chapter 34 

 EEC AND EKG OBSERVATIONS IN SEALAB II 



C. W. Sem-Jacobsen 



Gaustad Sykehns 



Oslo, Norway 



INTRODUCTION 



High-pressure-oxygen toxicity, anoxia, and nitrogen narcosis produce marked changes in 

 behavior and in the electroencephralographic record. Minor changes in the EEG are seen as 

 early warnings. 



The purpose of the present study was to determine if prolonged submergence (15 days) in 

 an artificial atmosphere of He, O 2, N 2, 205 ft below the surface of the sea would cause perma- 

 nent or transient physiological or pathological changes in the brain, and study an correlation 

 between such changes and fluctuation in the environment including the gas mixtures. 



The experience with biological recordings from free-swimming divers in the ocean or in a 

 habitat at 200 ft depths is very limited, and a number of expected and unexpected artifacts were 

 encountered in Sealab II. If proper precaution was not taken, gross artifacts due to air bubbles 

 from the respiration or movement in the salt water were encountered. In the same way salt 

 water would through internal shorting to the body, short out the electrodes more or less com- 

 pletely. Artifacts due to the movement in the ocean as an infinite body moving in the earth's 

 magnetic field were also encountered. The electrical signals generated by the waves against 

 the bep.ch were of an order of 10 millivolts. Electrical potentials generated by magnetic storms 

 over Indonesia propagated through the ocean, and arrived at the location of Sealab H between 

 1700 and 1800 in the early evening. 



These latter potentials would in the EEG recordings give slow-wave artifacts similar to 

 those generated by some brain tumors or unconsciousness. Muscle artifacts were only a minor 

 problem in the recording. 



RESULTS 



A number of good recordings were obtained from free-swimming divers in the ocean and 

 the aquanauts inside Sealab H during the operation. The number of records obtained during 

 the operation were limited, and the results are therefore given with some reservations. 



Recordings from aquanaut R show a marked increase of the alpha-frequency after he had 

 been in the habitat four to six hours (Fig. 100). On the staging vessel on Sept 12, when the 

 electrodes were attached the frequency of the alpha activity was 10-11 cps. In the habitat that 

 first evening about 2000 the activity was up to 14-15 cps. The next evening, Sept. 13, it was 

 down to 13 cps, and two days after he went down, on Sept. 14, his alpha was back to 11 cps. 



During the same period there were some marked changes in the gas mixture at the time 

 of recording as reported by Dr. Larson. 



CO2 O2 N2 PSI absolute 



Date (Percent) (Percent) (Percent) pressure 



Sept. 12 0.056 5.51 21.6 100.8 



Sept. 13 0.02 4.60 22.0 100.0 



Sept. 14 0.05 4.20 21.9 100.8 



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