Why did surgeons race against the clock until a dentist put a patient to sleep in 1846?

Because the longer an operation lasted, the more dangerous it was: the shock of surgery itself could kill. Before anesthesia was introduced, the physiologic stress of surgery caused significant complications and many deaths from shock, and the faster the surgery was, the lower the rate of complications. That is why you read of very quick amputations. Surgery was a race against the patient's own body.

On 16 October 1846, that changed in an operating theatre at the Massachusetts General Hospital, in Boston. Two weeks earlier, on 30 September, the dentist William Morton had performed a painless tooth extraction after giving a patient ether. After reading a favourable newspaper account of it, the Boston surgeon Henry Jacob Bigelow arranged a demonstration, and at it the surgeon John Collins Warren painlessly removed a tumour from the neck of a patient. The theatre came to be known as the Ether Dome and has been preserved as a monument to the event. Who deserved the credit was disputed: a Georgia surgeon, Crawford Long, had used ether as an anesthetic in 1842 but did not publish until 1849, and Boston's Ether Monument was designed not to choose sides.

The news spread rapidly around the world. The first recorded use of ether outside the United States was in London. A year later James Young Simpson, a Scottish obstetrician, was the first to demonstrate the anesthetic properties of chloroform on humans, and in 1853 John Snow gave it to Queen Victoria when she was in labor.

The new gift was not free of risk. The advent of anesthesia allowed more complicated and life-saving surgery to be completed, and decreased the physiologic stress of the surgery, but added an element of risk: two years after ether was introduced, the first death directly related to anesthesia was reported.