PRINCIPAL INVESTIGATOR(S): G. Wyckliffe Hoffler, and Robert L. Johnson 



EXPERIMENT TITLE/NUMBER : Apollo Flight Crew Cardiovascular Evaluations 



PROGRAM/MISSION : Apollo 7-9, 15-17 



CLASSIFICATION : Human 



DISCIPLINE(S) : Cardiovascular 



OBJECTIVES : To determine the response of the cardiovascular system to 

 weightlessness . 



PROTOCOL : Lower body negative pressure (LBNP) was used, with 5 minutes rest, 



15 minutes reduced pressure, and 5 minutes recovery, using 3 different 

 pressure levels. There was also a passive test of 5 minutes resting supine 

 and 5 minutes passive standing. Ambient temperature and oral temperature were 

 recorded pre- and postf light for orthostatic evaluations. Physiological 

 measurements were recorded in real time on strip chart recording, and FM 

 magnetic tape. 



EQUIPMENT : LBNP device, antihypotension garment, electrocardiograph, 

 thermometers, physiological sensors. 



RESULTS : The resting supine heart rate was elevated significantly in 54% of 

 the crewmen on the first day postf light. Application of -50mm Hg LBNP 

 elevated the rate in 82%. The Apollo 15 LMP experienced presyncope during the 

 last second of -40mm Hg, while the Apollo 8 CMP and LMP, Apollo 9 LMP, Apollo 



16 LMP and CMP all developed presyncope during the -50mm Hg level of LBNP. 



The passive standing test had the same elevated heart rate results. There was 

 also a significant decrease in the systolic and pulse pressure during LBNP in 

 the first postf light evaluation. There was a significant decrease in weight 

 postflight . 



CONCLUSIONS : Postflight orthostatic evaluations during the Apollo program 

 indicated that reduction in orthostatic tolerance is a consequence of space 

 flight exposure. Heart rate, the most reliable index, was increased, while 

 systolic and pulse pressures were decreased during immediate postflight 

 evaluations using lower body negative pressure and passive standing as the 

 orthostatic stress. Postflight changes in leg volume during LBNP were equal to 

 or less than those seen during preflight baseline evaluations. Body weight, 

 resting calf girth, supine leg volume, and cardiothoracic ratios were all 

 diminished immediately postflight, and return to preflight values was not 

 complete within the postflight testing time frame. The wearing of a lower 

 body positive pressure garment during the reentry and immediate postflight 

 period offered some protective benefit by way of reducing lower body pooling 

 of fluid. 



PUBLICATIONS : 78, 82, 270, 271, 460 



32 



