Effect of nifedipine on bronchomotor tone and histamine reactivity in asthma.

it is difficult to explain how successful resuscitation is possible after 40 minutes' submersion.2 The reduced oxygen requirement in profound hypothermia has been suggested by some authors as the mechanism by which tissue viability is maintained in these circumstances,2 but this alone is an incomplete explanation, as for the submerged body to cool to a degree at which oxygen requirements are sufficiently reduced, heat transfer by mass flow-that is, circulation -must be present (a dead body cools relatively slowly). The degree of cooling encountered in our cases can be explained only by the fact that circulation was maintained for some or all of the period of submersion. The persistence of cardiac activity during such a prolonged period of apnoea supports the hypothesis that some protective mechanism may be present. We do not know whether ventricular fibrillation was present before resuscitative efforts were started and must concede that these efforts alone may have initiated the arrhythmia. Our cases show yet again that successful resuscitation is possible after long periods of immersion and emphasise the importance of performing electrocardiography early in the immersion incident, preferably at the accident site, before death is pronounced.