Present position of the electrical stimulation test.

The electrical stimulation test to ensure complete ECORDER gastric vagotomy at the time of operation was first described by Burge and Vane in 1958. NBULB No drugs with an anticholinergic action should be used for treatment during the few weeks preceding operation. E ELECTRODE Simple antacids only may be given. Antacids, containing belladonna and drugs of the phenothiazine group, in particular, must be avoided. Premedication for the operation should be limited to papavaretum and anaesthesia Al R maintained with thiopentone, gallamine, nitrous oxide, and oxygen only. An electrode is placed around the lower oesophagus. A ,C\ FIG. 1. The principle of the t cuffed oral gastric tube seals the lower oesophagus and C LAMP brings intact vagal nerve trunks into good contact with the silver electrodes. An intestinal clamp is placed across the prepyloric stomach. The stomach is then distended with air to a pressure of about 70 mm H20, and the FIG. 2. The mark III instr pressure recorded on a suitable instrument. Even the Manometer smallest intact nerve trunk causes a pressure rise on Stimulator stimulation. When nerve section is complete there is no Electrode plug rise whatsoever of the gastric pressure; often there is a Batteries slight fall. The principle is illustrated in Figure 1. The mark III instrument (Fig. 2) is built into a standard sphygmomanometer box. Coloured water replaces the mercury in the manometer. A thin washer with a tiny hole is placed at the base of the manometer to damp the changes of pressure caused by respiration. The transistorized stimulator is built into the base of the box where, too, the batteries are housed.-_ The electrode (Fig. 3) is stimulated by a square wave current of 40 volts and a frequency of 15 per second. Figure 4 shows the cuffed gastric tube through which the gastric pressure is measured. A rise of pressure on stimulation of as little as 2 mm H20 is regarded as significant and indicative ofincomplete nerve section. Working to these standards, a surgeon well experienced in vagotomy may expect to achieve complete nerve section without the test in only 50%.-of cases. .. The set is now supplied with a simple electrode (Fig. 5) for any peripheral nerve stimulation. It is of particular. use in parotidectomy. 155 6 test.