Head restraint device based on vacuum bladder technique for use in vestibular studie

Carroll, W.

Lowery, C. A.

Niven, J. I.

English

NASA Technical Reports Server

Distribution of this document i s  unlimited. 
A HEAD RESTRAINT DEVICE FOR VESTIBULAR STUDIES 
W. Carroll Hixson, Jorma 1. Niven, and Charles A. Lowery 
Approved 
Ashton Graybiel, M. D. 
Director of Research 
Bureau of Medicine and Surgery 
MR005.04-002 1 . 1 42 
NASA Order R-93, 
Re I eased 
Captain H. C. Hunley, MC USN 
Commanding Officer 
20 January 1967 
* This researchwas conducted under the sponsorship of the Office of Advanced Research 
and Technology, National Aeronautics and Space Administration. 
NAVAL AEROSPACE MEDICAL INSTITUTE 
NAVAL AEROSPACE MEDICAL CENTER 
PENSACOLA, FLORIDA 32512 
https://ntrs.nasa.gov/search.jsp?R=19670016639 2020-03-12T11:29:29+00:00Z
SUMMARY PAGE 
THE PROBLEM 
To develop a head restraint system which would provide custom-fitted restraint of  
individual subjects with minimal preparation time. 
ii 
FINDINGS 
A restraint system based on a vacuum bladder technique was constructed from standard, 
commercially available materials. It provides a degree o f  restraint comparable to that avail- 
able with permanent, rigid head/torso molds individually fitted to each subject without the 
attendant cost in  preparation time and money. 
INTRODUCTION 
I -  
t '  
Of various methods used in vestibular experimentation to hold the head in some fixed 
orientation, the bite-bar for human subjects and tooth-clamp assembly for animal subjects 
have probably provided the highest degree of rigid constraint for the head. These methods are, 
however, unusable, or at least undesirable, in a variety of experimental situations, e.g., 
those in which continuous voice communications are essential, those in which severe motion 
sickness and the aspiration of vomitus may occur, and in linear oscillation in which device mal- 
function may produce impact. The bite-bar has additional disadvantages in that its efficacy 
i s  dependent upon the cooperation of the subiect; inadequate pressure may permit head movement 
and excessive pressure may p d u c e  f i d e  x i s e  3r srtifscts to contaminate the recoding of  
corneo-retinal potentials or similar electrophysiological indices. 
When such considerations have forbidden the use of the bite-bar method with our human 
subjects, we have sometimes resorted to standard U. S. Navy aviation helmets with adjustable 
head liners and chin straps or to individually fitted head and torso molds fabricated from plaster- 
of-paris or polyester impregnated glass cloth. The latter technique provides excellent restraint, 
but i t s  usefulness i s  limited by the time and cost required for the development of a separate mold 
for each subject; it i s  not at a l l  practical for single, brief tests and, even in long or repeated 
applications, restricted by the number of subjects which can be conveniently handled. 
It i s  for such reasons as these, probably, that we have received numerous requests from 
vestibular investigators for a brief technical description of  a simple vacuum bag restraint system 
developed for use with our rotating devices. The basic principle involves the use of atmospheric 
pressure to force a flexible, airtight bladder f i l l ed  with solid particles to become rigid when 
evacuated. The flexibility permits the bladder to be molded to the configuration of any object, 
such as the head, which i s  to be secured in one position. The rigidity i s  maintained as long as 
the vacuum i s  intact. The principle i s  not original with us, however. Indeed, it i s  our under- 
standing that similar procedures have had long-time industrial application in vacuum molding, 
although we are unable to cite any specific instance of such use. A brief description of the 
materials and methods used in the application of  the system in our laboratory follows. 
MATERIALS 
The primary elements of the vacuum bag restraint system are two rubber bladders, an 
inflating needle and tubing, a vacuum pump, and 6 pounds of plostic granules (see l i s t  of mate- 
rials). The bladders are standard ones of the type used in boxers' striking bags and are available 
in any sporting goods store. Their chief advantages are availability, low cost, and adequate 
flexibil i ty for molding to shape, coupled with sturdiness to resist wear and handling. 
The inflating needle i s  likewise available in any sporting goods store. The tubing i s  
standard, 3/8-inch, gum-rubber laboratory tubing; actually the ohly requirement i s  that i t  be 
able to resist evacuation without collapsing. The vacuum pump i s  of the standard diaphragm type 
available in most laboratories. 
The plastic granules are used to create a buffer to fil l the bladders to facilitate molding 
and to increase rigidity. They are of  the type called "cooking crystals," used by hobbyists for 
molding plastic objects and are readily available in most hobby supply stores. They appear to be 
made from a roughly formed plastic rod of about 1/16-inch average diameter and are broken into 
irregular 1/2O-to-1/IO-inch segments. Their small size lends itself to ready shaping of the 
bladder, and the irregularities in shape promote interlocking for rigidity when the bladder i s  
evacuated. 
1 
METHOD 
In the actual preparation of the restraint assembly, each bladder i s  f i l led with 3 pounds 
(approximately 1-1/2 quarts) of granules through a small, circular hole made in one side. After 
the fi l l ing i s  completed, the hole i s  sealed with an ordinary, automobile inner-tube cold patch. 
The bladder i s  then evacuated far about 30 seconds by means of the inflating. needle connected 
by the tubing to a vacuum pump. With the inflating needle removed, the evacuated bladder i s  
quite rigid and usually maintains its shape well for at least twelve hours. In this respect, leak- 
age at the bladder valve may occur i f  a small granule becomes lodged within the valve mecha- 
nism. This problem can usually be corrected by applying a small positive pressure to the bladder, 
resulting in i t s  partial inflation. 
A photograph of  a bladder before and after insertion o f  the plastic grains i s  shown in 
Figure 1. In Figure 2 a photograph of  a bladder being manually shaped to the contours of a 
hand i s  shown at the left; the resulting contours being rigidly held after evacuation are shown 
at the right. The specific application o f  the method in one device i s  shown in the photographs 
presented in Figure 3. An angle-iron support for the bladder assembly was attached to the chair 
as shown at the upper left. The bladder assembly i s  then placed between this bracket and the 
head as shown at the upper right. The experimenter manually compresses and forms the bladder 
assembly between the head and the bracket as shown at the lower left and then evacuates the 
bladder by means o f  a foot-operated switch controlling the vacuum pump. After approximately 
sixty seconds, the bladders are rigid and the head restraint i s  complete as shown at the lower 
right. 
The vacuum bag restraint system i s  adaptable to fixing the orientation of the head, torso, 
and/or limbs of any human or animal subject. Obviously improvements could be made in materi- 
als, e.g., more flexible casing and technique, e.g., precision cutting and assembly of patterns 
to improve the basic f i t  of  the bladder or to leave access openings where desired. The above 
description i s  meant only to show how commercially available materials of low cost and simple 
modification procedures can be used to provide a restraint system equal to or better than most of 
the methods currently in use. 
LIST OF MATERIALS 
1. Striking bag bladder, two Kantleek Model SR 1545-R (Seamless Rubber Company, New 
Haven, Connecticut) 
2. Plastic Cooking Crystals, 6 pounds (available in hobby supply stores or from Southwest 
Hobbies Inc., Wichita Falls, Texas) 
3. Air Pump, pressure-vacuum, motor driven, 0-30 inches of mercury (Model 1-093-5V1 , 
Fisher Scientific Co., U. S. A.) 
2 
Figure 1 
Striking bag bladder before and after insertion of plastic grains. 
Figure 2 
Plastic-filled bladder i s  manually shaped to the hand to illustrate its flexibility 
(left) and the fidelity and rigidity of the resulting contours after evacuation (right). 
3 
" - 1 
? 
,-T . - 
i 
- --e- ----- - -. 
I 
Figure 3 
Typical application of the head restraint system. A simple aluminum frame (A) provides support for the 
bladder units placed at each side of the subject's head (B). The bladders are easily shaped to the head 
for a snug fit before evacuation (C) and hold .their contoured shape rigidly after evacuation (D). 
4 
Unc I ossified 
Securitv Classification 
ORIGINATIN G A C T I V I T Y  (Corporete author) 
Naval Aerospace Medical Institute 
Pensacola. Florida 
Naval Aerospace Medical Center 
2a REPORT S E C U R I T Y  C L A S S I F I C A T I O N  
Unc I ass i f  ied 
2 b  G R O U P  
N/A 
I. DESCRIPTIVE NOTES (Type of report a d  lncluaive date.) 
~~~ 
I. REP0 RT DATE 7 9 .  T O T A L  N O .  O F  P A G E S  
6 
I. AUTHOR(S) (Laat n m e .  f l n t  name. ini t ia l )  
76. N O .  O F  R E P S  
Hixson, W. C., Niven, Jorma I., and Lowery, Charles A. 
1. SUPPLEMENTARY NOTES 12. SPONSORING MIL ITARY ACTIVITY 
MR005.04-002 1 
C. Ob. O T H E R  R E P O R T  NO(S) ( A n y  other number. that may bo aaaldnad 
hi. N It) 
1 4!? 
d. 
0. A V A  ILABILlTY/LIMITATION NOTICES 
I 
Distribution of this document i s  unlimited. 
1 
3. ABSTRACT 
A restraint system based on a vacuum bladder technique was constructed from standard, 
commercially available materials. It provides a degree of restraint comparable to that avail- 
able with permanent, rigid head/torso molds individually fitted to each subject without the 
attendant costs in preparation time and money. 
Llnr.lnPzrfld .. 
Security Classification 
Security Classification 
14 
K E Y  WORDS 
Restraint systems I 
Vestibular studies I 
INSTRUCTIONS 
1. ORIGINATING ACTIVITY Enter the name and address 
of the contractor, subcontractor, grantee, Department of De. 
fense activity or other organization (corporate author) issuing 
the report. 
2.2. REPORT SECUWTY CLASSIFICATION Enter the o v e r  
all security classification of the report. Indicate whether 
“Restricted Data” i s  included Marking is to be in acco rd  
ance with appropriate security regulations. 
26. GROUP Automatic downgrading i s  specified in DoD Di- 
rective 5200.10 and Armed Forces Industrial Manual. Enter 
the group number. Also, w k n  applicable. show that optional 
markings have been used for Group 3 and Group 4 as  author- 
ized. 
3. REPORT T I T L E  Enter the complete report t i t le i n  all 
capital  letters. T i t l e s  in all cases should be unclassified. 
If a meaningful t i t le  CaMOt be selected without classifica- 
tion, show title classification in all capi ta ls  in parenthesis 
immediately following the title. 
4. DESCRIPTIVE NOTES If appropriate, enter the type of 
report, e.g., interim, progress, summary, annual, or final. 
Give the inclusive dates  when a specific reporting period i s  
covered. 
5. AUTHOR@): Enter the name(s) of author(s) as shown on 
or in the report. 
If military, show rank and branch of service. The  name of 
the principal author is an  ahsolute minimum requirement. 
6. REPORT DATE Enter the date of the report a s  day. 
month, year; or month, year. If more than one date  appears 
on the report, u se  date  of publication. 
7a. TOTAL NUMBER O F  PAGES The total page count 
should follow normal pagination procedures, Le., enter the 
number of pages containing information. 
7b. NUMBER O F  REFERENCES: Enter the total number of 
references cited in the report. 
8e. CONTRACT OR GRANT NUMBER: If appropriate, enter 
the applicable number of the contract or grant under which 
the report was written. 
ab, %, & 8d. PROJECT NUMBER. Enter the appropriate 
military department identification, such as project number, 
subproject number, system numbers, task number, etc. 
9s. ORIGINATOR’S REPORT NUMBER(S): Enter the offi- 
cial  report number by which the document will b e  identified 
and controlled by the  originating activity. This  number must 
b e  unlque to thls report. 
96. OTHER REPORT NUMBER(S): If t he  report has  been 
assigned any other report numbers (either by the originator 
o r  by the sponsor), a lso enter this number(8). 
10. AVAILABILITY/LIMITATION NOTICES Enter any l i m  
itations on further disseminstion of  the report, other than thou, 
Entei l a s t  name, first name, middle initial. 
imposed by security classification, using standard statements 
such as: 
(1) “Qualified requesters may obtain copies  of t h i s  
report from D D C ”  
( 2 )  “Foreign announcement and dissemination of this 
report by DDC is not authorized” 
(3) “U. S. Government agencies may obtain copies  of 
this  report directly from DDC. 
users  shal l  request through 
Other qualified DDC 
(4) “U. S. military agencies  may obtain copies  of this 
report directly from DDC Other qualified use r s  
shall  request through 
(5) “All distribution of this  report i s  controlled Qual- 
ified DDC users  shall  request through 
If the report has  been furnished to the Office of Technical 
Services,  Department of Commerce, for s a l e  to the public, indi- 
c a t e  this  fact  and enter the price, i f  known. 
It SUPPLEMENTARY NOTES: Use for additional e x p l a n e  
tory notes. 
12. SPONSORING MILITARY ACTIVITY Enter the name of  
the departmental project office or laboratory sponsoring ( P a r  
ing for) t he  research and development Include address. 
13. ABSTRACT: Enter an abstract  giving a brief and factual 
summary of the document indicative of the report, even though 
i t  may a l so  appear elsewhere in the body of the technical re- 
port. If additional space  is required, a continuation shee t  she  
be attached. 
It is highly desirable that the abstract  of c lass i f ied repod 
be unclassified.  Each paragraph of the abstract  shal l  end wit1 
an  indication of the military security c lassi f icat ion of the in- 
formation in the paragraph, represented as (Ts). (s), (C) .  o r  (U 
There i s  no limitation on the length of the abstract .  How- 
ever, the suggested length is from 1 5 0  to 2 2 5  words. 
14. KEY WORDS: Key words s r e  technically meaningful term! 
or short  phrases that characterize a report and may be used a s  
index e n t d e s  for cataloging the report. 
se lected SO that no security classification is requied.  Identi. 
f iers.  such a s  equipment model designation, trade name, milits 
project code name. geographic location, may be used a s  key 
words but will  b e  followed by an indication of technical con- 
text. The assignment of  l inks,  d e s .  and weights is optional. 
Key words must be 
Unclassified 
Security Classification 


A head restraint device for vestibular studies

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server