Michael P. Hocking

Gastric electrical stimulation for medically refractory gastroparesis

BACKGROUND & AIMS This study investigated the efficacy of gastric electrical stimulation for the treatment of symptomatic gastroparesis unresponsive to standard medical therapy. METHODS Thirty-three patients with chronic gastroparesis (17 diabetic and 16 idiopathic) received continuous high-frequency/low-energy gastric electrical stimulation via electrodes in the muscle wall of the antrum connected to a neurostimulator in an abdominal wall pocket. After implantation, patients were randomized in a double-blind crossover design to stimulation ON or OFF for 1-month periods. The blind was then broken, and all patients were programmed to stimulation ON and evaluated at 6 and 12 months. Outcome measures were vomiting frequency, preference for ON or OFF, upper gastrointestinal tract symptoms, quality of life, gastric emptying, and adverse events. RESULTS In the double-blind portion of the study, self-reported vomiting frequency was significantly reduced in the ON vs. OFF period (P < 0.05) and this symptomatic improvement was consistent with the significant patient preference (P < 0.05) for the ON vs. OFF period determined before breaking the blind. In the unblinded portion of the study, vomiting frequency decreased significantly (P < 0.05) at 6 and 12 months. Scores for symptom severity and quality of life significantly improved (P < 0.05) at 6 and 12 months, whereas gastric emptying was only modestly accelerated. Five patients had their gastric electrical stimulation system explanted or revised because of infection or other complications. CONCLUSIONS High-frequency/low-energy gastric electrical stimulation significantly decreased vomiting frequency and gastrointestinal symptoms and improved quality of life in patients with severe gastroparesis.

Assessment of gastric emptying using a low fat meal: establishment of international control values.

OBJECTIVE:The diagnosis of gastroparesis implies delayed gastric emptying. The diagnostic gold standard is scintigraphy, but techniques and measured endpoints vary widely among institutions. In this study, a simplified scintigraphic measurement of gastric emptying was compared to conventional gastric scintigraphic techniques and normal gastric emptying values defined in healthy subjects.METHODS:In 123 volunteers (aged 19–73 yr, 60 women and 63 men) from 11 centers, scintigraphy was used to assess gastric emptying of a 99Tc-labeled low fat meal (egg substitute) and percent intragastric residual contents 60, 120, and 240 min after completion of the meal. In 42 subjects, additional measurements were taken every 10 min for 1 h. In 20 subjects, gastric emptying of a 99Tc-labeled liver meal was compared with that of the 99Tc-labeled low fat meal.RESULTS:Median values (95th percentile) for percent gastric retention at 60, 120, and 240 min were 69% (90%), 24% (60%) and 1.2% (10%) respectively. A power exponential model yielded similar emptying curves and estimated T50 when using images only taken at 1, 2 and 4 h, or with imaging taken every 10 min. Gastric emptying was initially more rapid in men but was comparable in men and women at 4 h; it was faster in older subjects (p < 0.05) but was independent of body mass index.CONCLUSIONS:This multicenter study provides gastric emptying values in healthy subjects based on data obtained using a large sample size and consistent meal and methodology. Gastric retention of >10% at 4 h is indicative of delayed emptying, a value comparable to those provided by more intensive scanning approaches. Gastric emptying of a low fat meal is initially faster in men but is comparable in women at 4 h; it is also faster in older individuals but is independent of body mass.

Jejunoileal Bypass for Morbid Obesity: Late Follow-up in 100 Cases

To evaluate the results of jejunoileal bypass for morbid obesity, we studied 100 patients with intact bypasses an average of more than five years after surgery. Mean weight loss at five years was 102.7 lb (46.6 kg) (33 per cent). Although nearly half the patients regained some weight between one and five years after surgery, only 17 per cent regained 20 lb (9 kg) or more. Medical benefits (such as improved glucose tolerance and lowered blood pressure) were maintained at five years, but side effects and complications continued to occur in the late postoperative period. Diarrhea (more than three stools per day) persisted in 58 per cent of the patients, and electrolyte disturbances occurred in over a third. Diminished levels of B12 or folate or both were present in 88 per cent. Twenty-one per cent of the patients had nephrolithiasis, and 20 per cent of those who were at risk required cholecystectomy. Progressive hepatic structural abnormalities occurred in 29 per cent of the patients, and there was a 7 per cent incidence of cirrhosis. Although 81 per cent of the patients had satisfactory results at five years, side effects and complications continued to occur, mandating careful follow-up indefinitely. The risk-to-benefit ratio at five years after surgery seems acceptable, but the continued untoward effects of the bypass in the late postoperative period have led us to abandon this procedure in favor of gastric bypass. Only continued longitudinal follow-up will determine whether on balance jejunoileal bypass represents such a serious long-term health hazard that prophylactic restoration of intestinal continuity is indicated.

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.

Long-Term Consequences After Jejunoileal Bypass for Morbid Obesity

This study assesses the long-term results ofjejunoileal bypass (JIB) in 43 prospectively followedpatients whose surgical bypass remained intact.Follow-up was 12.6 ± 0.25 years from JIB. Weightloss and improved lipid levels, glucose tolerance,cardiac function, and pulmonary function weremaintained. Adverse effects such as hypokalemia,cholelithiasis, and B12 or folate deficiency decreasedover time. The incidence of diarrhea remained constant(63% vs 64% at five years), while the occurrence ofhypomagnesemia increased (67% vs 43% at five years, P< 0.05). Nephrolithiasis occurred in 33% of patients. Hepatic fibrosis developed in 38% of patientsand was progressive. Overall, after more than 10 years,35% of patients appeared to benefit from JIB as definedby alleviation of preoperative symptoms and the development of only mild complications (vs47% at five years). On the other hand, irreversiblecomplications appeared to outweigh any benefit derivedfrom the JIB in 19% (vs no patients at five years; P < 0.01). In summary, patients with JIBremain at risk for complications, particularly hepaticfibrosis, even into the late postoperativeperiod.

Ketorolac prevents postoperative small intestinal ileus in rats

The effect of ketorolac, a parenterally administered, nonsteroidal anti-inflammatory drug, was examined in a rat model of postoperative ileus. Small intestinal transit was measured by calculating the geometric center (GC) of distribution of 51CrO4. Laparotomy significantly delayed transit (GC: 2.2 +/- 0.2 after laparotomy versus 5.6 +/- 0.5 for unoperated controls, p < 0.01). The administration of ketorolac (1 mg/kg) improved the GC to 5.2 +/- 0.2 (p < 0.01), indicating normal intestinal transit after surgery in ketorolac-treated animals. Small intestinal myoelectric activity was recorded in rats with implanted electrodes. Animals treated with saline 2 hours postoperatively did not show return of the migrating myoelectric complex (MMC) in 183 +/- 25 minutes. In contrast, rats receiving ketorolac postoperatively had return of MMC activity in 59 +/- 18 minutes (p < 0.01). Preoperative ketorolac treatment reduced the duration of MMC inhibition after surgery from 197 +/- 55 minutes to 13 +/- 5 minutes (p < 0.05) when compared with saline. In summary, ketorolac hastens the return of MMC activity when given postoperatively. When ketorolac is administered preoperatively, it completely prevents the delay in intestinal transit and the inhibition of myoelectric activity seen in postoperative ileus. We concluded that ketorolac may be of benefit in the prevention and treatment of postoperative ileus.

Delayed gastric emptying of liquids and solids following Roux-en-Y biliary diversion.

Recent reports cite an increased incidence in delayed gastric emptying following Roux-en-Y biliary diversion for alkaline reflux gastritis. The effect of Roux-en-Y diversion on the gastric emptying of liquids and solids was evaluated following vagotomy and antrectomy and vagotomy and subtotal gastrectomy. Twenty dogs underwent placements of large Thomas cannula in the stomach. Four dogs with intact stomachs served as controls. Eight dogs each with vagotomy and antrectomy were subdivided into Roux-en-Y gastrojejunostomy (RYA) and a Billroth II (B-IIA) group. Eight dogs each with vagotomy and subtotal gastrectomy were subdivided into similar groups. Four dogsacRoux-en-Y (RSTG) and four dogsacBillroth II (B-IISTG). Gastric emptying of solid food, normal saline and 25% dextrose was evaluated. RYA dogs demonstrated a significant delay in gastric emptying of solids compared with corresponding B-IIA animals. RYA dogs had 76, 61 and 42% of solid food retained at three, five and eight hours while B-II animals retained 56, 41 and 20%, respectively. The results are highly significant at all time intervals (p ≤ 0.001 at five and eight hours). Control animals retained 34, 17 and 3% of solid food at three, five and eight hours. RSTG animals had 73, 52 and 28% retained solids at three, five and eight hours, while B-IISTG animals had 55, 42 and 13% retention, respectively (p ≤ 0.05 at eight hours). Normal saline was significantly delayed in both Roux-en-Y subgroups compared with B-II dogs (p ≤ 0.02 in V/A, p ≤ 0.05 in V/STG). There was a trend toward delayed emptying of 25% dextrose in the Roux-en-Y groups, but significance was achieved only in the RYA compared with B-IIA groups (p ≤ 0.02 at 30 minutes). Delayed gastric emptying following Roux-en-Y gastrojejunostomy is documented in the experimental animal which underwent vagotomy and appears greater in magnitude than that observed following vagotomy and B-II gastrectomy. These data corroborate the clinical observations of severe delayed gastric emptying in patients undergoing Roux-en-Y diversions for alkaline gastritis

Gastric dysrhythmias following pylorus-preserving pancreaticoduodenectomy

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.

Erythromycin enhances gastric emptying in patients with gastroparesis after vagotomy and antrectomy

We studied the effect of erythromycin on gastric emptying in nine patients with gastroparesis following truncal vagotomy and antrectomy, and assessed their clinical response to chronic oral erythromycin. Gastric emptying was evaluated using a solid-phase radio-labeled meal. Patients were studied after erythromycin 200 mg intravenously (N=9) and after an oral suspension of erythromycin 200 mg (N=7) each given 15 min after ingestion of the meal. Three parameters of gastric emptying were analyzed: half-emptying time (T1/2), area under the curve, and percent gastric residual at 2 hr. Nine patients were subsequently placed on oral suspension erythromycin 150 mg three times a day before meals (range 125–250 mg three times a day) and symptoms of nausea, vomiting, postprandial fullness, and abdominal pain were assessed before and after erythromycin. Intravenous erythromycin markedly accelerated the gastric emptying (all three parameters studied) of solids (P<0.01) in seven of nine patients with postsurgical gastroparesis [baselineT1/2 154±15 min; after intravenous erythromycin,T1/2 56±17 min (mean ±sem)]. Oral erythromycin enhanced (P<0.05) the gastric emptying rate (T1/2, area under the curve) in five of seven patients (baselineT1/2 146±16 min; after oral erythromycin,T1/2 87±20 min). Of the nine patients who were placed on oral maintenance erythromycin, three showed clinical improvement after two weeks. In summary, erythromycin significantly enhances gastric emptying in many patients with vagotomy and antrectomy-induced gastroparesis; however, only a small subset of patients respond clinically to chronic oral erythromycin.

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.