Device and method for inducing bradycardia

The specification discloses a device for inducing dive reflex, and the associated bradycardia and vasoconstriction in the human through the application of cold stimulus to the facial nerve, which communicates with the parasympathetic nervous system. The device comprises a pair of opposed temperature-controllable, face-engaging members and a tension member interconnecting and biasing the face-engaging members toward one another to secure the face-engaging members on the face over a portion of the area in which the facial nerve surfaces. A method of inducing dive reflex using the device is also disclosed.

BACKGROUND OF THE INVENTION 
The present invention relates to medical devices and methods of using same, 
and more particularly such devices and methods for producing bradycardia 
in the human body. 
Dive reflex, also known as diving reflex, is the mechanism through which 
the human body defends itself from hypothermia and resulting death, when 
submerged in cold water. The reflex is most graphically illustrated by the 
resuscitation of children, who have been submersed in farm ponds during 
the winter for periods exceeding the threeminute brain-death criterion. In 
dive reflex, the body, through selective vasoconstriction, isolates those 
tissues with extended anaerobic capability from those with relatively 
little anaerobic capability (the heart and brain). Consequently, 
circulation to the extremeties is greatly diminished, while circulation to 
the brain and heart continues at generally adequate levels. Additionally, 
the pulse-rate slows and a relatively constant blood pressure is 
maintained. Typically, the resulting minimum dive-reflex pulse-rate is 
approximately 60 to 70 percent of the quiescent rate. By trunking blood to 
the brain and heart, and slowing the pulse-rate, the body is able to 
supply the required oxygen to both the brain and the heart for extended 
periods of cold water submersion. 
Although the dive reflex phenomenon has been known for a considerable 
period of time, the triggering mechanism has only recently been 
determined. Through selective anatomica immersion, it has been determined 
that the receptor mechanism is located in the face. See J. Finley et al, 
Autonomic Pathways Responsible for Bradycardia on Facial Immersion, 
Journal of Applied Physiology, Volume 47(6), Pages 1218-22 (December 
1979). More recently, it has been hypothesized that the triggering 
receptor is the facial nerve which surfaces at the cheeks, forward of the 
ears to the nose. The facial nerve communicates with the auricular branch 
of the vagus nerve, which provides the autonomic pathway to the heart 
through the general visceral efferent fibers (parasympathetic branch of 
the vagus nerve). The application of a cold stimulus to the facial nerve 
induces dive reflex and slows the pulse-rate through its communication 
with the vagus nerve. 
SUMMARY OF THE INVENTION 
I have conceived that if dive reflex can be induced in a controlled 
environment, a considerable workload can be removed from the heart e.g., 
during post-infarction convalesscent periods. Such a pulse-rate reduction, 
undder constant blood pressure, would facilitate the recovery of patients 
due to the reduced requirement for oxygen by the heart. Additionally, 
because the blood supply to the extremeties is greatly reduced during dive 
reflex through vasoconstriction, artificial inducement of the phenomenon 
could also be used to reduce traumatic bleeding in the extremeties. 
Recognizing the medical benefits to be gained through the inducement of 
dive reflex, I have conceived a device and method for inducing the reflex 
without immersing the face in cold water. The device includes 
cheek-engaging means, means for mounting the cheek-engaging means on a 
person's face, more particularly over a portion of the area where the 
facial nerve surfaces, and means for controlling the temperature of the 
cheek-engaging means in a range sufficiently low to induce dive reflex 
through the application of cold stimulus to the facial nerve. The method 
includes the steps of providing a device having temperature-controllable 
face-engaging means, mounting the device on the face of a person with the 
face-engaging means covering a portion of the area where the facial nerve 
surfaces, and controlling the temperature of the face-engaging means in a 
range sufficiently low to induce dive reflex. 
The device and method of the present invention have several medical 
applications. First, the workload on the heart may be reduced by inducing 
dive reflex, and the associated bradycardia, in that patient. Such induced 
bradycardia is especially beneficial to post-infarction patients, and 
those who may be bradycardial drug resistant. Second, traumatic bleeding 
in the extremeties may be reduced by inducing dive reflex, due to the fact 
that the associated vasoconstriction reduces the volume of blood 
circulated through the limbs. 
These and other objects, advantages, and features of the invention will be 
more readily understood and appreciated by reference to the written 
specification and appended drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The portions of the parasympathetic nervous system pertinent to dive reflex 
are illustrated in FIG. 1. By way of orientation, head 30 includes eyebrow 
34, eye 36, nose 38, mouth 40, and ear 42; and heart 32 is located in 
thoracic cavity 31. Vagus nerve 46 leads from the brain (not shown) 
through head 30 and neck 44 into thoracic cavity 31. Vagus nerve 46 
includes superior ganglion 48, located just rearward of ear 42, from which 
auricular nerve 50 branches. Facial nerve 52 leads from auricular nerve 50 
opposite superior ganglion 48 and surfaces over an area 54 of the 
patient's cheek 53. Area 54 extends widthwise from just forward of ear 42 
to eyebrow 34, eye 36, nose 38, and mouth 40 and heightwise between an 
area above eyebrow 34 and an area below mouth 40. General visceral 
efferent fibers 56 extend from vagus nerve 46 and surface in heart 32 to 
control the heart and its pulse-rate. 
Facial nerve 52, auricular nerve 50, vagus nerve 46, and general visceral 
efferent fibers 56 serve as the autonomic pathway through which dive 
reflex is effected. When cold stimulus is applied to at least a portion of 
area 54 in which facial nerve 52 surfaces, the parasympathetic nervous 
system slows the heartbeat communicating with heart 32 through auricular 
nerve 50, vagus nerve 46, and general visceral efferent fibers 56. Maximum 
heartbeat reduction is estimated to be 40 percent. The parasympathetic 
nervous system also causes vasoconstriction and its associated reduction 
in circulation to those body extremeties with extended anaerobic 
capability. Accordingly, dive reflx can be selectively induced by applying 
a carefully controlled temperature source to area 54 of cheeks 53 in which 
facial nerve 52 surfaces. 
A device 10 for inducing dive reflex in the human body is illustrated in 
the drawings and generally includes headset 12 (FIGS. 2 and 3), control 
box 14 (FIG. 2), and pulse monitor 16. Headset 12 in turn includes a pair 
of opposed face-engaging assemblies 18a and 18b (FIG. 3) and tension 
assembly 20 interconnecting the two face-engaging assemblies. Each 
face-engaging assembly 18 (FIG. 4) comprises face-engaging plate 22, 
backing plate 24, a plurality of thermo-electric chips 26 secured 
therebetween, and heat sink 28 secured to backing plate 24 opposite the 
thermo-electric chips. 
Device 10 is used (FIG. 2) by positioning headset 12 on the patient's 
cheeks 53 with each face-engaging assembly 18 covering area 54 where 
facial nerve 52 surfaces (see also FIG. 1). Pulse monitor 16 is secured to 
the patient's chest 140. Thermo-electric chips 26 are then activated so 
that face plate 22 becomes cool and backing plate 24 becomes warm. As 
face-engaging plate 22 becomes cool, cold stimulus is applied to facial 
nerve 52, inducing dive reflx, with its associated bradycardia and 
vasoconstriction. Through control box 14, the temperature of face plates 
22 may be regulated to a preselected temperature corresponding; to a 
predetermined percentage reduction in pulse-rate. Control unit 14 may 
alternatively maintain a predetermined pulse-rate as sensed by monitor 16, 
by regulating the temperature of face plates 22. 
Face-engaging assemblies 18a and 18b (FIG. 3) are generally identical to 
one another. Accordingly, only assembly 18a (FIG. 4) will be described in 
detail. Face plate 22 is generally planar and is constructed of 
heavy-gauge aluminum or a semi-rigid, thermally-conductive polymer. Plate 
22 is defined by two generally parallel side edges 60 and 62 and outwardly 
concave upper and lower edges 64 and 66. Five threaded apertures 68 extend 
through face plate 22. Backing plate 24 is similar to face plate 22, being 
also generally planar and constructed of heavy-gauge aluminum or a 
semi-rigid, thermally-conductive polymer. The silhouette of backing plate 
24 which is defined by generally parallel side edges 70 and 72 and concave 
upper and lower edges 74 and 76 is identical to that of plate 22. 
Apertures 78 extend through backing plate 24 and are generally aligned 
with apertures 68 in plate 22 when the plates are aligned with one 
another. Additionally, two threaded apertures 80 extend through plate 24 
proximate upper and lower edges 74 and 76. 
Thermo-electric chips, or solid state heat pumps, 26 are generally well 
known to those having ordinary skill in the art. One thermo-electric chip 
particularly well suited to the present invention is that sold as model 
number CP 1.4-71-06L by Materials Electronic Products Corporation of 
Trenton, N.J. Each of chips 26 is generally identical to one another, and 
inclues a cold ceramic surface 81, hot ceramic surface 82, positive 
terminal 84, and negative terminal 86. When a voltage is applied across 
terminals 84 and 86, heat is transferred from cold surface 81 to hot 
surface 82 so that surface 81 becomes relatively cold and surface 82 
becomes relatively hot. Chips 26a and 26b are connected in series through 
lines 88a, 90, and 92a. Similarly, chips 26c and 26d are connected in 
series by lines 88b, 94, and 92b. Chip pair 26a and 26b is connected in 
parallel with chip pair 26c and 26d to lines 88 and 92. 
Insulation block 96 is also positioned between plates 22 and 24 and defines 
four generally identical pockets 98, each of which closely receives one of 
chips 26. Insulation 96 is a generally planar, rectangular piece, 
fabricated from a thermally and electrically non-conductive polymer or any 
other material having similar characteristics. Aperture 100 extends 
through a central portion of insulation 96. The thickness of insulation 96 
is generally identical to the thickness of each of chips 26 and, in the 
preferred embodiment, is approximately 0.15 inches. 
Face plate 22 and backing plate 24 are secured together entrapping and 
compressing insulation 96 and chips 26 therebetween, with each of chips 26 
positioned within one of pockets 98. Screws such as 158 are inserted 
through each of apertures 68 and secured in one of apertures 78 to draw 
plates 22 and 24 together. Fiber washer 160 is positioned on screw 158 
between screw head 158a and plate 24, and fiber washer 162 is positioned 
on screw 158 between plates 22 and 24 to insure that the screws do not 
conduct heat between the plates. The screw located in apertures 78a and 
68a also passes through aperture 100 in insulation 96. Thermo-electric 
grease is applied to both the hot and cold faces of each of the chips 26 
prior to mating with face plate 22 and backing plate 24, to facilitate 
heat transfer. When securely fastened, each of chips 26 is compressed 
between the plates, with plate 22 engaging each of front surfaces 81 and 
plate 24 engaging each of hot surfaces 82. After plates 22 and 24 are 
secured together, silicon 101 (see FIG. 3) is injected between the plates 
to provide additional insulation. 
Heat sink 28 is fabricated from aluminum and connected to backing plate 24 
opposite chips 26. Heat sink 28 includes generally parallel side walls 102 
and 104 as well as concave upper and lower edges 106 and 108, all of which 
generally align with edges 70, 72, 74, and 76, respectively, on plate 24. 
The heat sink further comprises backbone plate 113 from which a plurality 
of transverse heat-dissipating fins 114 extend. Plate 113 defines central 
aperture 166. Securing flanges 115a and 115b are generally parallel to 
plate 113 and extend from outermost fins 114a and 114b, respectively. 
Apertures 110a and 110b extend through flanges 115a and 115b proximate 
upper and lower edges 106 and 108, respectively, and align with apertures 
80 in backing plate 24. Thermo-electric grease, to facilitate heat 
transfer, is applied between heat sink 28 and backing plate 24. Heat sink 
28 is secured to backing plate 24 by screws such as 164 extending through 
apertures 110 and secured in apertures 80. Each of fins 114 engages plate 
24 to dissipate heat therefrom. Of course, other cooling means could be 
substituted for heat sink 28, for example liquid cooling. 
A rubberized thermally-conductive fabric cover 168 (shown in phantom in 
FIG. 2) may optionally be installed over assembly 18, more particularly 
face plate 22 to improve the comfort of device 10. 
Swivel mount 116 is well known and includes two generally cylindrical 
pieces 116a and 116b which pivot with respect to one another. Piece 116a 
defines a threaded bore 118 so that assembly 116 may be secured to heat 
sink 28 by inserting a screw through aperture 166 and into bore 118. Two 
recesses 120 (one not visible) are located in generally opposite sides of 
piece 116b. 
Tension assembly 26 (FIG. 3) is also generally well known in the art, and 
in the preferred embodiment is identical to tension assembly found on 
stereo headphones. More particularly, tension assembly 20 includes two 
plastic brackets 122a and 122b, and two tension members 124 connected to 
and extending therebetween. Fingers 126a and 126b are frictionally 
slidably mounted in bracket 122a and extend into recesses 120 on swivel 
piece 116b (see FIG. 4) to secure tension bar 20 to face-engaging assembly 
18a. Similarly, fingers 128a and 128b are slidably mounted in bracket 122b 
and are secured to swivel assembly 116. 
Thermocouples 130 and 132 are positioned between chips 26c and 26d, 
respectively, and face plate 22. These thermocouples are well known and 
sense the temperature of cold surfaces 81 of the thermo-electric chips. 
Lines 134 and 136 lead from thermocouples 130 and 132, respectively, and 
together with lines 88 and 92 comprise cable 138 (FIGS. 2 and 3) which 
leads to control unit 14 (FIG. 2). Pulse monitor 16 is also well known and 
is secured to chest 140. Line 142 interconnects monitor 16 with control 
unit 14. 
Control unit 14 (FIG. 2) includes pulse-rate display 144 which displays the 
current pulse-rate sensed through monitor 16, and temperature display 146 
which displays the current temperature sense at thermocouple 130 (see FIG. 
4). Unit 14 further includes adjusting knobs 152 and 154 as well as 
pulse-rate-set display 150 and temperature set display 156 responsive 
respectively thereto. The temperature of face plates 22 may be controlled 
in either of two manners, as selected by switch 148 in control unit 14. 
When the switch is in its first position (as shown in FIG. 2), the desired 
pulse-rate may be selected on display 150 by turning adjusting knob 152 
until the selected pulse-rate appears on the display. Control unit 14 will 
then, through control circuitry well known, regulate the current supplied 
to chips 26 to regulate the temperature of face plates 22 so that the 
desired pulse-rate is maintained as sensed by monitor 16. Suitable control 
circuitry is sold under model number 149 by Omega Engineering, Inc., of 
Stamford, Conn. When switch 148 is in a second opposite position, the 
desired temperature of plates 22 may be set by adjusting knob 154 until 
the desired temperature appears on display 156. Control unit 14 will then 
regulate current supplied to chips 26 to maintain plate 22 at the selected 
temperature. When switch 148 is in its first position, display 156 shows 
all zeroes to indicate that the temperature may not be set. Likewise, when 
switch 148 is in its second position, display 150 shows all zeroes to 
indicate that the pulse-rate may not be set. 
Thermocouple 136 is connected to control circuitry within control unit 14 
to deactivate device 10 and sound an audible warning if the temperature at 
the thermocouple exceeds a predetermined maximum parameter or falls below 
a minimum parameter to prevent scalding and freezing of the facial tissue. 
Such control circuitry is sold under model number 166 by Omega 
Engineering, Inc. Control circuitry is also included in control unit 14 to 
deactivate device 10 and sound an audible alarm if the pulse-rate, as 
sensed by monitor 16, exceeds a predetermined maximum rate or falls below 
a minimum rate. 
OPERATION 
Device 10 is used by first mounting headset 12 and pulse monitor 16 on the 
patient's body (FIG. 2). Each of face-engaging assemblies 18a, and more 
particularly face plates 22 are mounted to overlie a substantial portion 
of area 54 where facial nerve 52 surfaces. Tension bar 20 urges assemblies 
18a and 18b toward one another to engage the patient's cheeks, or face, to 
secure headset 12 on the patient's head 30. Pulse monitor 16 is then 
secured to chest 140 in a well-known manner. Headset 12 and pulse monitor 
16 are then connected to control unit 14 through cable 138 and line 142, 
respectively. 
The temperature of plates 22 is then maintained, controlled, or regulated 
in a range sufficiently low to induce dive reflex, and the associated 
bradycardia and vasoconstriction, through facial nerve 52. It has been 
discovered that temperatures between 40.degree. to 59.degree. F. produce 
the most effective dive reflex with the pulse-rate being generally linear 
between these two temperatures. As cold stimulus is applied to facial 
nerve 52, the parasympathetic nervous system induces dive reflex in the 
patient, and more particularly induces bradycardia through facial nerve 
52, auricular nerve 50, and vagus nerve 46. When face plates are 
maintained at a temperature of approximately 40.degree. F., maximum 
bradycardia is effected and the pulse-rate is approximately 60 percent of 
its normal quiescent value. 
The degree of bradycardia may be controlled in one of two manners, 
depending upon the position of switch 148 on control unit 14. First, the 
pulse-rate may be maintained at a preselected level; and second, the 
temperature of face plates 22 may be maintained at a preselected 
temperature. When switch 148 is in its first position as shown in FIG. 2, 
the desired pulse-rate may be set by adjusting knob 152 to display the 
desired value at display 150. Control unit 14 will then regulate the 
temperature of face plates 22 upwardly or downwardly to maintain the 
pulse-rate at this desired value. Control unit 14 will lower the 
temperature of plates 22 if the pulse-rate exceeds the preselected value 
and will raise the temperature of plates 22 if the pulse-rate falls below 
the preselected value to maintain the pulse-rate at or near the 
preselected value. Alternatively, when switch 148 is in a second, opposite 
position, the temperature of face plates 22 may be adjusted using knob 154 
to display the desired temperature on display 156. The face plates will 
then be maintained at this value regardless of the current pulse-rate. In 
either control method, the current pulse-rate is displayed on display 144 
and the current temperature of plate 22 is displayed at display 146. 
In the event of a system malfunction, causing the temperature of face plate 
22 to exceed a predetermined maximum parameter of fall below a 
predetermined minimum parameter, thermcouple 132 signals control unit 14 
that the temperature of the face plates is outside of the acceptable 
temperature range. If the patient's pulse-rate exceeds the predetermined 
maximum rate or falls below the minimum rate, monitor 16 signals control 
unit 14 that the pulse rate is outside of the acceptable pulse-rate range. 
In either event, control unit 14 then cuts power to chips 26 and sounds an 
alarm indicating a system malfunction. 
It should be understood that the above description is intended to be that 
of a preferred embodiment of the invention. Various changes and 
alterations might be made without departing from the spirit and broader 
aspects of the invention as set forth in the appended claims, which are to 
be interpreted in accordance with the principles of patent law, including 
the doctrine of equivalents.