Method and apparatus of a positioning system for airway management

A positioning system provides for airway management of a supine subject. A number of bags are provided for supporting the head and lower neck/upper shoulders area of the subject. Once the bags are positioned under the subject, each bag is pressurized using a pressurized fluid source which is controlled by a mechanical controller. The mechanical controller comprises a number of mechanical switches for regulating the pressure in each bag. By manipulating the mechanical switches, the pressure in each bag is adjusted to align the subject's head and lower neck/upper shoulders area such that the mouth, pharynx and trachea are linearly aligned.

BACKGROUND 
Airway management in the medical field may be accomplised by a process 
known as intubation. The intubation process refers to the passage of a 
tube through the nose or mouth into the trachea for maintenance of the 
tracheal airway during anesthesia, for relief of an imperilled airway from 
any cause or for artificial respiration. Situations requiring intubation 
arise in the operating room, the emergency room, on the hospital floor or 
even in the field with emergency paramedical personnel. 
Anatomical variations in a patient's upper airway make some intubation 
procedures more difficult than others. These difficult intubations are 
exascerbated by the supine position of the patient during the procedure. 
For example, a short-necked, emphysematous patient supine on a flat 
surface will offer an acute orotracheal angle making intubation difficult. 
In some cases, such difficulties are assessed in advance and estimations 
of optimal head and neck support are made. However, medical personnel 
frequently make such assessments during laryngoscopy, which is an 
inspection of the larynx by means of a laryngoscope. In these situations, 
a failed first attempt at intubation usually results in a scramble for 
extra pillows to alter position of the patient's head. During this 
potentially life threatening time, the patient may not be breathing on his 
own and is unventilated. 
SUMMARY OF THE INVENTION 
The present invention is a method and apparatus for airway management which 
provides a mechanically controlled positioning system for the alignment of 
a patient's head and neck so as to produce a linear alignment of the 
mouth, pharynx and trachea within seconds. In a preferred embodiment, the 
method and apparatus of the present invention may be used to effectuate 
tracheal intubation or bronchoscopy. Alternatively, the present invention 
may be used for the positioning of any part of a patient's body in a wide 
range of surgical procedures including a maternity procedure. 
In accordance with the present invention, a pair of airtight bags which are 
preferrably pneumatic bags are provided to support the head and lower 
neck/upper shoulders area of a supine patient. Each bag is linked to a 
pressurized fluid source via a mechanical controller. One bag is 
positioned under the occiput of the patient's head and the other bag is 
situated under the lower neck/upper shoulders area. A foam latex cushion 
which may be placed over each bag covers that side of the bag which 
contacts the patient. The distance between the bags may be maintained by a 
strap. An adhesive material, preferably comprising one half of a hook and 
loop connector may be attached to a portion of the strap. A strip of 
adhesive material, preferably comprising the other half of the hook and 
loop connector may be attached to the underside of each bag. Both bags are 
then affixed to the strap by the preferred hook and loop connector (i.e. 
Velcro.TM.), assuring a constant separation between the bags. 
The pressurized fluid source which may be liquid or gas-based and which is 
controlled by a controller is used to inflate the bags. The pressurized 
fluid source may comprise a pump and a plenum chamber. In a preferred 
embodiment, the pump is a linear electrical motor-powered pump capable of 
delivering gas up to a maximum pressure of 300 Torr. The pump delivers 
pressurized gas into the plenum chamber which provides a fully pressurized 
reserve volume. The plenum chamber has a preferred volume which is 
comparable to the combined volume of the two bags. Thus, the combination 
of the high-pressure pump and plenum chamber effectuates the rapid 
delivery of a sufficient volume of high pressure gas to provide full 
inflation of the two bags within seconds. Furthermore, each bag will rise 
about five inches at full inflation from a fully deflated state allowing a 
wide range of positioning orientations. 
Using the controller, the pressure in each bag is regulated so as to align 
the relative position of the patient's head and lower neck/upper shoulders 
area such that the mouth, pharynx and trachea are linearly aligned. The 
controller has interface ports which are connected to hoses from the bags 
as well as a hose from the the pressurized gas source thereby linking the 
bags to the pressure source. In a preferred embodiment of the present 
invention, the controller has only mechanical components and comprises two 
three-position mechanical switches to control the pressure in the two 
bags. Each switch has a first switch position corresponding to 
pressurization, a second switch position corresponding to maintaining a 
constant pressure and a third switch position corresponding to 
depressurization. 
In a preferred system each mechanical switch is configured to control the 
pressure in one bag using a mechanical valve assembly comprising a pair of 
mechanical valves. Preferrably, the valves are spring-loaded pneumatic 
valves such as spool valves. The two valves within the assembly are 
connected in a series arrangement. Further, a first valve in the assembly 
controls pressure to the bags from the pressurized gas source, and a 
second valve of the assembly has a venting connection for controlling 
depressurization of the bags. 
The above and other features of this invention including various novel 
details of construction will now be described with reference to the 
accompanying drawings and pointed out in the claims.

DETAILED DESCRIPTION OF THE INVENTION 
A positioning system for airway management of a supine subject in 
accordance with the present invention is shown in FIG. 1. For any tracheal 
intubation, the head and lower neck/upper shoulders area offer the only 
two points of freedom for alignment of the mouth, pharynx and trachea. 
Thus, proper adjustment of the relative position of the head to the lower 
neck/upper shoulders area is a critical prerequisite to the intubation 
procedure. 
Accordingly, the positioning system of this invention may be used according 
to the following method for positioning of the subject's head and lower 
neck/upper shoulders area. A first bag 10 is positioned under the occiput 
of the subject's head, and an identical second bag 10 is positioned under 
the lower neck/upper shoulders area. Each bag is pressurized with fluid 
from a pressurized fluid source 44 as regulated by a controller 20. The 
pressure in each bag is then adjusted using a pair of mechanical switches 
22 on the controller. Within seconds, the position of the head and lower 
neck/upper shoulders area are adjusted so as to produce a linear alignment 
78 of the mouth 72, the pharynx 74 and the trachea 76 as shown in FIG. 2. 
In a preferred embodiment of the present invention, a pair of airtight bags 
10 are used to support the occiput 80 of the head and lower neck/upper 
shoulders area 88 of a supine subject 70 shown in FIG. 2. Each bag is 
approximately five inches by twelve inches when fully deflated and is 
capable of rising five inches at full inflation. Further, each bag has a 
volume of about one and a half liters and may be filled with liquid or 
gas, though gas is preferred. The pressure rating for each bag is 
approximately 5 psi. 
An adhesive strip such as one half of a hook and loop connector 
(Velcro.TM.) is attached to the underside of each bag 10. Once the two 
bags have been positioned under a subject, the distance between them is 
maintained using a strap. A strip of adhesive material 16, such as the 
other half of the hook and loop connector is attached to a portion of the 
strap. The strap allows different functional lengths to be selected 
between the bags 10. The adhesive feature ensures that neither bag moves 
out from under the patent during the positioning procedure. 
A foam latex cover 12 is positioned on top of each bag 10 as shown in FIG. 
3. The cover is sufficiently large to completely cover the side of the bag 
that encounters the subject 70. The the cover provides a soft, relatively 
flat surface upon which the subject may be placed without sliding off and 
which maintains a relatively stable shape during inflation and deflation 
of the bag. For sanitary purposes, the covers 12 may be replacable and 
disposable. 
A pressurized fluid source 44 is employed to pressurize the bags 10 in 
about five seconds, though preferrably in two seconds, and comprises a 
pump 40 and a plenum chamber 50. The pump is a linear electrical 
motor-powered pump capable of continuous operation and pressure 
maintenance. The maximum deliverable pressure of the pump is about 300 
Torr which approximately matches the rated pressure of the bags 10. The 
bags contain a pressure relief valve which ensures that the pressure in 
the bags does not exceed 5 psi. The pump 40 delivers pressurized gas to 
the plenum chamber 50. The plenum chamber serves as an integrator for the 
pressurized source and has a volume of about three liters which is 
equivalent to the volume of the two bags. This feature ensures that a 
reserve volume of fully pressurized gas is always available so that the 
system may operate continuously. 
The pump 40 is capable of delivering pressurized gas at a rate of 40 liters 
per minute which equals 1.5 liters per two seconds. Since the the volume 
of the plenum chamber 50 is double the volume of each bag, the pressurized 
fluid source, including the pump and the pressurized plemun chamber, is 
capable of fully inflating both bags simultaneously in about two seconds. 
Thus, the position of the subject's head and lower neck/upper shoulder 
area can be adjusted quickly to produce a generally linear airway making 
intubation possible in seconds. 
A controller 20 couples the bags 10 to the pressurized source 44 for 
inflation and to the external environment for deflation. As shown in FIG. 
4, the bags 10 are coupled to the controller 20 by a pair of hoses 14. 
Similarly, the pressurized gas source is coupled to the controller 20 by a 
hose 16. The pressure within each bag is adjusted by manipulating one of 
two three-position mechanical switches 22 on the controller 20. Each 
switch has a first switch position for pressurizing the corresponding bag, 
a second switch position for maintaining a constant pressure within the 
bag and a third switch position for depressurizing the bag. 
The controller may be conveniently positioned next to the patient, where 
the physician controls the present invention with one hand while 
manipulating a laryngoscope with the other hand. The pressurized fluid 
source may be positioned out of the physician's way such as under the 
operating table. Alternatively, the pressurized fluid source may be a 
central pressurized air supply having a wall connection port. 
For some surgical procedures, an assistant may be required to adjust the 
position of the patient periodically during the procedure. Since the 
present invention may be operated using only one hand, the assistant's 
other hand remains sterile. Thus, the assistant may actively assist the 
physician with his sterile hand during the surgical procedure. 
Each mechanical switch 22 is configured to control the pressure in one bag 
using two valves 26 and 28 as shown in FIG. 5. In a preferred embodiment, 
the valves are spring-loaded pneumatic valves such as spool valves. Thus, 
valve 26, for example, comprises a spring 28 and a valve chamber 29. Each 
pair of valves is connected in series through a mechanical switch 22 and 
controls the gas flowing through the conduit 34. For each pair of valves, 
a first valve 26 is used to effectuate pressurization of an associated bag 
and a second valve 30 is used to allow depressurization of the bag. 
Each pair of valves is mechanically linked to a switch 22 by connecting 
rods 24. As shown in FIG. 5, the switch 22 is normally at the second 
switch position where the bag is isolated from the external environment 
and the pressurized source. At the second switch position, the first valve 
26 resides in conduit 34 to prevent pressurized gas from entering the bag, 
and the second valve seals hole 36 to prevent gas in the bag from escaping 
into the external environment. Consequently, selecting the first switch 
position by depressing the right side of switch 22 moves the first valve 
26 into valve chamber 29 by compressing spring 28. The second valve 30 is 
not affected by selecting the first switch position. With valve 26 
positioned in its chamber 29, a coupling path is formed between the 
pressurized source and a bag through conduit 34 for pressurizing the bag. 
Releasing switch 22 from the first position causes the first valve 26 to 
return to its original position in conduit 2 which halts pressurization. 
Similarly, selecting the third switch position by depressing the left side 
of switch 22 moves the second valve 30 into valve chamber 33 after 
compressing spring 32. First valve 26 is unaffected by the second switch 
position thereby isolating the pressurized source from the bag. With valve 
30 positioned in the bottom of the valve chamber 33, a coupling path is 
formed between the bag and the external environment through vent hole 36 
for depressurizing the bag. Releasing switch 22 from the third switch 
position allows valve 30 to return to its original position thereby 
sealing the hole 36. 
One feature of the present invention is that the controller has no 
electrical parts and few moving parts. Functioning with strictly 
mechanical components, the controller operates safely without electricity. 
This feature is extremely significant in medical procedures, where it is 
normally desirable to keep electricity as far away from the patient as 
possible. Having very few moving parts, the controller operates with high 
reliability. 
While this invention has been particularly shown and described with 
reference to specific preferred embodiments, it should be understood that 
those skilled in the art would be capable of devising various changes in 
form and detail without departing from the spirit and scope of the 
invention. For example, the valves are shown schematically for clarity of 
description but would preferrably be spool valves. Although a pair of 
valves supports each mechanical switch, alternatively a single valve may 
support a switch. Moreover, the spring element may be located in the 
switch assembly rather than in the valve assembly. Furthermore, other 
variations of the embodiment described herein will be apparent to those 
skilled in the art. Thus, the present invention is not to be limited to 
the positioning of the head and neck of a supine subject since it may be 
used to position other anatomical areas of a supine subject in a wide 
range of surgical procedures. For example, the present invention may be 
employed to position a subject's abdomen for a maternity procedure.