Biomedical subjects

M P Hocking

Publications and source records attributed to M P Hocking.

At least 19 recordsLinked to original sources

PubMed1992

Does selective vagotomy prevent delayed gastric emptying and altered myoelectric activity following Roux-en-Y gastrojejunostomy?

Delayed gastric emptying occurs frequently following Roux-en-Y gastrojejunostomy. The role of vagal denervation in the etiology of this "Roux-stasis syndrome" is controversial. This study evaluates the effect of selective vagotomy on gastric emptying and motility following Roux-en-Y. Four dogs underwent control gastric emptying studies. The animals then underwent selective vagotomy, antrectomy, and Billroth II gastrojejunostomy, with placement of serosal electrodes. Gastric emptying was assessed with simultaneous myoelectric recordings, and the animals were converted to Roux-en-Y, followed by repeat studies. Gastric emptying was unchanged following selective vagotomy, antrectomy, and Billroth II gastrojejunostomy (T 1/2: 132 +/- 18 min [SEM] versus 118 +/- 14 min control) but was markedly delayed following Roux-en-Y diversion (T 1/2: 286 +/- 44 min; p less than 0.01). All animals went into the fed pattern following Billroth II gastrojejunostomy (migrating myoelectric complex [MMC] interval: 326 +/- 6 min postprandial versus 92 +/- 5 min fasting; p less than 0.01), but no fed pattern was recognized in three of four animals following Roux-en-Y diversion (MMC interval: 68 +/- 12 min postprandial versus 62 +/- 1.5 min fasting; p = NS). In a canine model, selective vagotomy does not prevent delayed gastric emptying or myoelectric alterations following Roux-en-Y.

Anastomosis, Roux-en-Y↗

PubMed1992

Human gastric myoelectric activity and gastric emptying following gastric surgery and with pacing.

Postoperative gastric myoelectric activity, gastric emptying, and clinical course were correlated in 17 patients at high risk of developing gastroparesis after gastric surgery. In addition, an attempt was made to pace the stomach with an electrical stimulus and determine the effect of pacing on early postoperative gastric emptying. Gastric dysrhythmias (bradygastria, slow wave frequency < 2 cycles/min; tachygastria, slow wave frequency > 4 cycles/min) persisted beyond the first postoperative day in 6 patients (35%). Delayed gastric emptying was identified by a radionuclide meal in 15 patients (88%), but symptoms of gastroparesis developed in only 6 of 15 (40%). Patients with postoperative gastroparesis had more frequent dysrhythmias than asymptomatic patients (67% vs. 18%), but these differences were not significant, although we cannot exclude a type II statistical error. Gastric rhythm was entrained in 10 of 16 patients (63%). Pacing increased the gastric slow wave frequency (3.1 vs. 4.1 cycles/min; P < 0.01) but did not improve gastric emptying (gastric retention at 60 minutes, 86% +/- 6% for control and 90% +/- 2% for paced). In conclusion, gastric dysrhythmias do not appear to play a major role in the development of postsurgical gastroparesis. Although gastric rhythm could be entrained in the majority of patients, pacing did not improve gastric emptying overall.

Adult↗

PubMed1992

Preoperative and postoperative motility disorders of the stomach.

Improved technology has expanded the study and understanding of gastrointestinal motility. Although no clear cause and effect relation has been demonstrated, altered motility has been found in association with a variety of nonsurgical and postoperative settings. As this relation is better defined, perhaps patients who are at risk to develop complications of surgery can be better identified so that treatment can be tailored toward their specific defect. Technological advances can also be expected to provide new and more effective interventions in this expanding field.

Anastomosis, Roux-en-Y↗

PubMed1992

Surgical approach to the obese patient.

Morbid obesity is a life-threatening disorder associated with medical and psychological complications. The failure of medical therapy has led to the development of a new surgical discipline called bariatric surgery, which has evolved over the past three decades. Initial techniques created malabsorption to produce weight loss. Due to complications, later techniques limited oral intake to produce weight loss. Currently, most bariatric surgeons perform either gastric bypass or gastric partition (vertical banded gastroplasty or vertical ring gastroplasty). However, other techniques are also being evaluated, including a modified intestinal bypass, gastric banding, and a new gastric balloon. Only with continued follow-up will we determine the ultimate risk/benefit ratio of these procedures and their place in the management of the morbidly obese. In the setting of an experienced multidisciplinary team committed to long-term follow-up, surgical therapy can be considered.

Gastric Bypass↗

PubMed1991

Pharmacokinetics of ranitidine after partial gastrectomy in dogs.

The effect of gastric surgery on the pharmacokinetics of ranitidine was studied in six dogs, all serving as their own controls. Prior to and after surgery, each dog received a single oral dose (5 mg/kg of body weight) of a ranitidine solution. The surgery consisted of partial gastrectomy (antrectomy) and truncal vagotomy. Ranitidine plasma and urine concentrations were measured by reversed-phase ion-pair liquid chromatography with UV detection. Pharmacokinetic parameters were estimated by noncompartmental data analysis techniques. Gastric surgery tended to slow the absorption of ranitidine as reflected by a slight increase of the time necessary to reach the peak plasma concentration. The maximum observed plasma concentration was slightly lowered. The amount of drug absorbed remained unchanged as reflected by no change in the AUCs. Other parameters such as mean residence time, elimination half-life, apparent oral clearance, and fraction excreted unchanged in the urine remained unchanged. However, due to the small number of animals and the considerable intersubject variability, none of these trends reached statistical significance.

Absorption↗

PubMed1991

Erythromycin enhances delayed gastric emptying in dogs after Roux-Y antrectomy.

Delayed gastric emptying occurs in up to 50% of patients after truncal vagotomy and Roux-Y antrectomy and is often resistant to nonsurgical therapy. This study evaluates the effect of erythromycin, metoclopramide, and motilin on delayed gastric emptying in four dogs after Roux-Y antrectomy. Solid food gastric emptying was measured using a radionuclide technique. Study groups were: (1) saline control; (2) erythromycin 1 mg/kg intravenously over 1 hour; (3) erythromycin 3 mg/kg by mouth 45 minutes prior to feeding; (4) metoclopramide 0.6 mg/kg intravenously over 1 hour; and (5) motilin 500 ng/kg intravenously over 1 hour. After Roux-Y antrectomy, saline control dogs had 73% +/- 5% (SEM) gastric retention at 2 hours. After intravenous and oral erythromycin, gastric emptying improved at 2 hours to 27% +/- 6% and 39% +/- 5% (p less than 0.01 compared with control). Erythromycin intravenously and by mouth improved gastric emptying compared with metoclopramide (64% +/- 8%, p less than 0.05). Motilin enhanced gastric emptying to a similar degree as erythromycin, with a 2-hour gastric retention of 37% +/- 4% (NS). Erythromycin improved gastric emptying in dogs with severe Roux-Y gastroparesis and may have clinical application.

Administration, Oral↗

PubMed1991

Erythromycin acts through a cholinergic pathway to improve canine-delayed gastric emptying following vagotomy and Roux-Y antrectomy.

We have demonstrated that erythromycin improves gastric emptying in dogs following truncal vagotomy and Roux-en-Y antrectomy (VRYA). To explore its mechanism of action we studied gastric emptying and myoelectric activity in a canine Roux model and administered atropine simultaneously with erythromycin. Tachyphylaxis was evaluated following short-term administration. Four dogs with delayed gastric emptying following VRYA were studied. Radionuclide solid gastric emptying was measured, with simultaneous myoelectric recordings obtained from the duodenum and Roux limb. Study groups were: (1) saline control (VRYA dogs); (2) erythromycin 1 mg/kg iv over 1 hr; (3) erythromycin 3 mg/kg po tid for 1 week, with repeat studies using erythromycin 1 mg/kg iv over 1 hr; and (4) atropine 0.5 mg/kg iv bolus, followed by a 1-hr infusion of atropine 0.05 mg/kg and erythromycin 1 mg/kg. Control Roux animals had severe gastric retention (73 +/- 5% at 2 hr, compared to 27 +/- 6% following iv erythromycin (P less than 0.01). Clustered spike bursts were observed in the Roux limb following erythromycin. Atropine abolished the gastrokinetic response and suppressed the myoelectric response to erythromycin (81 +/- 3% retention at 2 hr, P less than 0.01 compared to erythromycin alone). The response to erythromycin was unchanged after 1 week of tid administration (40 +/- 14% retention at 2 hr postprandial, P = NS). Erythromycin improves gastric emptying in VRYA dogs via a cholinergic pathway and does not exhibit tachyphylaxis following short-term administration.

Anastomosis, Roux-en-Y↗

PubMed1991

Antiperistaltic and isoperistaltic intussusception associated with abnormal motility after Roux-en-Y gastric bypass: a case report.

Antiperistaltic and recurrent intussusceptions are extremely rare in the adult. We report a patient with both. The patient developed an antiperistaltic intussusception distal to her Roux enteroenterostomy years after a Roux-en-Y gastric bypass for morbid obesity. The diagnosis was made preoperatively with gastrointestinal contrast radiography and ultrasonography. At surgery, the intussusception was reduced, and 12 inches of nonviable bowel was resected, with a functional end-to-end anastomosis. An isoperistaltic intussusception occurred in the early postoperative period just distal to the anastomosis. Manometric evaluation of the Roux limb after the second operation showed altered gastrointestinal motility, consisting of orad-propagated and aboard-propagated migrating motor complexes, minimal phase 2 activity, and lack of conversion to the fed pattern with a liquid meal. Although manometry was not performed before the development of the intussusception, our findings are consistent with the hypothesis that altered intestinal motility may contribute to the development of intussusception.

Adult↗

PubMed1991

Marginal ulcer following gastric bypass for morbid obesity.

Four hundred twelve patients underwent gastric bypass for treatment of morbid obesity between 1981 and 1985 at the University of Florida Affiliated Hospitals. Thirty-four patients (8.2%) developed marginal ulcers, considerably higher than the 0-3 per cent ulcer occurrence commonly reported in the literature. Factors predisposing to ulcer formation include: (1) a large gastric pouch; (2) a vertically oriented pouch; and (3) staple-line dehiscence. Twenty-two of 34 patients (65%) with symptomatic marginal ulcers were noted to have staple-line disruption. Twenty-one of these patients (95%) eventually required operative therapy for their ulcers compared with four of 12 patients (33%) with an intact gastric staple line. Surgical therapy consisted of takedown of the Roux-en-Y limb with resection of the ulcer and gastrogastrostomy. Staple-line dehiscence is a significant etiologic factor in the development of marginal ulcer following gastric bypass and when present constitutes an indication for reoperation.

Adolescent↗

PubMed1990

Effects of truncal vagotomy and partial gastrectomy on the pharmacokinetics of propranolol enantiomers in dogs.

The effect of partial gastrectomy on the pharmacokinetic parameters of (+)- and (-)-propranolol were investigated in six dogs. (+/-)-Propranolol (3 mg/kg body weight) was administered orally before and after surgery and the plasma concentrations of (+)- and (-)-propranolol were determined using an indirect enantioseparation technique. There were significant differences (p less than or equal to 0.05, paired t-test) in the area under the concentration-time curves (AUCs) and the maximum plasma concentration (Cmax) between (+)- and (-)-propranolol. The ratio AUC(+):AUC(-) was 1.73 +/- 0.28. These differences between the enantiomers remained unchanged after surgery. Other pharmacokinetic parameters showed no stereoselectivity. After partial gastrectomy, there was a slight, but nonsignificant decrease in time to reach maximum plasma concentration (tmax) and in the absorption half-life for both enantiomers. The maximum plasma concentration increased slightly. The elimination half-life and the mean residence time remained unchanged before and after surgery. Therefore, it is unlikely that there are any clinically relevant changes in the pharmacokinetics of (+)- and (-)-propranolol after partial gastrectomy.

Animals↗

PubMed1990

APUD update.

Apudomas are a diffuse group of tumors that have interested surgeons for a long time. With recent developments in their radiological localization and pharmacological control, they are now treated in a truly multidisciplinary approach. In this chapter, recent developments in the radiological, surgical, and medical approaches to these tumors are reviewed. Emphasis is placed on how non-surgical developments have affected the surgical treatment of specific apudomas. Resulting changes in surgical philosophy are also reviewed.

Apudoma↗

PubMed1990

Gastric dysrhythmias following pylorus-preserving pancreaticoduodenectomy. Possible mechanism for early delayed gastric emptying.

Transient delayed gastric emptying is reported as a frequent complication following pancreas-preserving pancreaticoduodenectomy (PPW). We placed serosal electrodes on the stomach of a patient undergoing PPW. Myoelectric recordings were obtained postoperatively and correlated with simultaneous radionuclide liquid gastric emptying studies. The patient developed early postoperative gastric atony, associated with frequent gastric dysrhythmias. These dysrhythmias may have been exacerbated by a perihepatic abscess. The gastric dysrhythmias correlated with alterations in liquid gastric emptying. Gastric dysrhythmias may be a mechanism for gastric dysfunction in the early postoperative period.

Adenocarcinoma↗

PubMed1990

Gastric emptying and myoelectric activity following Roux-en-Y gastrojejunostomy.

The purpose of this study was to compare gastric emptying and Roux myoelectric activity in a canine model. Four dogs underwent truncal vagotomy, antrectomy, and 40 cm Roux-en-Y gastrojejunostomy, with placement of serosal electrodes. Following recovery, gastric emptying was determined scintigraphically with a radiolabeled solid meal, and fasting and fed small-bowel myoelectric activity was obtained. Gastric emptying was markedly slowed compared to control unoperated animals (202 +/- 91 versus 46 +/- 12 min; P less than 0.05). Slow wave frequency declined in the Roux limb compared to the duodenum (14.2 +/- 0.4 versus 18.0 +/- .06 counts per minute; P less than 0.01). No gradient in slow wave frequency was observed in the Roux limb, although one animal was noted to have reversed propagation of slow waves in the proximal Roux limb. Migrating myoelectric complexes (MMCs) were coordinated between the Roux limb and jejunum distal to the enteroenterostomy, but not with the duodenum. Periodicity of the MMCs was different in the Roux limb and duodenum (98.6 +/- 6.3 versus 138 +/- 17.5 min; P less than 0.05). None of the animals converted to the fed myoelectric pattern with a 272 kcal meal (MMC periodicity in the Roux limb = 99 +/- 10 min postprandially, P = N.S.). These quantitative and qualitative alterations in myoelectric activity may contribute to the observed delay in gastric emptying following Roux-en-Y gastrojejunostomy.

Anastomosis, Roux-en-Y↗

PubMed1990

Pouch outlet obstruction following vertical ring gastroplasty for morbid obesity.

We have experienced a 14% (38 of 264 patients) incidence of pouch outlet obstruction following vertical ring gastroplasty. Initial management consisted of dilatation in 34 of 38 patients (94%). Ten of 34 patients (29%) were spared reoperation by 1 to 3 dilatations. Non-passage of an endoscope through the stoma immediately following dilatation predicted the need for surgery; 4 of 11 patients (36%) with passage underwent reoperation compared with 17 of 20 patients (85%) without passage (p less than 0.02). Surgical findings included "tipped bands" in 9 of 28 patients (32%); fibrous reaction to the band in 10 of 28 patients (36%); adhesions with angulation of the pouch in 2 of 28 patients (7%); and no identifiable cause of obstruction in 7 of 28 patients (25%). Surgical therapy consisted of removal of the band (2 patients), removal of the band and replacement with a similar length or larger band (20 patients), "tacking" the band in the horizontal position (4 patients), or conversion to a Roux-Y bypass (2 patients). The first three options were associated with an unacceptably high rate of weight regain and/or continued symptoms, whereas the last-named procedure met with good success.

Anastomosis, Roux-en-Y↗

PubMed1990

Myoelectric effects and histology after stapled occlusion of the small bowel.

Braun enteroenterostomy with stapled occlusion of the afferent limb has been advocated to treat bile gastritis and to avoid the motility effects of Roux-en-Y gastrojejunostomy. However, the motility effects of stapled occlusion are unknown. Myoelectric activity and histologic features were studied after stapled occlusion of the small bowel in a canine model. A 35 cm "recirculating loop" was created with a side-to-side anastomosis, beginning 25 cm from the ligament of Treitz. Serosal electrodes were placed at 5 cm intervals on the loop; at a second operation in one dog and simultaneously in three dogs, the bowel was occluded midway between two electrodes with 4.8 mm staples. Fasting recordings were obtained at weekly intervals to 6 months after surgery and were analyzed for slow wave frequency proximal and distal to the staple line and for propagation time of phase 3 of the migrating myoelectric complex across the staple line. The side-to-side anastomosis did not alter myoelectric activity. However, after stapled occlusion of the small bowel, the slow wave frequency dropped from a mean of 18.2 +/- 0.4 cpm proximally to 15.4 +/- 1.0 cpm distally (p less than 0.05). This correlated with loss of myogenic continuity in three of four animals. Propagation of phase 3 slowed across the staple line (115 +/- 27 seconds versus 47 +/- 9 seconds) (p less than 0.02). The bowel lumen recannulated in all animals. Stapling across the small bowel alters myoelectric activity, and occlusion of the bowel lumen may not be permanent.

Anastomosis, Surgical↗

PubMed1990

Altered motility and bacterial flora after functional end-to-end anastomosis.

The functional end-to-end technique with a gastrointestinal stapler is commonly used for small-bowel anastomosis, but the effects of this anatomically side-to-side anastomosis on motility are unknown. Fasting small-bowel myoelectric activity and culture results were compared in six animals undergoing handsewn end-to-end and functional end-to-end anastomoses. Serosal electrodes were placed at 10 cm intervals, and the small bowel was divided 25 and 55 cm from the ligament of Treitz. The functional end-to-end and end-to-end techniques were performed in each animal in random order. Fasting myoelectric recordings were obtained at weekly intervals for up to 20 weeks after operation. New electrodes were placed, and additional recordings were obtained from 29 to 39 weeks, 51 to 63 weeks, and 108 to 112 weeks after operation. The recordings were visually inspected for passage of phase 3 of the migrating myoelectric complex (MMC). By 12 to 20 weeks after operation, 91% of MMCs crossed the end-to-end anastomoses versus 22% across the functional end-to-end anastomosis (p less than 0.001). Even 2 years after surgery only 56% of MMCs crossed the functional end-to-end anastomosis. Quantitative bacterial cultures suggested a trend toward bacterial overgrowth in the functional end-to-end anastomosis. These results demonstrate that the functional end-to-end anastomosis alters small-bowel motility to a greater degree than an end-to-end anastomosis and may predispose to bacterial overgrowth.

Anastomosis, Surgical↗

PubMed1988

Effect of various prokinetic agents on post Roux-en-Y gastric emptying. Experimental and clinical observations.

The effect of various prokinetic drugs was assessed in animals with Roux-en-Y gastrojejunostomy. The agents tested were (1) bethanechol 2.5 mg subcutaneously at 0 min and 30 min postprandially (pp); (2) metoclopramide 20 mg intravenous bolus at 0 min pp; (3) a combination of 1 and 2; (4) oxytocin 5 mg intramuscularly at 0 min and 240 min pp; (5) motilin at 100 ng/kg/hr; or (6) 300 ng/kg/hr continuous intravenous infusion from 0 to 270 min pp. Only bethanechol administration resulted in significantly less gastric retention (65 +/- 6% vs 32 +/- 5% retention at 5 hr). (P less than 0.002). The animal results with parenteral bethanechol were confirmed in humans with chronic delayed gastric emptying following Roux-en-Y gastrojejunostomy, with a decrease in gastric retention on radionuclide scan from 78.5 +/- 5% to 26 +/- 12% at 2 hr pp (P less than 0.01). Initially all patients responded with symptomatic improvement. However, subsequently 3/6 (50%) of patients required total or near total gastrectomy for recurrent symptoms of gastric stasis. Nevertheless, 2/6 (33%) of patients have no further evidence of gastric stasis, and a trial of bethanechol is recommended prior to considering further gastrectomy in patients with the Roux-stasis syndrome.

Animals↗

PubMed1988

Clinical and radionuclide evaluation of Roux-Y diversion for postgastrectomy dumping.

From 1973 to 1986, 22 patients underwent Roux-Y gastrojejunostomy for the early postgastrectomy dumping syndrome. In the early years, five patients underwent Roux-Y conversion with the addition of a 10 cm antiperistaltic jejunal segment interposed between the Roux-Y limb and the stomach. Within 4 years, all five patients had the jejunal segment removed due to severe symptoms of gastric retention. These patients underwent reconstruction to create Roux-Y limb only and joined the pool of 17 patients who underwent Roux-Y diversion only for the dumping syndrome. Overall, 19 of 22 patients (86 percent) had almost complete resolution of their dumping symptoms on long-term follow-up. Three patients showed no improvement, two with severe gastric retention and one with recurrent dumping symptoms. Overall, 5 of 22 patients (23 percent) had moderate to severe early and late postoperative gastric retention necessitating medical treatment in three and subsequent near-total gastrectomy in two. Although other procedures such as pyloric reconstruction or the addition of isoperistaltic or antiperistaltic jejunal interpositions have been reported to be equally successful in delaying gastric emptying and resolving dumping symptoms, we have preferred Roux-Y diversion for the treatment of combined alkaline reflux gastritis and dumping or the pure early vasomotor postgastrectomy dumping syndrome. As reported, we have abandoned the use of an antiperistaltic jejunal segment interposed between the stomach and the Roux-Y limb due to the high rate of postoperative gastric retention.

Anastomosis, Roux-en-Y↗