Thermal strain during diving in warm, contaminated water

Principal InvestigatorDavid Hostler, PhD

Funding Source: Office of Naval Research

AbstractDiving in category 1 and category 2 contaminated water requires the diver to be completely encapsulated in a heavy dry suit, helmet, and chemical resistant gloves. In water temperatures above thermoneutral, the diver will experience considerable heat strain that may limit work time and increases the risk of heat illness (e.g., exertional heat stroke). While the contaminated water dive kit protects the diver from toxins, it does not provide adequate thermal protection from heat stress in warm water. To date, there is only one large study of warm water diving that was conducted at NEDU in the late 1990s. There was anecdotal evidence of divers being so weak following warm water immersion that they had difficulty extracting themselves from the pool and/or became orthostatic after egress. These symptoms are common following exercise in the heat due to blood pooling in the limbs and cutaneous circulation. Thus, there is a need to reduce thermal strain while diving in warm contaminated water to both extend safe work time and alleviate heat stress. We hypothesize that pre-cooling to reduce core temperature prior to warm water submersion will improve diver safety and extend work times. Objectives: This proposal aims to: 1) describe the safe diving time during warm water submersion in divers and standby divers, 2) determine if pre-cooling is an effective intervention for extending work time, and 3) investigate the effects of diving in warm water on orthostatic tolerance and cardiovascular function following submersion. Methods: We propose to determine the time for core temperature to reach 38.5°C in divers and standby divers working in category 1 contaminated waters at typical (~28°C) and worst case (~32°C) warm water diving temperatures, and determine if a pre-cooling intervention extends those work times. The physiologic effects of diving in warm water on orthostatic tolerance and cardiovascular function following exposure to warm water will also be investigated post-submersion. Contribution to the Navy: The experimental aims of this proposal provide pertinent information regarding diver safety while working in warm contaminated water for divers and standby divers. The cooling intervention utilized in these aims can be directly implemented in tethered divers using commercially available equipment providing rapid solutions for the fleet.