate.
[0028] The Schwartz device appears to be specifically designed to
avoid vascular compression. For the small needle embodiment of
Schwartz, vascular compression resulting from injecting excessive
volume of drug into myocardium may precipitate infarction or
arrhythmia Likewise, for the long cannula embodiment of Schwartz
vascular compression appears to be contraindicated. The goal of
infusing fluid into a vessel containing a blood clot is to open the
vessel, and not compress it.
[0029] The Schwartz device also appears to be incapable of large
volume (e.g., multi liter) subcutaneous infiltration. The long
plastic Schwartz catheter appear to be specifically intended for
intravascular use. Moreover, Schwartz cannula cannot have holes
distributed along 100% of its entire length based on a contention
that such situation will lead to a contradictory situation. If the
Schwartz device does have holes along its entire length then either
the entire length of the cannula would have to be positioned inside
a vessel (unlikely without attaching the cannula proximally to
another catheter in which case the bulky attachment mechanism would
have to be passed through the wall of the vessel) or else some of
the holes would have an extravascular location(unlikely because the
therapeutic fluid would either leak onto the patient's skin or
extravasate into the perivascular and subcutaneous tissues). In
either case, the potential for serious adverse effects would be
significant.
[0030] Moreover, the Schwartz device does not appear to be capable
of being reciprocated in and out of the subcutaneous tissue of the
patient to locally anesthetize an entire compartment.
[0031] In summary, the Schwartz infiltrator is intended for 1)
intravascular insertion which demands a complex guidewire procedure
involving several steps, 2) intravascular drug delivery (for lysis
of blood clots) or intra myocardial injections, 3) injection of a
miniscule volume (micro liters) of drug.
[0032] Another type of device for delivering fluid to a patient is
described in U.S. Pat. No. 6,524,300, issued to Meglin. Similar to
the Schwartz device, the Meglin device appears to be an
intravascular device intended to inject a "medical agent into the
target lumen of the body." (see Col. 2, lns. 41-48). Meglin is
specifically intended to be inserted intralumenally into "a lumen
of a blood vessel or another cavity within a patient's body." (see
Col. 1, lns. 14-19). This is precisely opposite the goal of a
tumescent infiltration cannula. A tumescent infiltration cannula is
intended to deliver drugs to the subcutaneous space which excludes
the vascular space and cavitary space. As such, the Meglin device
appears to be specifically designed to avoid vascular compression
and to not induce vasoconstriction. An important aspect of the
Meglin device appears to be the size and density of the apertures
to control the rate of flow of fluidic medication. Moreover, it
appears that the medical professional utilizing the Meglin device
requires a great deal of training, expertise and education based on
a contention that the infusion segment of the device is located
intravascularly by locating a radiopaque marker band with a
fluoroscopy.
[0033] Another type of device for delivering fluid to a patient is
described in U.S. Pat. No. 6,375,648, issued to Edelman, et al..
Similar to prior art blunt or sharp tipped infiltration cannulas,
the apertures are restricted to the distal 25% of the cannula. The
reason is that otherwise, the fluidic medication would squirt out
of the apertures and contaminate the operating room. Col. 2, lns.
22-25 states that "once within the tissue of a patient a treatment
solution may be infused into the tissue by working the cannula 20
through the fat tissue of the patient." As understood, the Edelman
device suffers from the same deficiencies discussed above in
relation to the blunt or sharp tipped infiltration cannulas. The
Edelman cannula is reciprocated in and out of the subcutaneous
tissue, and thus, causes pain or discomfort to the patient.
Moreover, the only novel aspect of Edelman appears to be the
cannula's Teflon coating.
[0034] Surgical site infections are a significant source of
post-operative morbidity and mortality. They account for 17% of all
hospital acquired infections, require prolonged hospital stays and
contribute substantially to health care costs. The incidence of
surgical site infection is a function of the type of surgical
procedure, the surgeon, and the hospital. The risk of SSI is
significantly associated with a number of factors including
anesthetic risk scores, wound class and duration of surgery.
[0035] The true incidence of SSI is probably higher than what has
been reported in the literature. The primary surgical team is often
not aware of incisional infections diagnosed after hospital
discharge. Patients who had SSI diagnosed after discharge require
substantially more outpatient visits, emergency visits, radiology
services and home healthcare services. A study published in 2004
found such infections cost $6,200 per patient for home care
expenses associated with wound care. The major sources of infection
are microorganisms on the patient's skin. A number of preoperative
skin care techniques have been used to limit concentrations of
bacteria at the surgical site, including antiseptic preparations,
adhesive barrier drapes, topical antibiotics, hair removal and hand
hygiene.
[0036] Antimicrobial prophylaxis with intravenous (IV) antibiotics
is currently the most important clinical modality for preventing
SSI. The consensus recommendation for antimicrobial prophylaxis is
for antimicrobial agents to be given as an IV infusion of
antibiotics to be given within the first 60 minutes before surgical
incision and that prophylactic antimicrobial agents be discontinued
within 24 hours of the end of surgery.
[0037] Recent Center for Disease Control (CDC) guidelines for
antimicrobial prophylaxis do not mention preoperative perilesional
infiltration of antibiotics
(http://www.cdc.gov/ncidod/dhqp/pdf/guidelines/SSI.pdf). A recent
review of surgical site infections only discussed intravenous (IV)
delivery of prophylactic antibiotics. The possibility of
preoperative peri-incisional infiltration to prevent SSI was not
considered.
[0038] Several studies of SSI in the 1980's compared the
effectiveness of antimicrobial prophylaxis by IV infusion or by
peri-incisional infiltration. A 1981 study of the incidence of
wound infection among 405 abdominal surgery patients found no
significant difference between 1 gm of cephaloridine given
intravenously or intra incisional at the end of the surgery.
Following this trial, IV antibiotics at the induction of anesthesia
became standard practice.
[0039] An IV infusion of fluid is a common medical procedure to
treat patients. Unfortunately, an IV infusion is associated with an
inherent expense, difficulty and risk. There are also unfortunately
times when an IV line cannot be established in the patient. By way
of example and not limitation, the patient may be burned such that
a vein of the patient cannot be located to establish an IV access.
The patient may have been traumatized in such a way that will not
allow a doctor to perform an IV cut down procedure. Additionally,
the patient may be very obese such that the vein of the patient is
difficult to locate. In other situations, occurring in remote
locations where a trained medical professional is not available to
establish the IV such as the international space station or on an
airplane. Currently, there does not appear to be any in flight
capability for treating an acute traumatic injury on a plane or on
the space shuttle. If the pilot or astronaut survives the immediate
effects of an explosion, burn, or decompression injury, or if there
is an acute non-traumatic medical illness, it is assumed that the
victim must return to terra firma for any significant therapeutic
intervention such as providing systemic fluid replacement. Other
situations include a mass casualty situation where there are
insufficient number of trained medical professionals compared to
the number of victims/patients, etc.
[0040] Other methods of delivering a drug to a patient other than
an IV infusion may be oral delivery of the drug. Unfortunately,
oral delivery of the drug results in inconsistent absorption of the
drug into the gastrointestinal tract. The drug may alternatively be
delivered via periodic intramuscular injections. Unfortunately, the
fluidic drug serum may have varying levels of concentration at each
of the periodic injections.
BRIEF SUMMARY OF THE INVENTION
[0041] The present invention addresses the needs discussed above,
identified below and those that are known in the art.
[0042] An infiltration cannula and method of using the infiltration
cannula during an infiltration procedure is discussed herein. The
infiltration cannula preferably includes: a flexible cannula, a
hub, and a rigid stylet. The flexible cannula has a proximal end
and a distal end. The flexible cannula also has a plurality of
apertures disposed in a pattern about the distal end. The apertures
are configured to infiltrate fluid into the subcutaneous tissue of
a patient. The hub is configured to be held by a person performing
the infiltration procedure. The hub has a first end and an opposing
second end. The first end is attached to the proximal end of the
flexible cannula and the second end includes a connector configured
to connect to an input source for receiving the fluid to be
infiltrated into the subcutaneous tissue of the patient. The fluid
flows from the connector, through the hub and into the flexible
cannula.
[0043] The flexile cannula may be manufactured of plastic and the
rigid stylet may be fabricated from stainless metal or rigid
plastic. The distal end of the cannula is closed to cover the tip
of the rigid stylet or open with a hole allowing the tip of the
rigid stylet to protrude through. The tip of the rigid stylet is
either sharp to directly insert through the skin of the patient, or
so blunt that a skin incision is required to permit insertion of
the rigid stylet and the cannula into the subcutaneous space. The
stylet may be formed to have either a solid or hollow
cross-sectional configuration. The hollow rigid stylet may have
small holes distributed along its length in a pattern dissimilar or
identical to the pattern of holes placed along the flexible cannula
into which the stylet is inserted. Thus the stylet itself can be
used as an infiltration cannula.
[0044] The apertures may be arranged in a helical pattern or in a
spiral pattern.
[0045] The apertures may be distributed over about 33% to about
100% of the distal end of the tubular needle.
[0046] The apertures may be round or oval. The size of the
apertures need not necessarily be equal.
[0047] The fluid may comprise a local anesthetic or any other
therapeutic solution.
[0048] The infiltration procedure may be performed in conjunction
with conventional medical procedures such as liposuction, but
additionally may simply be used as a mode of systemic drug
delivery, or systemic fluid replacement therapy.
[0049] A method of infiltrating fluid into subcutaneous tissue of a
patient using an infiltration cannula, such as the one described
above may include the following steps.
[0050] A rigid stylet is inserted through a flexible infiltration
cannula. The infiltration cannula is inserted through a patient's
skin and into the subcutaneous tissue or muscle tissue of the
patient at a desired site with the stylet providing rigidity to the
flexible cannula during the insertion process. After the stylet is
withdrawn from the cannula, a fluid is provided from a fluid source
via the connector. The fluid is transported from the connector
through the hub and into the flexible cannula. The fluid is ejected
from the cannula into the subcutaneous tissue or muscle of the
patient via the apertures.
[0051] The infiltration cannula used in performing the method
preferably includes a connector for receiving the fluid from a
fluid source, a hub in communication with the connector and a
flexible cannula in communication with the hub. The tubular needle
has a plurality of apertures disposed in a pattern about a distal
end. The apertures are configured to infiltrate the fluid into the
subcutaneous tissue or muscle of the patient.
[0052] The above steps may be repeated intermittently, at intervals
between a few minutes to many hours.
[0053] After the desired amount of fluid has been infiltrated at a
given site, the infiltration cannula may be removed or may remain
in place for possible additional infiltration.
[0054] The infiltration cannula may additionally be inserted at a
new site.
[0055] Multiple infiltration cannulas (e.g., two) may be used
simultaneously. Use of multiple infiltration cannulas prevents
disruption of the infiltration process when one infiltration
cannula is removed and relocated. In particular, a second
infiltration cannula may be inserted closely adjacent to a first
infiltration cannula which has partially anesthetized the area in
which the second infiltration cannula is being inserted to reduce
the pain associated with inserting the second infiltration cannula
into non anesthetized tissue. Multiple infiltrators can be
simultaneously inserted into separate areas to facilitate more
rapid delivery of fluids.
[0056] The infiltration cannula discussed herein may provide for
(1) a simple subcutaneous insertion, (2) either regional drug
delivery directly into subcutaneous tissues or systemic drug when
intravascular access is not possible, and (3) infiltration of very
large volumes (e.g., multi liters) of tumescent fluid. The
infiltration cannula discussed herein allows tumescent infiltration
with less pain and greater safety.
[0057] In an aspect of the cannula, the same may be used to prevent
or minimize surgical site infections. For example, a solution of
epinephrine, an antibiotic drug, and optionally, lidocaine may be
administered to a surgical site.
BRIEF DESCRIPTION OF THE DRAWINGS
[0058] These as well as other features of the present invention
will become more apparent upon reference to the drawings
wherein:
[0059] FIG. 1 is a side elevation view of a stainless steel
infiltration cannula with a closed tip shown inserted in
subcutaneous tissue shown in partial cross section;
[0060] FIG. 2 is a section view of the infiltration cannula shown
in FIG. 1;
[0061] FIG. 3 is a side elevation view of a plastic infiltration
cannula with a closed tip shown inserted in subcutaneous tissue
shown in partial cross section;
[0062] FIG. 4 is an exploded view of the infiltration cannula shown
in FIG. 3 with a closed end;
[0063] FIG. 5 is a flow diagram illustrating an exemplary procedure
for using an infiltration cannula such as the one shown in FIG. 1
or the one shown in FIG. 3;
[0064] FIG. 6 is an exploded side elevation view of a plastic
infiltration cannula through which a stylet can be inserted with an
open end; and
[0065] FIG. 7 is a side elevation view of a hollow sharp-tipped
stylet with holes located along nearly the entire length of the
stylet.
DETAILED DESCRIPTION OF THE INVENTION
[0066] As described in further detail below, the present invention
takes advantage of the tumescent technique in order to provide
intermittent or continuous, brief or prolonged multi-liter
infiltration of local anesthetic, physiologic fluid, antibiotics or
other therapeutic solution with a significant decrease in patient
discomfort due to the elimination of the piston-like in and out
motion of the cannula. Once the cannula is positioned in place,
there is no need to repeatedly move the cannula in and out through
the tissue in order to deliver the fluid to a wide area. Using the
tumescent technique and stainless steel versions of the present
invention, the time needed in order to complete the infiltration of
a targeted anatomic area is reduced to nearly half of the time
required when using traditional prior art cannulas. The device and
method of the present invention can use multiple (e.g., two or
more) infiltration cannulas simultaneously. While one cannula is
actively dispersing tumescent fluid into the subcutaneous tissue,
the surgeon can reposition a second infiltration cannula. This
allows the infiltration process to proceed without interruption,
whereas prior art techniques of infiltration must be ceased each
time the cannula is withdrawn from the skin and re-inserted into
another direction.
[0067] The flexible plastic cannula version of the present
invention provides a means for relatively rapid fluid resuscitation
in emergency situations such as when establishing an intravenous
(IV) access is not feasible. A large volume of a tumescent
crystalloid solution to treat intravascular fluid deficit may be
delivered subcutaneously when an intravascular (IV) line cannot be
started for fluid replacement. (e.g., remote area, obese patient,
burn/trauma victim, unavailable trained medical professional,
etc.). As a further refinement, rapid systemic absorption of
physiologic saline can be achieved by adding a vasodilator drug to
saline and using the tumescent technique to deliver the solution
into subcutaneous tissue. For example, in the setting of
overwhelming mass casualties where there is no hope or expectation
of trained clinical personnel being available, the ability of
untrained first-responders to provide immediate fluid resuscitation
could save many lives. When a disaster causes an overwhelming
number of trauma or burn victims, or when a cholera epidemic leaves
victims with life-threatening dysentery and dehydration, it is
unlikely that there will be sufficient trained personnel to start
an IV line for IV fluid resuscitation. In such a setting, anyone
(e.g., adult of average intelligence with minimal clinical
training), perhaps even a victim himself, could simply insert one
or more disposable plastic infiltration cannulas directly through
the skin on the thigh(s) and into subcutaneous tissue and attach an
IV bag and then allow the force of gravity to propel the fluid into
the subcutaneous space in a tumescent fashion. The resulting
systemic absorption and redistribution into the intracellular and
intravascular compartments could be life-saving. This emergency
resuscitation procedure relies on the combination of 1) the
plastic-catheter embodiment and 2) absorption kinetics of tumescent
fluid delivered to subcutaneous tissue.
[0068] The flexible cannula may also have important applications as
in treating a wounded soldier in night-time combat conditions when
establishing an IV access in total darkness is nearly impossible or
using a flash light might attract enemy fire. The flexible cannula
may similarly have important applications in other areas of use
such as treating mass-casualty victims suffering hypovolemia as a
result of epidemic infections, biologic warfare, or trauma such as
explosions, burns or radiation exposure. The flexible cannula
similarly has applications in surgical patients wherein the surgeon
can provide localized pre-operative preemptive analgesia and
simultaneously provide tumescent delivery of a prophylactic dose of
an antibiotic aimed precisely at tissues targeted for surgical
intervention.
[0069] As is well known, the tumescent technique was discovered by
Jeffrey Alan Klein, M.D. (the present applicant) in 1985. Dr. Klein
first published a description of the tumescent technique in 1987
when he described the use of dilute lidocaine and epinephrine to
permit liposuction totally by local anesthesia. The technique for
tumescent local anesthesia is well known in dermatologic and
plastic surgery literature. A detailed description of the tumescent
technique has not been published in anesthesiology literature, and
therefore, the unique benefits of the tumescent technique are not
well recognized by anesthesiologists.
[0070] The tumescent technique comprises a drug delivery system
that takes advantage of a recently discovered reservoir effect of
injecting a relatively large volume of relatively dilute solution
of a drug into the subcutaneous tissue.
[0071] The present invention takes advantage of the tumescent
reservoir phenomenon for one of its important applications. After a
large volume (e.g., multi liter) of fluid containing dilute
epinephrine is injected into subcutaneous tissue, the
epinephrine-induced vasoconstriction dramatically slows the
systemic absorption of the fluid and minimizes surgical blood loss.
In effect, this large volume of subcutaneous fluid behaves in a
fashion that is analogous to the behavior of a slow-release tablet
in the stomach after oral ingestion. Although there is a relatively
large total amount of drug in the patient's body, the drug is
isolated from the systemic circulation by the fact that only the
drug on the outer boundary of the mass of drug is the available for
absorption, whereas the portion of the drug located within the
central portion of the mass of fluid is virtually isolated from the
systemic circulation by virtue of profound capillary
vasoconstriction. In contrast, when the tumescent fluid does not
contain epinephrine there is no clinically significant
vasoconstriction after tumescent infiltration, and the tumescent
fluid is absorbed relatively rapidly. This has important clinical
applications in situations where patients are hypovolemic or
dehydrated and unable to be given fluids by mouth or intravenously.
The tumescent technique permits rapid systemic hydration by direct
subcutaneous or intramuscular injection of a large volume of fluid
through a multi-fenestrated infiltration cannula described in this
invention.
[0072] There is a prior art technique known as hypodermoclysis
wherein a fluid is slowly and continuously infiltrated
subcutaneously using a type of steel hypodermic needle, known as a
butterfly needle, having a single distal aperture in order to
provide fluid to patients who cannot be given fluids by mouth and
for whom an IV access cannot be established. Typically
hypodermoclysis is used in the treatment of infants, or cancer
patients, in which IV access is not easily achieved. The technique
of hypodermoclysis is typically used to deliver relatively small
volumes of fluid, for example an adult might receive 70 ml per
hour. At this small hourly volume hypodermoclysis is not an
efficient method for the rapid systemic delivery of fluid in
emergency situations that might require two to four liters per
hour. The reason is that when using a cannula with only a single
distal aperture, the local interstitial fluid pressure increases
rapidly immediately adjacent to the single aperture as fluid
infiltrates locally, which in turn dramatically slows the rate of
subsequent fluid flow into the area. In contrast, the multiple
apertures formed along the length of the cannula as described in
the present invention, distribute the fluid throughout a much
larger volume tissue before there can be a sufficient increase in
the interstitial fluid to decrease the rate of additional
infiltration. Also, the amount of pain is reduced because the rate
of fluid flow through each of the apertures is less than the rate
of fluid flow through the single aperture at the distal end.
Further more, it is common practice to infiltrate the tumescent
fluid into the subcutaneous space under augmented external pressure
provided by an external peristaltic pump specifically designed for
tumescent infiltration. By way of example and not limitation, a
preferred suitable peristaltic infiltration pump is described in
pending U.S. patent application Ser. No. 10/811,733, filed Mar. 29,
2004, entitled INFILTRATION PUMP HAVING INSULATED ROLLERS AND
PROGRAMMABLE FOOT PEDAL, the disclosure of which is expressly
incorporated herein by reference.
[0073] The peristaltic pump provides a sufficient degree of
pressure to easily overcome the localized increased interstitial
pressure associated with the local effects of a tumescent
infiltration. On the other hand, in situations where a peristaltic
infiltration pump is not available, such as in remote locations
without any available electrical power, the present invention still
permits relatively rapid tumescent infiltration by virtue of the
multiple holes distributed along the length of the flexible
cannula. Furthermore, external hydrostatic pressure can be applied
to the fluid flowing into the flexible cannula from the fluid
reservoir by means of gravitational force derived from elevating
the reservoir one to two or more meters above the patient. When
using gravity to augment the flow of tumescent fluid, the
infiltration process can be continuous or intermittent. In
exemplary embodiments, the intermittent injections are administered
at intervals ranging from every few minutes to eight to twelve
hours or more.
[0074] With the tumescent technique for local anesthesia, a large
volume of dilute solution of local anesthesia and epinephrine is
injected into the subcutaneous space resulting in a large bolus (or
interstitial reservoir) of solution. The profound vasoconstrictive
effect (shrinking of the capillaries) caused by the dilute
epinephrine, produces a dramatic delay in the systemic absorption
of the local anesthetic, which prolongs the anesthetic effects of
tumescent anesthesia for eight to sixteen times longer than
traditional techniques.
[0075] Referring now to the drawings wherein the showings are for
purposes of illustrating preferred embodiments of the present
invention only, and not for purposes of limiting the same, FIGS. 1
and 2 illustrate a stainless steel (reusable) infiltration cannula
10 and FIGS. 3-4 and 6 illustrate a (single use) plastic
infiltration cannula 30. The cannula 10, 30 can be inserted under
the skin 52 and into the subcutaneous tissue 50 and tumescent local
anesthesia can be infiltrated either continuously until the
clinical goal is achieved or intermittently (by way of example and
not limitation, once every eight to twelve hours).
[0076] Stainless steel infiltration cannulas 10, such as the one
shown in FIGS. 1 and 2, are formed having precision high quality
and are preferably reusable. These cannulas can be used to provide
tumescent local anesthesia for surgical procedures, such as
liposuction, which require tumescent local anesthesia over a
relatively large area.
[0077] The cannula 10 includes a tubular needle portion 12 which
has a proximal end 14 and a distal end 16. The proximal end 14 of
the tubular needle 12 is attached to a hub 20 that is used by the
anesthesiologist or surgeon to grasp and hold the cannula 10 during
the infiltration procedure. The hub 20 is connected to the tubular
needle 12 at a first end 22 and has a connector 24, such as a luer
lock, at an opposing second end. The connector 24 is connected to a
fluid source, such as tubing connected to an IV bag. Fluid enters
the cannula 10 via the connector 24.
[0078] In exemplary embodiments, the tip at the distal end 16 is
closed. The local anesthetic is infiltrated into the patient via
apertures 18 located proximate the distal end 16 of the tubular
needle 12 of the cannula 10. It is contemplated that the apertures
18, 38 and 54 discussed herein may have a helical, spiral, linear
or any random or ordered pattern. Also, in exemplary embodiments,
the apertures 18 are disposed along the distal end 16 of the
cannula 10 in a spiral or helical pattern and are distributed over
the distal 33% to 100% of the tubular needle 12 of the cannula 10.
For example, if the length of the tubular needle D is 15 cm and the
apertures 18 at the distal end 16 cover a length d1 of 5 cm, the
pattern of apertures of the cannula 10 are preferably distributed
over 33% of the tubular needle 12 of the cannula 10. The size of
the aperture and density of apertures on the tubular needle is
limited by the structural integrity of the cannula. If the
apertures 18 are too large or too close together then the cannula
may bend or break during use (e.g., routine clinical applications).
Prior art cannulas wherein the apertures are limited to the distal
25% of the cannula eject the fluid into the subcutaneous tissue at
a high rate so as to cause discomfort to the patient. The apertures
18 which are located along a greater length of the cannula compared
to prior art cannula allows fluid to flow out of each of the
apertures at a slower rate but to achieve a greater amount of fluid
flow as an aggregate so as to reduce the amount of discomfort to
the patient due to the rate at which fluid flows out of each of the
apertures. When tumescent fluid is injected into subcutaneous
tissue, tumescent fluid spreads by means of simple bulk-flow
through the interstitial gel substance. This process is extremely
rapid and unimpeded by fibrous tissue.
[0079] The proximal portion 14 of the cannula 10 may be devoid of
apertures in order to prevent fluid from leaking out of the cannula
insertion site in the skin. Alternatively, if the proximal portion
14 of the cannula has aperture(s), then the hub may be used to
prevent fluid from leaking out of the cannula insertion site in the
skin in the follower manner. The hub of the infiltration cannula
serves as a connector. The distal end of the hub attaches to the
cannula, while the proximal end of the hub detachably connects to
the plastic tube set which carries tumescent solution to the
cannula. With a slight modification, the hub can also assist in
reducing or virtually eliminating leakage of tumescent fluid out
through the skin incision or adit site. An adit is a small round
hole in the skin typically produced by a biosy punch. The hub 20
may have a conical configuration. The hub 20 may become narrower
from the proximal end of the hub to the distal end of the hub. The
rate at which the hub 20 becomes narrow may be less than about
fifteen degrees with respect to a centerline of the hub. The outer
surface of the hub 20 may have a plurality of rounded circular
ridges equally spaced apart. The adit may be formed so as to have a
diameter which is less than a diameter of the cannula or the outer
surface of the hub. To minimize leakage of tumescent fluid out onto
the surface of the skin, the cannula may initially be inserted into
the adit. The adit is slightly stretched to accommodate the
cannula. The cannula may be fully inserted into the subcutaneous
tissue of the patient such that the distal end of the hub contacts
the adit. The hub may then be pushed into the adit such that the
inner diameter of the adit expands and slides over the rounded
circular ridges formed on the distal end of the hub. The hub is
gently wedged into the adit until there is a snug fit between the
infiltration cannula and the adit. Leakage of fluid out of the adit
may also be minimized by placing the proximal most aperture on the
cannula sufficiently deep within the subcutaneous tissue such that
fluid injected from the most proximal hole produces localized
interstitial tumescence and a snug fit of the tissue against the
cannula. It is also contemplated that the hub have other shapes
such as curved, linear, parabolic, or combinations thereof.
[0080] Flexible plastic infiltration cannulas 30, such as the one
shown in FIGS. 3, 4 and 6 are single use cannulas and can be used
in one of several unique ways. First, an anesthesiologist, surgeon,
untrained first responder, or even a victim can insert infiltration
cannula 30 with stylet 46 into the subcutaneous tissue 50, remove
the stylet 46, then attach an IV tubing to the infiltrator and
inject tumescent local anesthesia or other tumescent fluid into the
targeted area without subsequent repositioning of the infiltration
cannula 30. The plastic flexible nature of the tubular needle 32 of
the disposable plastic cannula 30 allows the patient to move or
change position of the body without risk of injury that might
result if a patient moves while a rigid steel cannula is
inserted.
[0081] Preferably, the stylet 46 is formed of a rigid material such
as metal, stainless steel, or plastic material. The stylet 46
should be sufficiently rigid so as to guide the tubular needle 32
of the cannula 30 into the subcutaneous tissue 50. The stylet 46
may be solid (see FIG. 4) or hollow (see FIG. 7) through its
center. The plastic cannula 30 can be blunt-tipped with the metal
stylet tip 48 covered by the rounded tip 39 of the plastic cannula
30, as shown in FIG. 4. Alternatively, the plastic cannula 30 can
be open-ended with the stylet 46 extending a short distance past
the end 39 of the plastic cannula 30 as shown in FIG. 6. In the
case of the open ended cannula, the stylet 46 can be either
blunt-tipped (see FIG. 6; requiring a skin incision to permit
insertion into the subcutaneous space), or sharp-tipped (see FIG.
7; permitting the cannula to be inserted directly through the skin
and into the subcutaneous space or muscle without requiring a
preparatory skin incision). The sharp-tipped stylet 46 can be
formed in either a solid (see FIG. 4) or hollow (see FIG. 7)
cross-sectional configuration. The utility of a sharp tipped hollow
stylet is that it can be inserted directly through the skin and
then advanced painlessly through the subcutaneous tissue by slowly
injecting local anesthetic solution through the stylet as it is
slowly advanced, thereby anesthetizing the tissue in advance of the
stylet's tip.
[0082] If the stylet 46 is hollow through its center 58, then
apertures 54 may be formed along an entire length or along a
portion (e.g., about 33% to 100%) of the length of the tubular
needle 56 of the stylet 46, as shown in FIG. 7. The hollow stylet
46 (see FIG. 7) may be utilized in a similar fashion as the cannula
10 shown in FIGS. 1 and 2 and described herein. By way of example
and not limitation, during use, the tubular needle 56 shown in FIG.
7 may be inserted into the cannula 30. The combined tubular needle
56 and cannula 30 may be inserted through the subcutaneous tissue
50 of the patient. The tubular needle 56 may be removed from the
patient and the cannula 30. The tubular needle 56 of the stylet 46
may now be reinserted into the patient at a different site and used
as a rigid cannula similar to the cannula 10 discussed in relation
to FIGS. 1 and 2.
[0083] The stylet 46 shown in FIG. 7 has apertures 54 about the
periperhy of tubular needle 56 of the stylet 46. The apertures 54
may have a pattern which is dissimilar to the pattern of apertures
38 formed in the tubular needle 32 of the cannula 30.
Alternatively, the apertures 54 may have a pattern which is
identical to the pattern of apertures 38 formed in the tubular
needle 32 of the cannula 30. As a further alternative, some of the
apertures 54 may have a pattern which is identical to the pattern
of apertures 38 formed in the tubular needle 32 of the cannula 30.
Also, some of the apertures 54 may have a pattern which is
dissimilar to the pattern of apertures 38 formed in the tubular
needle 32 of the cannula 30. During use, the medical professional
may insert the stylet 46 (see FIG. 7) with apertures 54 into the
cannula 30. The apertures 54 of the stylet 46 may be aligned or
misaligned to the apertures 38 of the tubular needle by turning the
stylet 46 within the cannula 30. The stylet 46 may have a hub with
a similar configuration as hub 40. The hub of the stylet 46 may
also be wedged into the adit of the patient to minimize or
eliminate leakage of fluid, as discussed herein.
[0084] The plastic cannula shown in FIGS. 3 and 4 is similar to an
IV catheter except the sharp hollow stylet used for the insertion
of an IV catheter can be replaced by a solid obturator/stylet 46
that can be either sharp or blunt tipped. Except for the removable
stylet 46, the plastic cannula 30 is similar to the stainless steel
cannula 10 shown in FIGS. 1 and 2 and described above. The plastic
cannula 30 includes a flexible tubular needle 32 having a proximal
end 34 and a distal end 36. The distal end has apertures 38 and the
proximal end 34 may be devoid of apertures. As stated above, in
exemplary embodiments, the pattern of apertures 38 in the cannula
30 are distributed over the distal 33% to 100% (see FIG. 4) of the
tubular needle 32 of the cannula 30. For example, if the tubular
needle 32 of cannula 30 shown in FIGS. 3 and 4 has a length D of 15
cm and the pattern of apertures are distributed over a length d1 of
13.5 cm, then the apertures 38 are distributed over 90% of the
cannula. As a further example, if the tubular needle 32 of cannula
30 shown in FIGS. 3 and 4 has a length D of 15 cm and the pattern
of apertures are distributed over a length d1 of 15 cm, then the
apertures 38 are distributed over 100% of the cannula. To stop
leakage of tumescent fluid out of the adit site, the hub may be
wedged into the adit site, as discussed above.
[0085] A typical infiltration cannula 10, 30 may have a diameter
equivalent to 20, 18, 16 or 14 gauge with small apertures 18, 38
placed every 5 mm along the cannula in a spiral or helical pattern.
The infiltration cannula 10, 30 may be 20-14 cm in length. A
typical infiltration cannula 10, 30 is 15 cm or 20 cm in length. It
will be appreciated that the dimensions used herein are exemplary
and that the cannula dimensions, range of gauge, length range of
cannula, relative size shape and pattern of apertures can vary
greatly depending upon clinical preference.
[0086] The proximal end 34 of the tubular needle 32 shown in FIGS.
3 and 4 is attached to a hub 40 that is used by the
anesthesiologist or surgeon to hold the cannula 30 during the
infiltration procedure. The hub 40 is connected to the tubular
needle 32 at a first end 42 and has a connector 44 at an opposing
second end. The connector 44 is connected to a fluid source. As
described above and shown in FIG. 4, the stylet 46 can be inserted
and removed from the cannula 30.
[0087] Infiltration using a plastic infiltration cannula 30, such
as the one shown in FIGS. 3 and 4, can be accomplished using an
infiltration pump. Alternatively, the force of gravity could be
used to push the tumescent fluid into the tissues by hanging a
reservoir plastic bag of tumescent local anesthesia (or other
dilute drug, such as a chemotherapeutic agent or antibiotics) on an
IV pole and connecting bag to the infiltration cannula by an IV
line.
[0088] Another application is the injection of tumescent local
anesthesia into a localized area through which a surgeon plans to
make a surgical incision. The effects of vasoconstriction,
resulting from the epinephrine in the tumescent local anesthetic
solution, within the tumesced tissue minimizes surgical bleeding.
In a uniquely preemptive fashion, the present invention can
produce, via the pre-operative infiltration of tumescent local
anesthesia, prolonged post operative analgesia and also
preemptively reduce the risk of surgical wound infections resulting
from the bacteriacidal effects of lidocaine.
[0089] Lidocaine is bactericidal in vitro against S. aureus, and
this effect increases with greater duration of exposure. In a
dose-dependent fashion, clinical doses of lidocaine have been shown
to inhibit the growth of bacterial pathogens commonly encountered
in nosocomial wound infections. A tumescent epinephrine induces
profound local vasoconstriction resulting in significantly delayed
systemic absorption of a tumescent antimicrobial drug from
subcutaneous tissue. In commercially available concentrations, the
systemic absorption of an aqueous solution of lidocaine requires
approximately 2 to 4 hours. In contrast, the systemic absorption of
tumescent lidocaine requires 24 hours or more. Accordingly, a
tumescent antibiotic can be expected to remain within the
peri-incisional tissue at least 12 times longer than a routine
aqueous antibiotic solution and the action would be far more
effective. Moreover, a tiny hematoma within an incision may be an
isolated avascular space and a potential nidus for an infection.
The profound and prolonged vasoconstriction induced by tumescent
epinephrine minimizes surgical bleeding and hematoma formation and
therefore reduces the risk of SSI. Hypothermia is a major risk
factor for postoperative SSI. Mild perioperative hypothermia, is
common among patients having surgery under general anesthesia. The
incidence of SSI was 5.8% in the normothermic (core body
temperature 37 degrees C.) group and 18.8% in the hypothermic group
(34.4 degrees C.) in a randomized, double blind trial. (Kurtz A,
Sessler D I, Lenhardt R. Perioperative normothermia to reduce the
incidence of surgical-wound infections and shorten hospitalization.
Study of wound infection and temperature group. N Eng J Med
334:1209-15, 1996). Hypothermia also causes delays in moving the
patient out of the recovery room. With surgery totally by tumescent
local anesthesia there is no evidence of post operative
hypothermia.
[0090] Infiltration of a tumescent solution containing lidocaine,
epinephrine, and an antibiotic is likely to provide significantly
improved SSI prophylaxis. Tumescent infiltration of antibiotics
into peri-incisional skin and subcutaneous tissue offers the
following advantages: prolonged local tissue concentrations of
antibiotics, prolonged systemic delivery of antibiotic to tissues
distant from the incision site, and significantly, the systemic
absorption of tumescent lidocaine mimics IV delivery of lidocaine
which is known to reduce postoperative pain and hasten post
operative discharge from the hospital. The infiltration cannula
discussed herein is the optimal device for tumescent delivery of
antimicrobial drugs.
[0091] Yet another application is to provide an easily accessible
route for systemic administration of crystalloid
fluids/electrolytes for systemic hydration or for other types of
drug therapy. Potential clinical applications include emergency
resuscitation with systemic fluids in situations where insertion of
an IV catheter into a vein cannot be readily achieved. Examples of
situations where emergency access for intravenous delivery of
fluids might not be possible include acute trauma or burn wound in
civilian or military situations and very obese patients in which
finding an accessible vein for IV access can be difficult even for
a physician skilled in performing "IV cut-down" procedures. The
infiltration cannula discussed herein may be a valuable adjunct to
fluid resuscitation in an ambulance or an emergency room. Another
application may be the emergency treatment of dehydration
associated with pandemic influenza, prolonged vomiting or diarrhea
as a result of chemical warfare or biological warfare (e.g.,
epidemic cholera among pediatric patients in rural third world
settings) or other types of medical emergencies which overwhelm a
medical center's capacity to care for incoming victims. A
subcutaneous infiltration catheter can easily be introduced by a
layman, whereas inserting an IV catheter into a vein of a patient
that is severely dehydrated can be difficult even for a skilled
physician. Delivery of systemic fluids by subcutaneous infiltration
is safer than an IV infusion in a zero gravity situation (for
example, the Space Station). The addition of a small amount of
capillary vasodilator (e.g., methylnicotinamide) to the
subcutaneous fluid can be used to accelerate the systemic
absorption of the fluid or drug into the intravascular space.
Further applicational uses for the present invention are described
in co-pending application Ser. No. 10/877,337, filed Jun. 25, 2004,
the disclosure of which is expressly incorporated herein by
reference.
[0092] The continous systemic drug delivery by tumescence has a
similar therapeutic effect to continuous IV infusion but without
the inherent expense, difficulties, and risk of an IV infusion.
Compared to either oral delivery of a drug (inconsistent absorption
from the gastrointestimal tract), or periodic intramuscular (IM)
injections of a drug (variable serum concentrations), continuous
systemic delivery is preferred in order to achieve prolonged and
relatively uniform blood concentrations of the drug. This is
especially true in critically ill patients. Tumescent delivery of a
drug, placed in a tumescent solution containing epinephrine as a
vasoconstrictor, produces a prolonged continuous system absorption
of the drug over an interval of more than 24 hours. The simplicity
and inexpensive equipment required to achieve continuous tumescent
systemic drug delivery is clearly an advantage among medically
impoverished populations, and in the demanding conditions of
battlefield or at the scene of a mass casualty.
[0093] Yet another application is related to astronauts and
systemic delivery of medication. In particular, the therapeutic
options for treating an injured astronaut are limited. The fate of
injured airplane pilots, passengers and astronauts are similar in
that we presently have virtually no in-flight capability for
treating an acute traumatic injury. If a pilot or astronaut
survives the immediate effects of an explosion, burn, or
decompression injury, or if there is an acute non-traumatic medical
illness, it is assumed that the victim must return to terra firma
for any significant therapeutic intervention such as providing
systemic fluid replacement. The tumescent infiltrator is capable of
providing systemic fluid and thus it is successfully solving a
problem that has either never before been recognized, or has never
before been solved by a simple device and technique.
[0094] The present invention allows improved emergency medical care
for an injured astronaut on-board the ISS. Repeated and prolonged
extra vehicular activities (EVA) expose astronauts to greater risk
of physical trauma injury. Potential injury to astronauts include
decompression injury-induced neurological injury and coma, acute
pneumothorax, burns, and radiation injury. Assembly and maintenance
of the ISS requires an unprecedented number of spacewalks, which
expose astronauts to the risk of decompression sickness (DCS). In
addition to humanitarian concerns, there is a strong economic
incentive to provide on-board care for acute illness or trauma: the
only alternative would be to abort an expensive mission and
immediately return the victim to earth.
[0095] At present, there is no safe and easy means of providing the
equivalent of IV fluids to a patient in space. Assuming there is a
fellow astronaut with the requisite clinical skill to insert an
intravenous (IV) catheter in a weightless environment, there is a
problem of zero gravity. Whereas gravity separates air and water
into distinct layers, in zero gravity there is a risk of air
bubbles from the IV bag entering the IV line and causing
intravascular air embolism. Because subcutaneous air is relatively
safe, the tumescent infiltration cannula, by allowing effective
systemic fluid resuscitation via subcutaneous infiltration,
overcomes the above problems, and allows a person without clinical
skills to safely provide the equivalent of IV fluids.
[0096] The cannula 10, 30 is intended to be inserted far enough
through the skin 52 so that all of the apertures 18, 38 are within
the fat 50 or muscle of the patient. If the apertures 18, 38 are
distributed over about 100% of the cannula, the hub may be wedged
into the adit to prevent or minimize leakage of the tumescent fluid
out of the adit. Once the cannula 10, 30 is properly positioned, it
can remain stationary while the local anesthetic (or other
pharmaceutical) solution is injected. Since the cannula remains
stationary, the associated pain or discomfort typically caused by
the reciprocating in and out movement of prior art cannulas is
reduced or eliminated. Accordingly, the cannula of the present
invention permits infiltration of multi liter volumes of tumescent
fluid into the patient in a safe and painless manner.
[0097] After one portion of the targeted area has been tumesced,
the infiltration is briefly terminated (either by turning off the
pump or by clamping the IV tubing) while the cannula 10, 30 is
repositioned into another area of the subcutaneous tissue.
Typically, the cannula is repositioned at the rate of about once
per minute. The infiltration is then restarted with the cannula
stationary in its new position. Since the apertures are distributed
over the distal 33% to 100% of the cannula, the apertures
distribute tumescent fluid into the patient along the entire length
of cannula insertion. The cannula does not have to be reciprocated
in and out to infiltrate the subcutaneous tissue like prior art
cannula. Progressing repeatedly in this fashion, eventually all the
fat within a targeted area becomes tumescent and profoundly
anesthetic. As such, such method can obviate the need for general
anesthesia or heavy IV sedation in most surgical procedures
restricted to the skin and subcutaneous tissue.
[0098] The infiltrator 10, 30 can also be used in the traditional
mode whereby the cannula 10, 30 is moved through the targeted
tissue while the fluid is simultaneously pumped through the cannula
10, 30 and into the subcutaneous tissue 50.
[0099] Another unique aspect of the tumescent technique's reservoir
effect is that one can conveniently achieve a long, slow, steady
absorption of a drug delivered to the subcutaneous space 50 using
periodic injections of a tumescent solution. In certain situations,
using a slow IV infusion, the alternative technique, can achieve a
slow systemic absorption of a drug but may be difficult, require
greater clinical expertise, be more expensive, and therefore, less
practical than the technique described herein.
[0100] FIG. 5 is a flow diagram illustrating steps performed in an
exemplary infiltration procedure using a cannula 10, 30 such as the
one shown in FIGS. 1 and 2 or the one shown in FIGS. 3 and 4,
respectively. The procedure begins by inserting the tubular needle
12, 32 of the infiltration cannula 10, 30 into a desired
subcutaneous tissue site 50, e.g., via an incision in the patient's
skin 52 (block 100). Fluid is then transported from the fluid
source (e.g., an IV bag) into the cannula 10, 30 via the connector
24, 44 that is connected to the fluid source. The fluid is
transported from the connector 24, 44 through the hub 20, 40 and
into the tubular needle 12, 32 (block 102). The fluid is then
ejected from the cannula 10, 30 into the subcutaneous tissue 50 of
the patient via the apertures 18, 38 at the distal end 16, 36 of
the tubular needle 12, 34 of the cannula 10, 30 (block 104).
[0101] The fluid is transported (block 102) and ejected (block 104)
until infiltration at the current site is completed (yes in
decision block 106). Complete infiltration at the current site may
take approximately one or two minutes. The fluid can be injected
into multiple sites in order to distribute the solution over a
greater area.
[0102] Infiltration at a particular site may be deemed complete
upon emptying of the fluid source or based on the anesthesiologist
or surgeon's decision to stop the infiltration at the current site.
After one portion of the targeted area has been tumesced, the
infiltration can be briefly terminated (either by turning off the
pump or by clamping the IV tubing) while the cannula 10, 30 is
repositioned into another area of the subcutaneous tissue. The
infiltration may then be restarted with the cannula stationary in
its new position. If the infiltration at a site is complete (yes in
decision block 106), the cannula is removed from the current site
(block 108). If the infiltration at the current site is not
complete (no in decision block 106), fluid is transported from the
fluid source (block 102) and ejected into the subcutaneous tissue
(block 104) until infiltration at the site is complete (yes in
decision block 106).
[0103] If infiltration is complete at the current site (yes in
decision block 106) but infiltration is not complete (no in
decision block 110), the tubular needle 12, 32 of the infiltration
cannula 10, 30 is inserted into a new area of subcutaneous tissue
50. By way of example and not limitation, the tubular needle 12, 32
may be inserted into a new area adjacent the current site. The
adjacent site may be partially anesthetized by infiltration of the
anesthetic solution at the current site. As such, pain to the
patient caused by insertion of the tubular needle 12, 32 is
minimized, eliminated or greatly reduced. The process described
above is performed until the infiltration process is complete (yes
in decision block 110). This process can be continuous or repeated
intermittently. It is contemplated that infiltration of up to about
50% of the patient's body may be achieved in the manner described
herein.
[0104] As described above, multiple infiltration cannulas (e.g.,
can be used at once). Thus, a second or additional cannulas can be
inserted (block 100) at the same time as a first cannula is being
removed (block 108). For example, the second cannula may be
inserted parallel to the first cannala and into an area immediately
adjacent to the area in which the first cannula is inserted. In
this manner, the pain usually associated with the insertion of the
cannula into the patient's fat tissue is reduced or eliminated
because the first cannula has already at least partially
anesthetized the area in which the second cannula is inserted. The
second cannula is positioned adjacent the first cannula
approximately every one or two minutes. The first cannula may then
be removed from the patient's body after the second cannula is
inserted. Moreover, the infiltration process need not be
interrupted in order to reposition a single cannula. Progressing
repeatedly in this fashion, eventually all the fat within a
targeted area becomes tumescent and profoundly anesthetic. As such,
such method can obviate the need for general anesthesia or heavy IV
sedation.
[0105] The plastic infiltration cannula shown in FIGS. 3 and 4 may
be used by either a lay person or a clinical professional for the
delivery of tumescent fluid for either tumescent local anesthesia,
tumescent antimicrobial therapy, or emergency delivery of systemic
fluids by tumescent infiltration. In an aspect of the cannulas 10,
30, it is contemplated that such cannulas 10, 30 may be utilized
for continuous systemic tumescent delivery of a drug which produces
a continous system absorption of the drug over nearly 24 hours in a
fashion similar to a continuous IV infusion.
[0106] The infiltration cannula 10, 30 discussed herein is a
subcutaneous device and not an intravascular device for
infiltration of multi-liter volumes of fluid into areas of up to
50% of the total body surface area. For example, the infiltration
cannulas 10, 30 infiltrates approximately 1,000 times the volume of
fluid delivered by the Schwartz device discussed in the
background.
[0107] Additional modifications and improvements of the present
invention may also be apparent to those of ordinary skill in the
art. Thus, the particular combination of parts described and
illustrated herein is intended to represent only a certain
embodiment of the present invention, and is not intended to serve
as a limitation of alternative devices within the spirit and scope
of the invention.
* * * * *
References