In Reply.—Spasm of the sphincter of Oddi can be induced by many stimuli. Fentanyl, morphine, narcotic analogues, highly alkaline, highly acidic, and cold contrast media can produce spasm. Manipulation of the common bile duct during a Kocher maneuver, dilation of the sphincter with probes, scoops, and catheters and pressure injections can all produce spasm.
In our patients, we could find no correlation between the dose of fentanyl and the occurrence of spasm of the sphincter of Oddi. Spasm occurred in some patients with single injections of fentanyl and did not occur in others with repeated injections. Certainly other factors such as individual sensitivity to fentanyl, type and timing of premedications, and the mechanical trauma of surgery are important in determining whether spasm will occur.
Decrease in the elevated pressure observed in the common bile duct 25 minutes after injection of fentanyl may represent receptive relaxation of the biliary tree