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

Clinical features and outcome of postoperative peritonitis following bariatric surgery

BACKGROUND

We assessed the clinical features and outcome of morbidly obese patients admitted to the intensive care unit (ICU) for management of postoperative peritonitis (POP) following bariatric surgery (BS).

METHODS

In a prospective, observational, surgical ICU cohort, we compared the clinical features, empiric antibiotic therapy, and prognosis of BS patients with those developing POP after conventional surgery (cPOP).

RESULTS

Overall, 49 BS patients were compared to 134 cPOP patients. BS patients were younger (45 ± 10 versus 63 ± 16 years; p < 0.0001), had lower rates of fatal underlying disease (39 vs. 64%; p = 0.002), and the same SOFA score at the time of reoperation (8 ± 4 vs 8 ± 3; p = 0.8) as the cPOP patients. BS patients had higher proportions of Gram-positive cocci (48 vs. 35 %; p = 0.007) and lower proportions of Gram-negative bacilli (33 vs. 44%; p = 0.03), anaerobes (4 vs. 10%; p = 0.04), and multidrug-resistant strains (20 vs. 40%; p = 0.01). Despite higher rates of adequate empiric antibiotic therapy (82 vs. 64%; p = 0.024) and high de-escalation rates (67% in BS cases and 51% in cPOP cases; p = 0.06), BS patients had similar reoperation rates (53 vs. 44%; p = 0.278) and similar mortality rates (24 vs. 32%; p = 0.32) to cPOP patients. In multivariate analysis, none of the risk factors for death were related to BS.

CONCLUSIONS

The severity of POP in BS patients resulted in high mortality rates, similar to the results observed in cPOP. Usual empiric antibiotic therapy protocols should be applied to target multidrug-resistant microorganisms, but de-escalation can be performed in most cases.

An empirical derivation of the optimal time interval for defining ICU readmissions

BACKGROUND

Intensive care unit (ICU) readmission rates are commonly viewed as indicators of ICU quality. However, definitions of ICU readmissions vary, and it is unknown which, if any, readmissions are associated with ICU quality.

OBJECTIVE

Empirically derive the optimal interval between ICU discharge and readmission for purposes of considering ICU readmission as an ICU quality indicator.

RESEARCH DESIGN

Retrospective cohort study.

SUBJECTS

A total of 214,692 patients discharged from 157 US ICUs participating in the Project IMPACT database, 2001-2008.

MEASURES

We graphically examined how patient characteristics and ICU discharge circumstances (eg, ICU census) were related to the odds of ICU readmissions as the allowable interval between ICU discharge and readmission was lengthened. We defined the optimal interval by identifying inflection points where these relationships changed significantly and permanently.

RESULTS

A total of 2242 patients (1.0%) were readmitted to the ICU within 24 hours; 9062 (4.2%) within 7 days. Patient characteristics exhibited stronger associations with readmissions after intervals >48-60 hours. By contrast, ICU discharge circumstances and ICU interventions (eg, mechanical ventilation) exhibited weaker relationships as intervals lengthened, with inflection points at 30-48 hours. Because of the predominance of afternoon readmissions regardless of time of discharge, using intervals defined by full calendar days rather than fixed numbers of hours produced more valid results.

DISCUSSION

It remains uncertain whether ICU readmission is a valid quality indicator. However, having established 2 full calendar days (not 48 h) after ICU discharge as the optimal interval for measuring ICU readmissions, this study will facilitate future research designed to determine its validity.

Risk factors and mortality after elective and emergent laparatomies for oncological procedures in 899 patients in the intensive care unit: a retrospective observational cohort study

Background

Abdominal surgeries for cancer are associated with postoperative complications and mortality. A view of the success of anaesthetic, surgical and critical care can be gained by analyzing factors associated with mortality in patients admitted to intensive care units (ICUs). The objective of this study was to identify the postoperative mortality rate and the causes of perioperative death in high-risk patients after abdominal surgery for cancer. A secondary objective was to explore possible risk factors for death in scheduled and emergency surgeries, with a view to finding guidance on preventable risk factors.

Methods

An observational study, in a 12-bed surgical ICU of a tertiary hospital. Patients admitted after abdominal surgery for cancer to the ICU for more than 24 hours’ care were included from January 1, 2008–December 31, 2009. Data were extracted from the minimum basic dataset. The main outcome considered was 90-day mortality.

Results

Of 899 patients included, 80 (8.9%) died. Seven died within 48 hours of surgery, 18 died between 2 and 7 days, and 55 died after 7 days. Non-survivors were older and had more respiratory comorbidity, chronic liver disease, metastasis, and underwent more palliative procedures. 112 patients underwent emergency surgery; mortality in these patients for resection surgery was 32.5%; in the 787 patients who underwent scheduled surgery, mortality was 4.7% for resection procedures. The estimated odds ratios (95% confidence interval) of preoperative patient factors in emergency surgery confirmed a negative association between survival and older age 0.96 (0.91–1), the presence of respiratory comorbidity 0.14 (0.02–0.77) and metastasis 0.18 (0.05–0.6). After scheduled surgery, survival was negatively associated with age 0.93 (0.90–0.96) and chronic liver disease 0.40 (0.17–0.91). Analysis of complications after emergency surgery also indicated a negative association with sepsis 0.03 (0.003–0.32), respiratory events 0.043 (0.011–0.17) and cardiac events 0.11 (0.027–0.45); after scheduled surgery, respiratory 0.03 (0.01–0.08) and cardiac 0.11 (0.02–0.45) events, renal failure 0.02 (0.006–0.14) and neurological events 0.06 (0.007–0.5).

Conclusions

As most deaths occurred after discharge from the ICU, postoperative sepsis, respiratory and cardiac events should be watched carefully on the ward.

Mineral malnutrition following bariatric surgery

Moderate/severe obesity is on the rise in the United States. Weight management includes bariatric surgery, which is effective and can alleviate morbidity and mortality from obesity-associated diseases. However, many individuals are dealing with nutritional complications. Risk factors include: 1) preoperative malnutrition (e.g., vitamin D, iron); 2) decreased food intake (due to reduced hunger and increased satiety, food intolerances, frequent vomiting); 3) inadequate nutrient supplementation (due to poor compliance with multivitamin/multimineral regimen, insufficient amounts of vitamins and/or minerals in supplements); 4) nutrient malabsorption; and 5) inadequate nutritional support (due to lack of follow-up, insufficient monitoring, difficulty in recognizing symptoms of deficiency). For some nutrients (e.g., protein, vitamin B-12, vitamin D), malnutrition issues are reasonably addressed through patient education, routine monitoring, and effective treatment strategies. However, there is little attention paid to other nutrients (e.g., zinc, copper), which if left untreated may have devastating consequences (e.g., hair loss, poor immunity, anemia, defects in neuro-muscular function). This review focuses on malnutrition in essential minerals, including calcium (and vitamin D), iron, zinc, and copper, which commonly occur following popular bariatric procedures. There will be emphasis on the complexities, including confounding factors, related to screening, recognition of symptoms, and, when available, current recommendations for treatment. There is an exceptionally high risk of malnutrition in adolescents and pregnant women and their fetuses, who may be vulnerable to problems in growth and development. More research is required to inform evidence-based recommendations for improving nutritional status following bariatric surgery and optimizing weight loss, metabolic, and nutritional outcomes.

The effect of obesity on outcomes in trauma patients: a meta-analysis

OBJECTIVE

This study aims to assess the effect of obesity on injury severity score (ISS), mortality and course of hospital stay among trauma patients.

METHOD

A systematic review of the literature was conducted by Internet search. Data were extracted from included studies and analysed using a random-effects model to compare outcomes in the obese (body mass index (BMI)≥30kgm(-2)) with the non-obese (BMI<30kgm(-2)) group.

RESULT

Eventually, 18 studies met our inclusion criteria with 7751 obese patients representing 17% of the pooled study population. The data revealed that obesity was associated with increased risk of mortality, longer stay in the intensive care unit and higher rates of complication. Additionally, obese patients seemed to have longer duration of mechanical ventilation and hospital length of stay but it did not reach statistical significance. No difference was observed in ISS between the two groups.

CONCLUSION

Evidence strongly supports the correlation of obesity with worse prognosis in trauma patients and further studies should target this kind of population for therapy and prevention.

The impact of obesity on sepsis mortality: a retrospective review

Background

Recent sepsis guidelines have focused on the early identification and risk stratification of patients on presentation. Obesity is associated with alterations in multiple inflammatory regulators similar to changes seen in sepsis, suggesting a potential interaction between the presence of obesity and the severity of illness in sepsis.

Methods

We performed a retrospective chart review of patients admitted with a primary billing diagnosis of sepsis at a single United States university hospital from 2007 to 2010. Seven hundred and ninety-two charts were identified meeting inclusion criteria. Obesity was defined as a body mass index (BMI) ≥ 30 kg/m². The data recorded included age, race, sex, vital signs, laboratory values, length of stay, comorbidities, weight, height, and survival to discharge. A modified APACHE II score was calculated to estimate disease severity. The primary outcome variable was inpatient mortality.

Results

Survivors had higher average BMI than nonsurvivors (27.6 vs. 26.3 kg/m2, p = 0.03) in unadjusted analysis. Severity of illness and comorbid conditions including cancer were similar across BMI categories. Increased incidence of diabetes mellitus type 2 was associated with increasing BMI (p < 0.01) and was associated with decreased mortality, with an odds ratio of 0.53 compared with nondiabetic patients. After adjusting for age, gender, race, severity of illness, length of stay, and comorbid conditions, the trend of decreased mortality for increased BMI was no longer statistically significant, however diabetes continued to be strongly protective (odds ratio 0.52, p = 0.03).

Conclusions

This retrospective analysis suggests obesity may be protective against mortality in septic inpatients. The protective effect of obesity may be dependent on diabetes, possibly through an unidentified hormonal intermediary. Further prospective studies are necessary to elaborate the specific mechanism of this protective effect.

Separating wheat from chaff: examining the obesity paradox in the critically ill

Obesity is an increasing burden globally. In the general population, the obese have an increased mortality risk. Regarding the critically ill, a growing body of literature supports the obesity paradox, the notion that obesity confers a protective effect in certain disease states. However, the paucity of methodologically sound trials prevents definitive interpretation and may obscure risks.

Body mass index is not associated with cytokine induction during experimental human endotoxemia

A higher body mass index (BMI) appears to be associated with lower mortality in critically ill patients, possibly explained by an altered innate immune response. However, the precise relationship between BMI and the innate immune response in humans in vivo is unknown. We investigated the relationship between BMI and the systemic cytokine response during experimental human endotoxemia. Endotoxemia was induced in 112 healthy male volunteers by intravenous administration of 2 ng/kg Escherichia coli endotoxin. Plasma concentrations of TNF-α, IL-6, IL-10 and IL-1RA were serially determined. The relationship between BMI and the cytokine response, as well as body temperature, was investigated. The BMIs of the participants ranged from 18.3 to 33.6 kg/m2, (median: 22.7 kg/m2). All participants showed a marked increase in plasma cytokine levels [median (interquartile range)] peak levels: TNF-α 509 (353–673) pg/ml; IL-6 757 (522–1098) pg/ml; IL-10 271 (159–401) pg/ml; IL-1RA 4882 (3927–6025) pg/ml; and an increase in body temperature [1.8(1.4–2.2)℃] during endotoxemia. No significant correlations were found between BMI and levels of any of the cytokines or body temperature. No relationship between BMI and the cytokine response was found in healthy volunteers subjected to experimental endotoxemia. These data question the relationship between BMI and cytokine responses in critical illness.

Impact of body mass index on clinical outcomes associated with percutaneous nephrolithotomy

INTRODUCTION

Percutaneous nephrolithotomy (PCNL) is the preferred treatment for patients with large renal calculi or stones that have not responded to extracorporeal shock wave lithotripsy (ESWL). The objective of this study was to compare outcomes and complications of PCNL in patients of various body mass indices (BMI) to determine the safety of this procedure in patients with elevated BMI.

METHODS

A retrospective chart review of 114 patients who underwent PCNL between 2006 and 2009 was performed. Patients were separated into 4 groups with respect to their BMI: (1) ideal body weight (BMI <25 kg/m(2)), (2) overweight (BMW 25-29 kg/m(2)), (3) obese (BMI 30-39 kg/m(2)) and (4) morbidly obese (BMI ≥40 kg/m(2)). One-way ANOVA and univariate logistic regression analysis were used to assess the association between BMI (classified into 4 levels) and variables including age, sex, stone size, length of stay, incidence of complications and stone-free rates.

RESULTS

The distribution of the 114 patients in each BMI category was: ideal body weight 39 (34%), overweight 24 (21%), obese 41 (36%), morbidly obese 10 (9%). There was no difference in the composition of groups with respect to age, sex, pharmacologically treated comorbidities or stone size. Mean length of stay in days, intra- and postoperative complication rates were not statistically different. Stone-free rates showed no significant difference between groups: 90% ideal body weight; 87% overweight; 90% obese; 80% morbidly obese (p = 0.83).

INTERPRETATION

Outcomes of PCNL were statistically independent of BMI. PCNL is a safe and efficacious treatment of stone disease in patients of all sizes.

Reporting the methodology of height and weight acquisition in studies of body mass index-based prognosis in critically ill patients

PURPOSE

Conflicting findings were reported on the body mass index (BMI)-based prognosis of critically patients. Errors in source weight and height data can confound BMI group allocation. The aim of the present work was to examine investigators' reporting on the methods of height and weight acquisition (HWA).

MATERIALS AND METHODS

PubMed and Embase databases were searched for studies describing BMI group-based risk of death in critically ill patients. Eligible studies were examined for reporting on (1) the use of measured and/or estimated HWA, (2) details of measuring devices, (3) device accuracy, and (4) methods of adjustment for acute and chronic fluid-related weight changes.

RESULTS

Thirty studies met the eligibility criteria, including 159,565 patients. No data were provided in 13 studies (52% of reported patients) on whether estimates or measurements were used for HWA. Measured HWA was used exclusively in 6 studies (3% of patients), and an unspecified combination of estimated and/or measured HWA was reported for the remainder. Only 1 study reported the specific devices used. None of the studies provided data on the bias and precision of measuring devices. Adjustment for chronic and/or acute fluid-related weight changes was addressed in 2 studies for each.

CONCLUSIONS

These findings demonstrate the prevalent risk for BMI group misallocation in the reviewed studies, which may confound BMI-based prognosis, raising concerns about the validity of reported BMI-related prognostic impact.

Endocrine, metabolic, and morphologic alterations of adipose tissue during critical illness

OBJECTIVE

Observational studies report lower mortality in obese than in lean critically ill patients, an association referred to as the "obesity paradox." This may suggest a possible protective role for adipose tissue during severe illness.

DATA SOURCES

Relevant publications were identified based on searches in PubMed and on secondary searches of their bibliographies.

DATA SYNTHESIS

The endocrine functions of adipose tissue might play a role in the adaptation to critical illness. In the acute phase of illness, the anti-inflammatory adiponectin is reduced, whereas proinflammatory cytokine expression in adipose tissue is up-regulated. In the prolonged phase of critical illness, both adiponectin and anti-inflammatory cytokine production are increasing. Studies on the proinflammatory adipokine leptin during critical illness are inconsistent, possibly due to confounders such as gender, body mass index, and feeding. Morphologically, adipose tissue of critically ill patients reveals an increased number of newly differentiated, smaller adipocytes. Accentuated macrophage accumulation showing a phenotypic switch to M2-type suggests an adaptive response to the microenvironment of severe illness. Functionally, adipose tissue of critically ill patients develops an increased ability to store glucose and triglycerides.

CONCLUSIONS

Endocrine, metabolic, and morphologic properties of adipose tissue change during critical illness. These alterations may suggest a possible adaptive, protective role in optimizing chances of survival. More research is needed to understand the exact role of adipose tissue in lean vs. obese critically ill patients, in order to understand how illness-associated alterations contribute to the obesity paradox.

Overcoming the learning curve of laparoscopic Roux-en-Y gastric bypass: a 12-year experience

BACKGROUND

Surgical treatment of morbid obesity with laparoscopic Roux-en-Y gastric bypass (LRYGB) is technically challenging and involves high-risk patients. In this study, the short-term outcome of LRYGB in a large population of patients has been evaluated, and morbimortality before and after overcoming the learning curve has been assessed. The objective of this study was to establish the learning curve for laparoscopic Roux-en-Y gastric bypass.

METHODS

This retrospective study involved 2281 patients submitted to LRYGB at São José do Avaí Hospital between August 1999 and December 2011. The parameters analyzed were operating time, rates of short-term postoperative complications, mortality, and conversion.

RESULTS

The study population was predominantly female (71.3%) and presented a mean age of 37.5 years and mean body mass index (BMI) of 45.15 kg/m(2). The average time in surgery was 119 minutes, and average hospital stay was 4.3 days. The incidence of postoperative complications (hemorrhage, fistula, and bowel obstruction) was 1.75%. The relative risk of complications diminished in line with the increased experience of the surgical team and tended to stabilize at<2.5% after the first 500 procedures. The mortality rate was .43%, and the main causes of death were pulmonary embolism and leaks (.14% each). The conversion rate was .17%.

CONCLUSION

Operating time and risks of adverse outcome were significantly reduced after a long learning curve of 500 consecutive procedures. The number of surgeries performed and the standardization of the laparoscopic technique used were the main factors contributing to the low rates of postoperative complications, mortality, and conversion.

Safety of bedside percutaneous tracheostomy in the critically ill: evaluation of more than 3,000 procedures

BACKGROUND

Bedside percutaneous dilational tracheostomy has been demonstrated to be equivalent to open tracheostomy. At our institution, percutaneous dilational tracheostomy without routine bronchoscopy is our preferred method. My colleagues and I hypothesized that our 10-year percutaneous dilational tracheostomy experience would demonstrate that the technique is safe with low complication rates, even in obese patient populations.

STUDY DESIGN

We conducted a retrospective review of all bedside percutaneous dilational tracheostomy performed by the Division of Trauma and Surgical Critical Care faculty from 2001 to 2011, excluding patients younger than 18 years of age. All major airway complications and procedure-related deaths were evaluated during the early (≤48 hours postprocedure), intermediate (in hospital), and late (after discharge) periods. Incidence of post-tracheostomy stenosis was also evaluated.

RESULTS

There were 3,162 percutaneous dilational tracheostomies performed during the study period. Mean body mass index was 28 (16% with body mass index ≥35), mean Injury Severity Score was 32, and mean APACHE II score was 19. Major airway complications occurred in 12 (0.38%) patients, accounting for 5 (0.16%) deaths. Early major complications included 3 airway losses and 1 bleeding event requiring formal exploration with procedure-related deaths occurring in 3 patients. Intermediate major complications included 2 tube occlusion/dislodgement events with 2 related deaths. Late complications included 5 (0.16%) cases of tracheal stenosis requiring intervention without associated deaths.

CONCLUSIONS

Bedside percutaneous dilational tracheostomy is safe across a broad critically ill patient population. The safety of this technique, even in the obese population, is demonstrated by its low complication rate. Routine bronchoscopic guidance is not necessary. Specially trained procedure nurse and process improvement programs contribute to the safety and efficacy of this procedure.

Body mass index and acute kidney injury in the acute respiratory distress syndrome

OBJECTIVES

Obesity is increasingly encountered in intensive care units but the relationship between obesity and acute kidney injury is unclear. We aimed to evaluate whether body mass index was associated with acute kidney injury in the acute respiratory distress syndrome and to examine the association between acute kidney injury and mortality in patients with and without obesity.

DESIGN

Retrospective study.

SETTING

Massachusetts General Hospital and Beth Israel Deaconess Medical Center.

PATIENTS

Seven hundred fifty-one patients with acute respiratory distress syndrome.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Acute kidney injury was defined as meeting the "Risk" category according to modified Risk, Injury, Failure, Loss, End-stage criteria based on creatinine and glomerular filtration rate because urine output was only available on the day of intensive care unit admission. Body mass index was calculated from height and weight at intensive care unit admission. The prevalence of acute kidney injury increased significantly with increasing weight (p = .01). The odds of acute kidney injury were twice in obese and severely obese patients compared to patients with normal body mass index, after adjusting for predictors of acute kidney injury (age, diabetes, Acute Physiology and Chronic Health Evaluation III, aspiration, vasopressor use, and thrombocytopenia [platelets ≤ 80,000/mm]). After adjusting for the same predictors, body mass index was significantly associated with acute kidney injury (odds ratio(adj) 1.20 per 5 kg/m increase in body mass index, 95% confidence interval 1.07-1.33). On multivariate analysis, acute kidney injury was associated with increased acute respiratory distress syndrome mortality (odds ratio(adj) 2.76, 95% confidence interval 1.72-4.42) whereas body mass index was associated with decreased mortality (odds ratio(adj) 0.81 per 5 kg/m increase in body mass index, 95% confidence interval 0.71-0.93) after adjusting for mortality predictors.

CONCLUSIONS

In acute respiratory distress syndrome patients, obesity is associated with increased development of acute kidney injury, which is not completely explained by severity of illness or shock. Although increased body mass index is associated with decreased mortality, acute kidney injury remained associated with higher mortality even after adjusting for body mass index.

Being overweight or obese is associated with decreased mortality in critically ill patients: a retrospective analysis of a large regional Italian multicenter cohort

PURPOSE

To describe the epidemiology of obesity in a large cohort of intensive care unit (ICU) patients and study its impact on outcomes.

METHODS

All 3902 patients admitted to one of 24 ICUs in the Piedmont region of Italy from April 3 to September 29, 2006, were included in this retrospective analysis of data from a prospective, multicenter study.

RESULTS

Mean body mass index (BMI) was 26.0 ± 5.4 kg/m(2): 32.8% of patients had a normal BMI, 2.6% were underweight, 45.1% overweight, 16.5% obese, and 2.9% morbidly obese. ICU mortality was significantly (P < .05) lower in overweight (18.8%) and obese (17.5%) patients than in those of normal BMI (22%). In multivariate logistic regression analysis, being overweight (OR = 0.73; 95%CI: 0.58-0.91, P = .007) or obese (OR = 0.62; 95%CI: 50.45-0.85, P = .003) was associated with a reduced risk of ICU death. Being morbidly obese was independently associated with an increased risk of death in elective surgery patients whereas being underweight was independently associated with an increased risk of death in patients admitted for short-term monitoring and after elective surgery.

CONCLUSIONS

In this cohort, overweight and obese patients had a reduced risk of ICU death. Being underweight or morbidly obese was associated with an increased risk of death in some subgroups of patients.

The effect of body mass index on the outcome of critically ill surgical patients

BACKGROUND

The incidence of obesity is rising, and an increasing number of obese patients are admitted to surgical intensive care units (SICUs). However, it is not clear whether obesity is an independent risk factor for increased morbidity and mortality in SICU patients. We examined the effect of obesity on morbidity and mortality in patients admitted to the SICU in this study.

METHOD

We reviewed prospectively acquired SICU data in normal and obese patients with an SICU length of stay >24 hours. Comparability of the groups was assessed using a χ(2) test or Fisher exact test, as appropriate, for categorical variables and analysis of variance (ANOVA) or the Kruskal-Wallis test, as appropriate, for continuous variables.

RESULTS

Of the 1792 consecutive patients evaluated, 711 had a normal body mass index (BMI), and 993 were either preobese or obese. There was no statistically significant difference across the 5 BMI groups with respect to any of the 3 comorbidity indices (Acute Physiology and Chronic Health Evaluation III [APACHE III], Simplified Acute Physiology Score, or Multiple Organ Dysfunction Score). There was no statistically significant difference in the intensive care unit (ICU) length of stay and hospital length of stay or time-to-ICU mortality (log-rank test P = .054) among the 5 BMI groups. A Cox regression analysis and backward elimination algorithm selected APACHE III to be the most important explanatory variable for survival time.

CONCLUSION

Obesity does not affect the mortality of patients admitted to the SICU. We conclude that obesity cannot be used as an independent predictive mortality outcome variable in patients admitted to the SICU.

[Guidelines for specialized nutritional and metabolic support in the critically ill-patient. Update. Consensus of the Spanish Society of Intensive Care Medicine and Coronary Units-Spanish Society of Parenteral and Enteral Nutrition (SEMICYUC-SENPE): obese patient]

As a response to metabolic stress, obese critically-ill patients have the same risk of nutritional deficiency as the non-obese and can develop protein-energy malnutrition with accelerated loss of muscle mass. The primary aim of nutritional support in these patients should be to minimize loss of lean mass and accurately evaluate energy expenditure. However, routinely-used formulae can overestimate calorie requirements if the patient's actual weight is used. Consequently, the use of adjusted or ideal weight is recommended with these formulae, although indirect calorimetry is the method of choice. Controversy surrounds the question of whether a strict nutritional support criterion, adjusted to the patient's requirements, should be applied or whether a certain degree of hyponutrition should be allowed. Current evidence suggested that hypocaloric nutrition can improve results, partly due to a lower rate of infectious complications and better control of hyperglycemia. Therefore, hypocaloric and hyperproteic nutrition, whether enteral or parenteral, should be standard practice in the nutritional support of critically-ill obese patients when not contraindicated. Widely accepted recommendations consist of no more than 60-70% of requirements or administration of 11-14 kcal/kg current body weight/day or 22-25 kcal/kg ideal weight/day, with 2-2.5 g/kg ideal weight/day of proteins. In a broad sense, hypocaloric-hyperprotein regimens can be considered specific to obese critically-ill patients, although the complications related to comorbidities in these patients may require other therapeutic possibilities to be considered, with specific nutrients for hyperglycemia, acute respiratory distress syndrome (ARDS) and sepsis. However, there are no prospective randomized trials with this type of nutrition in this specific population subgroup and the available data are drawn from the general population of critically-ill patients. Consequently, caution should be exercised when interpreting these data.

Impact of body weight and extreme obesity on the presentation, treatment, and in-hospital outcomes of 50,149 patients with ST-Segment elevation myocardial infarction results from the NCDR (National Cardiovascular Data Registry)

OBJECTIVES

The aim of this study was to assess the impact of extreme (class III) obesity (body mass index [BMI] ≥40 kg/m(2)) on care and outcomes in patients with ST-segment elevation myocardial infarction (STEMI).

BACKGROUND

Although its prevalence is increasing rapidly, little is known about the impact of extreme obesity on STEMI presentation, treatments, complication rates, and outcomes.

METHODS

The relationship between BMI and baseline characteristics, treatment patterns, and risk-adjusted in-hospital outcomes was quantified for 50,149 patients with STEMI from the National Cardiovascular Data Registry (NCDR) ACTION Registry-GWTG.

RESULTS

The proportions of patients with STEMI by BMI category were as follows: underweight (BMI <18.5 kg/m(2)) 1.6%, normal weight (18.5 kg/m(2) ≤BMI <25 kg/m(2)) 23.5%, overweight (25 kg/m(2) ≤BMI <30 kg/m(2)) 38.7%, class I obese (30 kg/m(2) ≤BMI <35 kg/m(2)) 22.4%, class II obese (35 kg/m(2) ≤BMI <40 kg/m(2)) 8.7%, and class III obese 5.1%. Extreme obesity was associated with younger age at STEMI presentation (median age 55 years for class III obese vs. 66 years for normal weight); a higher prevalence of diabetes, hypertension, and dyslipidemia; a lower prevalence of smoking; and less extensive coronary artery disease and higher left ventricular ejection fraction. Process-of-care measures were similar across BMI categories, including the extremely obese. Using class I obesity as the referent, risk-adjusted in-hospital mortality rates were significantly higher only for class III obese patients (adjusted odds ratio: 1.64; 95% confidence interval: 1.32 to 2.03).

CONCLUSIONS

Patients with extreme obesity present with STEMI at younger ages and have less extensive coronary artery disease, better left ventricular systolic function, and similar processes and quality of care. Despite these advantages, extreme obesity remains independently associated with higher in-hospital mortality.

Obesity is associated with neutrophil dysfunction and attenuation of murine acute lung injury

Although obesity is implicated in numerous health complications leading to increased mortality, the relationship between obesity and outcomes for critically ill patients appears paradoxical. Recent studies have reported better outcomes and lower levels of inflammatory cytokines in obese patients with acute lung injury (ALI)/acute respiratory distress syndrome, suggesting that obesity may ameliorate the effects of this disease. We investigated the effects of obesity in leptin-resistant db/db obese and diet-induced obese mice using an inhaled LPS model of ALI. Obesity-associated effects on neutrophil chemoattractant response were examined in bone marrow neutrophils using chemotaxis and adoptive transfer; neutrophil surface levels of chemokine receptor CXCR2 were determined by flow cytometry. Airspace neutrophilia, capillary leak, and plasma IL-6 were all decreased in obese relative to lean mice in established lung injury (24 h). No difference in airspace inflammatory cytokine levels was found between obese and lean mice in both obesity models during the early phase of neutrophil recruitment (2-6 h), but early airspace neutrophilia was reduced in db/db obese mice. Neutrophils from uninjured obese mice demonstrated diminished chemotaxis to the chemokine keratinocyte cytokine compared with lean control mice, and adoptive transfer of obese mouse neutrophils into injured lean mice revealed a defect in airspace migration of these cells. Possibly contributing to this defect, neutrophil CXCR2 expression was significantly lower in obese db/db mice, and a similar but nonsignificant decrease was seen in diet-induced obese mice. ALI is attenuated in obese mice, and this blunted response is in part attributable to an obesity-associated abnormal neutrophil chemoattractant response.

The relationship between body mass index and number of days spent in hospital in Scotland

In most countries in the Western world, more than 50% of adults are overweight or obese putting them at increased risk of hypertension, type 2 diabetes, coronary heart disease, stroke and other chronic disorders. It is not clear what impact increasing prevalence of over-weight and obesity has on hospital admissions. The objective of this study was to examine the relationship between body mass index (BMI) and number of days spent in hospital. The study was designed as a retrospective and prospective cohort study using nationally representative Health Survey data linked to NHS hospital admissions data. The study was set in Scotland. The participants were a nationally representative sample of 6968 (45%) men and 8700 (55%) women, of 16-74 years of age, living in private households whose BMI was recorded in the 1995 and 1998 Scottish Health Surveys. The outcome measure was the number of days spent in hospital between 1981 and 2004. The results showed that the proportion of participants in both normal weight (BMI 20-24.9 kg/m(2)) and over-weight (BMI 25-29.9 kg/m(2)) categories was 37%, with 21% in the obese (BMI ≥30 kg/m(2)) and 5% in the under-weight (BMI <20 kg/m(2)) categories. The median number of days spent in hospital between 1981 and 2004 was six. The odds ratios (95% confidence intervals) for spending above the median numbers of days in hospital adjusted for age, sex, socioeconomic status and behavioural factors (i.e. smoking, alcohol drinking and physical activity) were 1.29 (1.06-1.56) for the <20 kg/m(2) group, 1.00 (0.91-1.11) for the 25-29.9 kg/m(2) group and 1.24 (1.10-1.38) for the ≥30 kg/m(2) group compared with the 20-24.9 kg/m(2) group. In conclusion, extremes of BMI category identified at a single point in time are associated with spending above the median number of days in hospital over a 20-year period after adjusting for demographic, behavioural and socioeconomic exposures.

The epidemiology of intensive care unit readmissions in the United States

RATIONALE

The incidence of intensive care unit (ICU) readmissions across the United States is unknown.

OBJECTIVES

To determine incidence of ICU readmissions in United States hospitals, and describe the distribution of time between ICU discharges and readmissions.

METHODS

This retrospective cohort study used 196,202 patients in 156 medical and surgical ICUs in 106 community and academic hospitals participating in Project IMPACT from April 1, 2001, to December 31, 2007. We used mixed-effects logistic regression, adjusting for patient and hospital characteristics, to describe how ICU readmission rates differed across patient types, ICU models, and hospital types.

MEASUREMENTS AND MAIN RESULTS

Measurements consisted of 48- and 120-hour ICU readmission rates and time to readmission. A total of 3,905 patients (2%) were readmitted to the ICU within 48 hours, and 7,171 (3.7%) within 120 hours. In adjusted analysis, there was no difference in ICU readmissions across patient types or ICU models. Among medical patients, those in academic hospitals had higher odds of 48- and 120-hour readmission than patients in community hospitals without residents (1.51 [95% confidence interval, 1.12-2.02] and 1.63 [95% confidence interval, 1.24-2.16]). Median time to ICU readmission was 3.07 days (interquartile range, 1.27-6.58). Closed ICUs had the longest times to readmission (3.55 d [interquartile range, 1.42-7.50]).

CONCLUSIONS

Approximately 2% and 4% of ICU patients discharged to the ward are readmitted within 48 and 120 hours, within a median time of 3 days. Medical patients in academic hospitals are more likely to be readmitted than patients in community hospitals without residents. ICU readmission rates could be useful for policy makers and investigations into their causes and consequences.

The impact of comorbid [corrected] conditions on critical illness

OBJECTIVE

To review the current knowledge of common comorbidities in the intensive care unit, including diabetes mellitus, chronic obstructive pulmonary disease, cancer, end-stage renal disease, end-stage liver disease, HIV infection, and obesity, with specific attention to epidemiology, contribution to diseases and outcomes, and the impact on treatments in these patients.

DATA SOURCE

Review of the relevant medical literature for specific common comorbidities in the critically ill.

RESULTS

Critically ill patients are admitted to the intensive care unit for various reasons, and often the admission diagnosis is accompanied by a chronic comorbidity. Chronic comorbid conditions commonly seen in critically ill patients may influence the decision to provide intensive care unit care, decisions regarding types and intensity of intensive care unit treatment options, and outcomes. The presence of comorbid conditions may predispose patients to specific complications or forms of organ dysfunction. The impact of specific comorbidities varies among critically ill medical, surgical, and other populations, and outcomes associated with certain comorbidities have changed over time. Specifically, outcomes for patients with cancer and HIV have improved, likely related to advances in therapy. Overall, the negative impact of chronic comorbidity on survival in critical illness may be primarily influenced by the degree of organ dysfunction or the cumulative severity of multiple comorbidities.

CONCLUSION

Chronic comorbid conditions are common in critically ill patients. Both the acute illness and the chronic conditions influence prognosis and optimal care delivery for these patients, particularly for adverse outcomes and complications influenced by comorbidities. Further work is needed to fully determine the individual and combined impact of chronic comorbidities on intensive care unit outcomes.

The effect of obesity on adverse outcomes and metabolism in pediatric burn patients

Hypothesis

Obesity influences metabolism and increases the incidence of clinical complications and worsens outcomes in pediatric burn patients.

Design

Retrospective, single-center study.

Subjects

Five hundred ninety-two severely burned pediatric patients who had burns covering more than 30% of the total body surface area and who were treated between 2001 and 2008 were enrolled in this study. Patients were divided into ≥ 85th percentile (n = 277) and normal (n = 315) weight groups based on body mass index percentiles.

Results

Patients stratified below (normal) and ≥ 85^th percentile had similar age, gender distribution, and total burn size. No significant differences were detected in the incidence of sepsis (11% for obese vs. 10% for normal), the incidence of multiple organ failure (21% for obese and 16% for normal), or mortality (11% for obese vs. 8% for normal). Compared to the normal group, the ≥ 85^th percentile group had low levels of constitutive proteins (α2macroglobulin and Apolipoprotein A-1) (p < 0.05 for both) as well as high levels of triglycerides and the acute-phase protein, C-reactive protein (p < 0.05 for both) up to 60 days after injury. Patients ≥ 85^th percentile showed a significant higher loss of bone mineral density and lipolysis compared to normal individuals. Stepwise logistic regression analysis revealed that body mass index had a positive predictive value towards the maximum DENVER2 score, an index of organ failure (p < 0.001).

Conclusions

BMI ≥ 85^th percentile altered the post-burn acute phase and catabolic response but did not increase the incidence of sepsis, multiple organ failure, or mortality in pediatric burn patients. Our results suggest that impaired metabolism and an altered inflammatory response occurs already in patients starting at the 85th percentile BMI.

Nutritional support of the obese and critically ill obese patient

With the dramatic increase in the prevalence of obesity worldwide and in the United States, it is virtually certain that clinicians will be caring for bariatric and obese nonbariatric patients in increasing numbers. This patient population presents several difficulties from the medical and surgical management perspectives. In particular, nutrition of the bariatric patient and critically ill obese patient is challenging. A clear understanding of the nutritional assessment and unique management strategies available for the bariatric and the critically ill obese patient is essential to provide them with the safest and most effective care.

The effect of diabetes on mortality in critically ill patients: a systematic review and meta-analysis

Introduction

Critically ill patients with diabetes are at increased risk for the development of complications, but the impact of diabetes on mortality is unclear. We conducted a systematic review and meta-analysis to determine the effect of diabetes on mortality in critically ill patients, making a distinction between different ICU types.

Methods

We performed an electronic search of MEDLINE and Embase for studies published from May 2005 to May 2010 that reported the mortality of adult ICU patients. Two reviewers independently screened the resultant 3,220 publications for information regarding ICU, in-hospital or 30-day mortality of patients with or without diabetes. The number of deaths among patients with or without diabetes and/or mortality risk associated with diabetes was extracted. When only crude survival data were provided, odds ratios (ORs) and standard errors were calculated. Data were synthesized using inverse variance with ORs as the effect measure. A random effects model was used because of anticipated heterogeneity.

Results

We included 141 studies comprising 12,489,574 patients, including 2,705,624 deaths (21.7%). Of these patients, at least 2,327,178 (18.6%) had diabetes. Overall, no association between the presence of diabetes and mortality risk was found. Analysis by ICU type revealed a significant disadvantage for patients with diabetes for all mortality definitions when admitted to the surgical ICU (ICU mortality: OR [95% confidence interval] 1.48 [1.04 to 2.11]; in-hospital mortality: 1.59 [1.28 to 1.97]; 30-day mortality: 1.62 [1.13 to 2.34]). In medical and mixed ICUs, no effect of diabetes on all outcomes was found. Sensitivity analysis showed that the disadvantage in the diabetic surgical population was attributable to cardiac surgery patients (1.77 [1.45 to 2.16], P < 0.00001) and not to general surgery patients (1.21 [0.96 to 1.53], P = 0.11).

Conclusions

Our meta-analysis shows that diabetes is not associated with increased mortality risk in any ICU population except cardiac surgery patients.

Early versus late parenteral nutrition in critically ill adults

BACKGROUND

Controversy exists about the timing of the initiation of parenteral nutrition in critically ill adults in whom caloric targets cannot be met by enteral nutrition alone.

METHODS

In this randomized, multicenter trial, we compared early initiation of parenteral nutrition (European guidelines) with late initiation (American and Canadian guidelines) in adults in the intensive care unit (ICU) to supplement insufficient enteral nutrition. In 2312 patients, parenteral nutrition was initiated within 48 hours after ICU admission (early-initiation group), whereas in 2328 patients, parenteral nutrition was not initiated before day 8 (late-initiation group). A protocol for the early initiation of enteral nutrition was applied to both groups, and insulin was infused to achieve normoglycemia.

RESULTS

Patients in the late-initiation group had a relative increase of 6.3% in the likelihood of being discharged alive earlier from the ICU (hazard ratio, 1.06; 95% confidence interval [CI], 1.00 to 1.13; P=0.04) and from the hospital (hazard ratio, 1.06; 95% CI, 1.00 to 1.13; P=0.04), without evidence of decreased functional status at hospital discharge. Rates of death in the ICU and in the hospital and rates of survival at 90 days were similar in the two groups. Patients in the late-initiation group, as compared with the early-initiation group, had fewer ICU infections (22.8% vs. 26.2%, P=0.008) and a lower incidence of cholestasis (P<0.001). The late-initiation group had a relative reduction of 9.7% in the proportion of patients requiring more than 2 days of mechanical ventilation (P=0.006), a median reduction of 3 days in the duration of renal-replacement therapy (P=0.008), and a mean reduction in health care costs of €1,110 (about $1,600) (P=0.04).

CONCLUSIONS

Late initiation of parenteral nutrition was associated with faster recovery and fewer complications, as compared with early initiation. (Funded by the Methusalem program of the Flemish government and others; EPaNIC ClinicalTrials.gov number, NCT00512122.).

Extremes of weight centile are associated with increased risk of mortality in pediatric intensive care

Introduction

Although numerous studies have linked extremes of weight with poor outcome in adult intensive care patients, the effect of weight on intensive care outcome has not previously been reported in the pediatric population. The aim of this study was to investigate the relationship between admission weight centile and risk-adjusted mortality in pediatric intensive care patients.

Methods

Data were collected on 6337 consecutively admitted patients over an 8.5 year period in a 15 bed pediatric intensive care unit (ICU) located in a university-affiliated tertiary referral children's hospital. A weight centile variable was entered into a multivariate logistic regression model that included all other pediatric index of mortality (PIM-2) variables, in order to determine whether weight centile was an independent risk factor for mortality.

Results

Weight centile was associated with mortality in both univariate and multivariate analysis, with the lowest mortality being associated with weights on the 75^th centile and increasing symmetrically around this nadir. A transformed weight centile variable (absolute value of weight centile-75) was independently associated with mortality (odds ratio 1.02, P = 0.000) when entered into a multivariate logistic regression model that included the PIM-2 variables.

Conclusions

In this single-center cohort, weight centile was an independent risk factor for mortality in the ICU, with mortality increasing for patients at either end of the weight spectrum. These observations suggest that the accuracy of mortality prediction algorithms may be improved by inclusion of weight centile in the models. A prospective multicenter study should be undertaken to confirm our findings.

Impact of early parenteral nutrition completing enteral nutrition in adult critically ill patients (EPaNIC trial): a study protocol and statistical analysis plan for a randomized controlled trial

Background

For critically ill patients treated in intensive care units (ICU), two feeding strategies are currently being advocated, one by American/Canadian and the other by European expert guidelines. These guidelines differ particularly in the timing of initiating parenteral nutrition (PN) in patients for whom enteral nutrition (EN) does not reach caloric targets.

Methods/Design

The EPaNIC trial is an investigator-initiated, non-commercial, multi-center, randomized, controlled, clinical trial with a parallel group design. This study compares early (European guideline) versus late (American/Canadian guideline) initiation of PN when EN fails to reach a caloric target. In the early PN group, PN is initiated within 24-48 hours after ICU admission to complete early enteral nutrition (EN) up to a calculated nutritional target. In the late PN group, PN completing EN is initiated when the target is not reached on day 8. In both groups, the same early EN protocol is applied. The study is designed to compare clinical outcome (morbidity and mortality) in the 2 study arms as well as to address several mechanistical questions. We here describe the EPaNIC study protocol and the statistical analysis plan for the primary report of the clinical results.

Discussion

The study has been initiated as planned on august 01 2007. One interim analysis advised continuation of the trial. The study will be completed in February 2011.

Trial Registration

ClinicalTrials (NCT): NCT00512122

Glucose Metabolism, Not Obesity, Predicts Mortality in Critically Ill Surgical Patients

Our hypothesis was to determine if insulin resistance and hyperglycemia, rather than obesity, are predictive of mortality in the surgically critically ill. An observational study of an automated protocol in surgical and trauma intensive care units was performed. Two groups were created based on body mass index (BMI): Obese (OB) defined as BMI ≥ 30 (n = 338) and nonobese defined as BMI < 30 (n = 885). Euglycemia was maintained using an automated protocol using an adapting multiplier, which we used as our marker of stress insulin resistance. The primary outcome was hospital mortality. One thousand, two hundred and twenty-three patients met criteria with 73,225 glucose values. The OB group required more insulin (4.5 U/hr vs 3.2 U/hr, P ≤ 0.01) and had a higher mean multiplier (0.07 vs 0.06, P < 0.01) reflecting insulin resistance. There was no difference in mortality between OB and nonobese (11.6% vs 11.5%, P = 0.96). Logistic regression showed that insulin dose (odds ratio 0.864; 95% confidence interval 0.772-0.967, P = 0.01), and not BMI, was an independent predictor of survival in this population. Obesity is not an independent risk factor for mortality in the surgical critical care population. Insulin resistance and subsequent hyperglycemia are increased in obesity and are independent predictors of mortality.

Western diet enhances hepatic inflammation in mice exposed to cecal ligation and puncture

Background

Obese patients display an exaggerated morbidity during sepsis. Since consumption of a western-style diet (WD) is a major factor for obesity in the United States, the purpose of the present study was to examine the influence of chronic WD consumption on hepatic inflammation in mice made septic via cecal ligation and puncture (CLP). Feeding mice diets high in fat has been shown to enhance evidence of TLR signaling and this pathway also mediates the hepatic response to invading bacteria. Therefore, we hypothesized that the combined effects of sepsis and feeding WD on TRL-4 signaling would exacerbate hepatic inflammation. Male C57BL/6 mice were fed purified control diet (CD) or WD that was enriched in butter fat (34.4% of calories) for 3 weeks prior to CLP. Intravital microscopy was used to evaluate leukocyte adhesion in the hepatic microcirculation. To demonstrate the direct effect of saturated fatty acid on hepatocytes, C3A human hepatocytes were cultured in medium containing 100 μM palmitic acid (PA). Quantitative real-time PCR was used to assess mRNA expression of tumor necrosis factor-alpha (TNF-α, monocyte chemotactic protein-1 (MCP-1), intercellular adhesion molecule-1 (ICAM-1), toll-like receptor-4 (TLR-4) and interleukin-8 (IL-8).

Results

Feeding WD increased firm adhesion of leukocytes in the sinusoids and terminal hepatic venules by 8-fold six hours after CLP; the increase in platelet adhesion was similar to the response observed with leukocytes. Adhesion was accompanied by enhanced expression of TNF-α, MCP-1 and ICAM-1. Messenger RNA expression of TLR-4 was also exacerbated in the WD+CLP group. Exposure of C3A cells to PA up-regulated IL-8 and TLR-4 expression. In addition, PA stimulated the static adhesion of U937 monocytes to C3A cells, a phenomenon blocked by inclusion of an anti-TLR-4/MD2 antibody in the culture medium.

Conclusions

These findings indicate a link between obesity-enhanced susceptibility to sepsis and consumption of a western-style diet.

Intra-abdominal pressure and the morbidly obese patients: the effect of body mass index

BACKGROUND

Abdominal compartment syndrome and intra-abdominal hypertension cause morbidity and mortality. Body mass index (BMI) may affect intra-abdominal pressure (IAP). Knowledge of the baseline IAP in the obese and the effect of BMI are not clearly defined.

METHODS

IAPs were measured in 37 morbidly obese patients undergoing elective gastric bypass. Measurements were obtained via bladder pressure using a standard technique. IAP was measured after intubation (P1) and postoperatively after extubation (P2). Data collected included age, gender, BMI, previous surgeries, comorbidities, IAP, and laparoscopic versus open procedure.

RESULTS

Mean BMI was 47.7 kg/m (range, 37-71.8 kg/m), and mean age was 45 years (range, 32-64 years). P1 mean was 9.4 mm Hg +/- 0.6 mm Hg, and P2 mean was 10.0 mm Hg +/- 0.6 mm Hg. Laparoscopic versus open procedure was unrelated to postoperative IAP. Previous surgeries and comorbidities were unrelated to IAP. P1 increased as BMI increased. For each unit increase of BMI, IAP increased by 0.14 mm Hg +/- 0.07 mm Hg (p = 0.05). Higher BMI and age were independent predictors of increased P2, with IAP increased 0.23 mm Hg +/- 0.07 mm Hg for each unit BMI (p = 0.0015) and 0.20 mm Hg +/- 0.06 mm Hg for each year increase in age (p = 0.0014).

CONCLUSIONS

Baseline IAP in the obese is greater than normal weight population (0-6 mm Hg), but not in range of intra-abdominal hypertension (>12 mm Hg). Postoperative status is unrelated to IAP. Elevated BMI does impact IAP, but the incremental value is small. Markedly increased IAP should not be attributed solely to elevated BMI and should be recognized as a pathologic condition.

The association between body-mass index and patient outcome in septic shock: a retrospective cohort study

BACKGROUND

It is unknown whether body-mass index (BMI) and commonly defined BMI categories are associated with mortality in patients with septic shock.

METHODS

The database of a multidisciplinary intensive care unit (ICU) was retrospectively screened for adult patients with septic shock. BMI, demographic, clinical and laboratory variables together with outcome measures were collected in all patients. Subjects were categorized as follows: underweight, BMI < 18.5; normal weight, BMI 18.5-24.9; overweight, BMI 25-29.9; obesity, BMI >or= 30. Bivariate and multivariate logistic regression models were used to evaluate the association between BMI and outcome parameters.

RESULTS

In total, 301 patients with septic shock were identified. BMI was bivariately associated with ICU mortality (OR 0.91; 95% CI 0.86-0.98; P = 0.007). There was no significant association between BMI and ICU mortality in the multivariate model but an increasing BMI tended to be associated with lower ICU mortality (OR 0.93; 95% CI 0.86-1.01; P = 0.09). Although overweight (OR 0.43; 95% CI 0.19-0.98; P = 0.04) and obese (OR 0.28; 95% CI 0.08-0.93; P = 0.04) patients had an independently lower risk of ICU death than those with normal weight, there was no difference in the risk of ICU death between normal weight and underweight patients (P = 0.22). A high BMI was independently associated with a lower frequency of acute delirium (P = 0.04) and a lower need for ICU re-admission (P = 0.001) but with a higher rate of ICU-acquired urinary tract infections (P = 0.02).

CONCLUSIONS

BMI up to 50 does not appear to be associated with worse ICU and hospital mortality in patients with septic shock. In contrast, a high BMI may reduce the risk of death from septic shock.

Alterations in adipose tissue during critical illness: An adaptive and protective response?

RATIONALE

Critical illness is characterized by lean tissue wasting, whereas adipose tissue is preserved. Overweight and obese critically ill patients may have a lower risk of death than lean patients, suggestive of a protective role for adipose tissue during illness.

OBJECTIVES

To investigate whether adipose tissue could protectively respond to critical illness by storing potentially toxic metabolites, such as excess circulating glucose and triglycerides.

METHODS

We studied adipose tissue morphology and metabolic activity markers in postmortem biopsies of 61 critically ill patients and 20 matched control subjects. Adipose morphology was also studied in in vivo biopsies of 27 patients and in a rabbit model of critical illness (n = 22).

MEASUREMENTS AND MAIN RESULTS

Adipose tissue from critically ill patients revealed a higher number and a smaller size of adipocytes and increased preadipocyte marker levels as compared with control subjects. Virtually all adipose biopsies from critically ill patients displayed positive macrophage staining. The animal model demonstrated similar changes. Glucose transporter levels and glucose content were increased. Glucokinase expression was up-regulated, whereas glycogen and glucose-6-phosphate levels were low. Acetyl CoA carboxylase protein and fatty acid synthase activity were increased. Hormone-sensitive lipase activity was not altered, whereas lipoprotein lipase activity was increased. A substantially increased AMP-activated protein kinase activity may play a crucial role.

CONCLUSIONS

Postmortem adipose tissue biopsies from critically ill patients displayed a larger number of small adipocytes in response to critical illness, revealing an increased ability to take up circulating glucose and triglycerides. Similar morphologic changes were present in vivo. Such changes may render adipose tissue biologically active as a functional storage depot for potentially toxic metabolites, thereby contributing to survival.

A discussion of airway and respiratory complications along with general considerations in obese patients

Obesity is defined as the degree of excess weight associated with adverse health consequences. Within Great Britain, it is reported that a quarter of men and women are obese; these rates have trebled over the past 20 years. In 2001, it was estimated that obesity cost the National Health Service at least half a billion pounds, with a further two billion pounds lost on lower productivity and lost output. Obesity poses a significant risk factor for diseases, such as coronary heart disease, diabetes mellitus and certain forms of cancer, amongst others. Obese individuals pose significant problems to the clinician because of airway and respiratory complications. Sleep apnoea, obesity-hypoventilation syndrome, pulmonary atelectasis are associated with obesity and tracheostomy insertion is made all the more difficult in these patients. This article aims to discuss some of these issues relevant to the clinician and examine present strategies for dealing with them.

The impact of obesity on outcomes after critical illness: a meta-analysis

PURPOSE

To assess whether obesity is associated with mortality or other adverse intensive care unit (ICU) and post-ICU outcomes.

METHODS

A meta-analysis of studies from PubMed and EMBASE databases.

RESULTS

Twenty-two studies (n = 88,051 patients) were included. Pooled analysis demonstrated no difference in ICU mortality, but lower hospital mortality for obese and morbidly obese subjects (RR 0.76; 95% CI 0.59, 0.92; RR 0.83; 95% CI 0.66, 1.04, respectively) versus normal weight subjects. There was no association between obesity and duration of mechanical ventilation or ICU stay. Morbidly obese versus normal weight patients had longer hospitalizations. No study reported physical function, mental health, or quality of life outcomes after discharge.

CONCLUSIONS

Obesity is not associated with increased risk for ICU mortality, but may be associated with lower hospital mortality. There is a critical lack of research on how obesity may affect complications of critical illness and patient long-term outcomes.

Outcome prediction in critical care: the Acute Physiology and Chronic Health Evaluation models

PURPOSE OF REVIEW

A new generation of predictive models for critically ill patients was described between 2005 and 2008. This review will give details of the latest version of the Acute Physiology and Chronic Health Evaluation (APACHE) predictive models, and discuss it in relation to recent critical care outcome studies. We also compare APACHE IV with other systems and address the issue of model complexity.

RECENT FINDINGS

APACHE IV required the remodeling of over 40 equations. These new models calibrate better to contemporary data than older versions of APACHE and there is good predictive accuracy within diagnostic subgroups. Physiology accounts for 66% and diagnosis for 17% of the APACHE IV mortality model's predictive power. Thus, physiology and diagnosis account for 83% of the accuracy of APACHE IV.

SUMMARY

Predictive models have a modest window of applicability, and therefore must be revalidated frequently. This was shown to be true for APACHE III, and hence a major reestimation of models was carried out to generate APACHE IV. Although overall model accuracy is important, it is also imperative that predictive models work well within diagnostic subgroups.

[Operative management and fracture care of the lower leg with the Ilizarov fixator in morbidly obese patients: literature review and results]

Given the rising prevalence of obesity, surgeons and hospitals must become more familiar with the treatment and operative management of obese patients. Several additional pre- and postoperative considerations must be involved such as appropriate assessment of comorbidities and requirements for special equipment. There are still very few data regarding morbidly obese patients with BMIs >50 kg/m(2). After a general literature review of operative management of obese patients, we report on fracture care of the lower limb in such patients with custom-made Ilizarov ring fixators. We found them suited to bear enormous weight-loading but that associated comborbidities can limit successful fracture care.