Michael E Tunstall: A pioneering anaesthetist
Michael E Tunstall has worked for over 50 years in anaesthetics
It was the sheer technical satisfaction and sense of achievement that it gave.
It was simple. Gas (nitrous oxide) and air delivered through the old machines were in mixtures that were seriously hypoxic. The British Oxygen Company then made machines that would deliver nitrous oxide and oxygen 50% through mixing valves. But it meant that you had cylinders of different gases which had to be changed. But it occurred to me, why not put the two gases in the same cylinder? I knew that nitrous oxide at room temperature would start liquefying at about 500 psi, whereas you cannot liquefy oxygen at room temperature. I thought there might be a solution to this problem. So I wrote to the British Oxygen Company in March 1961 and asked them for information. They then supplied me with cylinders of the premixed gases at 2000 psi for testing on patients.
But in 1962