Hyperventilation response to cold water immersion: reduction by staged entry.

Staged immersion of humans into cold water was investigated to determine whether the hyperventilation response could be reduced by this behavioral technique. A simple, two-stage procedure involving immersion to the waist for 30 s before full immersion to neck level was compared to non-staged immersion. For the staged immersion, maximum values of respiratory minute volume and respiratory frequency were significantly reduced by 35% and 38%, respectively, from the maxima observed for non-staged immersion. These results indicate that if staged immersion into cold water is possible, it can attenuate the hyperventilation response and, therefore, the probability of sudden drowning. We recommend that this knowledge be incorporated into teaching programs concerning cold water safety.