Blind nasal intubation with propanidid.

Sir,—Dr Collier is disappointed that we did not comment on e.c.g. changes during hypotension. Alas, we cannot remedy this because no such changes occurred. A continuous recording was taken in each case and none showed any arrhythmia. If she has evidence that changes in rhythm during hypotension indicate cardiac hypoxia and a low cardiac output (and "considered by some" hardly rates as evidence), then she should publish it. The only relevant e.c.g. changes would be S-T segment depression and this has only been observed in the elderly (Rollason and Hough, 1960). If having measured the cardiac output, which is after all the most important single parameter of the circulation, and found it is little affected by hypotension, then one is encouraged in the belief that the method is relatively safe because tissue hypoxia is unlikely to occur when total blood flow is adequate. Our view that controlled hypotension is a safe procedure is based, not on ten patients, but on twenty-five years experience of the technique in this centre. Others, we know, have had similar results. Dr Collier's methods of producing a bloodless field are doubtless admirable in her hands. She must not, however, imagine that alternative methods are harmful to patients, and can be proved to be so if only the right tests are done. If she has evidence, we say again, let her produce it. Finally, we can assure her that the writers would certainly be willing to have our systolic pressures reduced to 60 mm Hg if the operative procedure warranted it. We assume that the anaesthetist would be competently trained in the method and have enough knowledge of the circulation to eschew irrelevant e.c.g. changes and ideas about arbitrary levels of "unsafe" systolic pressure. D. B. SCOTT, G. W. STEPHEN, R. L. MARSHALL