Preoperative Pneumoperitoneum: Low-Risk Surgical Adjunct to the Surgical Management of Dense Abdominal Adhesions.

Surgical lysis of intra-abdominal adhesions is associated with a high rate of complications. This brief report presents 24 patients with dense intra-abdominal adhesions who underwent preoperative progressive pneumoperitoneum (PPP) prior to surgical lysis of adhesions. PPP was successfully performed in 23 patients, with few adverse events, resulting in subjectively improved ease of intraoperative tissue dissection. One patient withdrew due to intractable pain during insufflation. The results suggest that PPP is a low-risk technique with the potential to improve access to intra-abdominal structures in patients for whom conventional surgical therapy is predicted to carry a high rate of complications.

Ethical considerations regarding the implementation of new technologies and techniques in surgery.

Ethical considerations relevant to the implementation of new surgical technologies and techniques are explored and discussed in practical terms in this statement, including (1) How is the safety of a new technology or technique ensured?; (2) What are the timing and process by which a new technology or technique is implemented at a hospital?; (3) How are patients informed before undergoing a new technology or technique?; (4) How are surgeons trained and credentialed in a new technology or technique?; (5) How are the outcomes of a new technology or technique tracked and evaluated?; and (6) How are the responsibilities to individual patients and society at large balanced? The following discussion is presented with the intent to encourage thought and dialogue about ethical considerations relevant to the implementation of new technologies and new techniques in surgery.

Should isolated morbid obesity influence the decision to operate in hip and knee arthroplasty?

AIMS: We studied the outcomes of hip and knee arthroplasties in a high-volume arthroplasty centre to determine if patients with morbid obesity (BMI ≥ 40 kg/m2) had unacceptably worse outcomes as compared to those with BMI < 40 kg/m2. METHODS: In a two-year period, 4,711 patients had either total hip arthroplasty (THA; n = 2,370), total knee arthroplasty (TKA; n = 2,109), or unicompartmental knee arthroplasty (UKA; n = 232). Of these patients, 392 (8.3%) had morbid obesity. We compared duration of operation, anaesthetic time, length of stay (LOS), LOS > three days, out of hours attendance, emergency department attendance, readmission to hospital, return to theatre, and venous thromboembolism up to 90 days. Readmission for wound infection was recorded to one year. Oxford scores were recorded preoperatively and at one year postoperatively. RESULTS: On average, the morbidly obese had longer operating times (63 vs 58 minutes), longer anaesthetic times (31 vs 28 minutes), increased LOS (3.7 vs 3.5 days), and significantly more readmissions for wound infection (1.0% vs 0.3%). There were no statistically significant differences in either suspected or confirmed venous thromboembolism. Improvement in Oxford scores were equivalent. CONCLUSION: Although morbidly obese patients had less favourable outcomes, we do not feel that the magnitude of difference is clinically significant when applied to an individual, particularly when improvement in Oxford scores were unrelated to BMI. Cite this article: Bone Jt Open 2021;2(7):515-521.

Effect of surgically induced weight loss on pelvic floor disorders in morbidly obese women.

OBJECTIVE: To evaluate the effect of surgically induced weight loss on pelvic floor disorders (PFD) in morbidly obese women. SUMMARY BACKGROUND DATA: Although bariatric surgery may lead to the improvement of some obesity-related comorbidities, the resolution of global PFD has not been well described. METHODS: Women with a body mass index (BMI) of 35 kg/m(2) or more who were considering bariatric surgery were asked to complete 2 validated condition-specific questionnaires assessing the distress/quality of life impact of PFD, total and by domain (pelvic organ prolapse, colorectal-anal, and urogenital). Women who achieved a > or =50% excess body weight loss after surgery were asked to complete the same questionnaires for comparison. RESULTS: Of the 178 women who underwent surgery, 46 completed the postoperative questionnaires. Mean age of this group was 45 years (range, 20-67), and mean preoperative BMI was 45 kg/m(2) (range, 35-75). The prevalence of PFD symptoms improved from 87% before surgery to 65% after surgery (P = 0.02, 95% CI: 0.05%-53%). There was a significant reduction in total mean distress scores after surgery (P = 0.015, 95% CI: 3.3-32.9), which was attributed mainly to the significant decrease in urinary symptoms (P = 0.0002, 95% CI: 8.2-22.7). Reductions in the scores were noted for the other PFD domains as well. Quality of life total scores improved (P = 0.002, 95% CI: 4.8-27.1), as did scores in the urinary domain (P = 0.0005, 95% CI: 3.8-13.5) and the pelvic organ prolapse domain (P = 0.015, 95% CI: 0.6-9.5). Age, parity, history of complicated delivery, percent excess body weight loss, BMI, type of weight loss procedure and presence of diabetes mellitus and hypertension had no predictive value for postoperative outcomes. CONCLUSION: Surgically induced weight loss has a beneficial effect on symptoms of PFD in morbidly obese women.

Measurement of gastric pH in ambulatory esophageal pH monitoring.

BACKGROUND: Ambulatory esophageal pH monitoring is the method used most widely to quantify gastroesophageal reflux. The degree of gastroesophageal reflux may potentially be underestimated if the resting gastric pH is high. Normal subjects and symptomatic patients undergoing 24-h pH monitoring were studied to determine whether a relationship exists between resting gastric pH and the degree of esophageal acid exposure. METHODS: Normal volunteers (n = 54) and symptomatic patients without prior gastric surgery and off medication (n = 1,582) were studied. Gastric pH was measured by advancing the pH catheter into the stomach before positioning the electrode in the esophagus. The normal range of gastric pH was defined from the normal subjects, and the patients then were classified as having either normal gastric pH or hypochlorhydria. Esophageal acid exposure was compared between the two groups. RESULTS: The normal range for gastric pH was 0.3-2.9. The median age of the 1,582 patients was 51 years, and their median gastric pH was 1.7. Abnormal esophageal acid exposure was found in 797 patients (50.3%). Hypochlorhydria (resting gastric pH >2.9) was detected in 176 patients (11%). There was an inverse relationship between gastric pH and esophageal acid exposure (r = -0.13). For the patients with positive 24-h pH test results, the major effect of gastric pH was that the hypochlorhydric patients tended to have more reflux in the supine position than those with normal gastric pH. CONCLUSION: There is an inverse, dose-dependent relationship between gastric pH and esophageal acid exposure. Negative 24-h esophageal pH test results for a patient with hypochlorhydria may prompt a search for nonacid reflux as the explanation for the patient's symptoms.

Clinical Significance of Esophageal Outflow Resistance Imposed by a Nissen Fundoplication.

BACKGROUND: Attention has been focused on the amplitude of esophageal body contraction to avoid persistent dysphagia after a Nissen fundoplication. The current recommended level is a contraction amplitude in the distal third of esophagus above the fifth percentile. We hypothesized that a more physiologic approach is to measure outflow resistance imposed by a fundoplication, which needs to be overcome by the esophageal contraction amplitude. STUDY DESIGN: The esophageal outflow resistance, as reflected by the intra-bolus pressure (iBP) measured 5 cm above the lower esophageal sphincter (LES), was measured in 53 normal subjects and 37 reflux patients with normal esophageal contraction amplitude, before and after a standardized Nissen fundoplication. All were free of postoperative dysphagia. A test population of 100 patients who had a Nissen fundoplication was used to validate the threshold of outflow resistance to avoid persistent postoperative dysphagia. RESULTS: The mean (SD) amplitude of the iBP in normal subjects was 6.8 (3.7) mmHg and in patients before fundoplication was 3.6 (7.0) mmHg (p = 0.003). After Nissen fundoplication, the mean (SD) amplitude of the iBP increased to 12.0 (3.2) mmHg (p < 0.0001 vs normal subjects or preoperative values). The 95th percentile value for iBP after a Nissen fundoplication was 20.0 mmHg and was exceeded by esophageal contraction in all patients in the validation population, and 97% of these patients were free of persistent postoperative dysphagia at a median 50-month follow-up. CONCLUSIONS: Nissen fundoplication increases the outflow resistance of the esophagus and should be constructed to avoid an iBP > 20 mmHg. Patients whose distal third esophageal contraction amplitude is >20 mmHg have a minimal risk of dysphagia after a tension-free Nissen fundoplication.

Bowel habits after gastric bypass versus the duodenal switch operation.

BACKGROUND: One of the perceived disadvantages of the biliopancreatic diversion with duodenal switch operation is diarrhea. The aim of this study was to compare the bowel habits of patients after duodenal switch operation or Roux-en-Y gastric bypass. METHODS: A prospective comparative case series design was used. Forty-six patients who underwent duodenal switch (n=28) or gastric bypass (n=18) were asked to complete a daily diary for 14 days after losing least 50% of their excess body weight. Data were collected on number of bowel episodes, incontinence, urgency, stool consistency, and awakening from sleep to defecate. Background variables were recorded from the medical files. RESULTS: The duodenal switch group was heavier (body mass index 53.5 vs 47.0 kg/m(2), p=0.03) and older (47.5 vs 41.0 years, p=NS) than the gastric bypass group. Median time to 50% excess body weight loss was 22 months in the duodenal switch group compared to 10.0 months in the gastric bypass group (p=0.001). Patients after duodenal switch surgery reported a median of 23.5 bowel episodes over the 14-day study period compared to 16.5 in the gastric bypass group (p=NS). There was no between-group differences in any of the other bowel parameters studied. CONCLUSIONS: Although duodenal switch is associated with more bowel episodes than gastric bypass, the difference is not statistically significant. Bowel habits are similar in patients who achieve 50% estimated body weight loss with duodenal switch surgery or gastric bypass.

Maintenance of weight loss in patients with body mass index >60 kg/m2: importance of length of small bowel bypassed.

BACKGROUND: It is commonly believed that weight loss after biliopancreatic diversion/duodenal switch is inversely related to the length of the alimentary limb and the common channel. However, the effect of the biliopancreatic limb length (BPL) on weight loss has received little attention. METHODS: A total of 1001 patients after biliopancreatic diversion/duodenal switch (209 men and 792 women, mean age 42 +/- 10 yr, mean body mass index [BMI] 52 +/- 9 kg/m(2)) were divided into 2 groups according to the ratio of the BPL to the total small bowel length (SBL): a BPL < or =45% of the SBL versus a BPL >45% of the SBL. The nutritional parameters and percentage of excess weight loss were compared between the 2 groups. RESULTS: In patients with a BMI of < or =60 kg/m(2), the percentage of excess weight loss at 1 year postoperatively was 66.8% for those with a BPL < or =45% of the SBL and 69.3% for those with a BPL >45% of the SBL (P = NS). At 2 years, the corresponding percentages were 73.7% and 79.5% (P = NS) and, at 3 years, were 73.4% and 75.2% (P = NS). In patients with a BMI >60 kg/m(2), the corresponding percentages of excess weight loss was 56.8% versus 61.4% (P = .07) at 1 year, 62.2% versus 77.5% (P = .04) at 2 years, and 59.8% versus 77.5% at 3 years (P = .05). CONCLUSION: The results of our study have shown that amount of weight lost after biliopancreatic diversion/duodenal switch is directly related to the proportion of small bowel bypassed in patients with a BMI >60 kg/m(2). Also, the effect increased with the duration of follow-up. In less heavy patients, the BPL/SBL ratio had a minimal effect on long-term weight loss and a more pronounced effect on nutritional parameters.

Percutaneous gastric drainage as a treatment for small bowel obstruction after gastric bypass.

The authors report the case of a patient who developed small bowel obstruction after laparoscopic gastric bypass. Imaging revealed an obstruction at the enteroenterostomy resulting in dilation of the bypassed stomach and proximal small bowel. The bypassed stomach was percutaneously drained using CT guidance, leading to resolution of the small bowel obstruction. Biliopancreatic limb obstructions can be successfully treated non-operatively after gastric bypass.

Revision of the duodenal switch: indications, technique, and outcomes.

BACKGROUND: Duodenal switch (DS) operation combines both restrictive and malabsorptive components and has become an accepted operation in selected patients with morbid obesity. Complications develop in some patients, which are refractory to dietary supplementation. We report a series of 33 patients who required partial revision of the DS. STUDY DESIGN: During the 10-year period after September 1992, 701 patients had DS operation performed; of these, 33 (5 men and 28 women) patients required revision. Revision was performed by side to side enteroenterostomy 100 cm proximal to the original anastamosis. Outcomes measures reviewed include postoperative complications, nutritional parameters, and weight change. RESULTS: Revision was performed a median of 17 (range 7 to 63) months after DS. Indications for revision included protein malnutrition (n = 20), diarrhea (n = 9), metabolic abnormalities (n = 5), abdominal pain (n = 3), liver disease (n = 2), emesis (n = 2), and gastrointestinal bleed (n = 1). Median body mass index at the time of revision was 28. Median serum albumin was 3.6 g/dL and improved to 4.0 g/dL postoperatively (p = 0.01). Complications occurred in 5 of 32 patients (15%) and included wound infection (n = 2), respiratory failure (n = 1), gastrointestinal bleed (n = 1), and small bowel obstruction (n = 1). There was no perioperative mortality. During a median followup period after revision of 39 months, the median weight gain was 18 pounds. Three patients requested repeat operation because of weight regain. CONCLUSIONS: Patients requiring revision of DS for malnutrition can be corrected by a technically simple procedure, but they are at considerable risk for complications. Although many patients are anxious about regaining their weight after reversal, they can be reassured that substantial weight gain is unlikely.

The value of pulmonary function testing prior to bariatric surgery.

BACKGROUND: Pulmonary function tests (PFTs) are often abnormal in the morbidly obese and improve after bariatric surgery. Our aim was to determine the utility of obtaining preoperative PFTs in assessing postoperative risk. METHODS: 146 consecutive patients undergoing open bariatric surgery were analyzed. Patients were divided into those who had postoperative complications (Group A, n=27) and those who did not (Group B, n=119). PFTs and BMI were compared between Groups A and B. PFT parameters are reported as the median percentage of age-matched controls. RESULTS: Patients in Group A compared to Group B were heavier (BMI 58 vs 51 kg/m(2), P=.001) and older (46 vs 40 years, P=.02) than those in group B. They had reduced forced vital capacity (80% vs 97%, P<.001) and forced expiratory volume in 1 second (84% vs 99%, P=.002). They also had reduced vital capacity (VC, 85% vs 102%, P<.001) and total lung capacity (89% vs 99%, P=.01). They had decreased maximal voluntary ventilation (93% vs 106%, P=.003). They had lower arterial pO(2) (76 mmHg vs 85 mmHg, P=.001) and higher arterial-alveolar gradient (23 vs 17, P=.007). The strongest predictors of postoperative complications on multivariate analysis were reduced VC (RR 2.29 for each 10% decrease in VC, P=.0007) and age (RR 6.4 for age >40 years, P=.01). CONCLUSIONS: PFTs help to predict complications after bariatric surgery. The greatest reduction in VC may occur in patients with central obesity, reflecting increased intrabdominal pressure and diminished chest wall compliance.

Long-term outcome of total knee replacement: does obesity matter?

BACKGROUND: Although arthritic complications are common in the obese, many surgeons are reluctant to perform joint replacements in this population. We compared outcomes of total knee arthroplasties (TKAs) in normal weight and obese patients. METHODS: 30 TKAs in 21 obese patients with BMI 30-49 (Group A--mainly mildly and moderately obese) were compared to a matched group of 53 TKAs in 41 non-obese patients with BMI 16-29.9 (Group B). Outcome measures included the Knee Society Score (a composite of clinical and functional parameters), radiographic results, and the need for revision or reoperation. RESULTS: Median follow-up was 11.3 years; no patients were lost to follow-up during this time. The Knee Society Score rose 92 points in Group A to a final score of 184, and 95 points in Group B to a score of 193. There was no statistical difference in Groups A and B between the improvement in scores or the final score achieved. Osteolysis rates were not significantly different between the 2 groups (5% vs 13%), nor were radiolucency rates (0% vs 9.7%). Median alignment was also similar in both groups (8.1 degrees vs 8.0 degrees valgus). 13.3% of Group A required reoperation while none required revision, and 13.2% of Group B required reoperation with 3.8% requiring revision. Survival rates were similar in both groups (71.4% vs 61.5%). CONCLUSIONS: Moderate obesity does not affect the clinical and radiologic outcome of TKA. However, TKA results in improved mobility, enhancing the success of subsequent weight loss therapy.

Sleeve gastrectomy in the high-risk patient.

BACKGROUND: One of the surgical options available for the super-obese patient is the sleeve gastrectomy. We present results of this operation in a series of 118 patients. METHODS: The charts of all patients who have had the sleeve gastrectomy performed were reviewed for demographic data, complications, weight, and nutritional parameters. RESULTS: Median age was 47 years (16-70). Median BMI was 55 kg/m(2) (37-108), with 73% of patients having a BMI > or =50 kg/m(2). 41% of the patients were male. The operation was performed by laparotomy in all but three cases, which were performed laparoscopically. Median hospital stay was 6 days (3-59). There was one perioperative death (0.85%). 18 patients (15.3%) had postoperative complications. Median percent excess weight loss was 37.8% at 6 months, 49.4% at 12 months, and 47.3% at 24 months. Median follow-up was 13 months (1-66). At 1 year postoperatively, the percentage of patients with normal serum levels of albumin was 100%, hemoglobin 86.1%, and calcium 87.2%, compared to 98.1%, 85.6%, and 94.3% preoperatively. 6 patients requested conversion to a duodenal switch during the follow-up period; all left the hospital in 4-6 days without major complication. CONCLUSIONS: Although the sleeve gastrectomy does not result in as much weight loss as the duodenal switch or gastric bypass, it can be used as a stand-alone operation or as a bridge to more complex procedures in the high-risk super-obese patient.

Response of the lower esophageal sphincter to gastric distention by carbonated beverages.

Gastroesophageal reflux disease often occurs in patients with normal resting pressure and length of the lower esophageal sphincter. Such patients often have postprandial reflux. The mechanism of postprandial reflux remains controversial. To further clarify this, we studied the effect of carbonated beverages on the resting parameters of the lower esophageal sphincter. Nine asymptomatic healthy volunteers underwent lower esophageal sphincter manometry using a slow motorized pull through technique after ingestion of tap water and carbonated beverages. Resting pressure, overall length, and abdominal length of the lower esophageal sphincter were measured. All carbonated beverages produced sustained (20 minutes) reduction of 30-50% in all three parameters of the lower esophageal sphincter. In 62%, the reduction was of sufficient magnitude to cause the lower esophageal sphincter to reach a level normally diagnostic of incompetence. Tap water caused no reduction in sphincter parameters. Carbonated beverages, but not tap water, reduce the strength of the lower esophageal sphincter. This may be relevant to the pathogenesis of gastroesophageal reflux disease, especially in Western society.

Longitudinal gastrectomy as a treatment for the high-risk super-obese patient.

BACKGROUND: Bariatric surgery in patients with significant co-morbid conditions is associated with increased perioperative risk. METHODS: From 1995-2001, 795 patients were operated upon at our institution for the diagnosis of morbid obesity. Of these, 671 (84.4%) had the duodenal switch (DS) procedure. Longitudinal gastrectomy (LG) entails a greater curvature linear gastrectomy creating a gastric tube with a volume of 100 ml along the lesser curvature of the stomach. This procedure was performed for 21 patients (median age 50.5, median BMI 56). 9 patients were offered LG preoperatively because of their known high perioperative risks. 12 patients were initially planned for DS, but the procedure was limited to LG alone because of either unexpected intraoperative findings (n=9) or intraoperative hemodynamic instability (n=3). 5 patients developed complications, and there were no deaths. RESULTS: 19 out of 21 patients were available for a median follow-up of 17.5 months (6.25-20.25). Median weight loss and median %EWL at 12 months were 44.5 kg and 45.1%, respectively. Estimated daily dietary volume at 1 year was 35% of preoperative values. Of 10 patients followed for >or= 1 year, 4 of 10 achieved more than 50% EWL and 8 patients were taking less or were completely off medications for diabetes, hypertension and congestive heart failure. Weight loss plateaued at 1 year for the majority of patients. CONCLUSIONS: LG is a safe and effective option for high-risk morbidly obese patients. Weight reduction is accomplished by limitation of caloric intake. LG can be offered to high-risk morbidly obese patients as an interim procedure to help decrease perioperative risk before DS.

Calcium metabolism in the morbidly obese.

BACKGROUND: Morbidly obese patients are known to have abnormal calcium metabolism compared with the non-obese, but the clinical significance of this is unknown. Since surgical treatment of obesity may itself cause hyperparathyroidism, it is important to understand the preoperative physiology of these patients. METHODS: 213 consecutive patients (M 37 : F 176, ages 21-68) presenting for surgical treatment of morbid obesity between October 2000 and June 2002 were prospectively evaluated. Preoperative levels of serum calcium corrected for albumin, alkaline phosphatase, parathyroid hormone (PTH), 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D were measured. We recorded the prevalence of abnormalities in study parameters and correlated them with PTH levels. RESULTS: Hyperparathyroidism (PTH >65 pg/ml) was present in 25.0% of subjects. By contrast, abnormalities of serum calcium were rare. The prevalence of hypocalcemia was 3.5%, and of hypercalcemia was 0.5%. Only 4.3% of patients had increased levels of alkaline phosphatase. 21.1% of patients had abnormally low levels of 25-hydroxyvitamin D (median 15 ng/ml), and 23.1% had increased levels of 1,25-dihydroxyvitamin D (median 49 pg/ml). PTH was positively correlated with BMI (r=.30, P=<.001) and 25-dihydroxyvitamin D (r=.27, P=.01), and was negatively correlated with alkaline phosphatase (r=.21, P=.02). There was no correlation between PTH and calcium, 1,25-dihydoxyvitamin D, age, or sex. CONCLUSIONS: Parathyroid hormone levels are increased in the morbidly obese and are positively correlated with BMI. Recognition of preoperative hyperparathyroidism is important because of the risk of attributing postoperative hyperparathyroidism to the effects of surgery. Further studies are needed to elucidate the cause of elevated PTH in these patients.

Achalasia in the context of morbid obesity: a rare but important association.

BACKGROUND: The simultaneous occurrence of achalasia and morbid obesity is rare. Nevertheless, the surgical therapy of morbid obesity may be harmful, if undiagnosed achalasia were left untreated. We report the clinical presentation and response to treatment of achalasia in the context of morbid obesity. METHODS: From 1998 to 2002, 638 patients underwent surgery for morbid obesity. Preoperative upper gastrointestinal radiography was performed in all patients. Three patients had manometric confirmation of achalasia. The characteristic symptoms were recurrent episodes of regurgitation, chronic cough and aspiration. No patient reported dysphagia or recent weight loss. RESULTS: All patients had a duodenal switch procedure and in two a concurrent Heller myotomy was added. The other patient required a Heller myotomy after a duodenal switch had been performed, because the motility study was initially misinterpreted. All patients reported gradual resolution of presenting symptoms after myotomy. CONCLUSIONS: A careful symptomatic history focusing on aspiration, regurgitation and cough may identify the unusual combination of achalasia and morbid obesity. Treatment of morbid obesity alone may lead to progression of pulmonary symptoms.

Surgical treatment of morbid obesity in schizophrenic patients.

BACKGROUND: Newer antipsychotic medications have greatly improved the treatment of schizophrenia, but they are known to be associated with serious weight gain. Little is known about treatment of morbid obesity in this population. METHODS: 5 patients with schizophrenia and morbid obesity were studied. Weight loss was compared with that achieved by 165 non-psychotic patients who also underwent bariatric surgery during a 1-year period. RESULTS: 5 morbidly obese patients with schizophrenia underwent bariatric surgery between February 1999 and April 2003. All patients were well controlled on antipsychotics. The median BMI was 54 (51-70) and all had obesity-related co-morbidities. All patients had been previously treated unsuccessfully with conservative methods of weight reduction. 3 patients had a duodenal switch operation, 1 patient had a sleeve gastrectomy, and 1 had conversion of a silastic ring gastroplasty to biliopancreatic diversion. All patients were maintained on their antipsychotic medications until 24 hours before surgery. Median percent excess weight loss at 6 months was comparable to that achieved in the control group. CONCLUSIONS: Good control of schizophrenia may be achieved by newer therapies but at the risk of weight gain. The results of bariatric surgery in such patients are comparable to those of non-psychotic morbidly obese patients. Further follow-up is needed, but the results are encouraging.

Rhabdomyolysis of gluteal muscles leading to renal failure: a potentially fatal complication of surgery in the morbidly obese.

BACKGROUND: Rhabdomyolysis is a well-known cause of renal failure and is most commonly caused by ischemia/reperfusion or crush injury. We describe a new cause of this syndrome in a series of 6 patients who underwent necrosis of the gluteal muscles after bariatric surgery, 3 of whom eventually died of renal failure. METHODS: Potential etiologic factors were studied by comparing these patients with a consecutive series of 100 patients undergoing primary uncomplicated bariatric surgery during a 1-year period. Demographics, preoperative BMI, co-morbidities, duration of operation, and postoperative creatinine phosphokinase (CPK) levels. RESULTS: All patients presented with an area of buttock skin breakdown initially diagnosed as a simple decubitus ulcer. All had extensive myonecrosis of the medial gluteal muscles requiring extensive debridement. 5 of the 6 patients were male, with median BMI 67 compared with a median BMI 55 in the control group (P=0.0022). The patients were on the operating-room table for a median of 5.7 hours compared with 4.0 in the control group (P=0.01). 3 of the 6 developed renal failure requiring dialysis, which was fatal in all. One other patient developed a transient elevation of BUN and creatinine which did not require dialysis. Since recognition of this pattern, we now routinely perform serial CPK measurements. Median CPK rise in uncomplicated patients was to 1,200 mg/dl (SD 450-9,000), while CPK in affected patients ranged from 26,000 to 29,000 IU/l. We now routinely add additional buttock padding in very obese patients and institute aggressive hydration and mannitol diuresis if CPK rises above 5,000. No cases have occurred in the past 18 months in 220 patients. CONCLUSIONS: This is an important and potentially fatal complication of bariatric surgery. Very obese male patients with prolonged surgery are at risk of gluteal muscle necrosis with consequent renal failure, which we hypothesize is due to pressure by the operating-table leading to rhabdomyolysis and the creation of a compartment syndrome. Prevention may be aided by attention to intraoperative padding and positioning, and by limiting the duration of the operation.