Clinical significance of iron deficiency among candidates for metabolic surgery

BACKGROUND

Iron deficiency (ID), a known complication after metabolic surgery, is common among preoperative patients in the presence of inflammation. Evidence is now accumulating that preoperative ID may adversely affect perioperative outcomes.

OBJECTIVES

To investigate the relationship between preoperative iron status and the risk of postoperative severe anemia. In addition, this study investigates the relationship between preoperative iron status and length of surgical stay SETTING: A large regional tertiary health system.

METHODS

Among patients who underwent metabolic surgery between 2004 and 2020, 5171 patients had a full iron nutritional assessment prior to surgery. Study patients were divided into multiple smaller groups (10 female groups and 7 male groups) on the basis of levels of serum ferritin and Transferrin Saturation (T Sat) < or ≥20%. Study patients were followed after surgery and the time to the development of severe anemia (hemoglobin < 8 gm/dL) was recorded. Hospital length of stay (LOS) was analyzed in relation to preoperative iron status.

RESULTS

Lower ferritin levels were associated with older age in males (P = .0001) and younger age in females (P < .0001). For males, after adjustment for age, body mass index (BMI), and year of surgery, surgical LOS was prolonged in those with T Sat <20% (P = .0041). For females the time until the development of severe anemia was associated with baseline iron status (P < .0001).

CONCLUSIONS

Male preoperative patients for metabolic surgery with T Sat <20% are at risk for increased surgical LOS. Females with low ferritin levels consistent with ID are at increased risk for the development of postoperative severe anemia.

Prior metabolic surgery reduced COVID-19 severity: Systematic analysis from year one of the COVID-19 pandemic

Background

Obesity is a risk factor for COVID-19 severity. Recent studies suggest that prior metabolic surgery (MS) modifies the risk of COVID-19 severity.

Methods

COVID-19 outcomes were compared between patients with MS (n = 287) and a matched cohort of unoperated patients (n = 861). Multiple logistic regression was used to identify predictors of hospitalization. A systematic literature review and pooled analysis was conducted to provide overall evidence of the influence of prior metabolic surgery on COVID-19 outcomes.

Results

COVID-19 patients with MS had less hospitalization (9.8% versus 14.3%, p = 0.049). Age 70+, higher BMI, and low weight regain after MS were associated with more hospitalization after COVID-19. A systematic review of 7 studies confirmed that MS reduced the risk of post-COVID-19 hospitalization (OR = 0.71, 95%CI = [0.61-0.83], p < 0.0001) and death (OR = 0.44, 95%CI = [0.30-0.65], p < 0.0001).

Conclusion

MS favorably modifies the risks of severe COVID-19 infection. Older age and higher BMI are major risk factors for severity of COVID-19 infection.

"Bioelectrical impedance analysis in managing sarcopenic obesity in NAFLD"

INTRODUCTION

Sarcopenic obesity and its association with nonalcoholic fatty liver disease (NAFLD) is under-recognized by many healthcare providers in Western medicine due to the lack of awareness and diagnostic guidelines. The result is delayed recognition and treatment, which leads to further health deterioration and increased healthcare costs. Sarcopenic obesity is characterized by the presence of increased fat mass in combination with muscle catabolism related to chronic inflammation and/or inactivity. Previous research has recommended evaluating body composition and physical function performance to adequately diagnose sarcopenic obesity. Body composition analysis can be performed by imaging applications through magnetic resonance imaging, computed tomography, and dual-energy x-ray absorptiometry. Due to the cost of each device and radiation exposure for patients as evidenced in all three modalities, bioelectrical impedance analysis offers a noninvasive approach capable of providing quick and reliable estimates of lean body and fat mass.

METHODS AND RESULTS

This review analyzes the current evidence-based literature, indicating a lower skeletal muscle mass and increased visceral adipose tissue correlation to the advancement of fibrosis in fatty liver disease.

CONCLUSION

Given the substantial promising research conducted in predominantly Asian populations regarding body tissue distribution and NAFLD, additional prospective research is needed to extend these findings in Western populations.

New concepts in the diagnosis and management approach to iron deficiency in candidates for metabolic surgery: should we change our practice?

The near universal presence of chronic low-grade systemic inflammation among patients with severe obesity disrupts iron homeostasis and underlies the association between obesity and iron deficiency. Immune activation and inflammation result in a reduction in circulating iron and diminished iron bioavailability for erythropoiesis. Inflammation also alters blood levels of commonly measured markers of iron nutrition status, which makes the diagnosis of iron deficiency difficult and has led to new recommendations regarding laboratory markers for the diagnosis. Recent evidence using these newly recommended laboratory markers, which include levels of ferritin, C-reactive protein, and transferrin saturation, suggests that the actual prevalence of iron deficiency among candidates for metabolic surgery may be double or triple the prevalence identified by low levels of ferritin alone. Thus large numbers of surgical candidates have iron deficiency that has been heretofore largely unrecognized and inadequately treated. The assessment of iron status using the currently recommended markers in the presence of chronic inflammatory diseases and repletion of depleted stores for surgical candidates with deficiency during the preoperative period present an important opportunity for mitigating this condition in postoperative patients.

The relationship between specialized pro-resolving lipid mediators, morbid obesity and weight loss after bariatric surgery

Obesity and diabetes are associated with chronic inflammation. Specialized pro-resolving lipid mediators (SPMs)—resolvins (Rv), protectins (PD) and maresins (MaR)—actively resolve inflammation. Bariatric surgery achieves remission of diabetes, but mechanisms are unclear. We measured SPMs and proinflammatory eicosanoid levels using liquid chromatography-tandem mass spectrometry in 29 morbidly obese subjects (13 with diabetes) and 15 nondiabetic, mildly obese subjects. Compared to the mildly obese, the morbidly obese had higher levels of SPMs—RvD3, RvD4 and PD1—and white blood cells (WBC) and platelets. Post-surgery, SPM and platelet levels decreased in morbidly obese nondiabetic subjects but not in diabetic subjects, suggesting continued inflammation. Despite similar weight reductions 1 year after surgery (44.6% vs. 46.6%), 8 diabetes remitters had significant reductions in WBC and platelet counts whereas five non-remitters did not. Remitters had a 58.2% decrease (p = 0.03) in 14-HDHA, a maresin pathway marker; non-remitters had an 875.7% increase in 14-HDHA but a 36.9% decrease in MaR1 to a median of 0. In conclusion, higher levels of RvD3, PD1 and their pathway marker, 17-HDHA, are markers of leukocyte activation and inflammation in morbid obesity and diabetes and diminish with weight loss in nondiabetic but not diabetic subjects, possibly representing sustained inflammation in the latter. Lack of diabetes remission after surgically-induced weight loss may be associated with reduced ability to produce MaR1 and sustained inflammation.

Clinical Characteristics of Roux-en-Y Gastric Bypass Patients with Death from Accidental Overdose or Intentional Self-Harm: a Descriptive Study

PURPOSE

The objective of this descriptive study was to identify clinical characteristics of Roux-en-Y gastric bypass (RYGB) patients who died from intentional self-harm or accidental overdose postoperatively.

MATERIALS AND METHODS

This retrospective, descriptive study included RYGB patients from a large rural medical center that completed surgery between January 2004 and December 2014 and died from intentional self-harm or accidental overdose through December 2015. Specific causes of death were obtained from the National Death Index and clinical data from electronic health records. Clinical characteristics explored were age, sex, time to surgery, weight loss expectations, postoperative weight loss, medication, diagnoses, psychiatric histories (diagnoses, self-harm, suicidal ideation and behaviors, medications, substance use, preoperative Beck Depression Inventory-II scores), pain, social support, and reported life stressors.

RESULTS

Overall, 22 patients of 146 total deceased patients died from intention self-harm (n = 6) or accidental overdose (n = 16) over the study period (77.3% female, mean age at time of surgery = 38.4 ± 9.1 years). Younger age (< 40 years), history of self-harm or depression, preoperative pain, and use of opioids at the time of surgery emerged as common characteristics in weight loss surgery patients who died from intentional self-harm or accidental overdose. No trends regarding social support, life stressors, or actual or expected weight loss were identified.

CONCLUSION

Certain weight loss surgery patients may be at risk for death from self-harm or overdose and may benefit from greater surveillance postoperatively.

Metabolic surgery and iron homeostasis

Iron deficiency and anaemia after metabolic surgery, potentially modifiable nutritional complications, are becoming an increasing cause for concern as prevalence increases with time and there is limited evidence supporting the effectiveness of the current guidelines for prophylactic oral iron supplementation and treatment for deficiency. Abnormalities in iron nutrition predisposing to deficiency are common in severely obese patients, and the low-grade systemic inflammation, also common to these patients, reduces the effectiveness of oral iron supplementation. The surgical procedures result in alterations of foregut anatomy and physiology, which limit iron absorptive capacity and daily food intake. These alterations and the limited effects of oral iron supplementation explain the high prevalence of postoperative iron deficiency and anaemia. This review outlines current mechanisms concerning the pathogenesis of disordered iron nutrition in patients with severe obesity, current gaps in knowledge, and opportunities for quality improvement.

Genetic inactivation of ANGPTL4 improves glucose homeostasis and is associated with reduced risk of diabetes

Angiopoietin-like 4 (ANGPTL4) is an endogenous inhibitor of lipoprotein lipase that modulates lipid levels, coronary atherosclerosis risk, and nutrient partitioning. We hypothesize that loss of ANGPTL4 function might improve glucose homeostasis and decrease risk of type 2 diabetes (T2D). We investigate protein-altering variants in ANGPTL4 among 58,124 participants in the DiscovEHR human genetics study, with follow-up studies in 82,766 T2D cases and 498,761 controls. Carriers of p.E40K, a variant that abolishes ANGPTL4 ability to inhibit lipoprotein lipase, have lower odds of T2D (odds ratio 0.89, 95% confidence interval 0.85–0.92, p = 6.3 × 10⁻¹⁰), lower fasting glucose, and greater insulin sensitivity. Predicted loss-of-function variants are associated with lower odds of T2D among 32,015 cases and 84,006 controls (odds ratio 0.71, 95% confidence interval 0.49–0.99, p = 0.041). Functional studies in Angptl4-deficient mice confirm improved insulin sensitivity and glucose homeostasis. In conclusion, genetic inactivation of ANGPTL4 is associated with improved glucose homeostasis and reduced risk of T2D.

Genetic variation in ANGPTL4 is associated with lipid traits. Here, the authors find that predicted loss-of-function variants in ANGPTL4 are associated with glucose homeostasis and reduced risk of type 2 diabetes and that Angptl4^−/− mice on a high-fat diet show improved insulin sensitivity.

Bariatric Surgery Patients and Their Families: Health, Physical Activity, and Social Support

BACKGROUND

This study evaluated the social environment of bariatric surgery patients in the preoperative period.

METHODS

Forty bariatric surgery patients (mean = 46.2 ± 11.2 years), 35 adult cohabitating family members (mean = 45.2 ± 12.7 years), and 15 cohabitating children (mean = 11.5 ± 3.6 years) were recruited from a large rural medical center. Adult participants (patients and family members) completed height, weight, body composition, blood draws, and physical activity assessments (accelerometry), as well as eating behavior and social support inventories before the patient underwent bariatric surgery. Child participants completed demographic, height, and weight assessment only.

RESULTS

Over 90 % of adult family members were overweight or obese (body mass index (BMI) ≥ 25 kg/m², as were 50 % of children (BMI percentile ≥ 85 %). More than one third (37.1 %) of family members met the criteria for moderate to severe insulin resistance. Physical activity measured by accelerometry was moderately correlated between the patient and adult family members (r = 0.46, p = 0.023). Bariatric surgery patients reported high levels of social support from their family members on multiple social support measures.

CONCLUSIONS

Many family members of bariatric surgery patients also lived with obesity and related comorbidities, and demonstrate high sedentary behavior. However, patients reported high levels of support from family members, including support in following a healthy diet and engaging in physical activity. Engaging families in behavior change may help bariatric surgery patients and their families to become healthier.

All-Cause and Specific-Cause Mortality Risk After Roux-en-Y Gastric Bypass in Patients With and Without Diabetes

OBJECTIVE

This study assessed all-cause and specific-cause mortality after Roux-en-Y gastric bypass (RYGB) and in matched control subjects, stratified by diabetes status.

RESEARCH DESIGN AND METHODS

RYGB patients were matched by age, BMI, sex, and diabetes status at time of surgery to nonsurgical control subjects using data from the electronic health record. Kaplan-Meier curves and Cox regression were used to assess differences in all-cause and specific-cause mortality between RYGB patients and control subjects with and without diabetes.

RESULTS

Of the 3,242 eligible RYGB patients enrolled from January 2004 to December 2015, control subjects were identified for 2,428 (n = 625 with diabetes and n = 1,803 without diabetes). Median postoperative follow-up was 5.8 years for patients with diabetes and 6.7 years for patients without diabetes. All-cause mortality was reduced in RYGB patients compared with control subjects only for those with diabetes at the time of surgery (adjusted hazard ratio 0.44; P < 0.0001). Mortality was not significantly improved in RYGB patients without diabetes compared with control subjects without diabetes (adjusted hazard ratio 0.84; P = 0.37). Deaths from cardiovascular diseases (P = 0.011), respiratory conditions (P = 0.017), and diabetes P = 0.011) were more frequent in control subjects with diabetes than in RYGB patients with diabetes. RYGB patients without diabetes were less likely to die of cancer (P = 0.0038) and respiratory diseases (P = 0.046) than control subjects without diabetes but were at higher risk of death from external causes (P = 0.012), including intentional self-harm (P = 0.025), than control subjects without diabetes.

CONCLUSIONS

All-cause mortality benefits of RYGB are driven predominantly by patients with diabetes at the time of surgery. RYGB patients with diabetes were less likely to die of cardiovascular diseases, diabetes, and respiratory conditions than their counterparts without RYGB.

Gastric Bypass Surgery Produces a Durable Reduction in Cardiovascular Disease Risk Factors and Reduces the Long-Term Risks of Congestive Heart Failure

Background

Obesity and its association with reduced life expectancy are well established, with cardiovascular disease as one of the major causes of fatality. Metabolic surgery is a powerful intervention for severe obesity, resulting in improvement in comorbid diseases and in cardiovascular risk factors. This study investigates the relationship between metabolic surgery and long‐term cardiovascular events.

Methods and Results

A cohort of Roux‐en‐Y gastric bypass surgery (RYGB) patients was tightly matched by age, body mass index, sex, Framingham Risk Score, smoking history, use of antihypertension medication, diabetes mellitus status, and calendar year with a concurrent cohort of nonoperated control patients. The primary study end points of major cardiovascular events (myocardial infarction, stroke, and congestive heart failure) were evaluated using Cox regression. Secondary end points of longitudinal cardiovascular risk factors were evaluated using repeated‐measures regression. The RYGB and matched controls (N=1724 in each cohort) were followed for up to 12 years after surgery (overall median of 6.3 years). Kaplan–Meier analysis revealed a statistically significant reduction in incident major composite cardiovascular events (P=0.017) and congestive heart failure (0.0077) for the RYGB cohort. Adjusted Cox regression models confirmed the reductions in severe composite cardiovascular events in the RYGB cohort (hazard ratio=0.58, 95% CI=0.42–0.82). Improvements of cardiovascular risk factors (eg, 10‐year cardiovascular risk score, total cholesterol, high‐density lipoprotein, systolic blood pressure, and diabetes mellitus) were observed within the RYGB cohort after surgery.

Conclusions

Gastric bypass is associated with a reduced risk of major cardiovascular events and the development of congestive heart failure.

High allelic burden of four obesity SNPs is associated with poorer weight loss outcomes following gastric bypass surgery

Genome-wide association and linkage studies have identified multiple susceptibility loci for obesity. We hypothesized that such loci may affect weight loss outcomes following dietary or surgical weight loss interventions. A total of 1,001 white individuals with extreme obesity (BMI >35 kg/m(2)) who underwent a preoperative diet/behavioral weight loss intervention and Roux-en-Y gastric bypass surgery were genotyped for single-nucleotide polymorphisms (SNPs) in or near the fat mass and obesity-associated (FTO), insulin induced gene 2 (INSIG2), melanocortin 4 receptor (MC4R), and proprotein convertase subtilisin/kexin type 1 (PCSK1) obesity genes. Association analysis was performed using recessive and additive models with pre- and postoperative weight loss data. An increasing number of obesity SNP alleles or homozygous SNP genotypes was associated with increased BMI (P < 0.0006) and excess body weight (P < 0.0004). No association between the amounts of weight lost from a short-term dietary intervention and any individual obesity SNP or cumulative number of obesity SNP alleles or homozygous SNP genotypes was observed. Linear mixed regression analysis revealed significant differences in postoperative weight loss trajectories across groups with low, intermediate, and high numbers of obesity SNP alleles or numbers of homozygous SNP genotypes (P < 0.0001). Initial BMI interacted with genotype to influence weight loss with initial BMI <50 kg/m(2), with evidence of a dosage effect, which was not present in individuals with initial BMI ≥50 kg/m(2). Differences in metabolic rate, binge eating behavior, and other clinical parameters were not associated with genotype. These data suggest that response to a surgical weight loss intervention is influenced by genetic susceptibility and BMI.

Nutrition in critically ill obese patients

Critically ill obese patients require timely nutrition in the intensive care unit. Hypocaloric, high protein nutritional feeding might have a role in critically ill obese patients. Although critically ill obese patients need special medical and nutritional care as do nonobese patients in the ICU, there are some differences in the literature about the initiation, routes, and nature of nutritional support. This article reviews the norms of nutritional care among critically ill obese patients and the differences between these patients and those with a normal BMI.

Preoperative weight loss before bariatric surgery

HYPOTHESIS

Preoperative weight loss reduces the frequency of surgical complications in patients undergoing bariatric surgery.

DESIGN

Review of records of patients undergoing open or laparoscopic gastric bypass.

SETTING

A comprehensive, multidisciplinary obesity treatment center at a tertiary referral center that serves central Pennsylvania.

PATIENTS

A total of 881 patients undergoing open or laparoscopic gastric bypass from May 31, 2002, through February 24, 2006.

INTERVENTION

All preoperative patients completed a 6-month multidisciplinary program that encouraged a 10% preoperative weight loss.

MAIN OUTCOME MEASURES

Loss of excess body weight (EBW) and total and major complication rates.

RESULTS

Of the 881 patients, 592 (67.2%) lost 5% or more EBW and 423 (48.0%) lost more than 10% EBW. Patients referred for open gastric bypass (n = 466) were generally older (P < .001), had a higher body mass index (P < .001), and were more often men (P < .001) than those undergoing laparoscopic gastric bypass (n = 415). Total and major complication rates were higher in patients undergoing open gastric bypass (P < .001 and P = .03, respectively). Univariate analysis revealed that increasing preoperative weight loss is associated with reduced complication frequencies for the entire group for total complications (P =.004) and most likely for major complications (P = .06). Controlling for age, sex, baseline body mass index, and type of surgery in a multiple logistic regression model, increased preoperative weight loss was a predictor of reduced complications for any (P =.004) and major (P = .03) complications.

CONCLUSION

Preoperative weight loss is associated with fewer complications after gastric bypass surgery.

Open versus laparoscopic Roux-en-Y gastric bypass: a comparative study of over 25,000 open cases and the major laparoscopic bariatric reported series

BACKGROUND

Laparoscopic bariatric surgery has experienced a rapid expansion of interest over the past 5 years, with a 470% increase. This rapid expansion has markedly increased overall cost, reducing surgical access. Many surgeons believe that the traditional open approach is a cheaper, safer, equally effective alternative.

METHODS

16 highly experienced "open" bariatric surgeons with a combined total of 25,759 cases representing >200 surgeon years of experience, pooled their open Roux-en-Y gastric bypass (ORYGBP) data, and compared their results to the leading laparoscopic (LRYGBP) papers in the literature.

RESULTS

In the overall series, the incisional hernia rate was 6.4% using the standard midline incision. Utilizing the left subcostal incision (LSI), it was only 0.3%. Return to surgery in <30 days was 0.7%, deaths 0.25%, and leaks 0.4%. Average length of stay was 3.4 days, and return to usual activity 21 days. Small bowel obstruction was significantly higher with the LRYGBP. Surgical equipment costs averaged approximately $3,000 less for "open" cases. LRYGBP had an added expense for longer operative time. This more than made up for the shorter length of stay with the laparoscopic approach.

CONCLUSIONS

The higher cost, higher leak rate, higher rate of small bowel obstruction, and similar long-term weight loss results make the "open" RYGBP our preferred operation. If the incision is taken out of the equation (i.e. use of the LSI), the significant advantages of the open technique become even more obvious.

Small intestinal perforation and necrotizing fasciitis after abdominal liposuction

Liposuction, the most common aesthetic procedure performed in the United States, is not without risk, but the overall complication rate in the literature varies from less than 1% to 9.3%. A 55-year-old woman who had undergone abdominal liposuction with bilateral breast augmentation was hospitalized in a state of profound septic shock. A diagnosis of necrotizing fasciitis was made on the basis of findings that included abdominal skin discoloration, subcutaneous emphysema, and air in the subcutaneous plane seen on abdominal computed tomography (CT) scan. During the operative procedure for abdominal wall debridement, extensive necrosis of abdominal wall fascia with leakage of bilious fluid from defects in the rectus sheath was found. Subsequent peritoneal cavity exploration showed two perforations in the mid ileum with gross peritoneal cavity contamination.

Perioperative outcomes and risk factors in gastric surgery for morbid obesity: a 9-year experience

OBJECTIVE

Surgical treatment of severe obesity is the most rapidly growing specialty area of surgery. The rapid expansion of bariatric surgery has raised questions and concerns regarding possible increased surgical mortality and morbidity rates in both academic and community settings. The purpose of this study was to evaluate postoperative outcomes and risk factors for bariatric gastric surgery for severe obesity.

METHODS

A community experience of 1009 consecutive patients who underwent open surgical treatment of morbid obesity during a 9-year period was reviewed from a prospective database. The series included 858 primary gastric bypass operations and 151 revision operations. Perioperative outcomes, late complications, and weight loss results were recorded. Morbidity and mortality rates were analyzed according to patient age, body mass index (BMI), and gender.

RESULTS

The mortality rate in the series was 0.6%, and the morbidity rate was 20%. The major complication rate was 6.6%. There were no deaths in the 151 revision patients. The gastrointestinal leak rate was 0.8%, and the thromboembolism rate was 1%. Statistical analysis indicates that BMI is a risk factor for surgical complications.

CONCLUSION

Open gastric surgery for morbid obesity can be carried out in the community setting with low mortality and morbidity rates. BMI is a proven surgical risk factor.

The effect of bi-level positive airway pressure on postoperative pulmonary function following gastric surgery for obesity

The severely obese patient has varying degrees of intrinsic reduction of expiratory flow rates and lung volumes. Thus, the severely obese patient is predisposed to postoperative atelectasis, ineffective clearing of respiratory secretions, and other pulmonary complications. This study evaluated the effect of bi-level positive airway pressure (BiPAP) on pulmonary function in obese patients following open gastric bypass surgery Patients with a body mass index (BMI) of at least 40 kg/m2 who were undergoing elective gastric bypass were eligible to be randomized to receive either BiPAP during the first 24 h postoperatively or conventional postoperative care. Patients with significant cardiovascular and pulmonary diseases were excluded from the study. Forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1.0), peak expiratory flow rate (PEFR), and percent hemoglobin oxygen saturation (SpO2) were measured preoperatively, and on postoperative days 1, 2, and 3. Twenty-seven patients were entered in the study 14 received BiPAP and 13 received conventional postoperative care. There was no significant difference preoperatively between the study and control groups in regards to age, BMI, FVC, FEV1.0, PEFR or SpO2. Postoperatively expiratory flow was decreased in both groups. However, the FVC and FEV1.0 were significantly higher on each of the three consecutive postoperative days in the patients who received BiPAP therapy. The SpO2 was significantly decreased in the control group over the same time period. Prophylactic BiPAP during the first 12-24 h postoperatively resulted in significantly higher measures of pulmonary function in severely obese patients who had undergone elective gastric bypass surgery. These improved measures of pulmonary function, however, did not translate into fewer hospital days or a lower complication rate in our study population of otherwise healthy obese patients. Further study is necessary to determine if BiPAP therapy in the first 24 postoperative hours would be of benefit in severely obese patients with comorbid illnesses who have undergone elective gastric bypass.

Nonsurgical factors that influence the outcome of bariatric surgery: a review

OBJECTIVE

Severe obesity (ie, at least 100% overweight or body mass index > or =40 kg/m2) is associated with significant morbidity and increased mortality. It is apparently becoming more common in this country. Conventional weight-loss treatments are usually ineffective for severe obesity and bariatric surgery is recommended as a treatment option. However, longitudinal data on the long-term outcome of bariatric surgery are sparse. Available data indicate that the outcome of bariatric surgery, although usually favorable in the short term, is variable and weight regain sometimes occurs at 2 years after surgery. The objective of this study is to present a review of the outcome of bariatric surgery in three areas: weight loss and improvement in health status, changes in eating behavior, and psychosocial adjustment. The study will also review how eating behavior, energy metabolism, and psychosocial functioning may affect the outcome of bariatric surgery. Suggestions for additional research in these areas are made.

METHOD

Literature review.

RESULTS

On average, most patients lose 60% of excess weight after gastric bypass and 40% after vertical banded gastroplasty. In about 30% of patients, weight regain occurs at 18 months to 2 years after surgery. Binge eating behavior, which is common among the morbidly obese, may recur after surgery and is associated with weight regain. Energy metabolism may affect the outcome of bariatric surgery, but it has not been systematically studied in this population. Presurgery psychosocial functioning does not seem to affect the outcome of surgery, and psychosocial outcome is generally encouraging over the short term, but there are reports of poor adjustment after weight loss, including alcohol abuse and suicide.

CONCLUSIONS

Factors leading to poor outcome of bariatric surgery, such as binge eating and lowered energy metabolism, should be studied to improve patient selection and outcome. Long-term outcome data on psychosocial functioning are lacking. Longitudinal studies to examine the long-term outcome of bariatric surgery and the prognostic indicators are needed.

Eating disturbances and outcome of gastric bypass surgery: a pilot study

OBJECTIVE

We examined how the outcome of gastric bypass surgery (GBP) was effected by the interaction between presurgery eating disturbance status and length of time since surgery.

METHOD

Subjects were recruited from a list of patients who received GBP in the last 3 years. Twenty-seven patients 20.8 +/- 11.0 months postsurgery were interviewed.

RESULTS

Both current eating disturbance status and weight regain were predicted by the interaction between presurgical eating disturbance status and length of time since surgery. The significant time period in this interaction was 2 years or more postsurgery.

DISCUSSION

Patients with a presurgical eating disorder may experience a short-term improvement in their eating disorder following GBP that erodes on or after 2 years and is related to weight regain. Methods for improving surgical outcome in this population are discussed.

Nutritional support of the mechanically ventilated patient

As with all critically ill patients, those requiring mechanical ventilation are susceptible to the wasting of illness and cannot survive without prompt nutritional support. It may be fair to say that the proper provision of nutrients, and in particular the avoidance of overfeeding, are even more crucial for this subset of critically ill patients. To maximize the overall benefits of feeding, it is crucial to provide the nutritional support early and enterally whenever possible. Therefore, the best strategy for early removal of the mechanical ventilatory support must include the timely and careful administration of nutrients, micronutrients, minerals, vitamins, and fluid, in conjunction with standard intensive care therapeutics and the appropriate respiratory muscle-strengthening program.

Safety and long-term efficacy of revisional surgery in severe obesity

BACKGROUND

A National Institutes of Health Consensus Conference in 1991 established gastric surgery as accepted therapy for the treatment of severe obesity. The increasing prevalence of obesity in the United States, and the increasing numbers of patients undergoing gastric surgery for severe obesity, result in substantial numbers of patients being considered for revisional surgery. The indications and efficacy of revisional surgery remain controversial.

METHODS

Sixty-three patients were followed prospectively after undergoing revisional surgery for obesity between 1981 and 1994. All patients had previously undergone obesity operations. Weight data were recorded at the time of original obesity surgery, at revisional surgery, and at most current follow-up. Complications following revisional surgery were monitored.

RESULTS

The follow-up in the group is 98%. Revisional surgery after obesity surgery was associated with a 0% mortality rate and a serious complication rate of 16%. Body mass index (BMI) at the time of original surgery was 50 +/- 10 kg/m2, at revisional surgery 39 + 9 kg/m2, and at recent follow-up 34 +/- 10 kg/m2 (P < 0.001 vs original BMI). Those patients whose original BMI was > 50 kg/m2 lost significantly more weight (P < 0.0001) than those with an original BMI < 50 kg/m2.

CONCLUSIONS

Revisional gastric surgery is safe and does provide patients with the opportunity to achieve long-term weight control.

The role of gastric surgery in the multidisciplinary management of severe obesity

Severe obesity affects the health and quality of life of 4 million Americans. The major cost of treating severe obesity and its associated comorbidities of hypertension, diabetes, cardiovascular disease, pulmonary insufficiency, cancer, and degenerative arthritis as well as the poor long-term results of medical, drug, and behavioral therapy has increased the numbers of patients being referred for surgical treatment. Gastric bypass and vertical banded gastroplasty are the two procedures recommended for severely obese patients. These operations currently have low morbidity and mortality. Surgery should be considered adjuvant therapy and must be part of a multidisciplinary approach. The significant long-term weight control resulting from the surgical therapy is associated with improvement and, often, resolution of comorbidities, including diabetes, hypertension, hyperlipidemia, and pulmonary insufficiency.

Hemodynamic correlates of outcome in patients undergoing orthotopic liver transplantation. Evidence for early postoperative myocardial depression

OBJECTIVE

To describe the hemodynamic and oxygen transport patterns in survivors and nonsurvivors following liver transplantation (LT) and to assess their relationship to organ failure and mortality.

DESIGN

Retrospective cohort.

SETTING

Surgical ICU in a tertiary care university teaching hospital.

PATIENTS

Consecutive series of 113 adults undergoing LT between 1984 and 1992. Patients were excluded if they died intraoperatively (n = 2), required retransplantation (n = 8), or their records were incomplete (n = 7).

MEASUREMENTS AND MAIN RESULTS

Preoperative severity of illness was assessed by the acute physiology and chronic health evaluation (APACHE) II scoring system. Hemodynamic and oxygen transport variables were recorded immediately preoperatively and sequentially every 12 h during the first 2 postoperative days. Organ failures (pulmonary, renal, cardiovascular, hepatic, and central nervous system) were assessed for patients in the postoperative period. Patients were grouped as survivors (n = 82) or nonsurvivors (n = 14) with a mortality rate of 15%. Preoperative APACHE II scores were significantly lower in survivors compared with nonsurvivors (7 +/- 0 vs 11 +/- 2; p = 0.029). Both preoperatively and postoperatively, survivors sustained a relatively higher mean arterial pressure, stroke volume index, left ventricular stroke work index, cardiac index, and oxygen delivery as compared with nonsurvivors (p < 0.01). The postoperative decline in systemic blood flow that was seen in both groups was particularly prominent in nonsurvivors during the first 12 h following LT (p < 0.03). Nonsurvivors sustained an approximately fivefold increase in the rate of organ failure (p < 0.0001); all patients (n = 6) with 4 or more organ failures died.

CONCLUSION

Nonsurvivors of LT have less cardiac reserve pretransplant; postoperatively, they demonstrate early myocardial depression and subsequently lower levels of cardiac index and oxygen delivery. Patients who develop these hemodynamic patterns are more prone to organ failure and death.

Biosynthesis of 9-cis-retinoic acid from 9-cis-beta-carotene in human intestinal mucosa in vitro

The role of 9-cis-beta-carotene (9-cis-beta-C) as a potential precursor of 9-cis-retinoic acid (9-cis-RA) has been examined in human intestinal mucosa in vitro. By using HPLC, uv spectra, and chemical derivatization analysis, both 9-cis-RA and all-trans-retinoic acid (all-trans-RA) have been identified in the postnuclear fraction of human intestinal mucosa after incubation with 9-cis-beta-C at 37 degrees C. The biosynthesis of both 9-cis-RA and all-trans-RA from 9-cis-beta-C was linear with increasing concentrations of 9-cis-beta-C (2-30 microM) and was linear with respect to tissue protein concentration up to 0.75 mg/ml. Retinoic acid was not detected when a boiled incubation mixture was incubated in the presence of 9-cis-beta-C. The rate of synthesis of 9-cis- and all-trans-RA from 4 microM 9-cis-beta-C were 16 +/- 1 and 18 +/- 2 pmol/hr/mg of protein, respectively. However, when 2 microM all-trans-beta-C was added to the 4 microM 9-cis-beta-C, the rate of all-trans-RA synthesis was increased to 38 +/- 6 pmol/hr/mg of protein, whereas the rate of 9-cis-RA synthesis remained the same. These results suggest that 9-cis-RA is produced directly from 9-cis-beta-C. Furthermore, incubations of either 0.1 microM 9-cis- or all-trans-retinal under the same incubation conditions showed that 9-cis-RA could also arise through oxidative conversion of 9-cis-retinal. Although only 9-cis-RA was detected when 9-cis-RA was used as the substrate, the isomerization of the all-trans-RA to 9-cis-RA cannot be ruled out, since both all-trans-RA and trace amounts of 9-cis-RA were detected when all-trans-retinal was incubated as the substrate. These data indicate that 9-cis-beta-C can be a source of 9-cis-RA in the human. This conversion may have a significance in the anticarcinogenic action of beta-C.

The oxygen cost of breathing may predict weaning from mechanical ventilation better than the respiratory rate to tidal volume ratio

OBJECTIVE

To compare the respiratory rate to tidal volume ratio with the oxygen cost of breathing to see which could more accurately predict the outcome of ventilator weaning for surgical patients.

DESIGN

Prospective comparison of two modalities used to predict the likelihood of successful ventilator weaning.

PATIENTS

Twenty-eight consecutive patients with chronic respiratory insufficiency requiring long-term mechanical ventilation in the surgical intensive care unit at New England Deaconess Hospital, Boston, Mass, were studied.

MAIN OUTCOME MEASURES

The oxygen cost of breathing and the respiratory rate to tidal volume ratio were measured during spontaneous breathing. Patients extubated within 2 weeks of being studied were designated as extubated while patients not extubated within this period or requiring reintubation were recorded as not extubated.

RESULTS

The oxygen cost of breathing predicted successful extubation in all five patients who were extubated, and failure in 20 of 23 patients who could not be extubated (sensitivity, 100%; specificity, 87%). In contrast, the respiratory rate to tidal volume ratio predicted extubation for only two of five patients who were extubated and predicted failure in only 12 of 23 patients who could not be extubated (sensitivity, 40%; specificity, 52%).

CONCLUSION

For this group of patients requiring prolonged ventilation, the oxygen cost of breathing proved to be a more reliable predictor of both successful extubation and failure.

Could the oxygen cost of breathing be used to optimize the application of pressure support ventilation?

Pressure support ventilation (PSV) is a new ventilator modality that augments spontaneous inspiratory pressure with selected levels of positive airway pressure. There is presently considerable interest in its use in the management of critically ill, ventilator-dependent patients. The optimal method for application has not yet been established. This study investigated the effects of PSV on the oxygen cost of breathing (OCOB), a clinically applicable technique for quantitating the work of breathing. The OCOB and other bedside variables of pulmonary function were measured during PSV in ventilator-dependent patients where weaning was limited by an inability to sustain respiratory work. Nine studies were performed in 8 patients in the surgical intensive care unit. The OCOB, tidal volume (VT), respiratory rate (RR), and minute ventilation (VE) were measured at various levels of pressure support. The OCOB was calculated from the difference in oxygen consumption (VO2) during mechanical and spontaneous ventilation both at CPAP and with PSV. With increasing levels of PSV, the OCOB was observed to steadily decrease from 22% to 8% (p < 0.001). There were also statistically significant increases in VT and decreases in RR. VE appeared not to be influenced. The results of this study suggest that the bedside measurement of the OCOB may be an accurate, simple, and reproducible method of titrating the level of applied pressure support in order to optimize respiratory work.

Reevaluation of current transfusion practices in patients in surgical intensive care units

Widespread interest in the complications associated with packed red blood cell (PRBC) transfusions has led to the scrutiny of traditional transfusion practices. Recently, attempts have been made to define more clearly the indications for PRBC transfusions in patients, particularly those who are critically ill. At present, however, transfusions continue to be ordered based on a hemoglobin level less than 10 g/dL. We report herein the impact on oxygen consumption of PRBC transfusions administered for a hemoglobin concentration less than 10 g/dL in 30 surgical intensive care unit patients who were euvolemic and hemodynamically stable. For the group as a whole, transfusion had a negligible effect on oxygen consumption. Fifty-eight percent of all such transfusions failed to change oxygen consumption by greater than 10% and could therefore be considered of questionable benefit.

Impact of gastric restrictive surgery on hypertension in the morbidly obese

Hypertension is a major health risk factor in patients who are morbidly obese. Two hundred eighty-nine morbidly obese patients undergoing gastric restrictive surgery were evaluated for the presence of hypertension (blood pressure greater than or equal to 160/90 mm Hg or currently undergoing antihypertensive therapy) pre- and postoperatively. Of 74 (26%) preoperatively hypertensive patients, 67 (91%) were available for follow-up. Preoperative hypertension resolved in 66% (44 of 67) of patients following gastric restrictive surgery. Superobese and morbidly obese patients had similar reductions in hypertension after surgery (69% versus 63%). Patients not receiving antihypertensives preoperatively had a greater reduction of hypertension than those medically treated preoperatively (78% versus 58%). The amount of weight loss significantly predicted the reduction of hypertension, whereas follow-up weight achieved did not. The amounts of weight loss for patients with resolved and persistent hypertension were 89.3 +/- 5.6 lbs (mean +/- standard error of the mean +ADSEM+BD) and 66.0 +/- 8.3 lbs, respectively (p less than 0.02). For patients with resolved hypertension, follow-up weights for the morbidly obese and superobese were 162.0 +/- 10.8 lbs (133% +/- 4% ideal body weight +ADIBW+BD) and 220.4 +/- 9.5 lbs (170% +/- 7% IBW). Gastric restrictive surgery is effective therapy for hypertension in morbidly obese patients. Patients need not achieve weights approaching IBW to enjoy the benefits of gastric restrictive surgery on hypertension.

Heart disease and hypertension in severe obesity: the benefits of weight reduction

Severe obesity is associated with abnormalities of cardiac structure and function. These include an increased cardiac workload and ventricular hypertrophy. Hypertension in combination with severe obesity seriously burdens the heart because the increased preload and afterload compound cardiac work. Weight reduction induced by gastric operations for severe obesity is associated with resolution of hypertension, reduction in ventricular wall thickness and cardiac chamber size, as well as improved systolic function. Additional data are needed to predict when in the course of development of obese cardiomyopathy the changes in contractile function become irreversible. Additionally, the impact of coronary artery disease on the progression of obese cardiomyopathy and the effects of surgical weight reduction on cardiac structure and function need to be further clarified. Studies of the association between obesity, its treatment, and modification of cardiovascular risk are a major focus of preventive cardiology today.

Left ventricular filling abnormalities in asymptomatic morbid obesity

Indexes of left ventricular (LV) diastolic filling were measured by pulse Doppler echocardiography in 16 asymptomatic morbidity obese patients presenting for bariatric surgery and were compared with an age- and sex-matched lean control population. No patient had concomitant disorders known to affect diastolic function. All patients had normal systolic function. LV wall thickness and internal dimension were measured in order to calculate LV mass. Fifty percent of morbidly obese patients had LV diastolic filling abnormalities as assessed by the presence of greater than or equal to 2 abnormal variables of mitral inflow velocity. The ratio of peak early to peak late (atrial) filling velocity was significantly decreased in obese compared with control patients (1.16 +/- 0.26 vs 1.66 +/- 0.30, p less than 0.001). The peak velocity of early LV diastolic filling was significantly reduced in obese patients (75 +/- 15 vs 98 +/- 19 cm/s, p less than 0.001). The atrial contribution to stroke velocity as assessed by the time-velocity integral of late compared with total LV diastolic filling was significantly increased in obese patients (36 +/- 7 vs 27 +/- 4%, p less than 0.001). Obese patients had significantly increased LV mass (214 +/- 45 vs 138 +/- 37 g, p less than 0.001), even when corrected for body surface area (95 +/- 16 vs 76 +/- 16 g/m2, p less than 0.002). However, increased LV mass did not correlate with indexes of abnormal diastolic filling in obese patients. These data suggest that abnormalities of diastolic function occur frequently in asymptomatic morbidly obese patients and may represent a subclinical form of cardiomyopathy in the obese patient.