Sir

I read with great interest in your 100 Years Ago column (Nature 428, 705; 200410.1038/428705b) an excerpt from the 14 April 1904 issue of Nature which addressed the increasing death rates under chloroform anaesthesia. Back then, the American and British schools of anaesthesia had chosen to use different general anaesthetics. The Americans had embraced diethyl ether, with its more forgiving margin of error, allowing administration by physicians, nurses or medical students. The British preferred chloroform, despite its narrower margin of error, which led to more frequent complications (including death) and required a physician to administer it safely. The ongoing controversy in America over whether nurses or physicians should administer anaesthetics is, arguably, left over from this early difference in practice.

The irony is that the 1904 author criticized “the ignorant and careless anaesthetist” for using ‘cardiac syncope’ (a loss of consciousness or fainting due to the heart not pumping enough blood to the brain) as an excuse following death under chloroform. However, the most likely cause of death in patients who died suddenly under chloroform anaesthesia was — we now know — a ventricular fibrillation or tachycardia, causing the patient to immediately become pulseless and unconscious. So cardiac syncope was probably the correct postmortem diagnosis, even though the physiological basis for the syncope could not have been fully appreciated until decades later.

So how did the anaesthetists of 1904 make such a reasonable diagnosis? Before the introduction of a cuff for measuring blood pressure, and recording it on a written graph, the anaesthetist's left hand customarily held the mask to the patient's face, while his left little finger continuously registered the pulse under the patient's chin. This could be skilfully done, after some training, while maintaining a firm mask-grip. The anaesthetist would therefore know immediately when the pulse faded. Indeed, this manual skill is still useful, whenever our microprocessor-controlled blood-pressure devices fail during a mask anaesthetic, and we must know the patient's status. We also derive the expression, “to keep one's finger on the pulse”, from this anaesthetic technique long predating the Edwardian era.