Urine acid output as a test of completeness of vagotomy

Peak acid output in response to sham feeding and changes in urine acid output 2 and 3 hours after a test meal have been measured in 20 normal volunteers, 17 asymptomatic patients after vagotomy, six patients with recurrent duodenal ulcer after vagotomy and ten normal subjects given a 48-h course of ranitidine, 150 mg 12-hourly. Gastric peak acid output in normal volunteers ranged from 6.9 to 22.1 mmol/h. All asymptomatic patients after vagotomy had a peak acid output less than 7 mmol/h, consistent with complete vagotomy. Five patients with recurrent ulcer had a peak acid output greater than 8 mmol/h, suggesting an incomplete vagotomy. Urine acid output after a test meal, expressed as the change from the basal rate of acid output, was always in a negative direction in normal subjects (fall in acid output = postprandial alkaline tide). This change was abolished in patients with complete vagotomy, in whom urine acid output increased after a meal. In five patients with incomplete vagotomy (and one other with recurrent ulcer and unknown vagal status) the urine acid output changed in a negative direction after a test meal. The relationship of urine acid output to gastric secretion was confirmed by the abolition of the postprandial alkaline tide in normal subjects given ranitidine. The results in patients with incomplete vagotomy did not overlap with those from patients with complete vagotomy. This suggests that this test could be used for the routine postoperative assessment of completeness of vagotomy.     

Evaluation of an intraoperative test for the completeness of vagotomy.

An intraoperative test for the completeness of vagotomy has been evaluated in 103 consecutive operations, including proximal gastric, selective and truncal vagotomies, and truncal vagotomy with antrectomy. At the completion of the vagotomy a pH probe was used to test gastric mucosal response to an intravenous infusion of pentagastrin, aiming to detect undivided vagal fibres by localizing residual areas of acid secretion. Testing was performed in 86 out of 103 vagotomies, and in only 34% was the vagotomy judged complete at the first attempt. Residual areas of acid secretion (usually small) were detected in the remainder, and in early all of these it was possible to abolish these areas by dividing further vagal fibres. It is suggested that intraoperative pH testing improves the likelihood of a complete vagotomy. The test is also useful to plot precisely the antral-body junction when antrectomy is combined with vagotomy.     

A new intraoperative test for completeness of vagotomy: the PCP-GABA (beta-parachlorophenol-gamma-aminobutyric acid) test

PCP-GABA, an analogue of the neurotransmitter amino acid, GABA, is as effective a stimulant of vagal centers and acid secretion as sham feeding. Insulin hypoglycemia, a test hitherto widely used for the cephalic phase, is unsafe and nonspecific because it also stimulates catecholamine release which affects gastrin secretion. PCP-GABA, unlike insulin, causes no tachycardia or hypoglycemia; however, the major advantage of PCP-GABA is that it can be used safely intraoperatively to assess completeness of vagotomy. Its muscle relaxant action is an additional advantage in this regard. As an intraoperative test, PCP-GABA is given intravenously shortly after induction of anesthesia to stimulate acid secretion and to reduce gastric mucosal pH, which is measured by an intraluminal combination electrode. The electrode can be moved around through the intact gastric wall to take measurements from multiple sites. When vagotomy is complete, gastric mucosal pH increases to over 6. This test works well in the dog. We hope to assess its clinical use in the near future.     

Gastrocystoplasty in pigs and effect of selective antral vagotomy on acid secretion of the reconstructed bladder

INTRODUCTION: The aim of this study was to investigate the outcome of gastrocystoplasty and the effects of selective antral vagotomy (SAV) on the postprandial gastrin secretion from the antrum as well as on the acid secretion from the augmented bladder. MATERIALS AND METHODS: In this study on 12 male pigs, we applied subtotal cystectomy plus gastric augmentation plus SAV to the study group and the same procedure without SAV to the control group. The animals were followed up for 3 months with respect to feeding, weight, and urine output. The urine pH levels and the gastrin levels of the pigs in the two groups were then followed up and compared. RESULTS: The use of gastric segments in bladder reconstruction was found to be appropriate in terms of both gastric function and urinary system function. Nevertheless, regarding the effect of SAV, the differences between either the urinary pH levels or the gastrin levels of the pigs in the two groups were statistically significant. CONCLUSIONS: Although gastric segments in the bladder reconstruction were found to be appropriate in terms of both gastric function and urinary system function, SAV did not prevent postprandial gastrin secretion and the resulting increase of the urine acidity.     

Fasting and postprandial serum gastrin levels before and after highly selective gastric vagotomy, truncal vagotomy with pyloroplasty and truncal vagotomy with antrectomy: is there a cholinergic antral gastrin inhibitory and releasing mechanism?

Fasting serum gastrin levels and postprandial gastrin response were measured before and 1 month after highly selective vagotomy, truncal vagotomy with pyloroplasty and truncal vagotomy with antrectomy. The three groups of patients, 12 in each group, were closely matched for age, sex, maximum acid output and completeness of vagotomy. After highly selective and truncal vagotomy an identical and significant increase in fasting gastrin was observed, whereas after truncal vagotomy with antrectomy the pre- and postoperative fasting gastrin levels were not different. The net postprandial gastrin output over basal value was significantly increased after highly selective vagotomy, unchanged after truncal vagotomy and significantly lowered after truncal vagotomy with antrectomy. These results suggest the presence in the intact subject of a cholinergic inhibitory mechanism in the gastric body and fundus for the release of antral gastrin in the fasting and postprandial states and a possible cholinergic facilitatory mechanism for the release of antral gastrin after meals.     

EVALUATION OF AN INTRAOPERATIVE TEST FOR THE COMPLETENESS OF VAGOTOMY

An intraoperative test for the completeness of vagotomy has been evaluated in 103 consecutive operations, including proximal gastric, selective and truncal vagotomies, and truncal vagotomy with antrectomy. At the completion of the vagotomy a pH probe was used to test gastric mucosal response to an intravenous infusion of pentagastrin, aiming to detect undivided vagal fibres by localizing residual areas of acid secretion. Testing was performed in 86 out of 103 vagotomies, and in only 34% was the vagotomy judged complete at the first attempt. Residual areas of acid secretion (usually small) were detected in the remainder, and in nearly all of these it was possible to abolish these areas by dividing further vagal fibres. It is suggested that intraoperative pH testing improves the likelihood of a complete vagotomy, the test is also useful to plot precisely the antral-body junction when antrectomy is combined with vagotomy.     

Proximal gastric vagotomy and mucosal antrectomy: a comparative physiologic examination

Proximal gastric vagotomy-mucosal antrectomy (PGV-MA) was devised in an attempt to reduce the cephalic and hormonal phases of acid secretion without disturbing gastric emptying. The current study determines the effects of proximal gastric vagotomy (PGV), or PGV-MA on acid secretion, gastrin, and gastric emptying. Twelve dogs underwent measurement of gastric emptying, fasting and postcibal acid production, and fasting and postprandial gastrin levels. The animals then underwent either PGV or PGV-MA and the studies were repeated. PGV markedly decreased basal acid (P less than 0.001); however, there was still a large postprandial acid increase. In contrast, PGV-MA nearly abolished both fasting and postprandial acid secretion (difference from control and PGV significant at P less than 0.001). Gastric emptying was not significantly altered by either procedure. PGV was associated with increased fasting and postprandial gastrin levels, while PGV-MA produced lower gastrin levels at all intervals than either controls or PGV-MA. PGV-MA emulates the effects of truncal vagotomy and antrectomy on acid secretion, without affecting gastric emptying and deserves further investigation as a possible surgical alternative in the treatment of duodenal ulcer disease.     

Use of gastric pH-metry for peroperative evaluation of the completeness of vagotomy]

In 124 patients subjected to various types of vagotomy its completeness was tested peroperatively with Grassi test and intrastomach pH-metry. The results were compared with the Hollander test findings in 112 postoperative cases. It has been ascertained tat the peroperative pH-metry does not allow for judging on the completeness of vagotomy. The postoperative pH-metry tests show only the ability of the stomach mucous membrane to produce hydrochloric acid in response to the maximal histamine stimulation, which can be used for total evaluation of the effectiveness of the operation.     

Improved methodology for the Grassi test for intraoperative determination of completeness of vagotomy

The Grassi test for completeness of vagotomy is a useful adjunct to vagotomy that aids the surgeon in severing all the vagal innervation of the acid-producing portion of the stomach. The Congo Red stick allows the surgeon to perform the Grassi test with a significant reduction in the amount of equipment and personnel required by either pH electrode or liquid Congo Red methods.     

Gastroesophageal reflux in duodenal ulcer patients before and after vagotomy.

Gastroesophageal reflux was investigated in 80 patients with duodenal ulcer by analysis of symptomatology and the acid reflux test. Resting gastroesophageal sphincter pressure (GESP) and postvagotomy reduction in basal and pentagastrin stimulated gastric acid secretion were also studied. Reflux symptoms were present in 40% of the patients, and this incidence was significantly reduced two months after vagotomy. In patients studied late after operation reflux symptoms were still less frequent than before operation, but not significant. After vagotomy, no significant changes in the fasting GESP or in gastroesophageal reflux as determined by the pH glass electrode were demonstrated. Thus, the decrease in reflux symptoms may be explained by the significant reduction in gastric acid secretion. Denervation of the cardia and the lower esophagus does not influence GESP or gastroesophageal reflux.     

Effect of selective proximal vagotomy and truncal vagotomy on gastric acid and serum gastrin responses to a meal in duodenal ulcer patients.

To assess the effectiveness of selective proximal vagotomy (SPV) in reducing the acid response to food, we have compared pre- and postoperative gastric acid and serum gastrin responses to a meal in 11 duodenal ulcer patients with intractable pain treated by SPV, with those of seven ulcer patients with gastric outlet obstruction treated by truncal vagotomy and drainage (TV + D). Acid secretion was measured by an intragastric titration method which measures acid response to food within the stomach (5% amino acid meal) adjusted to various pH levels (5.5, 2.5, and 1.5). Studies were performed before and two to six weeks after operation. The preoperative intragastric acid output (IGAO) was about 50% of maximal acid response to Histalog. The mean preoperative IGAO at pH 5.5 For 11 SPV patients was 17.4 +/- 3.1 mEq/hour; this was decreased by 72% to 4.3 +/- 1.1 mEq/hour after operation. The mean IGAO at pH 5.5 in nine patients treated by TV + D was 21.6 +/- 3.4 mEq/hour; this was decreased by 67% to 7.3 +/- 2.1 mEq/hour. Gastrin levels were significantly higher in postop than in preop SPV PATIENTS EVEN THOUGH PH values were constant. Gastrin levels were higher in postop TV + D patients than in postop SPV patients. This study demonstrates that acid reduction achieved by SPV is reliable and at least comparable with that achieved by turncal vagotomy. Postoperative elevation of gastrin in the SPV patients suggests that the vagus may release a humoral inhibitor of gastrin release from the gastric fundus; there may also be a further direct vagal inhibitor of antral gastrin release.     

Prophylaxis of uric acid stones with alternate day doses of alkaline potassium salts.

Uric acid stone formation ordinarily is prevented by increases in the urinary pH after meals. This postprandial alkaline tide is lost in patients who make such calculi. Single dose, alternate day administration of an alkaline potassium salt will increase urinary pH and simulate this normal physiological mechanism. An important part of the regimen is patient self-monitoring to verify that the urinary pH increases to greater than 6.8, 1 1/2 to 2 hours after the medication is taken. In contrast to multiple dose daily regimens, this mode of base administration is tolerated better and easier to follow. In 17 patients, 7 with the recurrent gravel/colic syndrome and 10 with prior stones, this regimen abolished calculus formation during an average followup of 2 1/2 years. However, further studies are needed before this regimen can be recommended as standard therapy for uric acid stone prophylaxis.     

Experience with the endoscopic test for completeness of vagotomy. Results of application in two medical centers

The need for a practicable and reliable test for completeness of vagotomy has been previously recognized. Until recently, all of the tests for completeness of vagotomy required cumbersome or delicate equipment or had deficiencies which prevented routine use. Recently we have modified the endoscopic Congo red test (ECRT) to allow more rapid and accurate performance; furthermore, we have found that the routine use of this test has affected the performance of proximal gastric vagotomy in our medical centers. At this time, we report the application of the ECRT in 41 patients at two medical centers, including patients from the University of Illinois at Chicago and the University of Marburg. The SIMPLIFIED ECRT, which is completed in less than five minutes, avoids the 15-20 minute delay required with other tests for complete vagotomy; it is the only test for complete vagotomy which can be performed intra- and postoperatively. To our knowledge, the test has not been performed previously in Europe. The similarity of results following ECRT in both settings reinforces our view that intraoperative testing affects the performance of vagotomy, and is useful in teaching aspects of operative vagotomy. The endoscopic test appears to be the test of choice for determining completeness of vagotomy.     

Intraoperative pH-metry in the prevention of incomplete vagotomy and ischemia of the gastric wall in selective proximal vagotomy

Experiments were conducted on 14 mongrel dogs to appraise the validity of the results of intraoperative pH-metry in the control of vagotomy completeness depending on the force of pressure exerted on the pH electrode with consideration for the type of a pH catheter used. The level of parietal pH increased with elevating pressure force due to diminished circulation in the gastric wall. The encountered diminution of circulation in the gastric wall after SPV increases still more the pH level and reduces the amplitude of its growth even in areas with maintained parasympathetic innervation with the use of histamine, which raises the probability of incomplete vagotomy. The authors conclude that pH-metry by slight application of the pH electrode to the gastric wall raises the validity of the values recorded and reduces the frequency of incomplete vagotomy in patients operated on in the clinic by 4.7 times. Increase of parietal pH to more than 6.7, irrespective of the force of the exerted pressure, is an indirect sign of ischemia of the gastric wall.     

Gastric, pancreatic, and biliary secretion and the rate of gastric emptying after parietal cell vagotomy.

We compared the gastric, pancreatic, and biliary secretory responses to a liquid test meal and the rates of gastric emptying of liquid and solid test meals in six patients at least 1 year after parietal cell vagotomy with eight unoperated subjects, one with duodenal ulcer disease and seven normal control subjects. Parietal cell vagotomy decreased gastric acid secretion to one third of normal, but total trypsin and bile salt secretion during the first 150 postcibal minutes were normal. The liquid test meal emptied from the stomach faster after parietal cell vagotomy, the pattern of emptying being exponential in the vagotomy patients and linear in the normal subjects. The rate of gastric emptying of a liquid meal, although faster than normal, was less precipitous after parietal cell vagotomy than after truncal vagotomy plus drainage or subtotal gastrectomy, and trypsin and bile salt concentrations were not diluted to abnormal levels, as occurs after these other procedures. Furthermore, emptying and dispersion of solid food remained normal after parietal cell vagotomy. These findings probably explain, at least in part, the decreased incidence of postprandial dumping and diarrhea that accompanies parietal cell vagotomy compared with the other popular operations for duodenal ulcer.     

The effect of vagotomy antrectomy or vagotomy pyloroplasty on the response of the antrum to meat extract in duodenal ulcer patients.

In 9 normal and 42 duodenal ulcer patients, acid and gastrin studies were performed. Basal, Oxo and Histalog stimulated acid secretion was conducted on each patient. In 24 patients post vagotomy pyloroplasty or vagotomy antrectomy, these studies were repeated within three months after surgery. Two groups of duodenal ulcer patients were identified; those who did respond and those who did not respond to Oxo stimulation. In the "responders," Oxo stimulated acid output and gastrin secretion increased significantly over basal values. Both vagotomy pyloroplasty and vagotomy antrectomy caused a similar significant decrease in Oxo and Histalog stimulated acid output. In two patients with incomplete vagotomy, antrectomy, but not pyloroplasty abolished the Oxo stimulated acid response. These data suggest that OXO stimulation test can select patients with a significant antral component in whom vagotomy and antrectomy would be the appropriate procedure. Our results also indicate that antrectomy will protect against recurrent ulceration in patients with incomplete vagotomy and may explain the lower incidence of stomal ulceration in patients with vagotomy antrectomy, compared to vagotomy pyloroplasty.     

Leucomethylene blue staining during vagotomy

Sixty patients were evaluated 10 years after vagotomy for duodenal ulcer. In 31 the stain leucomethylene blue had been used peroperatively to visualize remaining nerve twigs on the distal oesophagus when the surgeon had deemed the vagotomy to be complete and in 29 cases the staining technique was not used. The frequency of recurrent ulcer was not influenced by the use of the staining technique. a series of 48 patients who had a parietal cell vagotomy performed for duodenal ulcer was randomized into staining and control groups. There was no significant difference in the reduction of the preoperative peak acid output after pentagastrin stimulation between the two groups. Only 33 per cent of specimens stained contained nerve tissue. It is concluded that the colouring of the distal oesophagus with leucomethylene blue is of no clinical value in achieving completeness of vagotomy.     

Use of sham feeding tests in the control of complete denervation of the stomach in selective proximal vagotomy

Sham-feeding tests were preoperatively and postoperatively used by the authors in an attempt to check on completeness of selective proximal vagotomy. The quotient of sham feeding to peak acid output Pentagastrin seemed to provide useful information, in that context. This examination proved to differ from the Hollander test, in that it was harmless to the patient and also provided a better physiological approach to obtaining evidence to postoperative decline of secretion. Significant decline in gastric secretion was postoperatively recorded from 19 patients. Such decline was less strongly pronounced in one patient in whom recurrent ulcer developed together with pyloric stenosis. Induction of merely submaximum vagus stimulation and the need for good cooperation of the patient are considered drawbacks of the sham-feeding test.     

Intrinsic factor secretion after vagotomy

The intrinsic factor (IF) output during basal and Histalog-stimulated gastric secretion has been estimated in two series of patients with chronic duodenal ulcer before and 3 months or more after treatment by either highly selective vagotomy or truncal vagotomy and pyloroplasty. The effects of the two different vagotomy operations appear to be virtually identical and each produced significant reductions in intrinsic factor secretion after Histalog stimulation. This confirms the view expressed by previous workers that it is the vagotomy as such which is responsible, excluding the drainage procedure from any possible role. Furthermore, as these results were demonstrated 3 months after operation, it is likely that the depressed IF secretion is a permanent feature and one which, it is postulated, may become progressively more severe. In both series there is a marked reduction in IFoutput during the second hour of stimulated gastric secretion, indicating an early wash-out of preformed IF. This persists after vagotomy.     

Proximal gastric vagotomy and suprapyloric antrectomy. Experimental evaluation in dogs.

In five dogs with Heidenhain pouches, proximal gastric vagotomy and suprapyloric antrectomy did not alter the rate of gastric emptying of 300 mL of 1% dextrose or of 40 plastic spheres, or disrupt the barricade preventing duodenogastric reflux. However, the operation did slow gastric emptying of 50 g of cubed liver and increase the postprandial secretion of hydrochloric acid from the pouch. We concluded that suprapyloric antrectomy can be combined with proximal gastric vagotomy without disturbing the gastric emptying of liquids and indigestible solids or resulting in increased duodenogastric reflux. However, the operation does slow gastric emptying of digestible solids.