Ventilatory response to intractable pain.

Fifty-two patients, admitted to a pain relief unit, had a cannula placed in the radial artery to measure the paO2, paCO2 and pH of arterial blood every 2 h, for periods ranging from 12 to 24 h. The patients were divided into 3 groups: 14 had low back pain, 21 patients had pain from cancer, and 17 had pain from other causes. Twenty were male and 32 were female with a mean age of 53 years (range 16-82 years).