[abstract] THE PHYSICS AND PHYSIOLOGY OF THE DISTRESSED SUBMARINE: PART II - RESCUE.

Abstract

Any event that sinks a submarine has a high probability of causing compression of the submarine's atmosphere. The degree of pressurization can range from 1 ATA to ambient, and rescue is unlikely before 48 hrs. Compression significantly complicates the rescue process by imposing a decompression obligation and increasing the toxicity of the respired gases. Decompression schemes must have a low risk of serious bends and must be tailored to the available rescue hardware/system. An example would be the necessity of surface intervals prior to decompression because of the lack of a pressurized transfer capability in the present USN rescue system. Similarly, simple and well tested ascent rates for air saturation decompression are required. Increasing submarine internal pressure also increases the toxicity of inspired gases. For example, breathing air at pressures in excess of 3 ATA will produce symptoms of pulmonary oxygen toxicity in less than 48 hrs. Recent data shows that humans can safely tolerate exposures of 5 ATA air for 48 hrs., but survival may be compromised with significantly longer or larger exposures. While awaiting rescue, atmosphere control aboard a powerless submarine requires manual methods. A recent UK field study has demonstrated the feasibility of using a foot operated bellows/ canister device for carbon dioxide removal and atmosphere circulation under realistic distressed submarine conditions. Oxygen can be maintained at a physiologic partial pressure by periodic burning of oxygen candles and monitoring with Drager tubes. Hypothermia may be less of a problem then originally suspected depending on compartment size, flooding, number of survivors, and C02 absorbent used.