nasa technical memorandum...nasa technical memorandum imasatm x- 62,311 v)

NASA TECHNICALMEMORANDUM

IMASATM X- 62,311

V)<z

EVALUATION OF +GZ TOLERANCE FOLLOWING

SIMULATED WEIGHTLESSNESS (BEDREST)

Lester B. Jacobson, Kenneth H. Hyatt, Robert W. Sullivan,and Stephen A. Cantor

Department of MedicineU.S. Public Health Service HospitalSan Francisco, Ca.

and

Harold Sandier, Salvadore A. Rositano, and Ronald Mancini

Ames Research CenterMoffett Field, Ca. 94035

August 1973

https://ntrs.nasa.gov/search.jsp?R=19740001979 2020-06-20T23:13:23+00:00Z

CONTENTS

A. Introduction

B. Experimental Design

1. General

2. Detailed Protocol

a. Daily Procedures

b. Urine Collection and Analysis

Co Blood Chemistries and Hematology

d. Isotopic Volume Studies

e. 70° Tilt Studies

f. Lower Body Negative Pressure (LBNP) Studies

g. Exercise Studies

h. Centrifuge Studies

i. Metabolic Dietetic Program

3. Methodology

a. Biochemical Methods

bo Multiple Isotopic Volume Studies

c. 70° Tilt Studies

d. Lower Body Negative Pressure (LBNP) Studies

e. Exercise Studies

f. Centrifuge Studies

C. Results

1. Analysis of Data

2. General Data

3. Sodium Balance Studies

4. Potassium Balance Studies

5. Fluid Balance

6. Urine Creatinine Determinations

7. Serum Chemistries

8.' Isotopic Body Fluid Compartment Studies

9. 70° Tilt Studies

10. Lower Body Negative Pressure (LBNP) Studies

11. Exercise Studies

12. Centrifuge Studies

D. Discussion

E. References

III

F. Tables

1. General Data

2. Sodium Intake

3. Urine Sodium Excretion

4. Sodium Balance

5. Sodium Balance, Statistical Analysis

6. Potassium Intake

7. Urine Potassium Excretion

8. Potassium Balance

9. Potassium Balance, Statistical Analysis

10. Fluid Balance Summary

11. Fluid Balance Summary, Statistical Analysis

12. Urine Creatinine

13. Serum Chemistries

14. Body Fluid Compartments

15. Body Fluid Compartments, Statistical Analysis

16. Hematocrits

17. Heart Rate Response to 70° Tilt and Recovery

18. Blood Pressure Response to 70° Tilt and Recovery

19. Pulse Pressure Response to 70° Tilt and Recovery

20. Heart Rate Response to LBNP and Recovery

21. Average Heart Rate During LBNP

22. Maximum Heart Rate During LBNP

23. Maximum Heart Rate During LBNP, Statistical Analysis

24. Blood Pressure Response to LBNP and Recovery

IV

25- Rtf« Pressure Response to LBKP and Recovery.

M- »-rt Rate Response to Exercise and Recovery

«. Response to &ercl.e! Oxygen Consumption

»• "erive, Maxtnal ^ Vpc^ ^

». Centrifuge Studies: Heart fat. Response

30. Centrifuge Studies: Heart Rate Response to +3 2 c'

• Centrifuge Studies: Heart Rate Response to +3.8 o'

-rt Rate .riwg Centrifuge Studies, statLiCil .alysis

V

ABSTRACT

This study was undertaken to evaluate the magnitude of physiologic

changes which are known to occur in human subjects exposed to varying

levels of +G acceleration following bed rest simulation of weightlessness.z

Bed rest effects were documented by fluid and electrolyte balance studies,

maximal exercise capability, 70° passive tilt and lower body negative

pressure tests and the ability to endure randomly prescribed acceleration

profiles of +2G , +3G , and +4G . Six healthy male volunteers were studiedz z z

during two weeks of bed rest after adequate control observations, followed

by two weeks of recovery, followed by a second two-week period of bed

rest at which time an Air Force cutaway anti-G suit was used to determine

its effectiveness as a countermeasure for observed cardiovascular changes

during acceleration. Results showed uniform and significant changes in

all measured parameters as a consequence of bed rest including a reduced

ability to tolerate +G acceleration. The use of anti-G suits significantlyZ

improved subject tolerance to all G exposures and returned measured para-

meters such as heart rate and blood pressure towards or to pre-bed-rest

(control) values in four of the six cases.

VI

A. Introduction

Design limitations existent in the planning of the space shuttle

vehicle may be such that crew and passengers will be exposed to head-

ward acting (+G ) acceleration stresses of 2 to 4 G for periods of upz

to about 700 seconds. These periods of stress would occur following

periods of weightlessness, i.e., exposure to a "zero" gravitational

state, of various durations. Previous studies in this laboratory and

elsewhere utilizing bedrest as an analog of weightlessness, have docu-

mented changes in body fluid compartments and deterioration in exercise

(1 > 2)capabilities. ' These studies have also demonstrated that ortho-

static hypotension and even syncope may occur upon 70° passive tilting

(equivalent to a + 1 GZ stress) following periods of simulated weight-

lessness, suggesting that post-bedrest exposure to even higher accel-

eration stresses would exaggerate the undesirable orthostatic responses.

Therefore, the present study was undertaken to evaluate the magnitude

of the physiologic changes which would occur in humans exposed to +2.1 G ,z

+3.2 G , and +3.8 G stresses achieved in the human centrifuge followingz z *

bedrest simulations of weightlessness. A leading hypothesis explains

the observed decrease in orthostatic tolerance following weightlessness

to pooling of blood and extracellular fluid in the extremities and pelvis

in the presence of already diminished plasma and extracellular fluid

volumes. For this reason, the modifying effect of an inflated standard

Air Force cutaway G-suit on physiologic responses to these +G stressesZ

was evaluated.

B. Experimental Design

1. General

Healthy male volunteers, ages 24-27 years, served as subjects for

this study. All volunteers were recruited from the Federal Correctional

-2-

Institution, Lompoc, California, by permission of the U.S. Bureau of

Prisons. They were screened initially by the Medical Staff of F.C.I.-

Lompoc to exclude major or chronic health defects, and potential volun-

teers were subjected to a 70° passive tilt for twenty minutes to exclude

the presence of autonomic insufficiency. A tilt table with English

saddle was provided to the F.C.I, staff for this purpose.

On completion of the screening procedure, the volunteers were trans-

ported to the U.S. Public Health Service Hospital, San Francisco, California,

and admitted to the Metabolic Unit. A complete medical history was ob-

tained and a complete physical examination was performed. The following

laboratory tests were done and were normal: 12 lead electrocardiogram,

PA and lateral chest x-rays, complete blood counts, serum sodium,

potassium, CC , chloride, phosphate, calcium, total protein, albumin,

globulin, alkaline phophatase, bilirubin, glutaaic-oxalacetic-

transaminase (GOT), creatinine, fasting blood glucose, blood urea

nitrogen, VDRL, and complete urinalysis with microscopic examination.

The details of the study were explained to each subject verbally

and in writing, and each subject signed an informed consent form.

Each volunteer was prescribed a specific metabolic diet throughout

the study. The dietetic aspects of the study are covered in the detailed

protocol. Eight to nine days on this diet were allowed for an equili-

bration period. During this time the volunteers were instructed in

urine collection and in intake recording by the metabolic nurses.

The study consisted of five phases .(which followed the 8-9 day

diet equilibration period): a 14 day ambulatory period (A 1-14); a

15 day bedrest period (B 1-15); a 14 day recovery period (R 1-14); a

second 15 day bedrest period (B'l-15); and a second 14 day recovery

period (R'l-14). During the ambulatory phases the environmental

-3-

temperatures were maintained as nearly constant as possible, and no

exercise except normal walking was permitted in an attempt to avoid

large differences in insensible salt and water losses between the

ambulatory and bedrest phases. While at bedrest, the horizontal

position was required at all times with unrestricted movement in

this plane. Arm movement was limited to forearm raising with elbows

on the bed, and one pillow was permitted for head support. All oral

consumption and all excretory activities were performed in this

position. Excessive boredom was avoided by the use of radio,

television, reading material, and games.

2. Detailed Protocol

a. Daily Procedures

1) Temperature, pulse, and blood pressure measurementonce daily.

2) Determination of body weight on a metabolic balanceimmediately after completion of 7:30 AM urine collection.

3) Determination of oral fluid intake and urine output.

b. Urine Collection and Analysis

1) Twenty-four hour collections were made daily. Eachvoided sample was placed in a gallon container withoutpreservative. The urinal was rinsed with 50 ml ofdistilled water which was also poured into the container.The sum of the rinsing volume was deducted from the total24 hour volume to determine urine output. Total volumewas utilized in calculating chemical data. All urineswere refrigerated until sample aliquots were obtained,and the aliquots were frozen. Some daily aliquots werekept separate where necessary to show acute changes,and others were pooled. Pooling of the 5-7 day sampleswas accomplished by combining 10% volume aliquots ofeach sample into a single sample.

2) Urine Specimens Analysis

All samples were analyzed for Na, K, and creatinine.

..4-

c. Blood Chemistries and Hematology

Blood samples were drawn on Days A3, A9, B2, B13(or 14),R9, .B'2, B'14, R'12(or 13).

These were analyzed for Na , K , and hematocrit.

d. Isotopic Volume Studies

125Plasma volume was determined by I-RISA, extracellular

82 51fluid volume by Br, red cell mass by Cr, and total

3body water by 1^0 on the same days as the drawing of

blood samples listed above.

e. Tilt Studies

70° tilt studies were performed on Subjects 1 and 2 on

Days A13, B15, R13, and B'15. Tilt studies were not

performed on Subjects 3,4,5 and 6 who were subjected,

instead, to lower body negative pressure (LBNP) studies

(vide infra).

f. Lower Body Negative Pressure (LBNP) Studies

These studies were performed on Subjects 3,4,5 and 6

on Days A13, B15, R13, B'15, and R'14.

g. Exercise Studies

These studies were performed on Subjects 1 and 2 on

Days A13, B15, R13 and B'15 following recovery from the

tilt studies; and on Subjects 3,4,5 and 6 on Days A13,

B15, R13, B'15, R'14 following recovery from LBNP studies.

h. Centrifuge Studies

In all subjects, three training runs were performed in

the nine diet equilibration days before the start of the

first ambulatory period, and formal (data) studies were

performed on Days A14, Rl, R14, and R'l, i.e., 24 hours

following the tilt or LBNP and exercise studies.

-5-

i. Metabolic Dietetic Program

All subjects were on a specific diet for the 8-9 day diet

equilibration period and throughout the entire study. Each subject

selected a menu of his own choice consisting of three meals and an

evening snack. The research dietician then calculated the nutrient

content of the chosen menu. Distilled water intake was allowed

ad lib, and a record of the volume consumed was recorded. The diet

was well-balanced, designed to maintain the subjects' body weight,

and the subjects ate all of the prescribed diet.

When particular diets were calculated to be inadequate

in vitamins, supplementation was given. Specific diet details are

elaborated below.

Subjects 1 and 2:

These subjects were fed a formula diet, prepared in the hospital's

main kitchen, with caloric values calculated to maintain body weight.

Each day the caloric intake and protein, fat, carbohydrate, sodium

and potassium contents of food consumed that day were calculated

from food content tables. The ranges of specific daily values are

listed below:

Diet Subject 1 Subject 2

Calories 2674 - 2983 2704 - 3066

Protein, grams 101.1 - 114.4 98.2 - 115.4

Fat, grams 130.3 - 157.0 129.4 - 140.4

Carbohydrate, grams 243.4 - 308.6 260.8 - 314.0

Sodium, milliequivalents 160.4 157.0

Potassium, milliequivalents 88.0 98«2

-6-

Sublects 3 and 4:

These subjects consumed a semi-metabolic balance diet using

Armour frozen dinners for entrees. Most foods other than the frozen

dinners were weighed, but a few foods (e.g., milk, bread, eggs) were

not weighed. Two daily menus were used in rotation for each subject,

the menus of each subject being slightly different (Tables A and B).

The nutrient compositions of the diets for Subjects 3 and 4 shown in

Table C were calculated from food content tables and from data

furnished by Armour Laboratories. These calculated values were used

as the daily intake in the calculation of sodium and potassium

balances. .

Subjects 5 and 6:

These subjects consumed a metabolic balance diet with three

rotating menus:v

Menu # 1 - served on Mondays, Wednesdays and Fridays

Menu # 2 - served on Tuesdays and Saturdays

Menu # 3 - served on Thursdays and Sundays.

The menus were the same for both subjects, and calories and

sodium were calculated to be about the same on all three menus

(Table D). Aliquots of the diet were analyzed for sodium and

potassium on Days A5, A9, AID, B13, B14, B15, B'l, B'2, B'3, B'13,

B'14, B'15; i.e., four aliquots of each of the three diets were

analyzed during the study. The results of these analyses and a

comparison with the calculated values are shown in Table E. The

calculated and analyzed values agree quite well. The average

analyzed values for the particular diet (1,2 or 3) consumed on

any given day were used to calculate sodium and potassium balances.

Breakfast

Lunch

Dinner

Snack

-7-

TABLE A

MENUS FOR SUBJECT 3

Menu # 54

Orange juiceCornflakesFried eggs (2)White toast (2 si.)ButterJellyWhole milkSugarPepper

,u

Pot Roast Beef Dinner(Rice, carrots, gravy)

LettuceTomatoFrench dressingWhite bread (1 si.)ButterApplesauceGraham crackers (2)Whole milkInstant teaSugarPepper

Baked Chicken Dinner(Baked pot., Green beanswith mushrooms)

LettuceMayonnaiseWhite bread (1 si.)Butter''Dropped cookie (1)Whole milkInstant teaSugarPepper

Instant coffeeCanned pears

Menu #56

Pineapple juiceOatmealFried eggs (2)White toast (2 si.)ButterJellyWhole milkSugarPepper

*Veal Patty Dinner

(Sweet potatoes, peas)LettuceFrench dressingWhite bread (1 si.)ButterVanilla wafers (4)Whole milkInstant teaSugarPepper

Filet Mignon Dinner(Baked pot., Green beanswith mushrooms)

LettuceTomatoMayonnaiseWhite bread (1 si.)Vanilla ice creamWhole milkInstant teaSugarPepper

Instant coffeeCanned peaches

2.0 grams NaCl for the day 2.6 grams NaCl for the day

Armour Frozen Dinners (Hospital Fare - Modified Diet)

Breakfast

Lunch

Dinner

Snack

-8-

TABLE B

MENUS FOR SUBJECT 4

Menu # 53

Orange juiceCornflakesPoached eggs (2)Whole wheat toast (2 si.)ButterJellyWhole milkSugarPepper

*Pot Roast Beef Dinner(Rice, carrots, gravy)

LettuceTomatoFrench dressingWhole wheat bread (1 si.)ButterApplesauceWhole milkInstant coffeeSugarPepper

*Baked Chicken Dinner(Baked pot., Green beanswith mushrooms)

LettuceMayonnaiseWhole wheat bread (1 si.)ButterWhole milkPepper

Instant coffeeSugarCanned pears

Menu #55

Pineapple juiceOatmealPoached eggs (2)Whole wheat toast (2 si.)ButterJellyWhole milkSugarPepper

*Veal Patty Dinner

(Sweet potatoes, peas)LettuceFrench dressingWhole wheat bread (1 si.)ButterVanilla wafers (2)Whole milkInstant coffeeSugarPepper

Filet Mignon Dinner(Baked pot., Green beanswith mushrooms)

LettuceTomatoMayonnaiseWhole wheat bread (1 si.)ButterVanilla ice creamWhole milkPepper

Instant coffeeSugarCanned peaches

2.6 grams NaCI for the day 3.0 grams NaCl for the day

Armour Frozen Dinners (Hospital Fare - Modified Diet)

-9-

TABLE C

CALCULATED NUTRIENT COMPOSITION OF SEMI-METABOLIC DIETS

Nutrient

Calories

Carbohydrate

Fat

Protein

Nitrogen

Calcium

Phosphorus

Sodium

Potassium

Magnesium

Iron

Vitamin A

Thiamin

Ribof lavin

Niacin

Vitamin C

Unit

grams

grams

grams

grams

mg.

mEq.

mg.

mg.

mEq.

mg.

mEq.

mg.

mEq.

mg.

IU

mg.

mg.

mg.

mg.

Subject

Menu 54

2768

281.6

133.2

110.7

17.71

1157

57.73

1631

3336

145.04

3734

95.74

298

24.50

12.3

5952

2.94

3.36

38.4

152

3

Menu 56

2770

268.5

140.4

108.2

17.31

1251

62.42

1717

3269

142.13

3534

90.61

334

27.46

15.4

10,737

1.45

2.57

18.6

80

Subject

Menu 53

2589

265.7

120.5

110.5

17.68

1152

57.48

1725

3326

144.60

3795

97.30

342

28.12

11.9

5482

2.94

3.26

38.9

152

4

Menu 55

2602

256.1

126.9

109.0

17.44

1249

62.32

1831

3278

142.52

3520

90.25

375

30.83

15.0

10,186

1.40

2.47

19.2

72

-10-

TABLE D

CALCULATED NUTRIENT CONTENT OF DIETS FOR SUBJECTS 5 and 6

Nutrient

Calories

Nitrogen

Protein

Fat

Carbohydrate

Alcohol

Calcium

Phosphorus

Sodium

Potassium

Magnesium

Iron

Vitamin A

Thiamin*

Riboflavin*

Niacin*

Vitamin C*

Vitamin D

Folacin

Vitamin Bfi

Vitamin B-^

Iodine

Cholesterol

Unit

grams

grams

grams

grams

grams

mg.

mg.

mEq.

mEq.

mg.

mg.

IU

mg.

mg.

mg.

mg.

IU

meg.

meg.

meg.

meg.

mg.

1

2506

17.23

107.7

92.2

290.6

11.9

991

1670

129

88

269

18.3

8318

3.08

5.14

42.3

244

641

172

2342

9.8

108

697

Menu Number2

2518

17.31

108.2

104.0

268.3

10.8

1002

1651

130

77

265

13.2

9094

2.92

5.15

48.9

150

847

71

2407

9.1

116

606

v

3

2493

14.83

92.7

72.2

350.8

9.9

999

1572

130

63

319

12.5

8202

3.02

4.13

46.0

117

474

125

1107

1.9

96

202

7 -day Mean

2506

16.56

103.5

89.8

301.4

11.0

996

1636

130

77

282

15.1

8506

3.01

4.85

45.2

181

652

130

2030

7.3,

107

530

Values include nutrients in one Hexavitamintablet, which was administered daily from(B13) through (R'14).

Menu Rotation:^ 1-3 times weekly.# 2 - twice weekly# 3 - twice weekly

-11-

TABLE E

DIET ANALYSIS(meq/24 hrs)

Subjects 5 and 6

Day

A 5

A 9

A 10

B 13

B 14

B 15

B' 1

B1 2

B1 3

B'13

B'14

B'15

Diet 1

Diet 2

Diet 3

Diet Number

3

1

2

1

2

3

2

3

1

1

2

3

SodiumAnalyzed Calculated

133.2 129.0

121.7 130.3

122.9 130.1

Sodium

123.8

134.9

120.8

135.4

124.5

124.0

118.6

124.6 "

129.2

133.3

122.8

119.2

Averages

Potassium

64.2

82.2

73.5

81.6

73.1

65.6

74.4

65.2

78.4

80.8

75.4

64.3

PotassiumAnalyzed Calculated

80.8

74.0

64.8

87.6

77.1

62.8

-12-

Menu # 1

Breakfast

TABLE F

MENUS FOR SUBJECTS 5 and 6

Menu # 2

Breakfast

Menu # 3

Breakfast

Orange juiceFrench toast (2 si.)ButterBrown sugar w/cinnamonWhole milkInstant coffeeSugarPepper

Lunch

CheeseburgerWhite toast (2 si)French Fried PotatoesCatsupStrawberry Shortcake(Angel cake, straw-berries, Cool Whip)

Coca ColaPepper

Dinner

Cabernet SauvignonBeef TenderloinBrown riceAsparagus (canned)Whole wheat bread (1 si)ButterVanilla ice creamPepper

Tomato juice Grape juiceOmelet w/Bac-o-Bits Peaches (canned)Whole wheat toast (1 si) Wheat GhexButterJellyWhole milkPepper

Whole wheat toast (1 si)ButterJellyWhole milkSugar

Lunch Lunch

Tuna Sandwich (1 1/2) Green Pea SoupJello w/Mandarin oranges Grilled cheese sandwichVanilla wafers Orange sherbetLemonade Wine Cooler (JohannisbergWhole milk Riesling w/Seven Up)Pepper Pepper

Dinner

Spaghetti & Meatballsw/Tomato sauceParmesan cheeseWhole kernel corn(canned)

Whole wheat bread (1 si)ButterLight Choc. Cool 'nCreamy PuddingHeineken BeerPepper

Dinner

Chicken Casserole (chicken,macaroni, peas)Green beans (frozen)Whole wheat bread (1 si)ButterButterscotch Cool 'nCreamy pudding

Cookie (1)Whole milkPepper

Snack

Canned pearsCookie (1)Whole milk .

2.5 grams NaClfor the day

Snack

Graham crackers w/peanut butterWhole milk

0.4 grams NaClfor the day

Snack

Peanut butter & jellysandwich

Pineapple (canned)

No NaCl in a saltshaker

-13-

Sample menus for the three diets are shown in Table F.

3. Methodology

a. Biochemical Methods - All studies were performed induplicate.

1) Sodium and potassium were determined iri serum,urine, and diet by standard techniques using anInstrumentation Laboratories flame photometer,Model 143.

2) Hematocrits were determined in standard fashion.The value used was an average of duplicate deter-minations on seven samples of blood drawn over asix hour period.

3) Creatinine was determined in urine by use of aTechnicon Autoanalyzer.

b. Multiple Isotopic Volume Studies

In the performance of multiple isotope studies on

repeated occasions the total body radiation dosage was less than

150 mr/week. The method used to achieve this, and the specific

methods involved in the calculation of plasma volume, extracellular

fluid volume, red cell mass, and total body water have been detailed

in earlier publications from this laboratory.

c. 70° Tilt Studies

Tilt studies were performed on Subjects 1 and 2 after

morning urine close-out. The patient was transported in the

horizontal position from his room to the tilt table which was

equipped with an English saddle. EKG was measured by a modified

Lead II using three chest electrodes, and beat to beat heart rate

was measured by a tachometer triggered by the R wave of the QRS

complex. Reproducible basal heart rate and manual cuff blood

-14-

pressure measurements were made. The subject was then placed in a

70° foot down tilt. The tilt was maintained for 20 minutes unless

presyncopal symptoms (symptomatic hypotension) or syncope occurred,

at which time the patient was returned to the horizontal position.

EKG and heart rate were recorded continuously, and blood pressure

was measured every 30 seconds during the tilt and for the first

five minutes of recovery; and these parameters were checked again

at ten minutes following cessation of the tilt. On Day B'15 the

tilt was performed with each subject wearing a G-suit inflated to

43 inches HO.

d. Lower Body Negative Pressure (LBNP) Studies

The LBNP studies were performed in Subjects 3,4,5 and 6

following morning urine, close-out. The subject was transported to

the LBNP device in a horizontal position. The lower portion of the

body, from the iliac crests downward, was positioned in the LBNP

box while the upper portion of the body remained on a guerney.

The device used for the study was an appropriately cushioned

rectangular shaped box constructed of plywood and with a rubber

(3)waist seal and sheet design as described by Wolthuis et al.

The vacuum was generated by a commercial vacuum cleaner, and the

negative pressure measured by a Wallace & Tiernan Model FA141

differential- pressure gauge. Blood pressure was measured by

auscultation with a cuff above a brachial artery, and EKG from a

modified chest lead. Instantaneous heart rate was derived from

this EKG by a cardiotachometer and was simultaneously displayed on

-15-

an oscilloscope and continuously recorded on photographic paper.

After baseline measurements of blood pressure and heart rate were

stable, the subject was exposed successively to -30mmHg, -40mmHg,

and -SOmmHg negative pressure for periods of five minutes each.

At the end of the study the vacuum was released immediately.

Blood pressure was measured every 30 seconds and heart rate

continuously during LBNP, and both parameters were measured at

1,2,3,4,5, and 10 minutes after return to normal atmospheric

pressure. If at any time the volunteer felt presyncopal and/or

the systolic blood pressure fell below 85 mmHg, the study was

terminated.

e. Exercise Studies

Following completion of the 70° tilt or. LBNP study, the

subject was allowed to return to baseline blood pressure and heart

rate values and was transferred in the horizontal position to an

exercise table to which a Godart Lanooy Ergometer was attached.

Four power levels were used in this study: 50 watts, 75 watts,

100 watts, and in Subjects 3,4,5 and 6 either 125, 150 or 175

watts depending on the level which was predicted to induce a heart

rate in excess of 160/minute in the individual subject at that

time. Each exercise level was sustained for six minutes.

When blood pressure and heart rate measurements were stable,

the subject began pedaling at a rate of 50 revolutions per minute

(rpm) and the ergometer was then set to the particular power level

desired. Blood pressure was measured by auscultation at 3 and 6

minutes. EKG and instantaneous heart rate were continuously recorded.

-16-

At each exercise level oxygen consumption between minutes 4 through 6

was calculated from the volume of expired gas measured in a Tissot

spirometer and the pO~ of the gas measured by a Clark type oxygen

electrode. Following termination of the highest exercise level the

blood pressure and heart rate were recorded at 1,2,3,4,5 and 10 minutes.

f. Centrifuge Studies

One day following the tilt or LBNP and exercise studies, the

subjects were transported from the USPHS Hospital, San Francisco to

the NASA-Ames Research Center at Moffett Field, California, a distance

of about 35 miles. During the ambulatory and recovery phases they

were allowed to ambulate and to sit in a car for travel; and during

the bedrest phases they were transferred from bed to guerney to

ambulance bed and were kept in the horizontal position until completion

of the centrifuge studies. All studies were performed between 8:30 AM

and 11:30 AM with the subjects in the fasting state. Physicians were

in attendance throughout the travel and study periods.

During acceleration studies EGG was measured by two sternal

electrocardiographic leads connected to a cardiotachometer, temporal

artery flow velocities were measured by ultrasonic flowmeters placed

over both superficial temporal arteries, and blood pressure was

measured manually by cuff and microphone over the left brachial artery

using a Gemini sphigmomanometry system. Following placement of these

devices, the subjects walked or were carried 30 feet to the Ames

Biosatellite Centrifuge into which they were secured. Acceleration

tolerance was assessed by a subject's response to peripheral lights

presented in a random fashion, by his ability to perceive a central

white light of 15 foot candles luminence, and by the presence or absence

-17-

of Doppler flow velocity signals from the superficial temporal arteries.

All data were continuously recorded on a Brush 8 channel direct writing

recorder and on an Ampex FR 1800 tape recorder. All subjects were

instructed not to perform straining maneuvers during acceleration

procedures. Throughout the studies voice communication was maintained,

and there was constant visual monitoring of the subject by means of

infrared television.

The +G centrifuge profiles consisted of three runs separated byz

five to ten minute rest and equilibration periods., The runs consisted

of: 1) 2.1 G for 670 seconds; 2) 3.2 G for 220 seconds; and

3) 3.8 G for 185 seconds. The rate of change of acceleration was

1.8 G per minute; and the rate of change on deceleration was about

this level when the subject had completed a run uneventfully, and much

faster (up to 18 G/min) when presyncope or syncope occurred. The seat

back angle was adjusted just prior to the start of centrifugation,

with the head upward to 30°, 19.5°, and 16.6° above the horizontal

plane for the +2.1, +3.2, and +3.8 G runs, respectively, in order to

maintain a full component vector of the acceleration along the long

axis of the body.•

At the completion of the second bedrest period of Subjects 1,2,

3 and 4, and of the first bedrest period of Subjects 5 and 6, an

inflated G-suit was worn. The specific suit employed was the Air Force

cutaway anti-G garment CSU-3/P inflated to 13 inches of t O, 45 inches

of H00, and 60 inches of H00 for the +2.1, +3.2, and +3.8 G runs,L . f. Z

respectively. At all other times no counter-pressure device was used.

Following completion of the studies the subjects were allowed

to rest and to eat or drink a portion of their metabolic diet ad Ub.

-18-

They were then returned to the USPHS Hospital, San Francisco by car

or ambulance.

C. Results

1. Analysis of Data: In this study data were accumulated on all

of the parameters discussed above during all phases of the study. In

evaluating the data in the different phases, attention was directed

not only to the effects of the bedrest periods relative to the ambula-

tory control and recovery periods, but also to the recovery periods

relative to the ambulatory control period. Interest in this latter

aspect has been prompted by earlier studies in this laboratory which

have shown that following a two week bedrest period, certain parameters

may require a two week or longer recovery period to return to their

ambulatory control values.

In analyzing the data, group means and standard errors (95%)

were calculated, and significances of values in different periods or

under different circumstances were determined by use of the paired(4\

"t" test. A P value of <0.05 was considered to document a

significant difference.

2. General Data: Table 1 contains the height, the initial and

final weights, and problems encountered by each subject during the

course of the study.

3. Sodium Balance Studies: The sodium balance, calculated as

the dietary sodium intake (Table 2) minus the urine sodium output

(Table 3), is shown in Table 4 and Figure 1. This balance obviously

disregards stool sodium and insensible sodium losses which should have

been relatively constant and insignificant during all phases of this

-19-

study. Since dietary sodium intake was essentially constant, the

sodium balance gives a relative estimate of extracellular fluid

volume changes as reflected in urinary sodium excretion during the

different phases of the study.

Table 4 and Figure 1 show that the effect of the tilt and

exercise (Subjects 1 and 2) is to significantly increase positive

sodium balance when compared with the previous days during both

bedrest and non-bedrest phases. This same phenomenon is seen in

13 of 16 instances of LBNP and exercise in Subjects 3,4,5 and 6.

Since exercise in the absence of tilt or LBNP was not performed, no

conclusions can be drawn of the relative importance of exercise in

inducing the sodium retention.

Table 4 also reveals a markedly negative sodium balance on Day Bl

in 5 of 6 subjects and on Day B'l in all subjects; on Day B2 in 3 of 6

subjects; and on Day B'2 in 5 of 6 subjects. The response is most

marked on the first bedrest day in 9 of 12 instances and on the

second bedrest day in the remaining three. Further, the initial

days of recovery periods are characterized by a markedly positive

sodium balance, the most markedly positive balance occurring on the

first recovery day in 11 of 12 instances, and on the second recovery

day in the remaining instance.

The mean values of the six subjects clearly demonstrate thet

increase in sodium balance on the tilt or LBNP and exercise days;

the markedly negative sodium balance on the first bedrest days

(Rl, B'l) and the less marked but still quite negative balance on

the second bedrest days (B2, B'2); the markedly positive sodium

-20-

balance on the first recovery days (Rl, R'l), and less marked but

still quite positive balance on the second recovery days (R2, R'2).

Table 5 shows the average sodium balance per day during the different

phases of the study, excluding the stress (i.e., tilt or LBNP and

exercise) days at the ends of the periods. Here again the lower

sodium balance in the bedrest relative to the recovery and ambula-

tory periods is demonstrated. These are the typical sodium balance

responses to bedrest and resumption of normal upright activity which

have been established in our laboratories, and document a physiologic

n 2)response to the bedrest period. ' '

Statistical evaluation of the sodium balance during different

phases of the study (Table 5 and Figure 2) shows significant decreases

in sodium balance when the second bedrest period is compared with the

first and second recovery periods. As expected, there are no significant

differences between the ambulatory control and the first and second

recovery periods. The failure of the overall results to show a signifi-

cant decrease in sodium balance during the first bedrest period when

compared with either the ambulatory control period or the first

recovery period requires discussion. The mean daily sodium balance

for Days B 1-14 was -1.9 meq/24 hrs versus 10.1 meq/24 hrs and

15.6 meq/24 hrs for the ambulatory control and first recovery periods,

respectively. Four of the six subjects showed the proper trend.

Subject 3 showed little change and Subject 1 showed a marked change

to positive rather than negative sodium balance. These latter two

results cause a large standard error which prevents achievement of

significance. The atypical results in these subjects may have been

-21-

due to unknown or undetected variations in their diets, since

neither was on a true metabolic diet. Also, it is possible that

neither subject had reached full equilibration with the diet by

the beginning of the ambulatory control period, since both showed

the expected decrease in sodium balance during the second period

of bedrest. In the case of Subject 1, the low urinary creatinine

values on Days B 8-14 (Table 12) suggest inaccuracies in urine

collection which would result in a higher calculated balance.

These results do point up the difficulties inherent in interpreting

data from small numbers of subjects in non-metabolic circumstances.

Subjects 5 and 6 who received accurately evaluated metabolic diets

consistently showed the expected changes in sodium balance.

4. Potassium Balance Studies: The potassium balance, Table 8

and Figure 2, is calculated from the dietary potassium intake

(Table 4) minus urinary potassium excretion (Table 7). This calcula-

tion excludes stool and insensible potassium losses which are small

and should be constant during all phases of the study. When the

balances are calculated for each period on days when no stresses

are applied to the subjects (Table 9), it is seen that the potassium

balance is lower during bedrest periods when compared with the

ambulatory control and recovery periods in five of the six subjects.

This decrease in potassium balance is the usual response to

bedrest and recovery established in this laboratory, and has been

attributed to loss of potassium from muscle breakdown during

bedrest periods.

These potassium balance differences achieved statistical

-22-

significance when the first bedrest period is compared with the

first recovery period, and when the first recovery period is compared

with the second bedrest period (Figure 2). There were no significant

differences between the ambulatory control and first recovery and

between the first and second recovery periods, as is expected.

The failure to achieve statistical significance when the first

bedrest period is compared with the ambulatory control period can

be attributed to the atypical response of Subject 1. The possible

reasons for the atypical response have been discussed under Sodium

Balance Studies (vide supra).

5. Fluid Balance Studies: The results of fluid balance studies,

i.e., oral intake minus urine output, are shown in Tables 10 and 11.

These balances obviously neglect stool and insensible fluid losses

which should have been relatively constant during all phases of the

study. Table 11 and Figure 2, displaying the group means during

different phases of the study, show statistically significant

lower fluid balances during the two bedrest periods when compared

with the ambulatory control and first recovery periods and no

significant differences between the ambulatory control and recovery

periods. This is the typical response to bedrest as previously

documented in these laboratories.

6. Urine Creatinine Studies: The results of urinary creatinine

excretion determinations are shown in Table 12. The values in each

subject, with few exceptions, are essentially constant throughout

the study.

7. Serum Chemistries: The serum sodium and potassium values

of each subject on particular study days are shown in Table 13.

-23-

These values are within normal limits in all subjects throughout

the entire study.

8. Body Fluid Compartment Studies: Detailed results of plasma

volume (PV), red cell mass (RCM), extracellular fluid volume (EFV),

total body water (TBW), and body weight are presented in Table 14.

Group means on particular study days are shown in Table 15 and in

Figure 3. It is seen that the PV is the first body fluid compartment

to have a statistically significant change during bedrest periods

when compared to ambulatory control and recovery periods. The PV

decreases by the second bedrest day (significantly in the second

bedrest period) and continues to decrease throughout the bedrest

periods. During recovery periods it rises to pre-bedrest values,

and there are no significant differences in PV between the ambula-

tory control, first recovery, and second recovery periods.

The EFV and TBW also demonstrate consistent changes during

bedrest periods, both decreasing. Although the decrease is

measurable on the second bedrest days, the decrease achieves

statistical significance only later in the bedrest periods. Thus,

EFV and TBW achieve statistically significant decreases during

bedrest periods more slowly than PV. As with PV, there are no

significant differences in EFV and TBW between the ambulatory

control and first and second recovery periods.

Red cell mass shows a consistent decrease throughout the

study, attributable to blood withdrawal. The decrease between

contiguous two week periods is not statistically significant.

However, the decrease is significant when R9 is compared with

-24-

the mean ambulatory control value. Results of hematocrit deter-

minations on study days are shown in Table 16.

9. Responses to 70° Tilt: The heart rate, blood pressure,

and pulse pressure responses to 70° tilt are shown in Tables 17,

18, 19 and in Figure 4. It is noteworthy that the maximum heart

rate achieved was much greater, and the minimum pulse pressure

much lower, following the first bedrest period than on the previous

ambulatory control or subsequent recovery periods. With the use of

G-suits inflated to 43 inches of water in the tilts following the

second bedrest period, the heart rates of both subjects were lower

than during tilt in the ambulatory control, first bedrest, arid

recovery periods. The pulse pressure of Subject 1 during the

G-suit tilt was greater than or equal to that in the ambulatory

control, first bedrest, and recovery periods; whereas in Subject 2

it was in the same range as during the initial bedrest period, and

well below the ambulatory control and recovery period values.

Although Subject 2 experienced presyncopal symptoms during tilt

following both bedrest periods, these symptoms appeared much

(five minutes) later when the G-suit was used. Thus, in both

patients the G-suit gave increased orthostatic tolerance in the

post-bedrest state. Subject 2, however, complained of significant

abdominal pain when the G-suit was inflated, and continued to have

abdominal tenderness .for 48 hours after the tilt. This abdominal

trauma may well have contributed to the hypotensive episode during

tilt.

10. Lower Body Negative Pressure (LBNP) Studies: The heart

rate responses of Subjects 3,4,5 and 6 to LBNP are presented in

-25-

Tables 20, 21, 22 and 23. Reference to Table 20 and Figures 5a and

5b shows that several heart rate responses are common to all subjects.

Firstly, in all subjects on all study days the average and maximum

heart rates were lowest during the -30mmHg and highest during the

-SOmmHg periods. Secondly, comparing all levels of LBNP on all

study days, it is seen that the highest average and highest maximum

heart rates achieved during LBNP occur following the bedrest periods

and at the highest tolerated level of negative pressure. Focusing

on responses at the -SOmmHg level which, being the most stressful

is most likely to bring out differences in response, it is seen

that the average and maximum heart rates in studies following bedrest

are greater than in the ambulatory control and recovery periods in

Subjects 3,4 and 5. Subject 6 experienced syncope and presyncope

during his two post-bedrest studies and was, therefore, quite

anxious during the last three LBNP studies. Perhaps it is for

this reason that his heart rate responses are less in accord with

those of the other subjects, i.e., higher during the two recovery

periods than following the first bedrest period.

Statistical analysis of the group means of the maximum heart

rate responses are shown in Table 23. Note that there is a

significantly higher heart rate at rest as well as during all

levels of LBNP during the first post-bedrest study when compared

with the ambulatory control period results. During the study

following the second bedrest period (B'15), the group means

±S.E.(95%) were nearly identical to those on B15 at all levels

of LBNP. However, statistically significant differences with R13

-26-

were achieved only at the -SOmmHg level. This suggests that not

all subjects had returned to their ambulatory control status by R13.

This possibility is strengthened by the fact that the group results

on R13 did not differ significantly from those of B15. The fact

that the group contained some subjects who had returned to control

levels is suggested by the failure to show statistically significant

differences between R13 and A13. The same findings exist in the

comparison of B'15 with R'14 and R'14 with R13. Thus, in reviewing

data from groups with a small number of subjects such as this,

individual results and group means ±S.E.(95%) must be considered

along with P values in the interpretation of results.

Table 24 shows that during LBNP there is a definite fall in

systolic blood pressure throughout the LBNP period on all study

days in Subjects 4,5 and 6, and on Days A13 and B15 in Subject 3.

However, the drop is of the same magnitude following bedrest

periods as during ambulatory control and recovery periods. There

is no consistent change in magnitude or direction of the diastolic

blood pressure in these studies, but in most instances the net

result is a fall in the pulse pressure (Table 25). However, the

magnitude of the pulse pressure fall is similar in the bedrest

and non-bedrest studies.

11. Response to Exercise: Table 26 shows that the heart rate

response to various levels of exercise is not consistently different

in magnitude or direction when bedrest periods are compared with

the ambulatory control and recovery periods. Neither is there a

dramatic difference in oxygen consumption at various levels of

-27-

exercise during these periods (Table 27). However, when, maximal

oxygen uptake is calculated by linear extrapolation of heart rate

and oxygen consumption data, ' ' several correlations are seen.

Table 28 and Figure 2 show significant differences in derived

maximal oxygen uptake between the ambulatory control and first

bedrest periods, between the first bedrest and the first recovery

periods, between the first recovery and second bedrest periods,

and between the second bedrest and second recovery periods. Also,

there are no significant differences in these derived values

between the ambulatory control and first recovery periods, and

between the first and second recovery periods. Thus, cardiovascular

performance, as reflected in the derived maximal oxygen uptake,

appears to deteriorate during a two week bedrest period and to

recover to pre-bedrest levels following a two week recovery period.

This decrease in maximal oxygen uptake occurred in nine of ten

measurable comparisons of post-bedrest with pre-bedrest results.

12. Centrifuge Studies: The heart rate responses to centri-

fugation are shown in Tables 29, 30 and 31 and in Figures 6 through 11.

The maximum heart rates in all subjects at all +G levels, with onez

instance excepted (+3.8 G , Subject 2, Table 31, vide infra) wereZ "

greater in the post-bedrest runs without G-suits than in the ambula-

tory control and recovery periods. Specifically, the maximum heart

rates in the bedrest without G-suit runs exceeded those in the

ambulatory control period runs by 20 to 48 (mean 32) at +2.1 GZ>

by 8 to 34 (mean 20) at +3.2 G , and, with the one exception, byZ

12 to 53 (mean 25) at +3.8 G . They likewise exceeded those in* Z

-28-

the recovery period runs by similar values: 7 to 48 (mean 33) at%

+2.1 G , 11 to 44 (mean 24) at +3.2 G , and with the one exception,.z z

20-32 (mean 24) at +3.8 G . When the heart rate responses in theZ

post-bedrest runs with and without G-suits are compared, a signifi-

cant effect of the G-suit on lowering heart rate is demonstrated.

With the G-suit the post-bedrest maximum heart rates were lower

than without G-suits by 5 to 50 (mean 24) in the +2.1 G runs,Z

by 4 to 50 (mean 22) in the +3.2 G runs, and (with the oneZ

exception) by 0 to 40 (mean 21) in the +3.8 G runs. In fact,Z

the maximum heart rates in the post-bedrest runs with G-suit were

in most instances very close to, and at times lower than, those in

the comparable ambulatory control and recovery period runs.

Subject 2's atypical maximum heart rate response at +3.8 GZ,

i.e., lower in the bedrest without G-suit run than in the ambulatory

control and recovery period runs, suggests increased vagal tone in

this run. Such a response may have been related to the presyncopal

symptoms which the patient had experienced in the immediately preceeding

+3.2 G run on BR-. In Subject 4's +2.1 G,, run with G-suit, thez z

G-suit spontaneously deflated early in the run. However, the run

was completed. It is noteworthy that in this instance the heart

rate response was essentially identical to that during the earlier

post-bedrest without G-suit run.

Statistical analysis of the group means of the maximum heart

rates during centrifuge studies are shown in Table 32 and Figure 11.

Since some subjects wore the G-suit in the run following the first

bedrest period (Rl) and others in the run following the second bedrest

-29-

period (R'l), the post-bedrest data are evaluated on days on which a

subject wore (BR+) or did not wear (BR-) the G-suit. Since the G-suit

deflated during Subject 4's +2.1 G run on R'l, this datum is excludedz

from the BR+ group and added to the BR- group. Note that in the

post-bedrest runs without G-suits (BR-), the maximum heart rates

achieved are significantly higher than in the ambulatory control,

recovery, and post-bedrest with G-suit (BR+) runs at the +2.1 GZ

and +3.2 G levels, and higher than in the recovery and BR+ periodZ

runs at +3.8 G . Further, it is noteworthy that there are noZ

significant differences in maximum heart rate response between the

post-bedrest with G-suit (BR+) and the ambulatory control or recovery

period runs at all +G levels, indicating that the post-bedrest useZ

of the G-suit in this study normalized the post-bedrest maximum heart

rate response.

At the +3.8 G level, statistically significant higher maximum

heart rates were not achieved in the post-bedrest without G-suit

run relative to the ambulatory control period. Statistically, the

lack of significance is attributable to Subject 3's very low

maximum heart rate on A14, giving a large standard error.

Perhaps of greater practical significance than maximum heart

rate response is the fact that subjects who had previously terminated

the post-bedrest runs prematurely were able to tolerate the runs for

significantly longer periods of time with the G-suit than without it.

It permitted Subjects 2 and 6 the 5 and 54 seconds, respectively,

needed to complete the +3.2 G run, and Subject 1 the 55 secondsZ

to complete the +3.8 G run. Also, in the +3.8 G run it allowedZ Z

-30-

Subject 2 102 seconds and Subject 6 124 seconds longer tolerance

than in the bedrest without G-suit run.

However, some complications related to the use of G-suits

occurred. All subjects developed some asymptomatic petechiae of

the feet and ankles, but Subjects 5 and 6 also developed painful

edema of the toes and feet which gradually disappeared over a 12

hour period.

It is noteworthy that those subjects who developed visual

impairment during centrifugation experienced peripheral light loss

(PLL) before central light loss (CLL). However, when CLL did occur

it followed PLL by only a few seconds. The one instance of loss of

consciousness (Subject 6, +3.2 G run, R14) occurred within secondsz

following CLL as the subject was stating that CLL was occurring.

In all instances of PLL and CLL the ultrasonic flowmeter signals had

indicated zero flow for at least several seconds prior to the onset

of visual impairment.

D. Discussion

This study attempted to 1) document and quantify a "bedrest

effect" by metabolic studies and cardiovascular stress tests, and

2) evaluate the influence of this bedrest effect on tolerance to

a specific +G acceleration with and without the use of the G-suit.

Both of these aims were achieved.

The bedrest effect was documented in several ways. The sodium

balance, dependent on the renin-angiotensin-aldosterone system

which is partly a gravity-activated system, was lower during bedrest

periods than during periods of upright posture. The fluid balance,

-31-

dependent largely on changes in sodium balance, was also lower

during bedrest periods. The potassium balance, presumably reflecting

changes in body muscle mass, diminished during bedrest. The plasma

volume, extracellular fluid volume, and total body water volume also

decreased during bedrest periods. The maximum heart rate response

to 70° tilt and LBNP, and the duration of tolerance to these stresses

in those individuals who developed syncope demonstrated lower ortho-

static tolerance following bedrest. Finally, the lower calculated

maximum oxygen uptake from exercise studies following bedrest documents

deterioration in cardiovascular performance. .

The data obtained in the 4G profiles used here should accuratelyz

predict the responses of passengers re-entering the earth's atmosphere

in the Space Shuttle Vehicle using an identical +G profile following•. z

a two week exposure to the weightless environment. Specifically, some

untrained passengers re-entering the earth's gravitational field at

these 4G in the unprotected state will have higher heart rates andz

will experience visual impairment earlier than in the control state.

Some passengers may even become syncopal. However, the wearing of the

Air Force cutaway G-suit inflated to the pressures used here should

normalize the heart rate responses and prolong the time to visual

impairment in all passengers. Nevertheless, some lay personnel

may still experience visual impairment or syncope. For such individuals,

additional G protection, e.g., straining maneuvers or higher G-suit

pressures, would have to be employed.

A most important objective, then, is the selection of persons who

will be able to tolerate s specific -KJ profile following specificZ

periods of weightlessness. In the specific +G profile used in this

-32-

study, Subjects 1,2 and 6 were unable to tolerate the acceleration

stresses following the two week bedrest period in the unprotected

state. Although the use of the inflated G-suit allowed Subject 1

to tolerate the 4G profile, Subjects 2 and 6 were still unable toz

complete it. And if catastrophes are to be avoided, persons like

Subjects 2 and 6 must be identified.

Since admission into this study required an ambulatory subject

to tolerate a 70° passive tilt, it is clear that this orthostatic

tolerance test will not be of high enough selectivity in ambulatory

subjects. Further, the fact that Subjects 3,4,5 and 6 in addition

tolerated the LBNP profile used here during the ambulatory control

period indicates that this test, used in ambulatory subjects, also

will not be adequately selective. Following two weeks of bedrest,

however, Subjects 2 and 6 were intolerant to tilt and LBNP suggesting

that performance of these tests following a two week bedrest period

will identify some of the people at risk. Such a long bedrest period

as a screening procedure is obviously impractical. Our studies have

demonstrated decreases in plasma and extracellular fluid volumes, and/a\

others ' have demonstrated diminution in 70° passive tilt tolerance

which occurs within 48-72 hours of bedrest. Thus, it is possible

that orthostatic tolerance tests may achieve the required selec-

tivity after an abbreviated period of bedrest.

The heart rate responses and tolerances to centrifugation

documented in this study are similar to those obtained in studies

with somewhat different protocols and aims. ' ' Specifically,

it has been shown that +G tolerance, measured by several endpoints,z

-33-

deteriorates following periods of bedrest. ' Further, the use

of the inflated G-suit has been documented to give increased -+Gz

tolerance in the control as well as the post-bedrest state; '

although in the present study its use seemed to worsen petechial

hemorrhages on the feet and ankles. It is possible that +G toleranceZ

in our subjects may have been increased to a greater extent than

observed had the G-suits been tailored to the individual subject

and had pressures in the G-suits been different. Others have found

that subjects wearing the best fitting G-suits, inflated almost to

the point of discomfort at 1 G, had the best -KJ tolerance, 'Z

although specific inflation pressures have not been published.

Finally, it has been observed that straining maneuvers may result

in increased -K5 tolerance, ' suggesting that the performance ofz

such a maneuver in our study might have supplemented the increased

•fG tolerance afforded by the inflated G-suit alone.z

-34-

E. References

1. Hyatt, K.H., Smith, W.M., Vogel, J.M., Sullivan, R.W. et al.

A Study of the Role of Extravascular Dehydration in the

Production of Cardiovascular Deconditioning by Simulated

Weightlessness (Bedrest). NASA Contractors Report

T-68099(G), December 1970.

2. Hyatt, K.H., Smith, W.M., Kamenetsky, L.G. and Vogel, J.M.

A Study of Post-Recumbency Orthostatism and Prophylactic

Measures for Prevention of this Phenomenon. NASA

Contractor's Report T-28565(G).

3. Wolthuis, R.A., Hoffler, G.W. and Baker, J.T. Improved

Waist Seal Design for Use with Lower Body Negative

Pressure (LBNP) Devices. Aerospace Medicine 42: 461-

462, 1971.

4. Snedecor, G.W. and Cochran, W.G. Statistical Methods,

Sixth Edition, Iowa State University Press, Ames, Iowa, 1967.

5. Wyndham, C.H. Submaximal Tests for Estimating Maximum

Oxygen Uptake. Canad. Med. Ass. J. 96: 736-745, 1967.

6. Wood, E.H. and Lambert, E.H. Some Factors which Influence

the Protection Afforded by Pneumatic Anti-G Suits. J.

Aviation Med. 23: 218-228, 1952.

7. Hyatt, K.H., Kamenetsky, L.G. and Smith, W.M. Extravascular

Dehydration as an Etiologic Factor in Post-Recumbency

Orthostatism. Aerospace Med 40: 644-650, 1969.

8. Vallbona, C., Cardus, D., Vogt, F.B. and Spencer, W.A.

The Effect of Bedrest on Various Parameters of Physiologic

-35-

Function. Part VIII. The Effect on the Cardiovascular

Tolerance to Passive Tilt. NASA Contractors Report 178,

April 1965.

9. Miller, P.B. and Leverett, S.D., Jr. Tolerance to Transverse

(+G ) and Headward (+G ) Acceleration after Prolonged BedX Z

Rest. Aerospace Med. 36: 13-15, 1965.

10. Leverett, S.D., Jr., Shubrooks, S.J., Jr. and Shumate, W.

Some Effects of Space Shuttle +G Re-entry Profiles onZ

Human Subjects. Preprints of the Scientific Program, 1971

Annual Scientific Meeting, Aerospace Medical Association,

Houston, Texas, April 26-29, 1971, pp. 90-91.

11. Parkhurst, M.J., Leverett, S.D., Jr. and Shubrooks, S.J., Jr.

Human Tolerance to High, Sustained 4G Acceleration.Z

Aerospace Med. 43: 708-712, 1972.

12. Parkhurst, M.J., Leverett, S.D., Jr., Shubrooks, S.J., Jr.

and Brown, W.K. Human Tolerance to Sustained, High +GZ

Acceleration. Preprints of Scientific Program, 1971

Annual Scientific Meeting, Aerospace Medical Association,

Houston, Texas, April 26-29, 1971, pp. 92-93.

-36-

TABLE 1

GENERAL DATA

Subject

1

2

Height (cm)

176

182

3

4

5

175

177

185

Weight (kg)Initial Final

65.13

98.23

64.78

97.05

79.96 80.37

72.42 71.96

69.54 68.10

Noteworthy EventsDuring Study

Abdominal pain and bruisefrom poorly fitting G suitduring tilt.

Extensive edema and purpuraof feet in post-bedrest withG suit centrifuge runs.

179 72.52 70.70 Same as 5.

-37-

TABLE 2

SODIUM INTAKE

(tneq/24 hrs)

Day of Study

Subject

3 5 and 6

A 1A 2-7A 8-12A 13A 14

B 1B 2B 3-7B 8-14B 15

R 1R 2R 3-7R 8-12R 13R 14

B1 1B1 2B1 3-7B1 8-14B1 15

R1 1R' 2R1 3-7Rf 8-13

160160160160160

160160160160160

160160160'160160160

160160160160160

160160160160

157157157157157

157157157157157

157157157157157157

157157157157157

157157157157

145' 144144145142

145142144144145

142145143144142145

142145143144142

145142144

145144144145142

145142144144145

142" 145143144142145

142145143144142

145142144

135126127121122

133123126127133

123133126127122133

123133126127123

133122127128

Pay of Study

-38-

TABLE 3

URINE SODIUM EXCRETION(meq/24 hrs)

Subject

A 1A 2-7A 8-12A 13A 14

B 1B 2B 3-7B 8-14B 15

R 1R 2R 3-7R 8-12R 13R 14

B' 1B« 2B1 3-7B' 8-14B1 15

R1 1R1 2R' 3-7R1 8-13

151154148102+

115*

22515416311398+

99*161144152113+150*

239171165151117+

174*108146159

174116130116+75*

186208142219120+

59*93149129122+85*

214207138140H5+

111*115145133

188146129105+135*

101183142140111+

84*133136132150+92*

169144126144134+

71*89123

19012213388+127*

19016212613293+

63*" 122124118100+80*

27516813312986+

58*72120

121119123130+97*

27380115130128+

30*91164109137+84*

18915211813272+

60*169130119

11012413092+83*

211101119133a.13 7+

52*97135125101+69*

144184128126

4-78+

74*101133116

\

Centrifuge Day

Tilt (Subjects 1,2) or LBNP (Subjects 3,4,5,6) and Exercise Day

=39.

TABLE 4

SODIUM BALANCE(meq/24 hrs)

(Intake minus urine Output)

Subject

D a y o f Study 1 2 3 4 5 6 Mean

A 1A 2-7A 8-12A 13A 14

B 1B 2B 3-7B 8-14B 15

R 1R 2R 3-7R 8-12R 13R 14

B' 1B' 2B1 3-7B1 8-14B1 15

R1 1R1 2R' 3-7R' 8-13

*Centrifuge Day

+Tilt (Subjects 1,2) or LBNP (Subjects 3,4,5,6) and Exercise

961258+45*

65634762+

61*'116847+10*

7911

• 5943+

14*52141

-17412741+82*

-29-5115-6227+

98*6482835+72*

-57-50191742+

46*421224

-43- 21540+7*

44-412434+

58*12712

- 8+53*

-2711708+

74*5321

-45221157+15*

-45-20181252+

79*23192642+65*

-133-23101556+

87*7024

1474

- 9+25*

-1404311

- 35+

93*42

. -3818-15+49*

-66-198

- 551+

73*-47- 39

252

- 329+39*

-78227

- 6- 4+

71*36- 9221+64*

-21-51- 2

45+

59*21- 612

-9131136+36*

-52- 78

- 129+

77*2901620 +52*

-64-268641 +

54*321012

-40-

TABLE 5

SODIUM BALANCE(meq/24 hrs)

Subject A 1-12 B 1-14

1 8.8 18.2

2 30.3 -31.4

3 1.7 2.9

4 11.8 7.8

5 6.3 -4.5

6 1.8 -4.5

Mean 10.1 -1.9

S.E.(95%) ±11.2 ±17.6

P

B vs A

R vs B

B1 vs R

R' vs B1

R vs A

R1 vs R

Day of Study

R 1-12

15.0

28.5

13.8

27.2

2.9

6.0

15.6

±11.1

Values

<0.3

<0.2

<0.005

<0.01

<0.2

<0.4

B1 1-14 R' 1-7

-3.7 15.4

7.6 21.1

4.2 33.1

-0.1 39.6

-5.7 1.6

-5.4 7.1

-0.5 19.6

±5.7 ±15.4

"Page missing from available version"

-42-

TABLE 6

POTASSIUM INTAKE(meq/24 hrs)

Subject

Day of Study 1 2 3 4 5 and 6

A 1A 2-7A 8-12A 13A 14

B 1B 2B 3-7B 8-14B 15

R 1R 2R 3-7R 8-12R 13R 14

B1 1B1 2B1 3-7.B1 8-14B1 15

R' 1R1 2R1 3-7Rf 8-13

8888888888

8888888888

888888888888

8888888888

88888888

9898989898

9898989898

989898989898

9898989898

98989898

9693949691

9691949396

919693949196

9196939391

969194

9793949790

9790949497

90- 9793949097

9097939490

979094

8273737474

8165757481

658175737481

6581757464

81747376

68707966+

88687482+

94818782+

77807984+

67656660+

79706955+

-43-

TABLE 7

URINE POTASSIUM EXCRETION(meq/24 hrs)

Subject

D a y o f Study 1 2 3 4

A 1A 2-7A 8-12A 13A 14 61* 55* 92* 78* 53* 64*

B 1B 2B 3-7B 8-14B 15

R 1R 2R 3-7R 8-12R 13R 14

B1 1B1 2B1 3-7B1 8-14B1 15

R' 1R1 2R1 3-7R1 8-13

*Centrifuge Day

+Tilt (Subjects 1,2) or LBNP (Subjects 3,4,5,6) and Exercise Day

7355756068+

87*56686974+74*

7266766963+

80*867273

5580849982+

52*88738073+52*

7370877977+

75*747875

701009587100+

102*85808094+93*

6888829094+

91*9486

8493888693+

69*9379

" 7360+91*

10980868756+

68*6572

6254726474+

61*61616562+55*

6158716452+

65*585365

6846717280+

48*54616559+56*

6472776860+

56*514562

-44-

TABLE 8

POTASSIUM BALANCE(meq/24 hrs)

(Intake minus urine Output)

Day of Study

A 1A 2-7A 8-12A 13A 14

B 1B 2B 3-7B 8-14B 15

Mean

R 1R 2R 3-7R 8-12R, 13R 14

B?

B1

B'B1

B1

123-7 .8-1415

R1 1R1 2R' 3-7R' 8-13

20189

22+27*

1533132820*

1*32201914+14*

1622121925+

8*2

1615

10302416+43*

431814

- 116+

46*10251825+46*

2528111921+

23*242023

2127

14+- 1*

26- 9- 1

6- 4+

-11*111314

- 3+3*

238

113

- 3+

53*- 3

8

20131513+12*

13- 3

684+

21*4

142130+6*

-191777

34+

29*2522

1587

14+21*

19113

107+

4*' 20

148

12+26*

4234

1012+

16*162011

364

19+10*

1319421+

17*27148

15+25*

19

- 264+

25*232814

12141116+19*

2212697+

13*17171516+20*

818

71116+

26*141916

K

Centrifuge Day

Tilt (Subjects 1,2) or LBNP (Subjects 3,4,5,6) and Exercise Day

-45-

TABLE 9

POTASSIUM BALANCE(meq/24 hrs)

Subject Day of Study

A 1-12 B 1-14 R 1-12 Bf 1-14

1 14.9 22.0 19.2 16.3

2 26.3 9.0 22.9 17.7

3 8.4 3.6 10.9 7.5

4 14.7 6.8 17.1 6.0

5 9.0 ^ 8 . 0 11.1 8.0

6 5.6 5.1 12.6 3.1

Mean ' 13.2 9.1 15.6 9.8

S.E.(95%) ±7.78 ±6.95 ±5.14 " ±6.16

P Values

B vs A <0.30

R vs B <0.05

B1 vs R <0.01

R' vs B' <0.20

R .vs A <0.20

R' vs R <0.50

R1 1-7

12.7

20.9

5.9

23.7

18.9

26.9

18.2

±8.06

-46-

TABLE 10

FLUID BALANCE SUMMARY(ml/24 hrs)

Subject

D a y o f Study 1 2 3 4

A 1A 2A 3A 4A 5A 6A 7A 8A 9A 10A 11A 12A 13A 14

B 1B 2B 3B 4B 5B 6B 7B 8B 9B 10B 11B 12B 13B 14B 15

828112970687810411917111198-327

90012071886

73217915818524045811027.5249615627698521621

-20927855838122538166123644671560390530191

390-2340491665841699411-329391-28056645466

901807780840331471600242-16456725656806465

1136162390425701411675152

-26946460911-4710

248869425597499265431679805409949255157493801

585-70-23147020059

-435-60689-35340119167285-687

1198518-730506760676-68095125

-164120696766582857

-51054420336630261-60446-10-44016671271487

-288693191695236-5891085

-1159211156830211477379446

-518666-369410186-39445-129351-29

5.. 851

172543481

-47-

TABLE 10


Subject

D a y o f Study 1 - 2 3 4

R 1R 2R 3R 4R 5R 6R 7R 8R 9R 10R 11R 12R 13R 14

B1 1B1 2B1 3B' 4B' 5B1 6B' 7B' 8B1 9B'10B'llB'12B'13B'14B'15

11096451017834123584185823413968683401190

995559685780-7167812836616136137191713

1616-420-37915553630466876720515236380-1321125

8461451086-20221265126326325575.J96595388515

841981375-129-274925-279827786405231521-424280

9611051235391-1427545176367075816-9706725

20554439851587684897537625813251031398

-431133-4471149688723174428303-911828213

1076375069056765529680336755946335-263484414

-1683407811280186-26011155

-674-18533123512

-989669

-51826980426391565221211612903016616

370761

712-306-165-39-89390-599861166345-19201511465796

-48-

TABLE 11


Subject A 1-12

Day of Study

B 1-14 R 1-12 B1 1-12

1

2

3

4

5

6

Mean

S.E.(95%)

775

752

332

318

566

435

530

±211.8

506

149

373

151

224

182

264

±151.9

853

683

395

441

434

472

546

±190.5

646

389

470

-32

247

121

307

±257.6

P Values

B vs A <0.05

R vs B <0.025

B1 vs R <0.05

R vs A <0.7

-49-

TABLE 12

URINE CREATININE(mgm/24 hrs)

' of Study

A 1-7

A 8-13

A 14

B 1-7

B 8-14

B 15

R 1

R 2-7

R 8-12

R 13

R 14

B'l-7

B'8-14

B'15

R'l

R'2-7

Subject

1

1770

1864

1789

, 1833

1554

1808

1915

1808

1917

1788

1777

1800

1807

1773

1829

1860

2

2066

2179

2253

2316

2613

2267

1647

2337

2384

2326

1875

- 2276

2317

2266

2332

2247

3

2355

2338

2345

2376

2409

2446

2501

2360

2283

2232

2512

2374

2346

2326

2483

2362

4

2037

1952

2047

2097

2113

2260

18.95

1953

1930

1878

2071

2079

2081

2018

1945

1943

5

1943

1971

1961

1946

1950

1965

1977

1986

1961

1959

1895

1901

1938

1997

2357

2013

6

1923

1922

2002

1965

2011

1788

1915

1987

2054

1918

1796

2039

2053

1974

2062

1968

-50-

TABLE 13

SERUM CHEMISTRIES

Subject Day of Study Sodium Potassiummeq/L meq/L

A 3 138 4.0A 9 138 4.0B 2 139 4.1B 13 142 4.6

1 R 9 140 4.0B1 2 140 4.5B'14 140 4.3R'12 140 4.0

A 3 1 3 8 3 . 7A 9 138 3.8B 2 138 4.0

„ B 13 139 3.7R 9 138 3.9B1 2 138 4.0B'14 137 " 3.8R'12 140 4.3

A 3 137 4.4A 9 138 4.6B 2 136 4.8

3 B 14 138 4.8R 9 137 4.6B1 2 137 4.8B'14 136 4.9

-51-

TABLE 13

SERUM CHEMISTRIES

Subject Day of Study Sodium Potassiummeq/L meq/L

A3 138 4.9A 9 139 4.2B 2 139 4.8

4 B 14 140 5.0R 9 140 4.7B' 2 140 5.2B'14 138 4.2

A 3 140 4.0A 9 141 3.9B 2 141 4.4

5 B 14 140 4.3R 9 143 4.2B1 2 143 4.3B'14 141 " 4.4R'12 140 4.0

A 3 139 3.8A 9 139 3.9B 2 139 3.8B 14 140 3.9

b R 9 142 3.8B' 2 140 3.9B'14 141 4.2R'12 142 4.5

-52-

TABLE 14

BODY FLUID COMPARTMENTS

RedPlasma Cell Extracellular Total Body

Subject Day of Study Volume Mass Fluid Volume Water Weight(ml) (ml) (L) (L) (kg)

A 3 3136 1917 14.75 41.00 65.11A 9 2904 14.13 39.91 64.48B 2 2720 13.70 39.35 63.26

1 B 14 2603 2018 13.84 38.96 63.06R 9 3255 1926 15.10 39.32 63.49B1 2 2931 1826 38.59 63.54B'14 2636 1838 14.45 37.68 63.08R'12 3234 1924 15.38 41*36 64.78

A 3 3474 2249 19.07 50.56 98.23A 9 3484 2215 19.04 49.23 98.43B 2 3471 2051 19.17 49.91 98.47B 14 3283 2204 18.04 48.73 97.38

2 R 9 3738 2084 19.75 49.41 97.34B' 2 3384 2105 97.23B'14 3230 2096 18.62 48.56 96.96R'12 3644 2099 19.40 51.43 97.05

A 3 3375 2028 20.00 52.06 79.96A 9 3181 1984 20.20 . 52.04 79.48B 2 4078 1990 20.08 52.74 80.38B 14 3252 1976 19.12 50,32 79.57

3 R 9 3384 1831 20.56 51.36 79.37B' 2 3332 1870 20.19 50.05 79.26B'14 3198 1910 19.65 49.87 79.46R'13 3437 1786 21.25 52.17 80.37

-53-

TABLE 14

BODY FLUID COMPARTMENTS

RedPlasma Cell Extracellular Total Body

Subject Day of Study Volume Mass Fluid Volume Water . Weight(ml) (ml) (L) (L) (kg)

A 3 3543 2024 17.57 46.53 72.42A 9 3763 1994 17.52 47.99 72.77B 2 3306 1946 16.50 46.74 71.43

, B 14 3465 1922 16.34 46.24 71.45R 9 3537 1782 17.08 47.28 71.23B1 2 3407 1812 16.47 45.20 70.15B'14 3392 1743 16.47 45.71 70.19R'13 3914 1670 18.41 46.38 71.96

*

A 3 3249 1892 15.40 44.01 69.54A 9 3297 1844 15.67 -. 42.44 68.82B 2 2857 1794 14.18 43.44 68.03B 14 2880 1726 14.56 42.02 68.00R 9 3585 1705 15.16 45.50 67.68B' 2 3184 1738 15.19 42.27 68.00B'14 2768 1670 14.98 41.95 67.71R'12 3071 1695 14.65 41.94 68.10

A 3 3597 1945 16.80 46.66 72.52A 9 3526 1963 17.06 44.06 72.38B 2 3354 43.30 71.62B 14 3157 1790 16.53 41.43 71.04R 9 3362 1722 16.52 44.32 71.26Bf 2 3225 1710 16.40 45.58 71.81B'14 2932 1696 16.07 43.69 70.35R'12 3362 1672 16.26 43.97 70.70

-54-

Day of Study

TABLE 15

BODY FLUID COMPARTMENTSGroup Mean ± S.E.(95%)

Plasma Volume(ml)

Red Cell Mass(ml)

P VALUES

ExtracellularFluid Volume

(L)Total Body Water

(L)

A 3

A 9

B 2

B 14

R 9

B1 2

B'L2

R'14

3396±186

3359±315

3142±411

3107±328

3477±184

3244±185

3026±309

3444±315

2009±136 '

2000±167

194-3±174

1939±175

1842±150

1844±148

1826±168

1808±181

17.26±2.14

17.27±2.31

16.73±3.56

16.40±2.10

17.36±2.42

17.06±3.45

16.71±2.14

17.56±2.68

46.80±4.28

45.94±4.79

45.91±5.13

44.62±4.72

46.20±4.44

44.34±5.28

44.58±4.70

46.21±4.91

B

B

R

B1

B1

R1

2

14

9

2

14

12

vs

vs

vs

vs

vs

vs

A*

A*

A*

R 9

R 9

R 9

<0

<0

<0

<0

<0

<0

.07

.01

.40

.02

.01

.80

<0

<0

<0

<0

<0

<0

.10

.20

.01

.95

.60

.20

<0.10

<oeooi<0.80

<0.20

<0.005

<0.60

<0

<0

<0

<0

<0

<0

.40

.02

.80

.20

.02

.995

A = A 3 + A 92

-55-

TABLE 16

HEMATOCRITS

Subject

Study Day

A 3

A 9

B 2

B 14

R 9

B1 2

B'14

R'12

1

46.6

46.4

47.3

50.4

43.9

46.9

47.4

44,0

2

46.5

46.0

45.1

- 49.5

43.4

44.3

45.6

44.1

3

46.3

45.8

46.1

47.2

44.5

44.6

45.3

41.2

4

44.0

41.9

44.5

43.8

40.7

42.5

41.2

35.7

5

43.9

43.1

45.5

44.6

42,5

44.2

44.2

43.6

6

42.3

42.7

43.2

43.3

40.8

42.0

43.4

40.2

-56-

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-60-

Subject

TABLE 21

AVERAGE HEART RATE+ DURING LBNP

(Beats/min)

LBNP Magnitude

Day of Study Rest -30mmHg -40mmHg -50mmHg

A 13B 15R 13B'15R'14

A 13B 15R 13B'15R'14

A 13B 15R 13B'15R'14

A 13B 15R 13B'15R'14

4957505155

4551545250

4852484952

4748635456

5262605349

6274606860

5160486453

5366728174

5473765850

7094688065

647658-8056

638486108"86

6994798056

85109819980

6892789574

96

101

Syncope.

Nausea, pallor, hypotension.

Calculated as the average of the heart rates at eachminute during each level of LBNP.

-61 — .

Subject

TABLE 22

MAXIMUM HEART RATE DURING LBNP(Beats/min)

LBNP Magnitude

Day of Study Rest -30mmHg -40mmHg

A 13B 15R 13B'15R'14

4957505155

5466645853

6083806154

-50mmHg

801058410158

A 13B 15R 13B'15R'14

4551545250

6678657271

7998698576

941158610386

A 13B 15R 13B'15R'14

A 13B 15R 13B'15R'14

4852484952

4748635456

5563506763

5870788790

7280738564

698896110'95

,**

72999310882

84100*101

110

Syncope.frNausea, pallor, hypotension.

-62-

Table 23

Maximum Heart Rate During LBNPGroup Means ±S.E.(9570)

(beats/minute)

LBNP Magnitude

Day of Study Rest -SOmmHg -40mmHg -SOramHg

A 13

B 15

R 13

B'15

R'14

B vs A

R vs B

B1 vs R

R' vs B1

R vs A

R' vs R

47±2

52±5

54±11

52±3

53±4

<0

<0

<0

<0

<0

<0

.7

.9

.3

.4

.05

.8

.5

.3

.2

.9

58±8.6

69±10

64±18

71±19

69±25

P Values

<0.005

<0,4

<0.3

<0.4

<0.4

<0.5

70±13

87±13

80±19

85±32

72±28

<0.02

<0.4

<0.6

<0.05

<0.4

<0.4

82±15

105±12

91±12

104±9

84±34

<0.005

<0.2

<0,005

<0.10

<0.3

<0.5

-63-

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-67-

TABLE 27

RESPONSE TO EXERCISE: OXYGEN CONSUMPTION(ml/min)

Subject Day of Study Baseline SOW 75W 100W 125W 150W 175W

A 13 264 850 * *B 15 248 * 1168 1505

1 R 13 212 940 1234 1541B'15 250 866 1177 1477

A 13 290 947 1271 1628B 15 280 953 1272 1662R 13 316 954 1272 1627B'15 297 954 1156 1670

A 13 178 950 1180 1571B 15 194 882 1134 1464R 13 184 * 1168 '*B'15 240 894 1103 1234 2250R'14 226 931 1261 1595 2370

A 13 192 1006 1320 1714B 15 190 920 1247 1557R 13 188 862 1297 1577B'15 241 902 1220 1551 1989R'14 253 949 1175 1614 2396

A 13 144 955 1203 1604 2600B 15 197 875 1103 1561 2271R 13 219 884 1279 1844 2562B'15 217 761 1220 1698 2197R'14 256 853 1251 1604 2869

A 13 218 938 1256 1592 2507B 15 200 921 1189 1654 1991R 13 234 1003 1205 1777 2654B'15 186 864 1231 1577 2023R'14 218 901 1298 1763 2681

*Technical inaccuracies in gas collection.

-68-

Subject

1

2

3

4

5

6

A 13

*

3011

2184

2829

2708

2601

B 15

2268

2679

2185

2156

2455

2256

Mean

TABLE 28DERIVED MAXIMAL OXYGEN UPTAKE

(ml/rain)

Day of Study

R 13 B1 15

2677 2146

2947 2788

* 2315

2491 2104

2742 2265

2854 2161

2667 2333 2742 2296

R1 14

2617

2564

2999

2612

2698

S.E.(95%) ±384.7 ±208.8 ±216.5 ±265.9 ±321.6

*Data inadequate for accurate calculation.

P Values

A 13 vs B 15

B 15 vs R 13

R 13 vs B'15

B'15 vs R'14

A 13 vs R 13

R 13 vs R'14

<0.05

<0.005

<0.01

<0.02

<0.9

<0.9

eo

atC

-69-

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FO

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670

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eats

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(sec

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Table 32

Maximum Heart Rate During Centrifuge StudiesGroup Means ±S.E.(95%)

(beats/minute)

Day of Study Rest +2.1 G +3.2 G +3.8 G

A 14

BR-

BR+

R 14

R14 vs A14

BR- vs A 14

BR- vs R14

BR+ vs A 14

BR+ vs R14

BR+ vs BR-

53±7.9

59±7.1

58±3.2

56±9.3

<0.4

<0.005

<0.4

<0.3

<0.6

<0.9

112±22

143±22

124±36

113±17

P Values

<0.95

<0.001

<0.005

<0.2

<0.4

<0.05

142±27

161±21

139±12

137±16

<0.3

<0.005

<0.005

<0.6

<0.7

<0.05

150±28

169±14

147±26

152±23

<0.95

<0.10

<0.05

<0.7

<0.7

<0.05

+ With G-suit.

- Without G-suit.

SODIUM BALANCE (meq./24 hrs.)GROUP MEANS AND STANDARD ERRORS

UJoz

80-

60-

40-

20-

1o° -20-

-40-

-60-

14

AMBULATORY CONTROL

oTILT OH LBNP DAY•CENTRIFUGE DAY

7

BEDREST

15 7

RECOVERY

14 " 7

BEDREST

15 7

RECOVERY

Figure I

Sodium Balance. Group means on specific days or inspecific periods of the study.

3000-

2500-

ZOOO-

JO-

DERIVED MAXIMUM OXYGEN UPTAKE (ml./min.)

I— P<O.OI-

FLUID BALANCE (ml./24hr)

'—p<o --LI—P<:o.02SI—P<O.OS '

SODIUM BALANCE (m«q./24hr.)

i—p<o.oi—'

l-p< o.3

POTASSIUM BALANCE (m«q/34hr.)

0.30—I J— P< O 01t— p<ro.05—*

— P< 0 ZO—J

ORYO L | '

BEDREST RECOVERY BEDREST RECOVERY

Figure 2

Sodium Balance, Potassium Balance, Fluid Balance andDerived Maximal Oxygen Uptake. Group means and standarderrors.

51.00-

47.00-

43.00-

39.00-

22.00-

17.00-

12.00-

4.00-

3.50-

3.00-

2.50-

TOTAL BODY WATER (L.)

EXTRACELLULAR FLUIDI

VOLUME (L.)

PLASMA VOLUME (L.)

0 7 14

(AMBULATOR| CONTROL

Figure 3

Body Fluid Compartments. Group means and standard errorson specific study days.

120 H

100 H

< 80 -\

60 H

10 20 0~ T I 1 I I I T

10 20 0 20

140-

"20-

100-

60

SUBJECT 2

••-PRESYMCOPE

O 10

o AMBULATORY CONTROL<• BEOREST WITHOUT G-SUIT• RECOVERY PERIOD• BEDREST WITH G-SUIT

20 0

PAIN, PRESYNCOPE

10

MINUTES

20 O 10 20

Figure 4

4. Heart Rate Responses to 70° Tilt (+1 GZ). Subjects 1and 2.

S -so

OAMBULATORY CONTROLoeCDREST I•RECOVERY I. etOREST 2•RECOVERY 2

Figure 5a

Heart Rate Responses to LBNP,

° AMBULATORY CONTROLOBEDREST I•RECOVERY I•BEOREST 2* RECOVERY 2

MINUTES

Figure 5b

Heart Rate Responses to LBPN. Subects 3» 4, 5,, and 6.

1601

600

o AMBULATORY CONTROL° BEOREST WITHOUT G-SUIT

Figure 6

Heart Rate Responses to +2.1 GZ. Bedrest without G-suitand ambulatory control runs in all subjects.

IZOn

40

600

• RECOVERY PERIOD• BEOREST WITH 6-SUIT

Figure 7

Heart Rate Responses to +2.1 G . Bedrest with G-suitand recovery period runs in all subjects.

600

o AMBULATORY CONTROL• RECOVERY PERIOD

Figure 8

Heart Rate Responses to +2.1 G . Ambulatory control andrecovery period runs in all subjects.

IK t4O<0 120 ISO 240 O CO 120 180 240 O 60 120

•0 120 ISO 24O 0 6O I2O ISO 24O 0 «O 120

o AMBULATORY CONTROL

ItO 240

a BEOREST WITHOUT 0-SUIT• RECOVERY PERIOD• REDDEST WITH 8- SUIT

SECONDS

Figure 9a

Heart Rate Responses to +3.2GZ, Subects 1 and 2,

0 60 120 ISO 240 0 60 120 ISO 240 0 6O 120 180 240

0 60 120 ISO 240 0 60 120 ISO 240 0 SO 120 ISO 240

o AMBULATORY CONTROL SECONDSDBEOHEST WITHOUT G-SUIT.RECOVERY PERIOD• BEOREST WITH G-SUIT

Figure 9b

Heart Rate Responses to +3,2GZ. Subjects 3 and 4,

0 60 120 ISO 240 0 60 120 180 240 0 60 120 ISO 240

0 60 120 ISO 240 0 60 120 ISO 24O 0 60 120 ISO 240

o AMBULATORY CONTROLoBEOREST WITHOUT G-SUIT• RECOVERY PERIOD• BEOREST WITH G-SUIT

Figure 9c

Heart Rate Responses to +3.2GZ. Subjects 5 and 6.

SUBJECT I

60 120 180

o AMBULATORY CONTROLOBEDREST WITHOUT 6-SUIT• RECOVERY PERIOD• BEOREST WITH G-SUIT

6O 120 180 60 120 ISO

SECONDS

Figure lOa

Heart Rate Responses to +3.8 Gz. Subjects 1 and 2,

< ion -

SUBJECT 3

—f— T—0 CO

T 1 I170 ISO

. r—r—r—r—

0 SO IPO ISO

ui 180-

i- 100-

o eo 120 no

oAMBULATORY CONTROLo BEOREST WITHOUT 6-SUIT• RECOVERY PERIOD• BEOREST WITH 6-SUIT

6O 120 ISO

SECONDS

1 I I I I I0 60 I2O 180

Figure lOb

120-

80-

60 120 180 0 60 120 180 0 6O 120 180

LIOHT LOSS

~] fV SUBJECT «

180- I

120-

0 60 120 180

oAMBULATORY CONTROL°BEQUEST WITHOUT 6-SUIT• RECOVERY PERIOD• BEOREST WITH 6-SUIT

60 120 180

SECONDS

Figure lOc


4-2. IGZ 4-3. 2GZ + 3.8G2

A BR- BR+ R A BR~ BR+ R A BR~ flR* Fo D • • o a • • o a • «

180-

160-

LJ

< 140-K

K

X

100-

80-

'

<

U<0.00|J .

P<O.OS-

<

i

1

1

1

i

l-P<O.OSJ

p<b.oosJ y

,

-P<0.7~

1

-

F T T -. IT1

U<oovi

-p<o.ioJ '

P<0.7 1

tI

-P<O.T-I

t-p<o.«J

11.

Figure 11

Maximtun Heart Rates During Centrifugation. Group meansand standard errors.

nasa technical memorandum...nasa technical memorandum imasatm x- 62,311 v)

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