Estimated survival times of humans wearing the Quick Don Immersion Suit and Cold Water Immersion Suits in Antarctic waters (-1.86°C)

A limited but realistic field evaluation of human thermal response to immersion in Antarctic sea water (-1.86°C) whilst wearing an Royal New Zealand Air Force (RNZAF) Quick Don Immersion Suit (QDIS) was conducted over two seasons in order to estimate survival times. An ice hole measuring 2 x 2m was cut in the ice adjacent to Scott Base. Volunteers would be wearing clothing worn by RNZAF C130 Hercules aircrew in the event of an emergency ditching en route to or from Antarctica, the QDIS and Mk15 life preserver. The subject floated horizontally in the water with approximately 15 cm of freeboard.

The core body temperature was measured from rectal temperatures with a thermistor inserted 10 cm into the rectum. Skin temperatures were measured from the toe (the lateral aspect of the fifth toe centered over the first and second phalanges of the right and left feet), the finger (measured on the anterior pad of the distall segment of digitus minimus of the right and left hands), chest, arm and calf and recorded on a data logger every 10 minutes until withdrawn from the water (when core body temperature dropped below 36.0 °C or the skin temperature fell below 7 °C, or it was deemed necessary to remove the subject). Preliminary estimates of survival were determined by linear extrapolation of the observed rectal temperature response to the core temper. Two types of re-warming methods were examined for efficiency: whilst still wearing the QDIS and in a sleeping bag after removal of the the QDIS. Some subjects were immersed a second time and the variability in the human response to replicate cold water immersions was examined. A limited assessment of the RNZAF constant wear immersion suit (CWIS) was conducted in the same manner as for the QDIS.