Unexpected complication of successful nerve block. Morphine induced respiratory depression precipitated by removal of severe pain.

A case is reported of a 76-year-old man with a right-sided mesothelioma who required large doses of oral narcotics to control his severe chest pain. After a successful chlorocresol intrathecal nerve block, respiratory failure was induced by doses of oral morphine at the same level as those used before the block, and also by substantially smaller doses. A considerable reduction in analgesic requirements may be possible following non-drug intervention to relieve pain and may be essential in patients with compromised respiratory function. This observation emphasises the importance of pain as a potent stimulator of the respiratory centre in patients with reduced respiratory reserve who are receiving narcotic drugs.