Test No. 2 was designed to determine if this attack of dysbarism might 

 conceivably have been caused by decompression from the simulated excursion 

 to 175 FSW, rather than from the 100-FSW habitat depth. The first test 

 procedure was repeated, but without the simulated excursion. Test No. 2 

 involved the subject who had developed bends in Test No. 1, plus a second 

 diver. The same 30-hr table was used. Once again, the first subject developed 

 bends during decompression, this time at 40 FSW, and both subjects had to be 

 recompressed. 



The second subject of Test No. 2 experienced an episode of apparent hypoxia 

 during the saturation exposure at 100 FSW. His symptoms were relieved by 

 increasing the Go percentage to 7%, thus making the breathing atmosphere 

 93% No and 7% 0^. The PN2 was maintained by increasing the habitat pressure 

 to 103 FSW. Edel continued to use the 103-FSW pressure and the higher PO2 

 percentage in the remainder of the preliminary Minitat tests although, indeed, 

 subsequent laboratory evaluation demonstrated later that the second subject of 

 Test No. 2 had an abnormal hypoxic respiratory response. 



The Department of Interior funded J&J directly for continued development of a 

 decompression table. Because of the dysbarism experienced in Tests No. 1 and 

 2, the table was recalculated. The result was a 36-hr decompression schedule 

 that included breathing O2 for 6 hr, 15 min, to be divided among 12 stops 

 commencing at 60 FSW. 



Two tests, No. 3 and 4, of this revised table (each involving two subjects) 

 were uneventful during decompression itself. But in both tests the subjects 

 developed significant signs of substernal distress and pulmonary inflammation 

 once they reached surface pressure. 



Calculations at the Institute of Environmental Medicine, University of 

 Pennsylvania, indicated that the O2 toxicity caused by this last decompression 

 schedule would result in an S/i decrement in vital capacity (VC) . The Medical 

 Advisory Board considered this decrement excessive. It therefore decreed that 

 a modification of the table used in Tests No. 3 and 4 should be made, ultimately 

 recommending that the decompression period should be extended to 50 hr, and that 

 it include two 360-min stops. (Such prolonged stops had been found necessary 

 by USN medical officers during development of decompression schedules for use 

 in SeaLab III.) 



The proposed new table was adjusted by computer computation at the UP, based on 

 a maximum Ti^ of 500 min and a Workman M-value of 49 FSW. A 49-hr, 20-min table 

 resulted, in which little O2 breathing (170 min) was involved, and in which the 

 toxic liabilities of O2 were predicted to cause less than a TL decrement in VC. 



This decompression schedule was then tested at J&J Marine Diving Co. in two runs 

 (Tests No. 5 and 6), each involving two subjects, following a pressure exposure 

 in which the previously described accelerated saturation technique was used. 

 All subjects remained asymptomatic of decompression sickness and oxygen toxicity. 



Ascent and Descent Excursion Limitations From 100 FSW 



The research program designed to develop decompression tables for the 100-FSW 

 dives included, as well, calculation and testing of the maximum safe descent 

 and ascent excursions from the habitat emplacement depth. The participants in 



IX-18 



