DISSOLVED GASES IN BODY FLUIDS 



223 



Table 17 

 SEALAB II BASELINE STUDIES 



RESULTS OF DECOMPRESSION STUDIES 



The most reliable and complete data were obtained during the decompression studies of 

 Teams 2 and 3. Decompression studies on Team 1 were not started until approximately half- 

 way through their decompression, since at the same time efforts were concentrated on Team 2 

 uptake studies. When it became evident that no worthwhile uptake data were going to be ob- 

 tained on Team 2, it was decided to switch to Team 1 decompression. The helium and nitrogen 

 decompression data obtained on Teams 2 and 3 agreed very well with the partial pressure of 

 helium and nitrogen recorded at the various stages of decompression. 



Decompression of Team 2 



Fig. 95 relates to the decompression studies on Team 2. The upper part of Fig. 95 is a 

 plot of the absolute partial pressure of inert gases in the atmosphere versus the decompression 

 time in hours. The total pressure in Sealab was approximately 6.8 atmospheres, and the com- 

 position of the major gases was02 - 7.9 percent, N2 - 14.2 percent, and He - 77.9 percent. In 

 all habitats, i.e., Sealab, PTC, and DDC, the percentages of O 2, N2, and CO2 were measured di- 

 rectly by gas chromatography, and helium was determined in all cases by difference.* 



A urine sample was taken just before the divers left Sealab. No samples were taken while 

 the divers were in the PTC, which was approximately one hour. The total absolute gas pres- 

 sure in PTC was decreased from 6.9 atmospheres in Sealab to 6.6 atmospheres, at which time 

 the men transferred to the DDC. Deck decompression was started at this time. The first ur- 

 ine samples from the DDC were obtained about two hours after entry. Decompression contin- 

 ued at a steady rate for ten hours (see point A, Fig. 95). At this time it was determined that 

 the O2 level was higher than desired. It was decided to purge the DDC with helium in order to 

 reduce the O2 level. This also resulted in a reduction of the Nj level. The helium level of 

 course increased during this time. After a total of 30 minutes for helium purging, decompres- 

 sion was resumed. After approximately 23 hours (point B, Fig. 95) another hold was instigated 

 for the purposes of sending in a medical team via the outer lock of the DDC. This step resulted 

 in an immediate loss of helium and similarly an increase in the N2 level, as the outer lock was 

 compressed to 2.3 atmospheres with air. Decompression was resumed, and after 32 hours the 

 DDC was flushed with air. 



In the lower half of Fig. 95 is plotted the concentration of inert gases in ml/liter for ur- 

 ine versus the decompression time in hours. Comparison of the changes in partial pressure 



*The gas mixture percentages and total pressures used to compute the absolute partial pres- 

 sures seen in Figs. 95 and 96 were supplied by the personnel of the New London Medical Re- 

 search Laboratory, U.S. Naval Submarine Base, New London, Connecticut. 



