A test for the completeness of vagotomy

Abstract

THE difficulty inherent in ensuring completeness of surgical vagotomy by the abdominal route is not in dispute. In 1958 Burge and Vane described a technique for use at operation to ensure that all motor fibres are divided. This depends on the rise in intragastric pressure produced by stimulating vagal efferent fibres in the region of the cardia. Unfortunately, the performance of the test lengthens appreciably the duration of the operation and this alone has tended to discourage its general adoption.An alternative method is here described in which the integrity of the afferent fibres in the nerve is the basis of the test. Studies in dogs have shown the proposed test to be a satisfactory index of the degree of integrity of the whole abdominal vagal system. Its possible clinical applications are discussed. METHODSTen mongrel dogs were anzesthetized with morphine (3 mg./kg. body-weight) and nembutal (25 mg./kg. body-weight). The blood-pressure and pulse-rate were recorded from a cannula in the femoral artery using a Statham P23 strain gauge and a Gross polygraph recorder.The abdomen was opened through a small midline incision and, in turn, the serosal surface of several parts of the stomach and small intestine was stimulated with a square wave stimulator using twin platinum electrodes with a I-cm. point separation.Stimuli ranged from 5 sec. to 50 sec. with band widths varying from I to 30 m.sec. and voltages from 10 V. to 60 V. The stimuli were applied for periods varying from 10 to 20 sec. The effects on pulse-rate and blood-pressure were noted.The chest was then opened and the vagi identified just above the diaphragm. The test was repeated after each separate vagal trunk was divided. Finally, the cesophagus itself was transected to ensure discontinuity of all fibres.In 3 dogs records were taken while the central end of each vagal trunk was stimulated with wellinsulated platinum electrodes, the range of stimuli being similar to the above save that 20 was the maximum voltage used.After these observations had been made, some animals had a bilateral cervical vagotomy, others were given hexamethonium, 25 mg., and atropine, 1/300, and I dog was given eserine 1.25 mg. All drugs were given by the intravenous route. RESULTSIn all dogs stimulation of the serosal surface of the stomach and small intestine produced a contraction of the wall of the viscus. In general, the most effective stimulus was found to be 50 pulses/sec. at 40 V. and I msec. waveband, but there was some individual variation around these values. Maximum stimulation produced a sufficiently tight ring of spasm to produce blanching of the wall.Production of a contraction ring was always accompanied by reflex circulatory changes. The mean blood-pressure was constantly elevated by IC-40 mm. Hg, and in all but 3 of the animals this was accompanied by a slowing of the pulse-rate, often to half its original value. These effects disappeared, together with the relaxation of the contraction ring, within a few seconds of stopping the stimulus. Fig. 12014 shows a typic...

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