DELAYED NEUROLOGICAL DETERIORATION AFTER ANOXIA

the United States there are now 3,000,000 people who go underwater at one time or another. By analogy Australia can expect to have 100,000. On many a hot Sunday afternoon the medical practitioner will be urgently called to treat strange variations on the theme of drowning, as inevitably the young and enterprising will explore for themselves the dangerous hidden boundaries to which man may go in the sea. Among other dangers described is the subtle sequence of events which in recent years has claimed several young lives on our coasts-a sequence in which the diver economizes on his oxygen or oxygennitrogen mixture supply while using a rebreathing circuit with carbon-dioxide absorption. He readily loses consciousness from breathing his residual pure nitrogen, his body having extracted the oxygen and the absorbent the carbon dioxide. The enigma of "shallow water blackout", here described as "oxygen syncope", is discussed, but no fully adequate explanation is yet available. The important and interesting matter of what residual damage occurs to cerebral cortical cells with the occasional inevitable anoxia every experienced diver meets is suggested, but not discussed. Miles wisely points out the hazard in the excellent "hookah system" as at present widely used in Australia. He shows the advantages of auxiliary reserve cylinders worn by the diver-available if fouling, kinking or surface failure causes cessation of air supply from above.