Appendix A

mtg

Mots Oz Flow 1 Liter NTPO.
Mosk Pressure

Ficcre A19. Mask donning during decompression.

Mass O2 Flow | Liter NTPD

Fieure A20.

IN 50 Scconosmd

Subject JSe.

Mosk Pressure mmHg.

——

“= DECOMPRESSION 8,000 TO 40,000 FEET IN 49 SECONDSumi

Heart Rote beots per minute

40~
Mask donning during decompression. Subject EMc.

18

No denitrogenation.


v 2

Movs Op Flow {Liter NTPO.

(Bees Op Flow ! Liter NTPD.

Fieure A7. Mask removal and redonning at 30,000 ft. Subject JSi. Phase 1.

v

i
qt
fog
2) 8
Hi
i}?

v
Tretia eerie pr eon

i ey nia i

el = =

El)

| 2

2] 8

a

72

i

Ficure A8. Comparison of mask pressure (P) at 48,000 feet as provided by commercial
and military regulators. Upper record commercial pressure schedule. Lower record

military pressure schedule.

Appendix A 12


‘Taste B4, Instantaneous and Mean Heart Rate During a Step-Function Altitude Chamber
Flight Profile to 43,000 Feet.

Subject
ae Altitude Barometric Heart Cardiotachometer Respiratory
Condition Feet Pressure Rate Min, Max. Rate Gas Inspired

crm. 5,000 632 84 78 ba} 16 Oo 100%
Commercial 18,000 380 84 80 90 16 0, 100%
Pressure 30,000 226 86 80 100 18 0% 100%
Schedule 43,000 122 109 90 120 11 05 100%

we nee eee ee | 40,000 wi 85 Excess Movement ul 0; 100%
jo_ Mas! 1 30,000 226 82 76 100 12 0; 100%
~~~ Hetaek Benewah 725 7 % 5 ro 0% 100%

J. Se. 5,000 632 82 78 102 rey 0, 10%
Commercial 18,000 380 87 82 100 13 05 100%
Pressure 30,000 226 89 80 105 B 0 100%
Schedule 43,000 122 104 % 18 19 0% 100%

we eee en eee ~ 40,000 11 %6 82 108 ul 0% 100%

TIT T He Mask Removal 30,000 226 = — on: - 0; 100%

1,273 725 77 70 90 ll 0, 100%

B. Or, 632 79 76 % 4 Oo 100%
Military 380 90 80 98 19 0, 100%
Pressure 226 4 7 7 7 0% 100%
Scale 122 119 101 126 19 05 100%

__e 141 85 82 102 sts 0; 100%

Just Prior f 226 80 78 86 R of 100%
we Mask, 226 98 82 124+ -- ate (a)
IIT II _ lRecovery 30,000 226 87 78 124+ 18 0, 100% (b}

1,273 725 mm 64 87 1 o 100%

c. Pr. 5,000 632 102 21 0, 100%

18,000 380 103 18 0} 100%

Pressure 30,000 226 101 Ww 0; 100%

Scale 43,000 122 140 8 0} 100%

eee eee ee ——— 40,000 141 115 80 Off-Scale 9 0; 100%

~ T Hag Removal_92.5 See 30,000 226 118 82 Off-Scale -- ate (©)

—-—--———~—~ Recovery 30,000 226 o1 82 112 13 Oo 100% (4)

1,273 725 110 90 120 15 oD 100%
J. St. 1,273 ns 95 80 u2 13 ©, 100%
1 5,000 632 93 88 112 16 oO 100%,
Pressure 18,000 380 96 86 108 5 05 100%
‘Schedule 30,000 226 % 85 98 15 05 100%
43,000 122 107 92 118 4 0, 100%
2 eee eee eee ee 40,000 141 98 85 114 16 0; 100%
Mask Removal 45.0 Sec 30,000 226 104 6 120 7 ate (e)
oni ~ Recovery 30,000 226 100 87 120 18 Oo, 100% += (f)
1,273 725 89 84 104 12 0 1007
‘MEAN: 5,000 632 88.0 82.40 103.0 15.6
18,000 380 92.0 85.00 101.4 16,2
30,000 226 90.8 84.00. 102.8 16.0
43,000 122 115.8 4.25% 120,5* 14,2

wee eee | 40,000 141 95.8 82.25% 108.0% = 12.2

TIT No Mask Removal 30,000 226% 82.0% 76.00% 100.0%" — 120%

— — Mask_Removal_73.3 Sec 30,000 226%% 106.6** 86,60%* 122,08 ----

wee Recovery 30,000 226%% 92.6%* 82.30% 118 ,.6** 16,3**

1,273 725% 85.48% 76.40%" 99,2 12 0
NG (a) H.R. Steady Increase 82-125
kN = 3 (>) =H, R, Steady Decrease 124-78 in 40 Seconds
wee N = 2 (c) H.R. Increase 80-Off-Scale
NOTE: Where not otherwise indicated N = 5. (4) H.R. 82 in 30 Seconds
(e) H.R, Steady Increase 96-120
(f) H.R, Steady Decrease 120-87 in 50 Seconds

Appendix B


with the exception that an ear oximeter and
impedance pneumograph were added. In addi-
tion, an experimental blood pressure device was
also utilized (Figure A4).

The output of the Waters ear oximeter was fed
into an Electronics for Medicine amplifier, dis-
played on a panel meter and oscilloscope and
also fed into one of the two direct readout visi-
corders, The impedance pneumograph signal
was amplified by a Physiograph and also re-
corded on one of the visicorders.

In the third phase, four of the subjects: were
exposed to a profile similar to that of the second
phase with the exception that the mask was re-
moved after 25 to 28 minutes of denitrogenation
and the subjects breathed air at 8,000 feet for
two minutes. A fifth subject was rapidly decom-
pressed from 8,000 to 40,000 feet without any
previous denitrogenation.

Prior to the decompression and during the
time the subject was breathing air, the chamber
safety observer would hang the mask back up
in its retention device. During the decompres-
sion, as the chamber passed through 14,000 feet,
an audible alarm bell alerted the subject. Fifteen
seconds later and at approximately 25,000 feet,
a red donning signal light was activated and the
subject donned the mask. Read-out of the mass-
flowmeter and mask-pressure-transducer data
indicated the subject’s completed mask donning at
an altitude of 28,000 to 31,000 feet during decom-
pression.

In Phase One, a standard sentence was re-
peated on command during normal and pres-
sure breathing, monitored and recorded for sub-
jective evaluation of intelligibility. Also, in the
first phase, the donning ability of the mask by
a hypoxic subject was to be evaluated at a level-
off altitude of 30,000 feet during descent. The
mask was to be removed at this altitude for a
period of time until hypoxia became evident
and redonned before useful consciousness was
lost.

Two of the subjects utilizing regulators
incorporating the commercial pressure-breath-
ing schedule did not appear to possess adequate
physiological well-being at 43,000 feet, and this
portion of the evaluation was cancelled. Symp-
toms of severe hypoxia developed in these two
subjects after 1 to 1-14 minutes dwell time at
48,000 feet, and an emergency descent to ground
level was simultaneously ordered by the re-

searcher and the attending flight surgeon. The
failure of the subjects to complete the prepro-
grammed flight profile at 43,000 feet was not
attributed to any defect in the regulator, but
rather to the lower pressure-breathing schedule
of the commercial pressure regulator. The fact
that the commercial regulator did produce pres-
sures in the mask within the range specified for
commercial regulators (Table 1) was verified by
intramask pressure measurements (Table B2).

The average tracheal-oxygen partial pressure
82.5 mm) of the three subjects utlizing the com-
mercial pressure-breathing regulator schedule
at an altitude of 43,000 feet is marginal and is
not considered to be adequate to maintain the
subject in a satisfactory physiological condition
at 43,000 feet.

Since minor variations in the tracheal-oxygen
partial pressure at 43,000 feet can produce sig-
nificant changes in physiological well-being, the
average tracheal-oxygen partial pressure (86.5
mm) of the two subjects utilizing the military
pressure-breathing schedule was sufficient to
allow them to complete the preprogrammed al-
titude profile satisfactorily.

One experienced chamber technician, utiliz-
ing a commercial pressure-breathing regulator,
successfully completed the donning evaluation at
30,000 feet. His mask removal time was, how-
ever, much shorter than the subjects using the
military pressure schedule (Figures A5, A6, and
AT). :

An evaluation of crew-member performance
when wearing the mask at various pressure-
breathing altitudes up to 43,000 feet was per-
formed in the initial evaluation as follows:

Each subject was trained on the Scow com-
plex coordinator. This device was originally
designed by Mashburn and subsequently modi-
fied by Dr. Jim Scow. The apparatus consists
of two manual and two pedal response controls.
The subject’s task is to effect a match or solut-
tion to a stimulus pattern of four lights, em-
ploying the four response controls. The dis-
play panel is divided into four quadrants, each
quadrant containing a vertical row of five
stimulus lights and a parallel row of five
response lights. Positioning of the appropriate
pedal or manual control lights a single re-
sponse light. A trial is successfully completed
only when all four of the controls are concur-
rently positioned correctly. At the base of the



APPENDIX B

Taste Bl, Pressure Breathing Versus Altitude of Typical Commercial and Military

Regulators.*

Typical military regulator ‘Typical commercial regulator

Altitude (in 20) (mm Hg) (in. H20) (mm Hg)
27,000 0.0- 1.0 0.0- 19 01-19 - 0.2- 8.5
29,000 0.0- 1.0 0.0- 19 0.1-8.2 0.2- 6.0
380,000 0.0- 2.5 0.0- 4.7 01-32 0.2- 6.0
* 82,000 0.0- 2.8 0.0- 5.2 0.1-8.2 0.2- 6.0
84,000 0.0- 3.0 0.0- 5.6 0.1-3.2 0.2- 6.0
36,000 0.0- 3.2 0.0- 6.0 0.1-B.2 0.2- 6.0
38,000 + 0.0- 84 0.0- 6.4 0.1-8.2 0.2- 6.0
89,000 0.3- 3.5 0.6- 6.5 0.1-4.7 02- 88
40,000 0.3- 5.6 0.6-10.5 O.7-4.7 13-88
41,000 2.0- 72 2247 41-88
42,000 34 8.6 22-72 4.1-13,4
48,000 5.3-10.2 4-2 8.8-18.4

* Personal communication R. K. Coulter, Chairman, SAE Committee A-10, Aireratt Oxygen Equipment.

19



Taste B7. Mask and Regulator Nitrogen Concentration, Calculated Tracheal-Oxygen

Partial Pressure, and Indicated Blood-Oxygen Saturation.
During the Decompression

Mask Worn Prior to and

Subject Nh Nyt Mask Pressure
and Altitude Barometric Regulator Mask + Barometric P,
Condition Feet Pressure Peak Min. Peak Min, Insp. Exp.
c, Pu 1,273 737.3 ~ a oo - oa -
127373713 2.00 2.00 3.00 1.50 735.8 738.3
8,000 565.0 3.00 1.80 3.00 2,00 563.0 566.0
R.D. 50 Sec. 8-40,000 250.0 ~ - tnd - 247.5 256.0
1 Mins 40,000 141.0 1,80 50 1.50 .20 145.0 148.0
2 Min. 40,000 141.0 100 120175 120, 1450 147.0
3 Min. 40,000 141,0 75 20 1.00 20 144.0 147.0
1,273 737.3 eee - --
c. Pr. 1,273 7% .6 aa _
1273 734.6 3.00 1.75
8,000 565.0 3.00 1.50 563.0 566.0
RD, 49 Sec, 8-40,000 250.0 1,20 .50 248.0 257.0
1 Min. 40,000 141, 20° 20 1467.0
2 Min, 40,000 141.0 50.50 0
3 Min. 40,000 141,0 1.00.50
Mask Removed 6,000 609.0 soo
B, Or. 1,273 735.6 ween =
1,273 735.6 2.50 1.20 3.00 1.50 733.6 736.6
8,000 565.0 3100 1:50 3.00 2.00 564.0 567.0
49 Sec, 840,000 141.0 175 175 1.00 4100-24910 256.0
1 Min, 40,000 141.0 1.75 75 75 25 145.0 149.0
2 Min, 40,000 161.0 '80 130 150 0100 © 143.5 147.0
3 Min. 40,000 141.0 75 125 150 0.00 144.0 147.0
1,273 141.0 see a ose ~ ~
J. Se. 1,273 730.9 =
1,273 730.9
33000 565.0
R.D, 49 Sec. 840,000 250.0
1 Min: 40,000 © 161.0
2 Min. 40,000 141.0
3 Min. 40,000 141.0
32,000 206.5
25,000 282.4
14,000 447.0
3, St. 1,273 737.0 115.75 2,00 1,00 735.0 739.0
8,000 565.0 75 «75 2,00 1.00 563.0 566.0
‘53 Sec. 8-40,000 (250.0 1.00 1,00 1,50 75 251.0 254.0
1 Min, 40,000 141.0 75 «75 1,00 50 145.0 149.0
2 Min, 40,000 1461.0 50 50 1,00 75 143.0 148.0
3 Min, 40,000 141.0 50 50 1,00 50 144.0 147.0
1273 737.0 180 180 2:00 1.00 735.0 738.0
MEAN: 1,273 735.1 1,69 1.18 2.45 1,24 733.8 736.8
8,000 565.0 1199 1115 2135 1140 563.4 566.2
RD, 50 Sec, 8-40,000 228.2 86% = .69% 1,80 1,81 250.0 256.2
1 Min, 40,000 141.0 is 148 88 119 14s.9 1485
2 Min. 40,000 161.0 tez 136 163 193 147.6
3 Min, 40,000 141.0 66 35 68 od 144.2 147.4
aN 4
NOTE: Exceptfor where otherwise indicated N = 5.
Appendix B 25

®,

T,

0,

O47 g?
Qfean)

684.0
505.0

$e22388
SEES2e5

sesies

bn gn oe

%

Bar

Oximeter Gas
% Sat Insp
96.0 Air
98.0 Oo, 100%
96.0 o 100%
94.7 0% 100%
93.0 05 100%
93.0 05 100%
%10 oF 100%
93.0 Ake
9.0 Ate
97.0 Ly 100%,
96.0 05 100%
95.0 02 100%
93.5 05 100%
8 0) 100%
93. 05 100%
97.0 rc
9.0 Ate

97:0 0, 100%
96.5 0) 100%
95.0 0% 100%
%'5 Of lon
95.0 oy 100%
95.0 02 100%
93.0 Abe
935 Ate
97.5 Oo, 100%
97:5 05 100%
97:2 05 100%
96.0 of 100%,
95.1 0% 100%
95.0 0) 100%
95.9 oD 100%
96.4 0, 100%
97.1 o 100%
97.0 Oo 100%
97:0 0, Loox
96:0 05 100%
95.0 0; 100%
95.0 oD 100%
4.0 0, 100%
99.0 0 100%
97.30

96.60

95.58

94740

9% 32

94:30



Taste B3. Mask and Regulator Nitrogen Concentration and Calculated Tracheal-Oxygen
Partial Pressure During a Step-Function Altitude-Chamber Flight Profile to 43,000 Feet,

Subject Nh N2% Mask Pressure (B-47) F.
and Altitude Barometric Regulator Mask + Barometric
Condition Feet Pressure Mean tegrated Mean Insp. Exp. (ean) Gas_Insp.
c, Pu. >,v00 632 +00 1.90 629,0 632.5 575 0, 100%
‘Commercial 18,000 380 200 2.00 378.0 381.0 326 0} 100%
Pressure 30,000 226 .00 1,80 224.0 227.0 175 0 100%
Schedule 3rd Min. at 43,000 122 .00 1.00 127.0 134.0 83 0, 100%
40,000 141 100 1.30@) 141.0 141.0 95 0, 100%
30,000 226 +00 2.5068) 226.0 228.0 175 0 100%,
1,273 ns +00 2.00! 723.0 727.0 664 0 100%
J. Se. 5,000 632 225 1.60 629.0 633.5 0, 100%
380 150 1,50 377.0 381.5 0% 100%
226 120 275 224.0 231.0 0, 100%
122 120 75 126.0 135.5 0} 100%
1 10 50 142.0 147.0 oD 100%
226 “Rapid Descent - No Readings Were 0 100%
725 20 175 721.0 727.0 05, 100%
632 +50 1.40 629.5 634.0 0, 100%,
380 1.50 1.50 378.0 381.5 oO 100%
226 +50 1.50 225.0 229.0 0; 100%
122 25 133.0 137.0 0 100%
wi +30 143.5 149.0 0, 100%
226 140 224.5 229.0 05 100%
226 125 Mask Off----------~ ale
226 4.00 222.0 229.5 0, 100%
5 1.00 722.0 727.5 0} 100%,
632 +50 629.0 633.0 575 0, 100%
+380 2,00 oD 100%
226 225 0; 100%
122 125 0% 100%
1 125 0% 100%
226 x alr
226 3150 0, 100%
725 3.00 0, 100%
5 00 0, 100%
632 100 05 100%
380 00 0, 100%
226 100 0, 100%
122 200 0, 100%
141 +00 0, 100%
226 +00 ake
226 +00 5.00 0, 100%
25 +00 1.60(e) 722.0 727.5 667 0; 100%
632 225 1.76 629.1 633.4 574.0 0, 100%
380 +80 2.06 377.8 381.5, 325.8 0; 100%
226 219 1152 224.4 228.4 175.6 03 100%
122 ars 180 134.9 84.0 03 100%,
141 113 +86 145.6 96.4 0 100%
226% 008% 2.65%% 227.56 176 .5ee 0 100%
moval, 734,3_Sec_30,000 226%" 13H 80..00%% ome ake
_ _ — ~ Begowery_30,000 2264" 3.758% 2.75% 228,80 174 08% 0, 100%
1,273 725 +86 : R71 667.2 03 100%
we V2} Nore: Where not otherwise noted N = 5.
(a) Ny 7% head movement
(>) Ne 12% head movement NOTE: Extreme deliberate head movements increased leakage
(ce) y 9% head movement to values indicated.

Appendix B 21



Appendix A

80-

g 2 x
8 8 3
are”

NITROGEN — PER CENT
a
$

x
2
On

15

(@-INITIAL WASHOUT TWENTY-
FIVE MINUTES PRIOR TO
DECOMPRESSION FROM 8,000
= 40,000 FT, SIERRA QUICK-
DON CREW MASK. Ne4

(O-WASHOUT DURING DECOMPRES-
SION FROM 8,000 - 40,000 FT.
FOLLOWING 2 MIN. BREATHING
AIR AT 8,000 FT. AND DONNING
MASK AT 29,000 31,000 FT,
SIERRA QUICK DON CREW
MASK, N=4

Q-WASHOUT DURING DECOM-
PRESSION FROM 6,000- 41,000
FT. NO PREVIOUS DENITROGE-
NATION. PURITAN QUICK-DON
CREW MASK. NG

30 45 60 75 90 105 120
TIME~SECONDS.

Ficvge A15. Comparison of initial nitrogen washouts prior to decompression with wash-

Moss Oz Flow 1 Liter NTPO

outs during decompression after 2 minutes on air,
followed an initial denitrogenation,

The 2-minute air-breathing period
The third curve was derived from unpublished

data obtained in a previous crew-mask evaluation.

DECOMPRESSION 8,000 TO 40,000 FEET IN $1 SECONDS

=
&

3
+.

Hwert Rate beots per minute
8 8

38
ri

2
3

Figure A16, Mask donning during decompression.

Subject CPu.

16




Taste B10. Ventilation Volume, Presure, and Frequency During Rapid Decompression

from 8,000 to 40,000 Feet. Mask Donning Accomplished During the Decompression.

Win. Tidat
Subject Vol, Vol. Impedance Mask Pressure
and Altitude Lin, ce, Pneunograph nm. Hg
BIPS Rate Factor Insp Bx
c.m. 318 141.00
100
= Abe 2 Min Pre R.D.
D. 51 Sec. 840,000 183.0 3.77 5.31 44212886 =1.00 +8.00 0, 100%
Don Mask 1 Min, 40,000 141.0, 91200 lag 1,317 112.36 14.00 +9.00 03 100%
30 Seconds 2 Min. 40,000 141.0 51779109826. 12138 +4100 +8.00 05 100%
28,000 Feet 3 Min. 40,000 141.0 51779109 «1,010 991.60 45100 +8.50 0; 100%
c. Pr. 1,273 721.6 so. 11 =1,00 +1,50 0, 100%
8,000 565.0 330 18 =1100 +100 0% 100%
8,000 565.0 a= 18 awie- == abr 2 Min Pre RD,
RD. 49 Sec. 8-40,000 178.0 1,001 16 10.00 +10,00 0, 100%
Don Mask 1 Min, 40,000 141.0 1)566 9 +4,00 +10.50 0% 100%
36 Seconds 2 Min, 40,000 141.0 1,138 10 +4200 +8.00 0, 100%
31,000 Feet 3 Min, 40,000 141.0 Lan 9 45100 +8.50 0% 100%
B. or. 1,273, 732.3, 7.17 80653715 -2.00 -1,50 0, 100%
000 565.0 5185 6.69 4461S =1150 41,50 02 100%
- Ate 2 Min Pre R.D.
B.D, 49 See. +8.00 0, 100%
Don ask 1 Min. T00 413.00 05 100%
29 Seconds 2 Min. 46.00 “11:50 0 100%
29,000 Feet 3 Min. 76.00 +11,00 0 100%
J. Se. 1,273 735.6 4.28 36913 81 1.50 41,50 0, 100%
8,000 $65.0 4208 353 121,00 =1100 1150 02 100%
8,000 $65.0 ates a> 15 162 - Ate 2 Min Pre R.D.
RD, 50 Sec. 840,000 182.0 9.26 1,093 124150 +1,00 +8,00 0, 100%
Don Mask) 1 Min. 40,000 141.0 816313159 1,132, 123.00 +4100 +8.50 0} 100%
31 Seconds 2 Min. 40,000 141.0 41587121 "601 «1250 45:00 +8.00 02 100%
29,000 Feet 3 Min, 40,000 141.0 4387.21 555 131.63 +4100 8100 0% 100%
B. He. 1,273 732.4 873 «152,90 12.00 Air +
8,000 565.0 18 1.00 si-- Air
RD. 40,000 175.0 18 6.00 -2,00 ¥8.00 0) 100%
Don Mask 40,000 141.0 19 $127 +4200 +1100 0 100%
30 Seconds 40,000 141.0, 21 2Lat 43.00 +10.00 05 100%
29,000 Fect. 3 Min, 40,000 141.0 19 1168 ¥500 410.00 0 100%
ven: 1,273 730.5 6.56 7.31 532 13.6 1,43 1,50 +1.60
8,000 565.0 41865156 3711814 1.00 2134.37
R.D, 49.6 Seconds 8-40,400 180.0 1105 16.91 986 14.6 9.07 = 170 8.40
Don Mask 120 Min, 40,400 138.4 10,78 17,111,295 13,4 4.87 +4180 110.40
30.8 Seconds 2.0 Min. 40,400 138.4 713511198 "884 13,6 4.27 +6140 +9110
29,200 Feet 3.0 Min. 40,400 138.4 1611132 916 12.6 3.54 45.00 +9.20
Mean includes Subject E. Mc who was not de-nitrogenated, and Subject B, Or,
whose terminal altitude was 42,000 feer,
+ Regulator positioned for air only. Subject hyperventilating for calibration
of impedance pneunograph.
Appendix B 28


regulator was removed and replaced with a
new military regulator. The defective military
regulator was not detected and replaced until
the second phase of the evaluations was com-
pleted. It was also found that a subject breath-
ing air and then donning the mask would induce
a minor increase in nitrogen in the breathing
hose. It could be demonstrated repeatedly that
the intrahose nitrogen decreased as the mask
nitrogen decreased during respiratory washout.
It appeared therefore that the pressure com-
pensating valve in the mask was allowing a minor
amount of gas in the mask to enter the breathing
hose. Concentrations encountered, however, are
minor, never exceeding 4% and in most instances
no more than 1%.

B. Second Phase—Rapid Decompression Wear-
ing the Mask. Subjects instrumented as shown
in Figure A4 were exposed to a rapid decompres-
sion from 8,000 to 40,000 feet as previously de-
scribed. Records of these decompressions are
reproduced in Figure A8 to Al2. The upper
record includes the ear-oximetry trace (labelled
S), altitude (A), mass-flowmeter volume (V),
and mask pressure (P). The lower record in-
cludes the electrocardiogram (EKG), cardio-
tachogram (C), and impedance pneumogram (I).
In addition, an experimental evaluation of a
method of rapidly determining blood pressure
during decompresion was included in the sec-
ond and third phase decompressions.

Since this was an experimental physiological
procedure that was conducted primarily to test
and develop the procedure per se and was not
essential to the evaluation of the mask, it will
not be discussed in this paper but will be reported
separately at a later date.

The impedance pneumogram exhibited varied
responses to decompression as shown in Table
B6. Four of the subjects exhibited considerable
increase in amplitude and one subject showed
a baseline shift and little or no increase in am-
plitude. The impedance pneumogram factor in
Table B6 is the ratio by which the amplitude
varies from the baseline amplitude that had been
established as unity for each subject at 8,000 feet
breathing oxygen prior to the decompression.

Electrocardiograph electrodes were also a
problem. The type of electrodes used had
previously proven satisfactory in exercise and
other rather severe applications. In these

chamber flights, conduction was occasionally
erratic, with a tendency for this to occur more
frequently during and following decompres-
sion. Since the ECG and cardiotachometer
utilize common electrodes, a defect in the ECG
results in an erratic nonreadable instantaneous
heart-rate record. This problem was subse-
quently traced to chemical erosion of the elec-
trodes, which made them subject to poor electrical
contact during body movement. The bucking
voltage utilized in the mass flowmeter drifted
out of balance due to a faulty electronic com-
ponent resulting in a downward or negative
trend (trace V in Figure A13) and indicated an
unrealistic minute and tidal volume during de-
compression for subject J. Se. (Table B6).

Blood-oxygen saturation as indicated by ear
oximetry did not show any significant transient
dips during decompression. Tracheal-oxygen
partial pressures were also considered adequate
(Table B7).

Significant outboard mask leakage was de-
tected in one subject during pressure breathing
at 40,000 feet. The leakage ceased at the end
of the second minute at 40,000 feet. The ex-
tent of leakage may be estimated by noting the
slope of the volume recording during the res-
piratory pause in Figure A3, The degree of
heart-rate elevation was not remarkable (Table
B8).

Q. Third Phase—Rapid Decompression and
Donning the Mask. Subjects instrumented as
in the second phase (Figure A4) were rapidly
decompressed from 8,000 to 40,000 feet in 40 to
45 seconds. Subjects had been breathing air
for 2 minutes at 8,000 feet prior to decompres-
sion. The subjects received a mask donning sig-
nal 15 seconds after passing through 14,000 feet.
The altitude at which subjects completed mask
donning varied between 28,000 to 31,000 feet.

Records of the decompressions are reproduced
in Figures A16 to A20. Four of the subjects
were decompressed following 25 to 28 minutes
of denitrogenation and 2 minutes of breathing
air. The fifth subject was decompressed with-
out previous denitrogenation. Initiation of the
first breath following completion of donning
may be obtained by examination of the mask-
pressure and mass-flowmeter recordings. Oc-
casionally, a sharp upturn in the mass-flow-
meter recording shortly before initiation of the



display panel is a timer which can be preset
at any interval up to 15 seconds. The timer
automatically resets when each problem is suc-
cessfully completed. If a subject does not com-
plete the problem in the preset time, two large
red lights immediately forward of the manual
controls are activated and remain on until the
subject’ successfully completes the problem.
The sweeping red hand of the timer followed
by the appearance of the red lights serves to
act as a motivation factor. As each problem
is successfully completed, a programming drum
moves one step and presents a new problem to
the subject. Each of these steps represents a
trial, and 25 trials represent a cycle or block.
Responses are recorded by means of an Esterline
Angus event recorder, while a counterprinter
yields the time to complete a cycle or block in
minutes and hundredths of a minute. The
shorter the block time, the higher the rate of
performance.

III. Results,

Readout of all data was accomplished at each
altitude or when a significant event occurred.

A. Phase One—Chamber Flight to 43,000 Feet.
Data obtained in the first phase are shown in
Tables B2, B3, and B4. The upper record in
Figure A8 was obtained on a subject using a
commercial regulator at 43,000 feet. The lower
record was similarly recorded at 43,000 feet
utilizing a military pressure-breathing regula-
tor. Oxygen regulators incorporating the com-
mercial pressure schedule did not provide ade-
quate pressure to maintain the subjects in a
satisfactory physiological state at 43,000 feet.
Military regulators with higher pressure sched-
ules appear to supply sufficient pressure. It
should be pointed out that in this instance the
regulator pressure schedule and not the mask
was deficient.

Physiological response and mask perform-
ance are shown in Tables B2, B3, and B4. As
would be expected, minute volume, mean tidal
volume, and heart rate reached their maximum
values at a pressure-breathing altitude of 43,000
feet. Heart rates increased steadily following
mask removal and decreased to normal within one
minute following redonning of the mask, a
normal response to the stress induced by hy-
poxia and recovery. Records of the three sub-
jects who completed the mask removal experi-

ment at 30,000 feet are reproduced in Figures
Abd, A6, and AZ.

Results of the subjective speech-intelligibility
evaluation and coordinator performance are
presented in Table B5.

Since operation of the complex coordination
task requires higher cerebral function, it is not
surprising that performance fell off when sub-
jects were utilizing the lower pressure schedule
of the commercial regulator or performing the
mask-removal—hypoxia experiment at 30,000
feet. One of the principal values of using the
complex coordinator was that it kept the subject
occupied with a task requiring mental and motor
coordination analogous to the demands of pilot-
ing an aircraft.

Two versions of the mask suspensions system
were used during these evaluations, one being
fabricated from plastic and the other of alumin-
ium. It was the investigators’ subjective evalu-
ation that the aluminum alloy suspension sys-
tem was more rigid and retained its shape for
donning over earphones and glasses more readily
than the plastic version.

The pressure-breathing characteristics and
tolerances of typical dilutor-demand pressure
breathing commercial and military oxygen reg-
ulators are presented in Table B1. These values
may be compared to the actual pressures ob-
tained in Figure A8.

It may be noted that minor concentrations of
nitrogen were detected in the breathing hose
from the military schedule regulator with the
regulator control positioned in the 100% oxygen
position. Tests were conducted at ground level
to attempt to isolate the source of the nitrogen.
Initially, the 21-gauge hypodermic sampling
needle was inserted downstream from the mass
flowmeter in the breathing hose to the mask.
It was removed and inserted upstream from the
flowmeter at the junction of the hose and out-
flow of the regulator. This arrangement was
tested repeatedly, and, although the nitrogen ap-
parently coming from the regulator was reduced,
it was not eliminated. It was thought that very
minute quantities of nitrogen might be entering
by way of a defective seat in the ambient-air
dilution shutoff. Occasionally, nitrogen concen-
tration in the supply exceeded that in the mask
(Table B38). Possibly, incomplete mixing at the
leaking regulator of oxygen and air could be
responsible. In any event, this military schedule


&
:
i
é
i
a
160
£40 14
H
p20
a1 RS
§ 100 VI
E oh
Femi
402
Fiaure A17, Mask donning during decompression. Subject CPr.
v
2
z
3 1
i
é
g

Heart Rate beats per minute

Ficure A18. Mask donning during decompression. Subject BOr.

Appendix A 17



V. Conclusions.

1, The Sierra Quick Don Oxygen Mask ap-
pears to provide adequate protection at 43,000
feet if it is utilized with a compatible and
reliable pressure-breathing demand regulator,
incorporating a pressure-breathing schedule that
will provide sufficient pressure to meet physiologi-
cal requirements.

2. Demand pressure-breathing oxygen regu-
lators incorporating a commercial pressure
schedule did not appear to provide sufficient
tracheal-oxygen partial pressure to maintain
subjects in a satisfactory physiological condition
at 43,000 feet.

3. Inboard leakage during demand breathing
and outboard leakage during pressure breathing
were minimal in most instances. In the one
instance where outboard leakage developed dur-
ing pressure breathing at 40,000 feet, the record
indicates that this leakage did not result in a

reduction in mask pressure since there was no
significant change in mask pressure when the
leakage was corrected prior to initiation of the
descent.

4, When worn prior to and during a decom-
pression, the mask provided adequate protection
and there was no indication of significant hy-
poxia.

5. When mask donning was accomplished in
response to a signal 15 seconds after passing
through 14,000 feet, during a 45-second rapid
decompression from 8,000 to 40,000 feet, there
was a marked transient drop in blood saturation
without Joss of useful consciousness.

6. Donning was readily accomplished with
one hand during decompression in an average
of 4.8 seconds. The suspension system is de-
signed to provide good peripheral vision and
allow donning over earphones and eye-glasses.

REFERENCES

1. Bennett, G.: Reactions and Performance of Pilots
Following Decompression. Aerospace Med. 82:134,
1961.

2. Brockxrry, W. V., and Haniran, D, T.: An Analysis
of the Oxygen Protection Problem at Flight Altitudes
Between 40,000 and 50,000 Feet. Final report on-Con-
tract FA-955, Federal Aviation Agency, Feb. 20, 1961.

8. Barron, ©. L, and Coox, T. J.: Effects of Variable
Decompressions to 45,000 Feet, Aerospace Med.
85 1425, 1965.

4, Standardization of Definitions and Symbols in Res-
piratory Physiology, Federation Proceedings 9, 3,
September 1950.



Taste B5. Summary of Speech Intelligibility, Complex Coordination and Personal
Equipment Worn During Chamber Flights to 43,000 Feet.

Subject and Altitude Chamber
equipment (feet) condition
©. PU. 1,278 Ase.
Polyurethane 18,000 Level
suspension with 18,000 Ase.
MBUS5/P facepiece 30,000 Level
United Airlines 30,000 Asc.
6F-2992-1 ear- 43,000 Level
phones 43,000 Desc.
Mask microphone 40,000 Dese,
Commercial 80,000 Level
regulator 30,000 Dese.
J. SE. 1,278 Ase.
Polyurethane 18,000 Level
suspension with 18,000 Ase.
MBUS/P facepiece 30,000 Level
United Airlines 30,000 Ase.
6F-2992-1 ear 43,000 Level
phones 43,000 Desc.
Mask microphone 40,000 Level
Commercial 40,000 Desc.
regulator
B. OR. 5,000 Ase.
Aluminum 18,000 Level
suspension with 18,000 Asc.
Sierra 358-05 30,000 Level
facepiece 80,000 Ase.
Minitel MS-50-1 43,000 Level
Boom microphone 43,000 Dese.
Military 40,000 Level
regulator 40,000 Dese.
*30,000 Level
30,000 Dese.
Cc. PR. 1,273 Ase.
Aluminum 18,000 Level
suspension with 18,000 Ase.
Sierra 358-05 30,000 Level
facepiece 30,000 Ase.
Minitel MS-50-1 43,000 Level
Boom microphone 43,000 Dese.
Military 40,000 Level
regulator 40,000 Dese.
*30,000 Level
30,000 Dese,
J. Si 5,000 Ase.
Polyurethane 18,000 Level
suspension with 30,000 Level
MBU5 facepiece 30,000 Asc.
United Airlines 43,000 Level
6F-2992-1 ear- 40,000 Level
phones 40,000 Dese.
Commercial *30,000 + Level
regulator 380,000 Dese,

* Mask Removal and Redonning.

Appendix B 23

Subjective

speech

intelligibility
(Volume and clarity)

5
5

AAA an x

xX KX XXXX

»

wan
XXX

aa

a

XxX X X XX

Cy

xX X X KX XX

x xX

xX XxX

5
5

AAA

a

wr

BO

cs

Complex-
coordination
task
(Time per block)

Pre 43,000 ft.
Average baseline
2.70

4.24

Pre 43,000 ft
Average baseline
2.48

3.00

Pre 43,000 ft
Average baseline
2.85

3.20

Pre 43,000 ft
Average baseline
3.64

5.01

2.30

2.38

3.47



AM 66-20

EVALUATION OF THE SIERRA, HANGING, QUICK-DON,
CREW, PRESSURE-BREATHING, OXYGEN MASK

Ernest B. McFadden, M.S.
Michael T. Lategola, Ph.D.

Approved by Released by
Billi ite [USdagee 10
J. Roserr Dux, M.D. P. V. Srecen, M.D.
Cuter, Crvin AEROMEDICAL Fevers Air SurGEON
InstITuTe
June 1966

FEDERAL AVIATION AGENCY
Office of Aviation Medicine



Appendix A.

HHH e

st 04 et nt

to Pe ne HP

Ficure A3. Reproduction of record indicating outboard leakage occurring up to the end
of the second minute. Leakage may be estimated by determining the mean slope of
the mass flowmeter (V) tracing during the respiratory pause and exhalation.
Subject OPr.

feet.

epooemae MELE -MCROCTHETEN MPEG ORME MAB EAR METER
Wise pacsaune once t wesaune Tmsnaoucen ass MoMMeTER
Tine sou antanceraccetay cace “@ wirovenae meek

Figure A4, Instrumentation of subjects during rapid decompression from 8,000 to 40,000

Ear oximetry, impedance pneumogram, and blood-pressure instrumentation

were added for these experiments. Phase 2 and 3.

10


(—_—_— 10 reconser ————,

APPENDIX A

CHAMBER FLIGHT PROFILE
SIERRA HANGING QUICK DON
OXYGEN MASK

8 S$ 8 38

Ss

PRESSURE ALTITUDE (thousand feet)

oO

T T T T T T T T

0 10 20 30 40 50 60 70 80
TIME (minutes)

Ficure Al, Altitude-chamber flight profile. Phase 1.

CHAMBER
WAL

NITROGEN MH 2
‘Sensor an

NITROGEN
'SENSOR

MASS: ba —,
reownerer EemmnnscaTion

NTERGRATOR

20
20]

—_

STRAIN a
‘GAGE

BRIOGe

[canoioTacnowe TER}

EKG_MONITOR|

HYPODERMIC NEEDLE ~ MICROCATHETER SAMPLING ORIFICE ~ MASK
$ Aho enessune omricepresgune Transoucce @ MASS FLOWMETER

CLECTROCARDIOGRAPH LEADS @) OXYGEN REGULATOR - DILUTER DEMAND
‘PRESSURE BREATHING TYPE MO-1 (@) HYPODERMIC NEEDLE - MICROCATHETER
‘SAMPLING ORIFICE - REGULATOR SUPPLY

MASK TEST ON COMPLEX COORDINATOR

Instrumentation and activity of subjects during altitude-chamber flight.
Phase 1,

Freure A2.

9



Taste B12. Instantaneous and Mean Heart Rates, Respiration, and Indicated Blood-
Oxygen Saturation. Mask Donning Accomplished During Decompression.

Twbject
tnd Barometric Heart Cardiotachoneter Oximeter Respiratory
Condition Altitude (Ft) Pressure Rate Min Mex, %Sat Rate Gas Inspired
c. Pu, 1,273 730.5 1% 76 8 (97.0 1% 0, 100%
8,000 365.0 m 67 80 97.0 % of 100%
2 Min. On Air 8,000 565.0 = - 97.0 % ale
R.D, |51 Sec. 8-40,000 183.5 8% 70 100 a9. n 0, 100%
Don Mask 1 Min. 40,000 141.0 90 85 98 (95.5 n of 100%
30 Sec. 2 Min. 49,000 141.0 90 84 98 (95.9 u 0% 100%
28,000 Fe. 3 Min. 40,000 141.0 90 8b 96 95.9 9 of 100%
c. Pr. 1,273 721.6 75 90 (96.0 un 0, 100%
8,000 565.0 86 98.0 18 05 100%
2 Min. On Air ~ 8,000 565.0 2 97.5 18 tr
RD, 49 Sec. 8-40,000 178.0 128 85.0 16 0, 100%
Don Mask’ 1 Min. 40,000 141.0 121 93.0 9 0} 100%
36 Sec. 2 Min. 40,000 141.0 17 93.0 10 0} 100%
31,000 Fe. 3 Min, 40,000 rosa) ny os - 940 9 0} 100%
B. Or. 1,273 732.3 6357 68 95.5 13 ©, 100%
8,000 565.0 6360 7 9955 15 02 10%
2 Min. On Air 8,000 365.0 ae > = -- alr
R.D, 49 Sec, 8-42 ,000 182.0 95 70 125 89.0 15 ©, 100%
Don Mask’ | 1 Min. 42,000 128.0 99 92 uo 97.0 16 0% 100%
29 Sec. 2 Min. 42,000 128.0 9190 105 99.0 1% 0, 100%
29,000 3 Min 42,000 128.0 96 87 104 99.0 13 0% loz
J. se. 1,273 735.6 al 7% 95 (7.2 3 0, 100%
8,000 $65.0 % 67 83 98.0 12 0? 100%
2 Min, On Air 8,000 565.0 75 70 8997.5 15 ale
RD, 50 Sec. 8-40,000 182.0 10786 125 85.2 2 0, 100%
Don Mask) i Min. 40,000 141l0 98 87 9414 12 02 100%
31 Sec. 2 Min. 40,000 11.0 soe 95.0 2 05 100%
29,000 Fe. 3 Min. 40,000 141.0 woe 95.0 B 0} 100%
E. Me. 1,273 732.4 8170 3 96.0 15 Air
No De-Nitrogenation 8,000 73214 9 88 15 95.7 18 Air
RD, 49 Sec. 8-40,000 175.0 13580 10 84.0 18 0, 100%
Don Mask 1 Min. 40,002 1410 wo 135 145 99.0 19 05 100%
30 Sec. 2 Min, 40,000 MLl0 130112 135 99.0 21 » OF 100%
29,000 Ft. 3 Min. 40,000 14510 1285 25 99.0 19 0 100%
MEAN: 1,273 730.5 75.2. 66.6 86.0 96.0 13.6
8,000 565.0% 73.8%, 67.3% 83.3% 9B.1* 14.8
2 Min. On Air 8,000 565.0% 83.9 76.504 gs 15H 97 34k 160K
R,D, 49.6 Sec. 840,400 18011 109.8 76.5% 122.5 86.4 1416
Don Mask 1 Min. 40,400 138.4 10916 99.8% 1is'ae 95.8 13.4
30.8 Seconds 2 Min. 40,400 138.4 107,0* 95.3% 11217 96.4 13:2
29,200 Feet 3 Min. 40,400 138.4 103.8" 85.34* —108.3**# 96.6, 12.6
ery
*HN = 3 NOTE: Unless otherwise noted N= 5.
wee Ns 2

Appendix B 30 67-3068


‘Taste B11. Mask and Regulator Nitrogen Concentration, Calculated Tracheal-Oxygen
Partial Pressure, and Indicated Blood-Oxygen Saturation, Mask Donning Accomplished
During the Decompression.

Subject Ne Mask Pressure ?1y" 87) Fy, ger
and Altitude Barometric Regulator + Barometric P, 2 ‘2 Oximeter
—_— t Peak Min.
c. Pu 1,273 730.5 o 0 729.5 732.0 ©, 100%
8,000 565.0 oO oO 564.0 566. 100%,
2 Min, On Air 8,000 565.0 - - wont fe
RD, 51 Sec. 840,000 183.5 a) 187.5 0, 100%
Mask Don 1 Min. 40,000 141.0 an) 143.0 of 100%
30 Seconds 2 Min. 40,000 141.0 a) 145.0 of 100%
28,000 Feet 3 Min, 40,000 141.0 ar) 146.0 0% 100%
c. Pr 1,273 721.6 ar) ©, 100%
8,000 565.0 0 o 0, 100%,
2 Min. On Air 8,000 565.0 - - ake
RD, 49 Sec, 8-40,000 178.0 0 0 oO, 100%
Mask Don 1 Min. 40,000 141.0 oO 0 0, 100%
36 Seconds 2 Min. 40,000 141.0 0 0 of 100%
31,000 Feet 3 Min, 40,000 141.0 o o % 100%
B. Or. 1,273 732.3 7 . 95.0 Air
1y273 732.3 oo 95.5 0 10%
2 Min, On Air 8,000 565.0 o 0 99.5 05 100%,
R.D, 49 Sec, 8-42 ,000 182.0 0 0 93.0 0 100%
Mask Don 1 Min, 42,000 128.0 0 0 97.0 9, 100%
29 Seconds 2 Min. 42,000 128.0 0 0 99.0 0 100%,
29,000 Feet 3 Min. 42,000 128.0 an) 99.0 05 100%
J. Se. 1,273 735.6 a) 97.2 0, 100%
8,000 565.0 ar) 98:0 02 100%
2 Min, On Air 8,000 565.0 - + 97.5 ake
RD, 50 Sec. 8-40,000 182.0 ° o 85.2 Ly 100%,
Mask Don 1 Min. 40,000 141,0 o oO m4 oD 100%,
31 Seconds 2 Min, 40,000 141.0 0 ° 95.0 o 100%
29,000 Feet 3 Min. 40,000 141.0 o 0 95.0 0 100%,
30,000 226.0 - - 96.0 0 100%
1,273 735.6 - oa 95.0 % 100%,
BR, Me. 1,273 732.4 - oe %.0 0 Ate
No De-Nitrogenation 8,000 565.0 Air Air 95.7 Air
B.D. 49 Sec. 8-40,000 175.0 0 o 183.0 63.0 84.0 o 100%
Mask Don 1 Min, 40,000 141.0 ° o 152.0 100.0 99.0 0 100%
30 Seconds 2 Min. 40,000 141.0 0 0 151.0 100.0 99.0 05 100%
29,000 Feet 3 Min, 40,000 141.0 o ° 150.0 101.0 99.0 oD 100%,
wean: 730.48 of OF 89 SIH 728,68 731.5% 96.3
565,.00% oe Oe 279% tok 563.9% 566.4% 97.6
2 Min, On Air 565 .00me - - = Cal 97.3
RD, 49.6 Sec, 180,10 ° o 188.5, 87.2
Mask Don 1 Min, 138.40 0 0 148.8 95.8
30.8 Seconds 2 Min, 138.40 ° ° 167.5 96.4
29,200 Feet 3 Min, 138.40 0 ° 167.4 96.6

Appendix B

NOTE: Where not otherwise noted N= 5.

WOTE: Mean includes Subject E. Mc who was not de-nitrogenated, and Subject B. Or.

whose terminal altitude was 42,000 feet.



first breath may be observed. This merely in-
dicates that the necessary altitude (27,000 to
32,000 feet) had been attained to activate the
automatic pressure-breathing characteristics of
the regulator. The system then became free-
flowing until the mask was donned.

Small high-frequency spikes in the mask-
pressure record preceding the first breath appear
to be a result of changes in mask pressure
associated with donning and seating the mask
to the face.

Blood saturation as indicated by ear oximetry
exhibited a marked transient drop 6 to 12 sec-
onds after mask donning, being even more pro-
nounced in the subject who had not completed
denitrogenation. The delay due to lung-ear
circulation time as well as the delay in reestab-
lishing an adequate alveolar and cerebral pO,
as a result of nitrogen washout was anticipated.
These factors have been intensively and sepa-
rately investigated by Ernsting, Bryan, Luft,
Donaldson, and Clamann and are discussed in
detailed by Blockley and Hanifan.*

The impedance-pneumograph factor and heart
rate increased dramatically following the mask
donning during decompression. Data obtained
during rapid decompression and delayed mask
donning are summarized in Table B10, Bil,
and B12. |

It is anticipated that crew-member protection
may not be provided if decompression is very
rapid, donning excessively delayed, or the ter-
minal altitude and dwell time at altitude in-
creased. The conditions of this study ap-
proached the physiological limitations for which
mask design cannot be expected to compensate.
Other problems, such as the use of long breath-
ing hoses, which prior to decompression may
contain significant quantities of nitrogen and
require excessive time for washout, may be largely
eliminated by improved mask-mounted regulator
design.

IV. Discussion.

In the first phase, the plastic and aluminum
mask suspensions were evaluated.

In the second and third phases of the evalu-
ation, the aluminum suspension equipped with
the MBU5/P facepiece was used exclusively.

This military facepiece design incorporates a
rather wide, flexible, and extensive inner facial
seal, providing good pressure-breathing char-

acteristics. The technique of donning the mask
is illustrated in Figure Al4. Training should
emphasize the importance of applying sufficient
force in Step 2 so that the telescoping cylinders
are fully extended and the mask centered over
the face as in Step 3. The tension is then re-
laxed and the mask allowed to seat on the face
as shown in Step 4 of Figure Al4. If the cylin-
ders are not extended sufficiently and the mask
is applied by dragging it downward across the
face, the flexible MBU5/P facepiece will ex-
hibit a tendency to roll up within the hardshell
and produce extensive leakage and inadequate
protection.

Subjects donning the mask during rapid de-
compression did not hurry their donning pro-
cedure excessively, but donned the mask with
careful but rapid deliberation, aware that ex-
cessive delay due to fumbling or dropping of
the mask could result in loss of consciousness.

The decompressions with mask donning on
four of the subjects were not considered to be
as realistic as desired, as, for reasons of safety,
nonemployee crew-member subjects were denitro-
genated prior to rapid decompression. This
ruling was relaxed to some extent by allowing 2
minutes of air breathing prior to decompression
in an attempt to allow reestablishment of nor-
mal air breathing concentrations of nitrogen in
the lungs. Comparison of initial nitrogen wash-
out at ground level with nitrogen washout dur-
ing decompression following 2 minutes of air
breathing in Figure A15 indicates that 2
minutes of air breathing may not have been a
sufficient time.

Nitrogen-washout data obtained in a previous
study of a hanging quick-donning crew oxygen
mask are shown in Table B9. Subjects in
these experiments were rapidly decompressed
from 6,000 to 41,000 feet in 41 to 49 seconds
without prior denitrogenation. The mean nitro-
gen-washout curve of these subjects is included
in Figure A15 and falls midway between the
mean washout curve established at ground level
prior to decompression and the mean washout
curve obtained during decompression following
2 minutes of air breathing. It is probable that
the nitrogen-washout time of subjects used in
this series of decompressions would have been
in closer agreement with the previous decompres-
sions if they had been breathing air exclusively
prior to decompression.


‘Taste B2. Ventilation Volume, Pressure and Frequency During a Step-Function Alti-
tude Chamber Flight Profile to 43,000 Feet.

Win. Min. Tidal
Subject vol. vol, Vol. Mask Pressure
and Altitude Barometric L/Min, LMMin, cc. Resp. mm. Hg.
Gondi tion Feet Pressure ATPD __BTPS "_ BIPS ny Ex nsp, Gas
c, Pu. 5,000 632 6.26 7.10 444 16 -3.00 + .50 0, 100%
chal 18,000 380 5.22 6.25 391 16 -2,00 41.00 05 100%
Pressure 30,000 226 7.75 (10.34 57418 -2,00 41,00 05 100%
‘Schedule 43,000 122 7.20 12,021,098 45.00 +12.00 0 100%
40,000 141 8.32 13.09 1,190 11 20.00 +4.00 0, 100%
No Mask Removal 30,000 226 6.27 8.36 «9697, 12 =2.00 42.00 0, 100%
1,273 25 6.15 6.91 628 AL 2.00 42.00 0 100%
J. Se. 5,000 632 6.72 7.62 693 23.00 41.50 0, 100%
reial 18,000 380 5.70 6.815243 =3.00 41.50 0, 100%
Eressure 30,000 226 56113. -2,00 45,00 0) 100%
Schedule 43,000 122 65819. 44.00 +13.50 0 100%,
40,000 141 545011 41,00 46.00 0 100%
No Mask Removal 30,000 226 sere se sere 0; 100%
1,273 725 1,052 u “e700 42.00 0} 100%
B. Or. 5,000 632 6.53 7.41 529 16 +2,50 42,00 0, 100%
Military 18,000 380 5.70 6.81 35819 2.00 41.50 0; 100%
Pressure 30,000 226 5.9% 7,86 462 17 =2.00 +3.00 05 100%,
Schedule 43,000 122 16,64t 23,82t 1,254 19 411,00 +15.00% 0, 100%
40,000 141 5.72 8.95 6394 42.50 +8.00 0, 100%
"Prior to Mesk Removal 30,000 226 4139 5.81 48412 +1,50° 43.00 0} 100%
"Mask Removal 82,5 _Sec_30,000 226 Heart Rate Steady Increase From 82-125----- Air
a _. 2ry_30,000 226 8.78 11.71 650-18 4.00 43.50 0, 100% #
1,273 725 9100 10.11 919A 3.00 42.50 05 100%
c. Pr. 5,000 632 8.40 9,53 454d 3.00 +1.00 0, 100%
Military 18,000 380 6.12 7.334078 1,50 41,00 0} 100%,
Pressure 30,000 226 4.03 5.33314 17 21.00 42.00 0, 100%
‘Schedule 43,000 122 6.00 9,831,229 8 43.00 +15.00¢ 0) 100%
40,000 141 3.33 5.21580 9 4#2.00 +6.00 100%
226 Heart Rate Steady Increase From 80-132 Off-Scale Oise
226 3.96 5.2 0313 +1,00 42,00 0, 100%
14273 25 7.66 8.60 573 15 -2.00 41.50 05 100%
J. St. 1,273 725 9.47 gig 13 23.00 42.50 0, 100%
Commercial 5,000 632 9.90 701 16 3,00 42.00 0; 100%
Pressure 18,000 380 7.22 57615 =2.50 42.00 0, 100%
Schedule 30,000 226 4.85 431 15 _  -2.00 +100 03 100%
43,000 122 3.84 45814 45,00 49.00 0, 100%
40,000 141 3.33 327,16 40,00 43,00 0, 100%
T TMask Removel 35. 0"sec_30,000 226 2=*-He: Steady Increase Fron 96-120----- alr
_ — - Regovery_30,000 226 11,09 18 -3.00 43.00 0, 100%
1,273 725 9.64 sol 12 3.00 42.50 0, 100%
MEAN: 5,000 632 7.56 564.2 15.6 -2,90 +1.40
18,000 380 5.99 451.2 16.2 42.20 +1.40
30,000 226 5.61 468.4 16.0 #1,80 +2.40
43,000 122 7.83 938.4 14.2  +6.80 +12.90
— — -40,000 1 4.90 656.2 12.2 +1.10 45.40
“Removal 30,000 226% 612 7H BL3GHIR 697 OKI OH -2 OME? OHHH
73.3_Sec_30,000 226% Heart Rate Steady Increase From 86-126-----*
wery_30,000 226% 5.73% 10.77 624.6% 16.3% 2.66% 42,834
1,273 725 8.60 9.602 -814.6 12.0 =2,80 #2.10

*#N=3

** N= 2 Except where otherwise indicated N =

tee N = 1
+ No indication of outbaord leakage. @ Heart Rate Steady Decrease Off-Scale
In excess of transducer range. to 82 in 30 seconds.
# Heart Rate Steady Decrease From 1 Heart Rate Steady Decrease From

124-78 in 40 seconds, 120-87 in 50 seconds.

Appendix B 20


‘Taste B8. Instantaneous and Mean Heart Rates, Respiratory Rate, and Indicated Blood-
Oxygen Saturation. Mask Worn Prior to and Decompression.

Subject
and Altitude Barometer Heart © Cardiotachometer © Oximeter Respiration
Condition Feet Pressure Rate Min. Max, % Sat Rate Gas Inspired
c. Puy 1,273 737.3 n 67 86 98 11.5 0, 100%
8,000 565.0 % - - 96 11,0 0; 100%
R.D, 50 Sec. 8-40,000 250.0 n - 94.7 11.0 0; 100%
1 Min, 40,000 141.0 76 - 93.0 10.0 0; 100%
2 Min, 40,000 141.0 az - 93.0 9.0 0; 100%
3 Min. 40,000 141.0 8 - - %.0 8.0 0 100%
c. Pr. 1,273 734.6 - - -- 97.0 -- 0, 100%
8,000 565.0 91 75 13 96.0 10.0 0; 100%
R.D. 49 Sec. 8-40,000 250.0 89 65 109 95.0 11.0 0; 100%
1 Min. 40 ,000 141.0 = - - 93.5 10.0 0, 100%
2 Min, 40,000 141.0 = = -- 93.5 11.0 0, 100%
3 Min. 40,000 141.0 98 80 112 93.5 8.0 0, 100%
B, Or, 1,273 735.6 87 97.0 18.0 0, 100%
8,000 565.0 96 96.5 16.0 04 100%
R.D, 49 Sec. 8-40,000 250.0 7 95.0 19.0 0; 100%
1 Min, 40,000 141.0 -- 94.5 15.0 0; 100%
2 Min. 40,000 141.0 - 95.0 14.0 ‘02 100%
3 Min. 40,000 141.0 -- - 95.0 14.0 02 100%
J. Se. 1,273 732.4 76 70 87 97.5 14.0 ©, 100%
8,000 565.0 23 65 87 97.5 9.0 0, 100%
R.D, 49 Sec. 8-40,000 250.0 82 2 100 97.2 11.0 05 100%
1 Min. 40,000 141.0 % 82 102 96.0 10.0 0; 100%
2 Min. 40,000 141.0 9 85 100 95.1 10.0 0; 100%
3 Min. 40,000 141.0 92 84 105 95.0 10.0 0; 100%
J. Si. 1,273 737.0 -- - -- 97.0 14.0 0, 100%
8,000 565.0 82 70 98 97.0 14.0 0; 100%
R.D. 53 Sec. 8-40,000 250.0 87 7 105 96.0 13.0 0} 100%
1 Min. 40,000 141.0 9% 84 104 95.0 14.0 0; 100%
2 Min, 40,000 141.0 1 85 105 95.0 14.0 0% 100%
3 Min, 40,000 141.0 = — = 94.0 14.0 05 100%
MEAN: 1,273 735.4 74.3% 68,3 866 97,3 14
8,000 565.0 79.6 70,5* 100.0 96.6 12.0
R.D, 50 Sec. 8-40,000 250.0 82.8 72.0% = 102.8 = 95.6 13.0
1 Min, 40,060 141.0 88.0% — 830m — 103 Oi 94.4 12.0
2 Min, 40,000 141.0 89,30 — 85D 102 SH 94.3 11.6
3 Min. 40,000 141.0 89.3% 2.0m 108. SHH 94.3 10.8
Nh
we 3 NOTE: Where not otherwise indicated N 5,
fk N= 2

Appendix B 26


catheter tubing. The inspired tracheal-oxygen
partial pressure is calculated from the following
equation:
Pr= (B-47)F,
o oO
2 2

Where

B=Ambient barometric pressure
47=Vapor pressure of HO at body temper-
ature (37°C) and 100% saturation

F,=10—-F,
° N
2 2

The 0.03% CO, in the ambient air is negligible
and may be disregarded.

Pressure-breathing characteristics of regula-
tors are given in Table B1 (all tables are in
Appendix B). A Technology Inc. Model MFM-
150-1 mass flowmeter was interposed in the sup-
ply hose between the regulator and the mask. A
Statham pressure transducer of 15 mm range
was connected through an orifice in the mask.
Telemedics EKG electrodes were carefully lo-
cated to produce a maximal signal with a mini-
mum of muscle-potential interference. The
signal was split and fed into a Waters Cardio-
tachometer and an EKG monitoring oscilloscope.
All signals were fed into a 14-channel visicorder
for direct read-out. Nitrogen analyzers provide
a convenient method of quantitatively deter-
mining the extent of inboard leakage of air and
the resultant dilution of inspired oxygen, pro-
viding the subject has previously completed
respiratory-nitrogen washout.

The mass-flowmeter signal was fed into an in-
tegrator so that, after a specified volume had
been sensed, the unit would discharge and re-
peat. This was set at one liter NTPD. Therefore,
all volumes required correction for chamber pres-
sure, temperature, and saturation. The minute
volume was recorded in terms of NTPD and
converted to ATPD and BTPS conditions. The
minute volume was not necessarily a true respira-
tory minute volume but rather a measure of the
inspired-oxygen volume flowing to the subject
upon demand or pressure. It is obvious that in-
board or outboard leakage at the mask algebra-
ically influences this measurement. Provisions
for estimating inboard and outboard leakage

were included in the experimental design allow-
ing for correction of the minute volume when
warranted. .

Inboard leakage may be determined by
measuring the amount of nitrogen-containing
ambient air (a convenient reference gas) enter-
ing the mask when the subject has completed
respiratory nitrogen washout while breathing —
100% oxygen. Outboard leakage can be detected
and estimated during pressure breathing by ob-
serving and measuring the slope of the mass-
flowmeter record during the respiratory pause
and exhalation. During the respiratory pause
and exhalation, the mass-flowmeter record should
be flat.

Outboard leakage is indicated in Figure A8
during pressure breathing. It was outstanding
during the first and second minutes, but ceased
at the end of the second minute, An estimate
of ‘the volume of leakage may be obtained by
measuring the mean slope of the flowmeter re-
cording during respiratory pause. Leakage may
fluctuate during expiration and_ inspiration.
Motion pictures were taken at maximum alti-
tude and during rapid decompression. Closed-
circuit television was used to monitor the subject’s
activity during the flight.

The minute volume, more accurately designated

MV, in accordance with standardized symbols,
+ was divided by the respiratory frequency (f)
to obtain the mean tidal volume (TV), ie.:
My,

t

TV=

where:
MV,=volume of gas inspired/minute

TV=mean volume of gas inspired per breath

f=respiratory frequency or number of breaths .
per minute

— =indicates a mean value

v= gas volume per unit of time

Individual tidal volumes may also be read
from the mass-flowmeter recording.

The second phase utilized a profile that con-
sisted of an ear check and a dwell time of 25
to 30 minutes at 8,000 feet to complete denitroge-
nation. The subject was then rapidly decom-
pressed from 8,000 to 40,000 feet in 45 to 50
seconds while wearing the mask. Instrumenta-
tion was similar to that used in the first phase


Mant Op Flow 1 Liter NTPO

Ficure A9, Rapid decompression wearing the mask. Subject CPu. I-Impedance
pneumogram.

Mots Op Flow Liter NTPO

40~ =

T
Figure Al0. Rapid decompression wearing the mask. Subject CPr. I-Impedance
Pneumogram.

Appendix A 13



ag-
naz

gu

Mass Op Flow | Liter NTPD.

eel ! 3
As = FHT sin

160 fee AadiibiabbebebeeeeAN AES MANA po sada

140 = = = =

B
8

Heart Rote beats per minute

Fioune A138, Rapid decompression wearing the mask. Subject JSe. I-Impedance
pneumogram,

Freure Al4. Mask-donning procedure. If equipped with the soft and flexible MBU5/P
facepiece, sufficient tension should begin to be applied at position 2 so that the
telescoping asembly is extended as the mask is brought down over the face to posi-
tion 3. If allowed to drag over the face during this motion, the facepiece may be
rolled up and distorted within the hardshell.

Appendix A 15



EVALUATION OF THE SIERRA, HANGING, QUICK-DON, CREW,
PRESSURE-BREATHING, OXYGEN MASK

I. Introduction.

Since the introduction of jet transports certi-
fied to operate at altitudes up to 41,000 feet,
there have been numerous changes and modi-
fications of crew oxygen masks in an attempt
to provide better comfort, protection, and don-
ning capability. Most of the early jet-transport
quick-don oxygen masks were designed to be
worn by crew members somewhat as personal
items of equipment that could be rapidly donned
in the event of a decompression. Crew resistance
and maintenance problems associated with these
masks have fostered the development of the
hanging quick-don crew oxygen mask, which is
regarded in some cases as a cockpit item. It is
not the purpose of this paper to compare the
merits and deficiencies of these two systems. The
primary objective is rather to determine the
physiological adequacy and protective efficiency
of a new hanging quick-don oxygen mask design
at altitude and during rapid decompression.
This should precede its installation in aircraft.
Other related parameters, including comfort,
crew member performance, communication, and
mask-donning capability, were evaluated.

The evaluation was performed in three phases.
The first phase consisted of exposing crew mem-
bers to a chamber flight profile as shown in fig-
ure Al, with a maximum altitude of 43,000 feet
while wearing the mask. The second phase con-
sisted of rapidly decompressing crew members
from 8,000 to 40,000 feet in 45 to 50 seconds
while wearing the mask. The third phase con-
sisted of rapidly decompressing these same
subjects from 8,000 to 40,000 feet in 45 to 50
seconds and donning the mask during the de-
compression. The donning signal was delayed
for 15 seconds after passing through 14,000 feet
during the decompression.

Since the subjects were well aware that they
were to be decompressed, the basic 15-second
delay was adopted after studying Bennett’s' in-

flight determinations of the reaction and don-
ning time of 42 BOAC pilots subjected to sur-
prise decompressions during training flights.
It was anticipated that trained subjects would
require approximately 5 seconds to accomplish
donning following the donning signal. This
would result in a total donning delay of approxi-
mately 20 seconds after passing through 14,000
feet. An analysis of Bennett's data by Blockley*
indicates that 99% of the pilots would have
completed donning within this time period.
Time-motion analysis of motion picture films
taken during these decompressions shows that
crew members accomplished mask donning in an
average time of 4.80 seconds with a range of 2.5
to 6.29 seconds. These data are in general agree-
ment with the data of Barron and Cook*® who
stated that their trained subjects required a mini-
mum of 8 to 4 seconds to accomplish donning.

II. Methods.

The first phase of the evaluation was based
on the chamber flight profile as shown in Figure
1. Five subjects were used in these evaluations.
Three of the subjects were transport pilots, one a
flight engineer student pilot, and the fifth subject
a chamber research technician student pilot.

After instrumentation, the subject was seated
in the chamber at the controls of a performance-
testing device to be described later. An ascent
to 10,000 feet followed by a descent to 5,000
feet was performed to assure ear-clearance
capability. The mask was then donned and the
subject placed on 100% oxygen. Denitrogenation.
was thereby initiated and allowed to continue for
approximately 30 minutes at 5,000 feet. During
denitrogenation various instrumentation checks
and calibrations were performed. The subject
was instrumented as shown in Figure A2% A
Custom Engineering and Development 300 AR
nitrogen analyzer continuously sampled gas from
the mask through a 0.03-inch-diameter micro-



‘Taste B6 Ventilation Volume, Pressure, and Frequency During Rapid Decompression
From 8,000 to 40,000 Feet. Mask Worn and Regulator in 100% Oxygen Position Prior
to and During the Decompression.

Vy Vy
Min. Min, Tidal
Subject. Barometric Vol, Vol. Vol. Impedance Mask Pressure
and Altitude Pre: Li L/Mi cc. ip.  Pneumograph mm. Hg
Condition Feet mm, Hg. ATPD __BTPS BIPs Rat Factor Insp. Exp, Insp, Gas
Cc. Pu. 1,273. 737.3 6.44 7.23 628 «(11,5 215 +1.0 0, 100%
8,000 565.0 5.49 28 570 11.0 -2.0 +1.0 0, 100%
RD. 50 Sec. 8-40,000 250.0 6.22 8.03 730-11.0 “215 +6.0 0, 100%
1 Min, 40,000 141.0 6.65 10,47 1,047 10.0 +4.0 47.8 Oo, 100%,
2 Min. 40,000 141.0 3.74 5.88 653° 9.0 +4.0 +6.0 Oo, 100%,
3 Min. 40,000 141.0 4.21 6.63 828 «8.0 +3.0 46.0 0, 100%
Cc. Pr. 8,000 565.0 6.56 7.51 751 10.0 1.00 -2.0 +1.0 o, 100%
B.D. 49 Sec, 8-40,000 250.0 3.60 4,65, 423, 11.0 73 2.0 +7.0 0, 100%
1 Min. 40,000 141.0 13,30 20,95. 2,095. 10.0 1.30 +3.0 +6.0 o 100%
2 Min. 40,000 141.0 12.40 19.559 1,777§ 11.0 1,50 43.0 +6.0 0, 100%
3 Min. 40,000 141.0 10.50 16.53° 2,066 8.0 1.10 43.0 46.0 0, 100%
B. Or. 1,273 735.6 6.00 6.74 374 18.0 0, 100%,
8,000 565.0 5.20 5.95 372 16.0 0, 100%
RD, 49 Sec. 8-40,000 250.0 7.52 9.72 $12 19.0 oD 100%
1 Min. 40,000 141.0 8.63 13.59 — 906.-:15.0 0 100%
2 Min. 40,000 141.0 7.49 11.79 842 14,0 0) 100%
3 Min. 40,000 141.0 7.49 11,79 842 14.0 0 100%
J. Se. 1,273 732.4 4.33 4.87 348 14,0 . +1.0 o 100%
8,000 565.0 3.17 3.63, 403, 9.0. 1. 41.0 0, 100%,
R.D. 49 Sec. 8-40,000 250.0 2.29% 2,95" 268*11.0* 3, +13.0 05 100%
1 Min. 40,000 141.0 4.62 7.27 727° (10.0 2. 48.5 0, 100%
2 Min. 40,000 141.0 3.46 5.46 = 546 10.02. 48.0 0} 100%
3 Min. 40,000 141.0 3.46 5.46 = 546 10.02. 48.0 0) 100%
J. St. 1,273 737.0 8.11 9.12 651 14.0 42.0 0, 100%
8,000 565.0 7.36 8.43 602 14.0 41.0 05 100%
R.D. 53 Sec. 8-40,000 250.0 6.22 8.03 618 13.0 +120 0, 100%
1 Min. 40,000 141.0 6.91 10.87 776 14,0 +8.0 oD 100%
2 Min. 40,000 141.0 4,58 7.22 516 14,0 +7.0 0, 100%
3 Min. 40,000 141.0 4.58 7.22 516 14.0 +6.0 oD 100%,
Post B.D. 1,273 737.0 7.44 8.36 557 (15.0 +1.0 0, 100%,
‘MEAN: 1,273, 735.5 6.22 6.99 500 14.4 75 41.2 0, 100%
8,000 565.0 5.56 6.36 539 12.0 1.00 41.2 0, 100%
R.D, 50 Sec. 8-40,000 250.0 5.17 6.87 510, 13.0 2.84 +8.8 05 100%
1 Min. 40,000 141.0 9.34 12.638 21,1108 11,802.71 47.66 0, 100%
2 Min, 40,000 141.0 7.729.988 "867" 10,1. -2..55 46.2 0% 100%
3 Min. 40,000 141.0 6.05 9.75 968 10.8 2,12 46.4 05 100%

corrected for outboard leakage during pressure breathing.
akage values in BTPS.

(b) Values corrected for outboard leakage of 10.4 L/Min.

(c) Values corrected for outboard leakage of 10.9 L/Min.

(4) Outboard leakage terminated.

* Values omitted in calculation of mean,

Appendix B 24


ACKNOWLEDGEMENTS

The authors acknowledge the assistance provided by R. K. Coulter, United
Airlines. In addition acknowledgement is due Dr. C. M. Brake, M. D.; W. F.
O’Connor, Ph.D.; C. W. Barnard; H. F. Harrison; B. Harbin; J. M. Simpson;
J. W. Fitch; and F. F. Winters, whose contributions made this evaluation
possible.

Qualified requestors may obtain Aviation Medical Reports from Defense Documentation
Center. The general public may purchase from Clearinghouse for Federal Scientific and
Technical Information, U.S. Dept. of Commerce, Springfield, Va, 22151


‘Taste B9. Respiratory Nitrogen Washout, Mask-Donning Time, and Decompression

Profile of Subjects Utilizing the Hanging-Type Puritan Sweep-on Mask, Equipped With

the Semi-Rigid Face Piece During a Chamber Study Conducted June 1963. Rapid De-
compression from 6,000 to 41,000 Feet.

BART RATE. NUTROGEN WASHOUT.
Donning Donning Donal
Following Mask Donning Sigal’ Tine’ Aleitude
Heart During Decompression Altitudes Tine Alettude in 4a
ett a ime % Nitrogen — a
SURE
Ground Level 1,273 ss 80.0% 6,000-16,000 5.8
Pre &, 6,000 60 47. 14;000-25,000 8:5
start BR, 641,000 111 19.5%
End B.D, 41,000 90 aot ‘Total Dec
Resting AG, L, 14273 wb oe Pine 6-415000 207-3 Bee.
3
2108.
‘MET Ka 8.
Ground Level 1,273 60 Ko.0% 6,000-14,000 4.5
Pre B.D, sio0 5 46.0% 147000-25,000 10.0
Stare B.D, 6,000- 99 40.0% s
61,000 ‘Total Decompression
End B.D. 41,000 66 26.0% Thee 6-41,000 = 45.0 Bec,
Resting ACG, L. 1,273 60 19:08
Te
3.0%
MET RT.
— 0 sec, “tK0.0n 6,000-16,000 5.5
7 15 Sec, 36.0%, 14000-25000 8.0
102 30 Sec. 15.0% 25 ,000- 4
‘Total Deconprevaton
End B.D. 4 102 45 Sec, 6.0% ‘Time 6-41,000 = 41,0 Sec.
Resgine AvG.L, 4,273 72 1 iin, 5.08
min, 1.0%
3Min, 0.0%
GRE
Ground Level 127378 40.0% 6,000-14,000 3.0
Pre B.D. 6,000 78 23.0% 14,000-25 ,000
start B.D, 61000- 84 9.0%
41,000 ‘Total Decompression
and B.D. 41,000 90 $m Tine 6-41,000 = 49.0 Sec.
2k
2.0%
1st
SUE GB
Ground Lavel 1273 see $0.0%, 6,000-14,000 4.5,
Pre B.D. 600069 70.0% 147000-25,000 9.0
Start B.D. 6,000- aL 13.0%
“61,000 "Total Decompression
End B.D. 419000" 87 2.0 ‘Tine 6-61,000 © 42.5 Sec,
olon
0.0%
AUBUECT Dade
Ground Lavel 127991 80.0% 6,000-16,000 3.0
De 61000117 20.0% 14,000-25,000 9.3
start 2.0, $1000- 147 sion
i "41,000 ‘Focal Decompres
nd B.D. 41,000,162 2.0% tine 661,000 + 62.0 Sec.
Beating G. L, 1,273 108 2.0% This eubject developed acute hyperventilation
0.08 syndrom. We responsive Coo! to
. UZeeiie’commatcatton watil 16,500
during emergency descent.
Ag
Ground Level 80.0% 6,000-14,000 5.05
Pre 8.0, 40.0% 167000-25,000 8.92
start R.D, 16.9%
"Total Decompression
Rod B.D, fed ine 6-41,000 = 44,5 See.
Bascing At G.L. om
2.38
1k

Excapt where othervise indicated = 6.

Appendix B 27



Figure A5. Mask removal and redonning at 30,000 ft. Subject BOr. Phase 1.

enn a seme

a eis

Ficure A6. Mask removal and redonning at 30,000 ft. Subject CPr. Phase 1.

Appendix A 11



Appendix A

Moss Op Flow | Liter NTPO

a 40-F

gon- F30-£

40-

‘igure All. Rapid decompression wearing the mask. Subject BOr. I-impedance

Moss Op Flow | Liter NTPD.

pneumogram.

Figure Al12. Rapid decompression wearing the mask. Subject JSi. I-Impedance

pneumogram.

14