Morbid obesity is an independent determinant of death among surgical critically ill patients

Bands and bypasses: 30-day morbidity and mortality of bariatric surgical procedures as assessed by prospective, multi-center, risk-adjusted ACS-NSQIP data

BACKGROUND

Previous multi-institution comparisons of open and laparoscopic Roux-en-Y gastric bypass (ORYGB and LRYGB), and laparoscopic adjustable gastric banding (LAGB) have been limited by the lack of unique current procedural terminology (CPT) codes. Specific codes have been available for LRYGB and LAGB since 2005 and 2006, respectively. We compare the short-term safety of these procedures, using risk-adjusted clinical data from a multi-institutional quality improvement program.

METHODS

The America College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) Participant Use File (PUF) was used to compare patients undergoing LRYGB with those undergoing ORYGB or LAGB.

RESULTS

ORYGB versus LRYGB: The 2-year study period (2005-2006) included 5,777 patients (ORYGB = 1,146, LRYGB = 4,631). Patients undergoing ORYGB experienced a higher 30-day incidence of mortality (0.79% vs. 0.17%; p = 0.002), major complications rate (7.42% vs. 3.37%; p < 0.0001), any complication rate (13.18% vs. 6.69%; p < 0.0001), return visits to the OR (4.97% vs. 3.56%; p = 0.032), and longer postoperative length of stay (LOS) (median 3 vs. 2 days; p < 0.0001). After risk adjustment, ORYGB continued to demonstrate higher odds of major complication (OR = 2.04; [1.54, 2.69]). LAGB versus LRYGB: Analysis of 1 year of data from 2006 included 4,756 patients (LRYGB = 3,580, LAGB = 1,176). Those treated with LAGB experienced an equivalent 30-day mortality (0.09% vs. 0.14%; p = 1.0), and a lower rate of major complications (1.0% vs. 3.3%; p < 0.0001), any complication (2.6% vs. 6.7%; p < 0.0001), return visits to the OR (0.94% vs. 3.6%; p < 0.0001), and shorter postoperative LOS (median 1 vs. 2 days; p < 0.0001). Risk adjustment showed that LAGB was associated with a lower major complication odds (OR = 0.29; [0.16, 0.53]).

CONCLUSIONS

Compared with LRYGB, ORYGB is associated with higher 30-day mortality and higher risk-adjusted major complication rate. While ORYGB may sometimes be indicated, a laparoscopic approach may be safer for RYGB when feasible. LAGB, compared with LRYGB, has a similarly low mortality rate and a small but statistically significant decrease in risk-adjusted 30-day complications. Clinical efficacy and long-term outcomes will need to be evaluated to determine superiority between these procedures.

The relationship between body mass index and postoperative mortality from critical illness

BACKGROUND

Conflicting data exist regarding the effect of body mass index (BMI) on postoperative mortality from critical illness. Few studies have examined this issue in surgical patients specifically. We tested the hypothesis that BMI is associated with mortality from surgical critical illness.

METHODS

Consecutive admissions to a university surgical intensive care unit (SICU) were analyzed from January 2005-August 2006. Admission BMI was analyzed as both a five-level categorical (underweight, <18.5 kg/m2; normal weight, 18.5-24.9 kg/m2; overweight, 25.0-29.9 kg/m2; obese, 30.0-39.9 kg/m2; morbidly obese, > or =40 kg/m2) and dichotomous (> or =40 kg/m2 vs. <40 kg/m2) variable among all patients as well as a subgroup of patients with a SICU length of stay (ULOS) > or =4 days. Multivariable logistic regression models were fit to determine the independent effect of BMI group on SICU mortality.

RESULTS

The total sample size was 946, with 490 patients admitted to the SICU for > or =4 days (51.8%). Of the variables tested, age, acute physiology and chronic health evaluation III score, gender, diabetes mellitus, and need for insulin infusion varied significantly among the five BMI groups. After adjustment for these variables, BMI was not predictive of mortality when analyzed as either a five-level categorical or dichotomous variable, regardless of ULOS.

CONCLUSION

BMI is not related to mortality of surgical critical illness. Several factors, including modern ICU care, may mitigate the risks of obesity in the SICU.

Influence of obesity on sepsis

Sepsis is the leading cause of death in non-coronary intensive care units worldwide, with a very high cost of care. There is a growing body of evidence suggesting that the increase in morbidity associated with severe obesity in critically ill patients results in increased resource utilization adding further to the cost of care. There is a relative paucity of information regarding the pathophysiology and treatment of obese critically ill patients, especially with sepsis. Obesity as an exclusion criterion in landmark trials is partly responsible for this paucity. While the preventive strategies for obesity will be the most definitive long-term solution, it will take a long time to affect outcomes in our intensive care units. In the meantime, our hospitals, including the intensive care units must continue to treat obese/morbidly obese critically ill patients with sepsis, making it essential to study and understand the pathophysiology and develop treatment strategies for obese with sepsis. Available laboratory data suggests an increased inflammatory response in obese septic individuals. However, the association between obesity and sepsis in the clinical setting is unclear due to controversial results. This article reviews the available clinical and laboratory data that addresses the effects of obesity on sepsis.

Higher body mass index predicts need for insulin but not hyperglycemia, nosocomial infection, or death in critically ill surgical patients

BACKGROUND

Strict glycemic control in critically ill patients has been an important advance in surgical critical care, as hyperglycemia is associated with a higher likelihood of death, complications, and nosocomial infections. Insulin resistance is particularly common in obese patients, but the impact of body mass index (BMI) on insulin requirements, ability to achieve euglycemia, and infectious outcomes in critically ill surgical patients has not been studied. We hypothesized that obese patients would not incur a higher likelihood of infection if euglycemia was maintained.

METHODS

Admissions to the surgical intensive care unit (ICU) from October 1, 2004, to October 31, 2006, were identified. Necessary data were available for 946 patients. The main predictor variable was BMI, which was analyzed as both a continuous and a five-level categorical variable. Data on insulin requirements as well as glycemic control were captured. The main outcome variable was the occurrence of at least one nosocomial infection. Additional outcomes were dysfunction of at least one organ system at any time during surgical ICU admission, quantified using the Multiple Organ Dysfunction Score, as well as the ICU length of stay and death. All statistical analyses were performing using SPSS version 11 for Macintosh.

RESULTS

Both the need for insulin infusion (p = 0.0001) and the mean insulin units/day among patients receiving infusions (p = 0.03) increased significantly with increasing BMI. However, periods of euglycemia were similar among BMI groups. A total of 152 patients (16.1%) incurred at least one nosocomial infection, for a total of 169 infections. The majority (n = 107; 63.3%) were ventilator-associated pneumonias. Neither infection (p = 0.99), organ dysfunction (p = 0.14), ICU length of stay (p = 0.22), nor mortality rate (p = 0.09) differed significantly by BMI group. The need for an insulin infusion was associated significantly with nosocomial infection (p = 0.0001). Additional predictors of infection were a higher Acute Physiology and Chronic Health Evaluation (APACHE) III score (p < 0.0001), age-adjusted APACHE III score (p < 0.0001), and emergency admission (0.001). After controlling for the need for an insulin infusion, BMI was not associated with infection.

CONCLUSIONS

Increasing BMI was associated significantly with insulin resistance. Despite insulin resistance, however, obese patients did not incur longer periods of hyperglycemia. Outcomes that have been associated consistently with glycemic control, such as nosocomial infection and mortality rate, did not differ according to BMI. These data suggest that BMI is not associated with infection during critical illness, and that this absence of an association may be influenced at least partially by the ability to maintain similar glycemic control in obese and non-obese patients.

Does body mass index affect infection-related outcomes in the intensive care unit?

BACKGROUND

Obesity is a worldwide healthcare concern, but its impact on critical care (intensive care unit; ICU) outcomes is not well understood. The general hypothesis is that obesity worsens ICU outcomes, but published reports fail to demonstrate this effect consistently. We hypothesized that increasing BMI would be an independent predictor of higher mortality rates in the surgical/trauma ICU.

METHODS

Data on patients with infections, defined by U.S. Centers for Disease Control and Prevention criteria, were collected prospectively from a single university surgical/trauma ICU. From 1996 to 2003, 807 such patients had measurable BMIs on admission to the ICU and were divided into underweight (<18.5 kg/m(2)), normal weight (18.5-24.9 kg/m(2)), overweight (25.0-29.9 kg/m(2)), obese (30.0-39.9 kg/m(2)), and morbidly obese (> or =40.0 kg/m(2)). The primary outcome was in-hospital death. Bivariate and multivariate analyses were performed.

RESULTS

In-hospital death was associated with increasing age, increasing average Acute Physiology and Chronic Health Evaluation (APACHE) II score, history of diabetes (p = 0.001), cardiac disease (p = 0.001), hypertension (p = 0.044), history of cerebrovascular disease (p = 0.021), renal insufficiency (p = 0.007), need for hemodialysis (p < 0.001), history of pulmonary disease (p = 0.012), requirement for mechanical ventilation while in the ICU (p = 0.107), history of malignant disease (p < 0.001), and history of liver disease (p < 0.001). The multivariate analysis selected age (odds ratio [OR] 1.03 per integer; confidence interval [CI] 1.0, 1.05), APACHE II score (OR 1.17 per integer; CI 1.12, 1.74), diabetes (OR 2.20; CI 1.32, 3.65), mechanical ventilation (OR 1.88; CI 1.21, 2.94), malignancy (OR 2.54; CI 1.43, 4.47), and liver disease (OR 5.01; CI 2.69, 9.32) as significant risk factors. When controlling for these variables, none of the BMI groups had an independent association with death compared with the normal weight group.

CONCLUSION

Contrary to the hypothesis, the data suggest no discernable independent association of increasing BMI with heightened mortality rate in the surgical/trauma ICU patient with infection.

Effect of obesity on intensive care morbidity and mortality: a meta-analysis

OBJECTIVE

To evaluate the effect of obesity on intensive care unit mortality, duration of mechanical ventilation, and intensive care unit length of stay among critically ill medical and surgical patients.

DESIGN

Meta-analysis of studies comparing outcomes in obese (body mass index of > or = 30 kg/m2) and nonobese (body mass index of < 30 kg/m2) critically ill patients in intensive care settings.

DATA SOURCE

MEDLINE, BIOSIS Previews, PubMed, Cochrane library, citation review of relevant primary and review articles, and contact with expert informants.

SETTING

Not applicable.

PATIENTS

A total of 62,045 critically ill subjects.

INTERVENTIONS

Descriptive and outcome data regarding intensive care unit mortality and morbidity were extracted by two independent reviewers, according to predetermined criteria. Data were analyzed using a random-effects model.

MEASUREMENTS AND MAIN RESULTS

Fourteen studies met inclusion criteria, with 15,347 obese patients representing 25% of the pooled study population. Data analysis revealed that obesity was not associated with an increased risk of intensive care unit mortality (relative risk, 1.00; 95% confidence interval, 0.86-1.16; p = .97). However, duration of mechanical ventilation and intensive care unit length of stay were significantly longer in the obese group by 1.48 days (95% confidence interval, 0.07-2.89; p = .04) and 1.08 days (95% confidence interval, 0.27-1.88; p = .009), respectively, compared with the nonobese group. In a subgroup analysis, an improved survival was observed in obese patients with body mass index ranging between 30 and 39.9 kg/m2 compared with nonobese patients (relative risk, 0.86; 95% confidence interval, 0.81-0.91; p < .001).

CONCLUSION

Obesity in critically ill patients is not associated with excess mortality but is significantly related to prolonged duration of mechanical ventilation and intensive care unit length of stay. Future studies should target this population for intervention studies to reduce their greater resource utilization.

Determination of reference ranges for transcutaneous oxygen and carbon dioxide tension and the oxygen challenge test in healthy and morbidly obese subjects

BACKGROUND

Transcutaneous monitoring of oxygen and carbon dioxide tension emerged decades ago as reliable, indirect measurements of arterial pressure of oxygen and carbon dioxide in neonates. Investigators have since found other valuable roles for this modality, particularly in critically ill adults. This investigation was undertaken to further characterize these measurements in normal and in obese adults, who are contributing to a rising proportion of intensive care unit admissions.

MATERIALS AND METHODS

Transcutaneous sensors were adjusted for barometric pressure and calibrated to reference gases. The following were measured: equilibration time; oxygen saturation; transcutaneous oxygen tension; and transcutaneous carbon dioxide tension on room air and after administering fraction of inspired oxygen of 1.0 for 5 min (Oxygen Challenge Test).

RESULTS

One hundred three healthy and 47 obese subjects were enrolled. Oxygen Challenge Test values were 131.5 +/- 57.4 and 171.6 +/- 65.9 mm Hg for obese and healthy subjects, respectively (P value <0.001). Smoking status, respiratory rate, and transcutaneous oxygen tension on room air best predicted the Oxygen Challenge Test response. A negative correlation was found between transcutaneous oxygen on room air and the Oxygen Challenge Test versus body mass index (P < 0.001).

CONCLUSIONS

Reference ranges were determined for transcutaneous oxygen and carbon dioxide tension and the Oxygen Challenge Test in obese and in normal, healthy subjects. Increasing body mass index was associated with a lower baseline transcutaneous oxygen tension, but it was not an independent predictor of the Oxygen Challenge Test response in multivariate analysis.

High mortality rate for patients requiring intensive care after surgical revision following bariatric surgery

BACKGROUND

To report the prognosis and management of patients reoperated for severe intraabdominal sepsis (IAS) after bariatric surgery (S0) and admitted to the surgical intensive care unit (ICU) for organ failure.

METHODS

A French observational study in a 12-bed adult surgical intensive care unit in a 1,200-bed teaching hospital with expertise in bariatric surgery. From January 2001 to August 2006, 27 morbidly obese patients (18 transferred from other institutions) developed severe postoperative IAS (within 45 days). Clinical signs, biochemical and radiologic findings, and treatment during the postoperative course after S0 were reviewed. Time to reoperation, characteristics of IAS, demographic data, and disease severity scores at ICU admission were recorded and their influence on prognosis was analyzed.

RESULTS

The presence of respiratory signs after S0 led to an incorrect diagnosis in more than 50% of the patients. Preoperative weight (body mass index [BMI] > 50 kg/m2) and multiple reoperations were associated with a poorer prognosis in the ICU. The ICU mortality rate was 33% and increased with the number of organ failures at reoperation.

CONCLUSION

During the initial postoperative course after bariatric surgery, physical examination of the abdomen is unreliable to identify surgical complications. The presence of respiratory signs should prompt abdominal investigations before the onset of organ failure. An urgent laparoscopy, as soon as abnormal clinical events are detected, is a valuable tool for early diagnosis and could shorten the delay in treatment.

Airway management in a 980-lb patient: use of the Aintree intubation catheter

We report a 22-year-old, 980-lb (445 kg) man with a body mass index of 163 kg/m(2), who needed intubation for tracheotomy surgery, as he was profoundly hypercarbic and reliant on a tight-fitting continuous positive airway pressure mask. Attempts at oral and nasal fiberoptic intubation during topical anesthesia were unsuccessful because of poor patient cooperation and epistaxis. Thus, after awake placement of a size 5 Laryngeal Mask Airway ProSeal LMA; (LMA North America, San Diego, CA), we induced anesthesia using sevoflurane. Then we placed an Aintree stylet (Cook Critical Care, Bloomington, IN) over a fiberoptic bronchoscope, and both were introduced through the LMA into the trachea. We then removed the fiberoptic bronchoscope followed by the LMA. A Parker size 7.5 endotracheal tube was then "railroaded" over the Aintree catheter into the trachea.

State of the Art Reviews: Relationship Between Diet/ Physical Activity and Health

Obesity and 4 of the leading causes of death—heart disease, cancer, stroke, and type 2 diabetes mellitus—are related to lifestyle. The combination of a healthy weight, prudent diet, and daily physical activity clearly plays a role in primary, secondary, and tertiary prevention of these and other chronic diseases. Because nearly 65% of the adult population is overweight or obese, weight loss and maintenance are central to this review article. Improved lipid profiles, blood pressure, insulin sensitivity, and euglycemia are associated with weight loss or a normal body weight; thus, maintaining a healthy weight is a universal recommendation for health. The methods for improving lifestyle described in the section on obesity include assessing nutritional status and stages of change of the client, setting realistic goals, eating a diet high in fruits and vegetables with low-fat sources of dairy and protein, and achieving appropriate physical activity levels. The importance of physicians discussing weight with clients and vice versa is stressed. The common features of lifestyle-related diseases make them amenable to similar lifestyle interventions.

Antimicrobial dosing considerations in obese adult patients

As obesity continues to increase in prevalence throughout the world, it becomes important to explore the effects that obesity has on antimicrobial disposition. Physiologic changes in obesity can alter both the volume of distribution and clearance of many commonly used antimicrobials. These changes often present challenges such as estimation of creatinine clearance to predict drug clearance. Although these physiologic changes are increasingly being characterized, few studies assessing alterations in tissue drug distribution and the effects of obesity on antimicrobial pharmacokinetics have been published. The available data are most plentiful for antibiotics that historically have included clinical therapeutic drug monitoring. These data suggest that dosing of vancomycin and aminoglycosides be based on total body weight and adjusted body weight, respectively. Obese patients may require larger doses of beta-lactams to achieve similar concentrations as those of patients who are not obese. Fluoroquinolone pharmacokinetics are variably altered by obesity, which prevents a uniform approach. Data on the pharmacokinetics of drugs that have activity against gram-positive organisms-quinupristin-dalfopristin, linezolid, and daptomycin-reveal that they are altered in the presence of obesity, but more data are needed to solidify dosing recommendations. Limited data are available on nonantibacterials. An understanding of the physiologic changes in obesity and the available literature on specific antibiotics is valuable in providing a framework for rational selection of dosages in this increasingly common population of obese patients.

Quantifying risk and benchmarking performance in the adult intensive care unit

Morbidity, mortality, and length-of-stay outcomes in patients receiving critical care are difficult to interpret unless they are risk-stratified for diagnosis, presenting severity of illness, and other patient characteristics. Acuity adjustment systems for adults include the Acute Physiology And Chronic Health Evaluation (APACHE), the Mortality Probability Model (MPM), and the Simplified Acute Physiology Score (SAPS). All have recently been updated and recalibrated to reflect contemporary results. Specialized scores are also available for patient subpopulations where general acuity scores have drawbacks. Demand for outcomes data is likely to grow with pay-for-performance initiatives as well as for routine clinical, prognostic, administrative, and research applications. It is important for clinicians to understand how these scores are derived and how they are properly applied to quantify patient severity of illness and benchmark intensive care unit performance.

Influence of morbid obesity on the single-dose pharmacokinetics of daptomycin

The present study characterized the single-dose pharmacokinetics of daptomycin dosed as 4 mg/kg of total body weight (TBW) in seven morbidly obese and seven age-, sex-, race-, and serum creatinine-matched healthy subjects. The glomerular filtration rate (GFR) was measured for both groups following a single bolus injection of [(125)I]sodium iothalamate. Noncompartmental analysis was used to determine the pharmacokinetic parameters, and these values were normalized against TBW, ideal body weight (IBW), and fat-free weight (FFW) for comparison of the two groups. All subjects enrolled in this study were female, and the mean (+/-standard deviation) body mass index was 46.2 +/- 5.5 kg/m(2) or 21.8 +/- 1.9 kg/m(2) for the morbidly obese or normal-weight group, respectively. The maximum plasma concentration and area under the concentration-time curve from dosing to 24 h were approximately 60% higher (P < 0.05) in the morbidly obese group than in the normal-weight group, and these were a function of the higher total dose received in the morbidly obese group. No differences in daptomycin volume of distribution (V), total clearance, renal clearance, or protein binding were noted between the two groups. Of TBW, FFW, or IBW, TBW provided the best correlation to V. In contrast, TBW overestimated GFR through creatinine clearance calculations using the Cockcroft-Gault equation. Use of IBW in the Cockcroft-Gault equation or use of the four-variable modification of diet in renal disease equation best estimated GFR in morbidly obese subjects. Further studies of daptomycin pharmacokinetics in morbidly obese patients with acute bacterial infections and impaired renal function are necessary to better predict appropriate dosage intervals.

Anesthetic management of the morbidly obese parturient

PURPOSE OF REVIEW

Regional analgesia for labor pain and general anesthesia for cesarean section in the morbidly obese parturient is associated with increased maternal and perinatal complications. The purpose of this review is to describe the anesthetic management of the morbidly obese parturient.

RECENT FINDINGS

Compared to the lean parturient, the morbidly obese parturient has an increased likelihood for initial failed epidural, subsequent epidural replacement, inadvertent dural puncture, and cesarean section with difficult intubation under emergent conditions.

SUMMARY

Early preoperative assessment, epidural insertion, and replacement for failed regional anesthesia/analgesia along with preparation for general anesthesia and difficult airway intubation is advocated to decrease potential complications in the morbidly obese parturient.

Body Mass Index and Outcomes in Critically Injured Blunt Trauma Patients: Weighing the Impact

BACKGROUND

The influence of increased body mass index (BMI) on morbidity and mortality in critically injured trauma patients has been studied, with conflicting results. The objective of this study was to investigate the relationship between stratified BMI and outcomes in blunt injured patients.

STUDY DESIGN

Consecutive adult trauma patients from July 2001 to November 2005 with Injury Severity Score (ISS) > or = 16 and blunt mechanism were evaluated using the National Trauma Registry of the American College of Surgeons. Demographics, injury severity, hospital course, complications, and mortality were compared among standard BMI strata. Logistic regression was used to determine odds ratios (OR) with 95% confidence intervals and evaluate BMI as an independent risk factor for morbidity and mortality. Statistical significance was set at p < 0.05.

RESULTS

The study group consisted of 1,543 patients. Controlling for age, gender, Injury Severity Score, and Revised Trauma Score, and using BMI 18.5 to 24.9 kg/m(2) as the reference category, morbid obesity (BMI> or =40 kg/m(2)) was associated with acute respiratory distress syndrome (OR 3.675, 95% CI, 1.237 to 10.916), acute respiratory failure (OR 2.793, 95% CI, 1.633 to 4.778), acute renal failure (OR 13.506, 2.388 to 76.385), multisystem organ failure (OR 2.639, 95% CI, 1.085 to 6.421), pneumonia (OR 2.487, 95% CI, 1.483 to 4.302), urinary tract infection (OR 2.332, 95% CI, 1.229 to 4.427), deep venous thrombosis (OR 4.112, 95% CI, 1.253 to 13.496), and decubitus ulcer (OR 2.841, 95% CI, 1.382 to 5.841). Morbid obesity was not associated with increased mortality (OR 0.810, 95% CI, 0.353 to 1.856).

CONCLUSIONS

This is the largest study to date evaluating the relationship between BMI and outcomes in critically injured trauma patients. Increasing BMI increases morbidity while having no proved influence on mortality.

Outcomes of morbidly obese patients requiring mechanical ventilation for acute respiratory failure*

OBJECTIVE

To examine the outcomes of morbidly obese patients with acute respiratory failure treated with mechanical ventilation.

DESIGN

Retrospective study.

SETTING

A 14-bed medical intensive care unit in an 800-bed university-based hospital.

PATIENTS

A total of 50 morbidly obese subjects with acute respiratory failure requiring ventilatory assistance.

INTERVENTIONS

None.

MEASUREMENTS

Arterial blood gas measurements, intubation rate, days of mechanical ventilation, intensive care unit length of stay, hospital length of stay, and mortality.

RESULTS

From January 1997 to December 2004, 50 morbidly obese patients with acute respiratory failure were treated with mechanical ventilation. Invasive mechanical ventilation was implemented in 17 patients with a mean body mass index of 53.2 +/- 12.2 kg/m2. A total of 33 patients were treated with noninvasive ventilation (NIV), of which 21 avoided intubation (NIV success) and 12 required intubation (NIV failure). Mean body mass index for the NIV success group was significantly less than for the NIV failure group (46.9 +/- 8.9 and 62.5 +/- 16.1 kg/m2, respectively, p = .001). Acute Physiology and Chronic Health Evaluation II scores were similar for patients treated with invasive and noninvasive ventilation. Significant improvements in pH and Paco2 were noted for the invasive mechanical ventilation and NIV success groups. No improvements in gas exchange were noted in the NIV failure group. Of patients treated with NIV, 36% required intubation. Hospital mortality for the invasive ventilation and NIV failure groups was increased.

CONCLUSION

The type of ventilatory assistance may influence clinical outcomes in morbidly obese patients with acute respiratory failure.

Surgical risk in patients with metabolic syndrome: focus on lipids and hypertension

The metabolic syndrome describes a clustering of risk factors that predispose individuals to cardiovascular disease and type 2 diabetes mellitus. Abdominal obesity is a key component of the metabolic syndrome, increasing the incidence of insulin resistance, vascular inflammation, dyslipidemia, and hypertension. Adipose tissue (now recognized as an endocrine organ) and its hormonal products appear to play a significant role in signaling organs throughout the body in the regulation of fat and glucose metabolism. These mechanisms are clearly involved in the development of cardiovascular and metabolic disease and may also lead to increased surgical risks. The components of the syndrome that are most likely to affect surgical patients are obesity, hypertension, and disorders of glucose metabolism. This article focuses on each of these risk factors, the effects on surgical patients, and strategies to improve outcomes in the perioperative period.

The role of body mass index and diabetes in the development of acute organ failure and subsequent mortality in an observational cohort

Introduction

Several studies have shown a correlation between body mass index (BMI) and both the development of critical illness and adverse outcomes in critically ill patients. The goal of our study was to examine this relationship prospectively with particular attention to the influence of concomitant diabetes mellitus (DM).

Methods

We analyzed data from 15,408 participants in the Atherosclerosis Risk in Communities (ARIC) study for this analysis. BMI and the presence of DM were defined at baseline. We defined 'acute organ failure' as those subjects who met a standard definition with diagnostic codes abstracted from hospitalization records. Outcomes assessed included the following: risk of the development of acute organ failure within three years of the baseline examination; in-hospital death while ill with acute organ failure; and death at three years among all subjects and among those with acute organ failure.

Results

At baseline, participants with a BMI of at least 30 were more likely than those in lower BMI categories to have DM (22.4% versus 7.9%, p < 0.01). Overall, BMI was not a significant predictor of developing acute organ failure. The risk for developing acute organ failure was increased among subjects with DM in comparison with those without DM (2.4% versus 0.7%, p < 0.01). Among subjects with organ failure, both in-hospital mortality (46.5% versus 12.2%, p < 0.01) and 3-year mortality (51.2% versus 21.1%, p < 0.01) was higher in subjects with DM.

Conclusion

Our findings suggest that obesity by itself is not a significant predictor of either acute organ failure or death during or after acute organ failure in this cohort. However, the presence of DM, which is related to obesity, is a strong predictor of both acute organ failure and death after acute organ failure.

The effect of obesity on 12-month survival following admission to intensive care: a prospective study

OBJECTIVE

Evaluate the effect of intensive care (ICU) admission body mass index (BMI) on 30-day and 12-month survival in critically ill patients and determine the impact of obesity on outcome.

DESIGN

Prospective, observational cohort study.

SETTING

Fourteen-bed medical and surgical ICU of a university-affiliated hospital.

PATIENTS

Four hundred and ninety-three adult patients.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

BMI (kg/m) was calculated from height (m) and measured weight (kg) within 4 hrs of ICU admission, using the PROMED weighing device, or premorbid weight (documented in the previous month) (BMImeasured). Follow-up was for >/=12 months post-ICU admission. Time to mortality outcome, censored at 30 and 365 days (12-months), was analyzed using a log-normal accelerated failure time regression model. Predictor variables were parameterized as time ratios (TR), where TR <1 is associated with decreased survival time and TR >1 is associated with prolonged survival time. Mean (sd) age and Acute Physiology and Chronic Health Evaluation II score were 62.3 (17.5) years and 20.7(8.4), respectively; 56.0% (285 of 493) of patients were male and 60.6% (299 of 493) medical. ICU admission weight and BMImeasured (available in 433 patients) were 79.1 (22.1) kg and 27.8 (7.0) kg/m, respectively. In 16.9% (73 of 433) of patients, weight was >/=100 kg, and in 29.8% (129 of 433), BMImeasured was >/=30 kg/m. Raw intensive care, 30-day, and 12-month mortality rates were 15.2% (66 of 433), 22.3% (95 of 433), and 37.3% (159 of 433), respectively. BMImeasured was a significant determinant of mortality at 30 days (TR 1.853, 95% confidence interval 1.053-3.260, p = .032) and 12 months (TR 1.034, 95% confidence interval 1.005-1.063, p = .019). The effect of BMI on 12-month mortality was linear, such that increasing BMI was associated with decreasing mortality.

CONCLUSIONS

ICU admission BMI was a determinant of short- to medium-term survival. Obesity was not associated with adverse outcomes and may be protective.

Recently published papers: dying Swans and other stories

The use of pulmonary artery catheters is under debate yet again. We look at two recent trials evaluating their impact on mortality. Our suspicions regarding obesity are proven and we also look at a simple, cost effective method of reducing ventilator-associated pneumonia. Finally, an intervention to improve the poor outcome associated with out-of hospital cardiac arrests is evaluated.