The relevance of the asphyxial defence response to conditions such as near-drowning and birth asphyxia is clear. In others, such as sudden infant-death, it provides an attractive hypothesis. The diving response has been used recently as a clinical tool for the treatment of certain cardiac arrhythmias and as a simple test of autonomic function. There would appear to be considerable scope for such applications, particularly as they apply to asphyxia and cardiovascular medicine. These considerations may indicate further avenues for investigation into a variety of medical and surgical problems. We suggest that some of these instances in which apnoea, hypoventilation and asphyxia are prominent parts of the clinical syndrome may be better understood by recognition of potential similarities in underlying mechanisms to the phenomena of diving responses. The subject has been reviewed (Angell-James & Daly, 1969b; Daly & Angell-James, 1979; Daly, Angell-James & Elsner, 1979a, b; Gooden, 1982).

Near-drowning

Drowning is a common cause of death, accounting for about 8000 fatalities per year in the USA (Baker, 1954; Boucher, 1962; Modell, 1971). Death from drowning may result from asphyxia alone, in which case little or no water is found in the lungs at autopsy, or from the consequences of inhalation of water combined with asphyxia (Miles, 1962).