U.S. patent number 3,889,670 [Application Number 05/429,534] was granted by the patent office on 1975-06-17 for non-invasive hyperbaric ventilator.
Invention is credited to Roy L. Campbell, Steven R. Loveland.
United States Patent |
3,889,670 |
Loveland , et al. |
June 17, 1975 |
Non-invasive hyperbaric ventilator
Abstract
A non-invasive hyperbaric ventilator system for the
bronchopulmonary disorders of patients requiring positive pressure
ventilation includes a Plexiglas chamber into which the patient's
head is inserted. A collar assembly around the patient's neck seals
the chamber and an adjustable pressure gauge for regulating gas
delivery pressures to the chamber and an expiratory resistance
valve cooperate to provide intermittent pressurization and
depressurization of the ventilator. The chamber is provided with a
plurality of studs and ports to accommodate the attachment of
adjunctive devices.
Inventors: |
Loveland; Steven R.
(Winston-Salem, NC), Campbell; Roy L. (Winston-Salem,
NC) |
Family
ID: |
23703665 |
Appl.
No.: |
05/429,534 |
Filed: |
January 2, 1974 |
Current U.S.
Class: |
128/203.12;
128/205.26; 128/205.24 |
Current CPC
Class: |
A61G
10/04 (20130101) |
Current International
Class: |
A61G
10/04 (20060101); A61G 10/00 (20060101); A61m
016/02 () |
Field of
Search: |
;128/204,203,191A,191R,188,1B,28,30,30.2,142,142.3,142.7,145.8,298,299 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gaudet; Richard A.
Assistant Examiner: Recla; Henry J.
Claims
We claim:
1. A non-invasive hyperbaric ventilator comprising a rigid chamber
having a base structure, rear, front, top and side walls, a hinged
hood formed from portions of said front, side and top walls, means
for sealing said hood in the chamber closed position, a collar
assembly having an opening for receiving the neck of a patient,
said collar assembly having one portion in the portion of the front
wall of said hood and a cooperating portion in the other portion of
said front wall, sealing means closing said opening in said collar
assembly and engaging the neck of a patient and said chamber to
seal the patient's head within said chamber to effect an air-tight
chamber, means, including a gas inlet port, for regulating the
therapeutic pressure within the chamber to a predetermined level
and intermittently controlling the supply of gas to said chamber
and facilitating expansion of the patient's lungs during
inspiration, and adjustable expiratory pressure relief means
communicating with said chamber for permitting displacement of a
volume of gas from said chamber when the patient exhales.
2. A non-invasive hyperbaric ventilator as recited in claim 1
wherein said expiratory pressure relief means comprises a normally
closed valve including a weight member displaceable by increased
pressure in said chamber due to the volume of gas that the
patient's lungs displace when the patient exhales thus permitting
depressurization of said chamber to a selected level to control
residual pressure within said chamber.
3. A non-invasive hyperbaric ventilator as recited in claim 1,
wherein said expiratory pressure relief means comprises a container
filled with a preselected amount of water and a conduit extending
from said chamber and having an end portion selectively positioned
below the water level in said container.
4. A non-invasive hyperbaric ventilator as recited in claim 1,
wherein said sealing means comprises a collar assembly secured
within said chamber opening and an inflatable member extending
around the patient's neck and supported within said collar assembly
for safe sealing of the patient's neck.
5. A non-invasive hyperbaric ventilator as recited in claim 4,
wherein said chamber is provided with means releasably securing a
collar assembly thereto, and said chamber opening is sufficiently
large to accommodate collar assemblies of various sizes and neck
sizes without modification to said chamber.
6. A non-invasive hyperbaric ventilator as recited in claim 1, and
further including means for supplying a predetermined amount of
moisture to the gas supplied to said chamber.
7. A non-invasive hyperbaric ventilator as recited in claim 1,
wherein said chamber is formed substantially entirely of
transparent material and includes a base structure, a hood assembly
pivotally secured thereto, and means for sealing and releasably
securing said base structure and said hood assembly together.
8. A non-invasive hyperbaric ventilator as recited in claim 1, said
chamber defining a port in an upper wall thereof for providing
access to the patient and a removable sealable door for normally
closing said port, said chamber further including a plurality of
ports for accommodating the attachment of adjunctive devices to
said chamber.
9. A non-invasive hyperbaric ventilator as recited in claim 1, and
further including means for providing a patient access to ambient
air in the event of unexpected depressurization of said
chamber.
10. A non-invasive hyperbaric ventilator as recited in claim 1, and
further including means for monitoring the pressure, humidity, and
temperature within said chamber.
Description
BACKGROUND, BRIEF SUMMARY AND OBJECTS OF THE INVENTION
The non-invasive hyperbaric ventilator of the present invention is
for the treatment of bronchopulmonary disorders of the adult,
adolescent, child or infant in acute distress requiring positive
pressure ventilation of a specific type known as continuous
positive airway pressure ventilation.
In normal, unassisted ventilation, inspiration is accomplished by
the contraction and descent of the diaphragm musculature, creating
a negative intra-pulmonary pressure. Expiration is accomplished
passively by the relaxation of the diaphragm and the elastic
contraction of lung tissue, thereby forcing the movement of gasses
outside of the body via the generation of positive pressure within
the intra-pulmonary space. Thus, normal breathing is characterized
by a negative phase inspiratory effort and a positive phase
expiratory process. It is important to note that at the end of the
expiratory cycle, the internal pressure within the lung space is
equal to, that is, at equilibrium with, the ambient pressure.
Positive Relative breathing is accomplished with the aid of a
mechanical device which forces a volume of gas into the lung cavity
at a certain pressure and flow rate. Thus, the inspiratory phase of
positive pressure breathing is characterized by the generation of
positive pressures within the lung space. At the end point of
inspiration, the machine shuts off, allowing the lungs to expire
their volume of gasses passively, as in normal breathing, again
generating a positive pressure within the lung space. Thus,
positive pressure breathing, accomplished with mechanical
assistance, is characterized by a positive inspiratory phase and a
positive expiratory phase. Again, as in normal breathing, pressures
within the lungs at the end point of expiration equals that of the
ambient atmospheric pressure. At this point, the machine will again
"trigger," beginning the expiratory cycle.
Continuous positive pressure breathing is also induced with the
utilization of mechanical apparatus. On the inspiratory phase, a
volume of gas is forced into the lungs at a certain rate and
pressure, causing the intra-pulmonary space to become positively
pressurized. At the end of inspiration, the machine switches off,
and allows the expiratory cycle to begin with the passive deflation
of the lungs, generating positive pressure naturally. However,
instead of allowing the patient's lungs to return to the ambient
atmospheric pressure at the end of the expiratory cycle, a residual
positive pressure gradient is introduced and maintained within the
lung space. This is known as positive end expiratory pressure or
peep. Thus, complete deflation of the lungs is prevented at the end
of the expiratory phase. The residual pressurization at the end of
the expiratory cycle is the chief therapeutic difference between
continuous positive airway pressure and simple positive pressure
ventilation. The net positive pressure within the lungs is
mechanically adjustable within certain ranges, depending upon
clinical judgment, but generally falls within the range of 5-15
centimeters of water pressure.
In the inspiratory phase of continuous positive airway pressure
ventilation, the mechanical device generates a positive pressure
gradient, thereby assisting or forcing the inflation of the lungs.
By assisting or controlling the patient's inspiratory efforts, his
breathing cycle is mechanically regulated to varying degrees. This
mechanical regimentation of the respiratory cycle is required for
patients in acute respiratory distress states of various pathologic
etyologies.
On the expiratory phase of continuous positive airway pressure
ventilation, the lungs deflate passively but complete deflation of
the lung cavity is prevented because the ambient pressure external
to the lung cavity is mechanically elevated and maintained. Thus,
the end point of the patient's expiratory cycle is physically
reached when the intra-pulmonary pressure within the lung cavity is
equilibriated with the ambient pressure in a breathing circuit or
chamber external to the lungs. By manipulating this ambient
pressure, the clinician is able to manipulate the residual
intra-pulmonary pressures at the end of the expiratory cycle. This
residual pressurization causes a physical "splinting" effect by
which the small airways of the lungs are physically forced open
preventing a collapse at the end of expiration when the lung would
normally return to atmospheric pressure without mechanical
assistance. This splinting effect, when combined with various
concentrations of oxygen, serves to significantly improve the
respiratory dynamics and blood gas exchange phenomena of the
patient.
Positive pressure ventilation and continuous positive airway
pressure ventilation have been traditionally administered with the
use of various complex mechanical devices. These devices are
connected to the patient's lungs via the establishment of a
mechanical circuit. For a mechanical circuit to be established, a
pliable prosthetic device known as an endotracheal or trachaeostomy
tube is inserted into the patient's trachea. In essence, the tube
serves as an artificial airway to prevent collapse or obstruction
of the trachea.
The mechanical ventilating device forces a volume of air into the
tube during the inspiratory cycle causing the positive pressure
inflation of the lung. The amount of pressure required to inflate
the lung is variable, depending upon the clinical condition and
size of the patient.
At the end of mechanical inspiration, the machine switches off and
the patient expires passively. Expired gasses are routed through
the artificial airway, into the mechanical circuit, and
subsequently vented to the atmosphere.
Patients are placed on mechanical ventilators only in the presence
of grave clinical conditions. Many physical problems are
encountered in the management of mechanical ventilator patients,
and, as such, the initiation of mechanical ventilation is
considered to be a life supportive endeavor. The management of such
patients requires great clinical skill, and the acquisition of
expensive and complex equipment.
By virtue of the hyperbaric ventilator being non-invasive, that is,
not requiring the insertion of prostatsis into the patient's
airways, many therapeutic benefits are derived.
The risk of nosocomiel infection is greatly reduced. The insertion
of a prostatsis forms a direct communication for the passage of
contaminated materials directly into the deep lung cavities. The
hyperbaric ventilator of the present invention does not in any way
destroy or bypass the body's natural physical defenses for the
resistance of disease.
The risk of severe dehydration is greatly reduced. The insertion of
a prostatsis forms a bypass of the body's mucosal tissues, which
serve to humidify and warm inspired gasses. The ventilator of the
present system in no way disrupts the integrity of these physical
systems.
The risk of tracheal stenosis, tracheal malascia, damage to the
vocal cords, and sub-glottal damage is eliminated with the use of
this system. The above pathologies are incurred frequently with the
use of an artificial prostatsis.
Because the system pressures are so low within the ventilator, the
decompensation of cardiac output seen in mechanical ventilators may
be reduced or eliminated.
The risk of asphyxiation due to system depressurization or
hyperpressurization is substantially minimized due to the safety
valve systems described and the collar assembly. Hyperbaric
ventilators in infants have traditionally employed an iris collar
which can be dangerously constricted under high pressure.
Other objects and advantages of the invention will become apparent
when considered in view of the following detailed description.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a schematic, perspective view of the ventilator chamber
of the present invention with the hood in the closed position and
illustrating selected instruments, valves, etc. associated
therewith;
FIG. 2 is a side elevational view of the positive pressure chamber
and an inflatable collar assembly for sealing a patient's head
within the chamber;
FIG. 3 is a schematic, perspective view of the ventilator with the
hood opened and illustrating the collar assembly;
FIG. 4 is a cross-sectional view taken along line 4--4 of FIG. 2
illustrating the seal between the hood and the base structure and
the hood alignment guide;
FIG. 5 is a schematic view illustrating the top of the ventilator
and further illustrating schematically the attachment of selected
adjunctive devices;
FIG. 6 is an enlarged cross-sectional view of a muffler located
internally of the chamber to reduce noise levels produced by the
high pressure gas source; and
FIG. 7 is a cross-sectional view of the expiratory pressure
valve.
DETAILED DESCRIPTION OF THE INVENTION
In the embodiment illustrated, the hyperbaric ventilator device 10
includes a chamber 12 into which a patient's head is inserted, as
shown by FIG. 2. The particular configuration and construction of
the chamber 12 may vary, however, in the embodiment illustrated the
chamber 12 is substantially square and formed of Plexiglas or other
suitable materials. The chamber 12 comprises a base structure 14
having a hood 16 pivotally attached thereto by hinge 18. The
ventilator hood 16 comprises approximately fifty per cent of the
total surface area of the chamber. The hood 16 can be retained in a
raised position, as shown by FIG. 3, by means of a vertical hood
latch 20, while over-extension of the hood is prevented by the hood
rest 22. When the hood 16 is lowered, guides 24 maintain the hood
16 in alignment with the base structure 14. The guides preferably
consist of strips of Plexiglas cemented to the inner surface of the
base structure 14 and which extend above the edges of the base
structure 14, as shown by FIGS. 3 and 4.
All inner faces of the hood 16 and base structure 14 are lined with
compressible gasket material 26. In the embodiment illustrated, the
gasket material 26 is cylindrical and the base structure 14 is
grooved, as shown by FIG. 4, to accommodate and retain the gasket
material 26. The inner face beneath the hinge 18 also is sealed
with gasket material.
When the chamber hood 16 is lowered, the gaskets are compressed and
the hood is retained in a closed position by two conventional
spring loaded latches 28, 28.
An opening 30 is provided in the front wall of chamber 12 with
approximately half of the opening being defined by the hood 16 and
with the other half of the opening being defined by the base
structure 14 of the chamber 12. A collar assembly 32 extends into
opening 30 and is removably secured in position by plastic guide
studs 34 and metal studs with wing nut fasteners 36. In order to
obviate physical modifications to the chamber itself, and to
accommodate collar assemblies of different sizes, depending upon a
patient's neck size, the holes for receiving the metal and plastic
studs are uniformly spaced. The collar assembly 32 consists of two
halves 38 and 40, a half being secured releasably to the chamber
base structure 14 and hood 16, respectively. The collar assembly 32
defines a trough or groove 42, FIGS. 1 and 3, for receiving an
inflatable latex tube 44 which assures safe sealing of the
patient's neck. The sealed surgical tube 44 of variable inflated
proportions is fitted into the collar assembly to insure a
comfortable and safe sealing of the neck region. The tube 44 is
placed into the trough 42, gently wrapped around the patient's
neck, and the hood 16 is carefully lowered and secured by latches
28. The tube 44 then is snugly inflated allowing hyperinflated
areas of the tube to extend beyond the collar assembly trough 42
for maximum area seal. In the event of patient crisis, the hood 16
can be lifted to the FIG. 3 position upon manipulation of the
latches 28.
The inflatable tube or collar 44 may be replaced with a foam rubber
collar, not shown, sealed in plastic film. The foam rubber collar
will still be delimited by the collar assembly trough 42.
A patient access port, normally closed by a porthole cover assembly
46, is provided in the top surface of the chamber 12. The assembly
46 includes a pressure sealed lid 48 removably secured in position
by a spring loaded restraint arm 50. The arm 50 rotates about pivot
pin 52 adjacent one end and includes a slot at the opposite end for
receiving a locking member 54. Pivoting of arm 50 and removable of
lid 48 permits manual manipulation of the patient's head.
Additionally, an extended length rubber glove, not shown, can be
sealed around the circumference of the port to allow the aseptic
manipulation of the patient without gross disruption of pressures
internally of the chamber 12.
The base structure 14 of the chamber 12 is provided with a
plurality of openings along the rear wall 56 for receiving
interchangeable plastic adapter studs 58. The studs 58, FIG. 3, are
arranged to accommodate the attachment of therapeutic adjunctive
devices to the chamber.
Upon inflation of the latex collar assembly 44, the patient's head
is sealed into the chamber 12 which is subsequently pressurized to
varying degrees with therapeutic gasses. This device does not
require the insertion of an indotracheal or trachaeostomy tube,
and, as such, is considered to be non-invasive.
In the embodiment illustrated, the chamber 12 is primarily
pressurized from a fifty pounds per square inch air or oxygen
generation source. This pressure is subjected to second and third
stage gradations. The therapeutic pressure range maintained within
the device is 5-20 centimeters of water pressure. The air or oxygen
generation source is coupled to an oxygen dilution mechanism 60,
which may be of the type manufactured by Veriflow Corporation,
Richmond, Cal.
The secondary pressure stage is known as a Bourdon pressure gauge
62 and may or may not be used in conjunction with the oxygen
dilution source 60. The Bourdon gauge is the immediate regulative
device for sensing pressures and obtaining the desired pressures
within the chamber 12, and is adjusted by an integral needle valve
assembly. The pressurized gasses are conveyed to the chamber 12 by
high pressure hose 64 and a pressure fitting 66. A tube 120, which
may be approximately four inches in length and three inches in
diameter and filled with a foam rubber 122 having an opening 124
therethrough, is attached internally of the chamber 12 to the high
pressure fitting 66. The foam rubber serves as a muffler to reduce
the noise level produced by the high pressure gas entering the
chamber.
When the chamber 12 is pressurized to the maximum desired level,
the patient's safety is insured by a maximum system pressure escape
valve 68 mounted at the top of the chamber base structure 14. The
maximum pressure escape valve 68 is a spring loaded, adjustable
pop-off valve. In the event pressures within the chamber exceeds
the desired therapeutic levels, the valve 68 is activated to
prevent further increase in chamber pressurization.
An anti-asphyxiation valve 70 is mounted at the top rear of the
chamber 12 adjacent the pressure escape valve 68. In the event of
unexpected system depressurization that has been unnoticed, patient
asphyxiation is prevented by the valve 70. The valve 70 is of a
conventional type, and when in the open position, aligned apertures
are sealed by a rubber diaphragm. Depressurization of the system
will cause the rubber diaphragm to fall downwardly and allow
patient access to the ambient air. Closing of this valve 70 negates
the anti-asphyxiation function.
Pressure within chamber 12 is monitored by standard pressure
manometer 72 which serves as a visual indication of chamber
pressure. The manometer 72, also mounted at the upper rear of
chamber 12, preferably has a 0-50 centimeters of water pressure
positive and negative pressure range. The thermometer 74, located
within the chamber, measures temperatures. In addition, nitrogen
within the chamber is monitored by a nitrogen analyzer 78, FIG. 5,
while carbon dioxide gas concentrations are monitored by a
capnograph 80. The nitrogen meter 70 is coupled to the chamber by
hose 82 and sampling port 84 while the capnograph communicates with
the chamber by hose 86 and gas sampling port 88.
Relatve humidity within the chamber 12 is monitored by a hygrometer
76. Because pressurized medical gasses are generally dehumidified
at the source, it is necessary to humidify gasses directed into the
chamber to varying degrees, depending upon the clinical conditions
of the patients. These gasses may be heated or chilled, as
required. Various standard high output medical humidifiers are
capable of achieving above 90 per cent relative humidity within the
ventilator chamber. A humidification device 90, FIG. 5, may be
connected to the chamber 12 by corrugated tubing 92.
Provision is made for the continuous monitoring of oxygen
concentrations in the ventilator by an oxygen analyzer 94 and
sensor 96 connected to a stud 58. The analyzer 94 may be of the
Biomarine Model 302 type. The oxygen analyzer is intended as an
adjunctive device not uniquely necessary to the functioning of the
ventilator.
A rubber anesthesia-reservoir bag 98 may be provided as an
adjunctive device for the manual "sighing" of patients. When the
chamber 12 is pressurized, the bag 98 is inflated, and can be
manually constricted to introduce greater pressures to the
patient's airways. The bag 98 communicates with chamber 12 through
the adapter 100, tube 102 and a stud 58.
Maximum therapeutic pressure limitation is accomplished with either
a water blow bottle assembly 104, as shown by FIG. 5, or a positive
expiratory pressure valve 106, FIG. 1, such as manufactured by
Boehringer Laboratories. Though the functions of each system are
analogous, their modes of operation are dissimilar. Continuous
positive airway pressure is accomplished with the application of a
positive pressure gradient in both the inspiratory and expiratory
phase. In the inspiratory phase, the positive pressure gradient
facilitates expansion of the lungs. In the expiratory phase, the
positive pressure gradient serves to keep the lungs partially
inflated at the end expiratory point. This produces the splinting
effect of small airways. It also requires the patient to exert more
effort in the expiratory phase to displace these increased
pressures, but facilitates inspiration by reducing labor.
When the patient's head is placed and sealed in the chamber 12, the
chamber is pressurized to a predetermined level in the range of
50-20 centimeters of water pressure. This is the positive pressure
gradient exerted on the inspiratory phase. Pressure in the chamber
12 will remain constant, a static phase, and will remain so until
the beginning of the dynamic expiratory phase.
When the patient exhales, a volume of gas is displaced from the
lungs. This volume of gas is displaced within the system through
port 103 and the valve 106 or the blow bottle system 104. When the
volume of gas is displaced by either of these systems, the chamber
will depressurize to a predetermined level above atmospheric
pressure. The residual pressure in the chamber exerts the splinting
effects within the lung spaces to benefit the respiratory exchange
of gasses. The amount of expiratory resistance is determined by
adjusting the therapeutic pressure limiting system.
The Boehringer valve system 106 utilizes a dead weight principle
for the generation of expiratory resistance. Balls of different
mass are placed in a calibrated plastic sleeve 110, the degree of
expiratory resistance being proportional to the mass of the ball.
When the ball 108 is at rest in the sleeve 110, the ventilator
system is sealed. However, when the patient exhales, the volume of
gas that his lungs displace and subsequent addition of pressure
within the chamber overcomes the gravitational weight of the ball.
Thus, the ball 108 is lifted in the sleeve and a volume of gas
passes from the chamber, through the sleeve 110, to the ambient
environment and the chamber depressurizes to a certain level. The
pressure deficit is determined by a mathematical relationship
between the mass of the ball, the system pressure, and the exhaled
volume of gas.
At the end of the expiratory cycle, the ball weight settles because
there is no longer enough pressure within the system to support the
weight in cylinder 112. The residual pressure that is momentarily
maintained within the system at the end expiratory point is the
pressure which produces the desired therapeutic effect. The ambient
chamber pressure at the end expiratory point will equal
substantially the pressure within the lungs. The pressure
regulating gauge 62 will sense the chamber depressurization and
initiate repressurization of the chamber. The
inspiratory/expiratory cycle then is repeated.
Analogously, the blow bottle system 104 produces expiratory
pressure resistance. A corrugated tube 114 extends from the port or
orifice 103 into a bottle of water 116. The level of the water upon
the tube 114 may be adjusted to increase or decrease expiratory
resistance when exhalation takes place within the chamber.
Expiratory resistance is generated by the hydrostatic force of the
water. When the expiratory pressure overcomes the hydrostatic
force, the tube 114 is evacuated and a volume of gas is lost to the
ambient atmosphere, and the system will depressurize to an extent.
Residual pressures remaining within the chamber will be determined
by the depth of the tube in the water.
Therefore, by adjusting the weight of the valve 106 or the level of
the water in the bottle 116, the clinician is capable of
controlling the residual pressures within the system. The partial
evacuation of the ventilator with the use of either system serves
to maintain a continuous passage of gas through the chamber, thus
facilitating the "washing out" of excessive concentrations of
carbon dioxide.
The method of delivering a continuous positive airway pressure by
this hyperbaric ventilator is an intermittent one, characterized by
a static inspiratory phase and a dynamic expiratory phase.
Therapeutic concentrations of oxygen (21-100 per cent) are
frequently administered to patients exhibiting respiratory
distress. In applicants' invention, specific concentrations of
oxygen can be maintained by utilizing the ventilator oxygen
controller 60 or other such device in which precise quantities of
oxygen can be blended with air, or by a medical humidification
system 90 with variable oxygen concentration.
The oxygen controller 60 or other such device is connected to fifty
psi air and oxygen sources coupled with the Bourdon gauge 62 as
shown by FIG. 5. The desired concentration then is dialed in
manually.
Another system utilizes the Bourdon gauge 62 and the medical
humidifier 90 independently. The ventilator is connected to a fifty
psi oxygen (or air) source by a high pressure hose. The ventilator
is additionally, by means of a separate connection, connected to a
standard high output medical humidifier, such as 90, with
adjustable gas concentration potential. The humidifier is tapped
into an air or oxygen source. By manipulating the gas sources for
both systems, and by varying the levels of gas entrainment in the
humidifier, desirable concentrations of gas can be maintained
within the ventilator with reasonable accuracy.
A maso-gastric tube 126 may be routed from viscera to outside of
the chamber to allow for depressurization of the stomach in the
event of gas trapping. The tube can be routed outside of the system
in a number of ways at the discretion of the clinician.
* * * * *