Atmospheric changes and physiological responses during a 6-day "disabled submarine" exercise

Survival time within a disabled submarine (SUBSUNK) is dependant on atmospheric composition and proper design and use of emergency atmospheric control systems. The objective of this study was to investigate atmospheric changes and physiological responses during a SUBSUNK trial.

There were 18 volunteers who were restrained within a 250 m3 front compartment of an Ula-class submarine submerged in 8 degrees C seawater for 6 d, 18 h. Atmospheric control was maintained according to emergency procedures using non-electrically powered chemical CO2 absorption, and O2 was replenished using chlorate candles. Atmospheric parameters, skin and body temperatures, weight, urine, and drinking volume were measured. Subjective responses to cold were measured on a visual analog scale (VAS), and symptoms were logged on the environmental symptoms questionnaire (ESQ).

Atmospheric temperature gradually decreased to a minimum of 14.1 degrees C. Toe, heel, and finger temperatures decreased significantly. Subjects reported inferior subjective thermal comfort on the VAS and increased cold stress on the ESQ. Except for CO2, no inorganic or volatile organic compounds exceeded occupational exposure limits. The PO2 and PCO2 ranged from 17.4-20.3 and 1.9-2.8 kPa, respectively, during the first 5 d. During the last 2 d, PO2 and PCO2 were deliberately maintained at about 15.8 and 3.1 kPa, respectively. Mean oxygen consumption and CO2 production were 23.8 and 19.8 L standard temperature and pressure (STP) x man(-1) x h(-1), respectively. Soda lime and lithium hydroxide CO2 absorption capacities were 126 and 405 L STP x kg(-1) respectively.

Atmospheric conditions can be controlled acceptably for 6 d, 18 h within the front compartment of an Ula-class submarine operating according to emergency SUBSUNK procedures.