A. P. H. Mclean

Surgery Decreases Long-term Mortality, Morbidity, and Health Care Use in Morbidly Obese Patients

Objective:This study tested the hypothesis that weight-reduction (bariatric) surgery reduces long-term mortality in morbidly obese patients. Background:Obesity is a significant cause of morbidity and mortality. The impact of surgically induced, long-term weight loss on this mortality is unknown. Methods:We used an observational 2-cohort study. The treatment cohort (n = 1035) included patients having undergone bariatric surgery at the McGill University Health Centre between 1986 and 2002. The control group (n = 5746) included age- and gender-matched severely obese patients who had not undergone weight-reduction surgery identified from the Quebec provincial health insurance database. Subjects with medical conditions (other then morbid obesity) at cohort-inception into the study were excluded. The cohorts were followed for a maximum of 5 years from inception. Results:The cohorts were well matched for age, gender, and duration of follow-up. Bariatric surgery resulted in significant reduction in mean percent excess weight loss (67.1%, P < 0.001). Bariatric surgery patients had significant risk reductions for developing cardiovascular, cancer, endocrine, infectious, psychiatric, and mental disorders compared with controls, with the exception of hematologic (no difference) and digestive diseases (increased rates in the bariatric cohort). The mortality rate in the bariatric surgery cohort was 0.68% compared with 6.17% in controls (relative risk 0.11, 95% confidence interval 0.04–0.27), which translates to a reduction in the relative risk of death by 89%. Conclusions:This study shows that weight-loss surgery significantly decreases overall mortality as well as the development of new health-related conditions in morbidly obese patients.

Host defense in blunt trauma: interrelationships of kinetics of anergy and depressed neutrophil function, nutritional status, and sepsis.

This study assessed the effects of blunt trauma on host defense, including the early kinetics of skin test anergy (A), depressed polymorphonuclear neutrophil (PMN) function, the duration of these changes, and the effect of the nutritional status of the host upon resolution of these defects. Of 31 pa

Delayed hypersensitivity and neutrophil chemotaxis: effect of trauma.

To investigate alterations in host defense produced by trauma, skin testing with five standard recall antigens was done on admission and weekly on 53 patients with blunt trauma and seven with penetrating missile injuries, who then were classified as normal (N), 2 or more positive responses; relatively anergic (RA), one positive response; or anergic (A), no response. Neutrophil chemotaxis was tested 145 times in 32 patients. Degree of injury was assessed by assigning one point to pelvic fracture, long-bone fracture, head, chest, or abdominal injury, to a maximum of five. The A and RA patients had greater trauma, 3 vs. 1.6 for N, and a significantly increased rate of sepsis (p less than 0.005) and mortality (p less than 0.05). Incidence of anergy depended upon age and extent of trauma. Neutrophil chemotaxis in A and RA patients was significantly (p less than 0.001) worse at 96.7 +/- 2.4 mu and 99.8 +/- 1.7 mu compared to N, 113.2 +/- 1.7 mu, and controls 121 +/- 4 mu. With recovery, chemotaxis returned to normal. It is concluded that failure of delayed hypersensitivity responses follows trauma, is related to the severity of injury and age of patient, and is associated with an abnormality of neutrophil chemotaxis and increased rate of sepsis.

Analysis of the Incidence and Risk Factors for Wound Infections in Open Bariatric Surgery

Background: Our clinical impression derived from >95% follow-up of patients was that our wound infection rate was higher than the 1-10% reported in the literature. The purpose of this study was to determine the incidence and risk factors for wound infection in open bariatric surgery. Methods: We queried our prospectively acquired bariatric surgery outcomes database, and retrospectively audited the charts of patients operated from April 1 to March 31, 2003. Risk categories were obtained using the National Nosocomial Infection Surveillance (NNIS) definitions and stratification. Expected site-specific rates were adjusted for duration of operation, degree of wound contamination, and underlying disease condition. Results: 269 patients undergoing a standardized open Roux-en-Y gastric bypass were studied. The mean age (SD) was 39.5 (10.5) years and the mean BMI was 54.3 (9.9). Operating time averaged 63 (17) minutes, and length of stay was 4.1 (1.3) days. Based on NNIS categories 10.9 wound infections were expected, but 54 were observed, for a rate of 20%. Bacterial isolates included S. aureus (39%), α-hemolytic strep (26%), Enterococcus (16%), P.mirabilis (9%), and multiple other bacteria at 10%. Epidural analgesia and delayed antibiotic prophylaxis administration (after the incision was made) increased the odds of developing a wound infection, whereas gender, age, BMI, duration of surgery, and incidence of diabetes had no effect.There was a high correlation between wound infection and subsequent incisional hernia formation. Conclusion: The incidence of wound infections following open bariatric surgery is high, and the current recommendations for antibiotic prophylaxis are ineffective. As these infections carry significant morbidity, effective methods to prevent them are needed.

Pre- and Post-prandial Plasma Ghrelin Levels Do Not Correlate with Satiety or Failure to Achieve a Successful Outcome after Roux-en-Y Gastric Bypass

Background: We tested the hypothesis that the amount of weight lost after Roux-en-Y gastric bypass (RYGBP) correlates with plasma ghrelin levels. Methods: 36 morbidly obese patients were studied 3 years after RYGBP (6 men, 30 women) with mean initial BMI 51 kg/m2 and 8 healthy controls (2 men, 6 women) with mean BMI 25 kg/m2. Subjects consumed a light breakfast, and the first blood sample was drawn at 1200 hrs immediately before lunch and the second sample at 1400 hrs. Satiety was assessed using a Visual Analog Scale (VAS). Patients were stratified as success (current BMI <35) or failures (current BMI ≥35). Results: Plasma ghrelin levels were significantly lower in patients after RYGBP (269 ± 66 pcg/ml) compared with lean controls (616 ± 112 pcg/ml, P<0.001). Ghrelin levels pre or post meals were not different between patients who had a successful weight loss (preoperative BMI 47, current BMI 29, 72% EWL) or those who achieved a less then ideal weight loss (preoperative BMI 48, current BMI 41, 29% EWL). There was no correlation between any of the VAS scores and plasma ghrelin. There was a strong inverse correlation between pre-prandial ghrelin levels and the preoperative or current BMI. Conclusion: Failure to lose weight after RYGBP does not correlate with pre- or post-prandial ghrelin plasma levels. Ghrelin levels were inversely proportional to BMI and did not correlate with satiety. These data do not support a role for higher plasma ghrelin levels for inadequate weight loss after RYGBP.

Determinants of susceptibility to sepsis and mortality: Malnutrition vs anergy☆

This study investigated whether increased susceptibility to sepsis and mortality is best determined by the nutritional state or by depressed host resistance, as indicated by anergy. One hundred and fifty Sprague-Dawley rats, 120–130 g, were presensitized with keyhole limpet hemocyanin (KLH) and fed a normal diet. At 3 weeks all rats had a reactive delayed-hypersensitivity skin test (DTH) response to KLH. Thirty rats were continued on this diet (Group I) and the rest were fed a 0.2% protein deficient diet. After 5 weeks of protein depletion 30 rats that maintained reactive DTH responses formed Group II and 30 rats that were anergic, as defined by a DTH response to KLH of < 5 mm induration at 24 hr, formed Group III. Carcass nitrogen studies confirmed that malnourished Groups II and III were comparably malnourished. All three groups were then challenged, via intraperitoneal injection, with a suspension of bacteriae and 10% BaSO4 (total 2.5 cc/100 g) at three doses. There was no significant difference in survival between nourished reactive (78%) and malnourished reactive (60%) rats. However, malnourished anergic rats had a significantly higher mortality (80%) compared to nourished reactive rats (22%, χ2 = 6.34, P < 0.025). Furthermore, a 40% difference in survival was observed between severely malnourished anergic and malnourished reactive DTH populations. We conclude that, while protein deprivation produces the state of anergy, survival from peritonitis challenge is determined, not by the malnutritional status per se, but by the adversely affected host immune state.