Safety of general anaesthesia and surgery in acute hepatic porphyria.
Patients with acute hepatic porphyria are denied essential operations because of concern that general anaesthesia and surgery will precipitate a life threatening porphyric crisis. This study assessed the safety of surgery under general anaesthesia in these patients. A combined prospective and retrospective case note study, with a biochemical study, was conducted in 25 patients with acute hepatic porphyria undergoing 38 surgical operations. Clinical outcome measures were survival and occurrence of porphyric crisis after surgery. The biochemical activity of porphyria was assessed by measurement of the perioperative 24 hour excretion of the haem precursors delta amino-laevulinic acid (ALA) and porphobilinogen (PBG). There were no deaths or crises after 29 operations in 19 patients who were known to have porphyria before their surgery, and therefore given only appropriate drugs. These operations include such major procedures as mitral valve replacement, hip replacement, coronary artery grafting, cholecystectomies, and renal transplantation. In eight of these patients the urinary excretion of ALA and PBG were studied, and showed no sustained postoperative increase. Nine operations were performed in eight patients before the diagnosis of porphyria was known and who thus received routine anaesthetic agents. Seven of these patients developed a postoperative porphyric crisis. Two of them died. It is concluded therefore that even the most major surgery can be undertaken safely in patients with porphyria. The risk is for undiagnosed cases.