The effect of body mass index on patient outcomes in a medical ICU

High PEEP extubation as guided by esophageal manometry

The ventilatory management of morbidly obese patients presents an ongoing challenge in the Intensive Care Unit (ICU) as multiple physiologic changes in the respiratory system complicate weaning efforts and make extubation more difficult, often leading to increased time on the ventilator. We report the case of a young adult male who presented to our ICU on two separate occasions with hypoxemic respiratory failure requiring intubation. Esophageal manometry (EM) guided positive end expiratory pressure (PEEP) titration was utilized during both ICU admissions to improve oxygenation and aid in extubation with spontaneous breathing trials performed on higher-than-normal PEEP settings and successful liberation on both occasions.

Body mass index as a predictor of the outcomes of acute clozapine toxicity: a cross-sectional study

Acute antipsychotic overdose is frequently reported nowadays. Clozapine is one of the atypical agents that are highly lipophilic, highly protein-bound, has a large volume of distribution, and accumulates in the brain and other tissues. Obesity is an essential factor controlling patients' treatment and clinical course. The current study aimed to study the prognostic value of body mass index (BMI) in patients with acute clozapine poisoning. All patients were evaluated on admission using the Poison Severity Score (PSS) and Glasgow Coma Score (GCS). The BMI was calculated. Mortality and the need for ICU admission were defined as primary outcomes, whereas secondary outcomes included cardiovascular complications and the need for mechanical ventilation. Thirty-eight patients presented with acute clozapine poisoning. The mean age of included patients was 25.2 ± 6. Patients were categorized regarding BMI into average weight (26.3%), overweight (31.6%), and obese (42.1%). Pearson's correlation indicated a significant positive correlation between BMI and respiratory rate (r = .364, p = .025). A significant negative correlation existed between BMI and GCS (r = .674, p ≤ .001). ROC curve reveals that BMI is an excellent predictor for the requirement of mechanical ventilation area under the curve (AUC > .9), a fair predictor of ICU admission AUC (.747). BMI had a sensitivity of 100% and specificity of 51.7 for the prediction of ICU admission. In conclusion, obesity increased the severity of toxicity and the incidence of poor clinical outcomes in patients with acute clozapine poisoning.

Adequacy of prescribed caloric and protein intake and reduction of mortality in critically ill patients with body mass indices <30 kg/m2

OBJECTIVE

Although the provision of nutrition helps minimize adverse outcomes in most patients in intensive care units (ICUs), little is known about the relative effect of energy and protein delivered on mortality in ICU patients with different ranges of body mass index (BMI). The aim of this study was to examine the relationships between adequacy of dietary energy and protein intakes separately and simultaneously, and short-term mortality in medical ICU patients across four BMI categories.

METHODS

We enrolled 1693 patients admitted to a medical center ICU in Taiwan during the period of 2005 to 2011, subcategorizing them by BMI levels: <18.5(n = 418), 18.5-24.9 (n = 889), 25-29.9 (n = 289), and ≥30 kg/m² (n = 97). Dietary energy and protein intake (DEI and DPI) were defined by the percent of prescribed dosages that each patient actually received: highly adequate (>80%), moderately adequate (60-80%), and inadequate (<60%), during the first 10 d in the ICU.

RESULTS

Mean DEI was 1237 kcal/d and DPI 47 g protein/d. Analyzed separately in our multiple regression models, moderately and highly adequate DEI (P_trends = 0.003-0.026) and DPI (P_trends = 0.001-0.004) were both significantly correlated with reduced mortality in patients with BMI <18.5, 18.5-24.9, and 25-29.9 kg/m² but not in those with BMI levels ≥30 kg/m². With DEI and DPI analyzed simultaneously, only APACHE II scores and DPI levels remained significantly related to reduced mortality in patients with BMI <30 kg/m².

CONCLUSION

Although the adequacy of delivery of prescribed DEI or DPI dosages appeared to be important for reduced risks for mortality in ICU patients with BMI <30 kg/m² when analyzed separately, DPI had a stronger effect on decreases in ICU mortality when the two were analyzed simultaneously. Further investigation may be needed to study the role of increased protein in improving clinical outcomes.

Association between comorbid sleep apnoea-hypopnoea syndrome and prognosis of intensive care patients: a retrospective cohort study

OBJECTIVE

In this study, we investigated the association between comorbid sleep apnoea-hypopnoea syndrome (SAHS) and the prognosis of patients in an intensive care unit (ICU) to determine whether this relationship varies between different disease subgroups.

METHODS

We conducted a retrospective cohort study using publicly available information from the critical care database Medical Information Mart for Intensive Care III. Adults (≥18 years of age) who attended the ICU for the first time were enrolled. Demographic information and clinical data were obtained from each patient. The primary outcome was 30-day mortality after ICU admission, and the secondary outcomes were in-hospital and ICU mortality. Multivariate logistic regression and Cox regression analyses were used to examine the associations between SAHS comorbidities and the research outcomes. Propensity score matching was used to adjust for potential confounding variables.

RESULTS

Of the 32 989 patients enrolled, 1918 (5.81%) were diagnosed with SAHS as a comorbid condition. Patients with SAHS had a significantly lower 30-day mortality rate compared with those without SAHS (5.27% vs 13.65%, respectively; p<0.001). The frequency of chronic obstructive pulmonary disease, cerebral disease, cardiovascular disease, hypertension, diabetes mellitus and renal failure was significantly different between the two groups. Patients with SAHS demonstrated significantly longer survival compared with patients without SAHS. Multivariate Cox proportional hazards regression identified a significant relationship between SAHS and mortality within 30 days (adjusted HR=0.610, 95% CI 0.499 to 0.747, p<0.0001).

CONCLUSION

SAHS as a comorbid condition decreases the risk of 30-day mortality, in-hospital mortality and ICU mortality among ICU patients.

Obesity and Overweight Are Independently Associated with Greater Survival in Critically Ill Diabetic Patients: A Retrospective Cohort Study

BACKGROUND

The relationship between obesity and the outcomes of critically ill diabetic patients is not completely clear. We aimed to assess the effects of obesity and overweight on the outcomes among diabetic patients in the intensive care unit (ICU).

METHODS

Critically ill diabetic patients in the ICU were classified into three groups according to their body mass index. The primary outcomes were 30-day and 90-day mortality. ICU and hospital length of stay (LOS) and incidence and duration of mechanical ventilation were also assessed. Cox regression models were developed to evaluate the relationship between obesity and overweight and mortality.

RESULTS

A total of 6108 eligible patients were included. The 30-day and 90-day mortality in the normal weight group were approximately 1.8 times and 1.5 times higher than in the obesity group and overweight group, respectively (P < 0.001, respectively). Meanwhile, the ICU (median (IQ): 2.9 (1.7, 5.3) vs. 2.7 (1.6, 4.8) vs. 2.8 (1.8, 5.0)) and hospital (median (IQ): 8.3 (5.4, 14.0) vs. 7.9 (5.1, 13.0) vs. 8.3 (5.3, 13.6)) LOS in the obesity group and overweight group were not longer than in the normal weight group. Compared with normal weight patients, obese patients had significantly higher incidence of mechanical ventilation (58.8% vs. 64.7%, P < 0.001) but no longer ventilation duration (median (IQ): 19.3 (7.0, 73.1) vs. 19.0 (6.0, 93.7), P = 1). Multivariate Cox regression showed that obese and overweight patients had lower 30-day (HR (95% CI): 0.62 (0.51, 0.75); 0.76 (0.62, 0.92), respectively) and 90-day (HR (95% CI): 0.60 (0.51, 0.70); 0.79 (0.67, 0.93), respectively) mortality risks than normal weight patients.

CONCLUSIONS

Obesity and overweight were independently associated with greater survival in critically ill diabetic patients, without increasing the ICU and hospital LOS. Large multicenter prospective studies are needed to confirm our findings and the underlying mechanisms warrant further investigation.

Relationship between nutritional status on admission to the intensive care unit and clinical outcomes

AIM

To determine the prevalence of malnutrition on admission to the intensive care unit (ICU) and the relationship between nutritional status on admission and clinical outcomes in adult critically ill patients.

METHODS

This was a prospective study in an adult ICU. Patients with expected length of stay (LOS) >48 hours in ICU were assessed for nutritional status using the patient generated-subjective global assessment (PG-SGA) within 48 hours of admission to ICU.

RESULTS

Primary outcomes were ICU and hospital mortality, ICU and hospital LOS and length of mechanical ventilation. A total of 166 patients were enrolled in this study. Patients were aged 59 ± 17 years on average with a mean BMI of 29 ± 7 kg/m² and a mean Acute Physiology and Chronic Health Evaluation II score of 19 ± 7. The prevalence of malnutrition in critically ill patients was 36% (n = 60). Mortality rate of malnourished patients was 9% (n = 15) compared to 7.8% (n = 13) in well-nourished patients (adjusted odds ratio, 2.17; 95% confidence interval, 0.9-5.03, P = .069). There was no difference in hospital mortality between malnourished patients and well-nourished patients (10.2% vs 10.2% adjusted odds ratio, 1.93; 95% confidence interval, 0.89-4.19, P = .096). There was no relationship between nutritional status and length of mechanical ventilation (3.0 vs 1.0 days, P = .382)or ICU LOS (4.7 vs 4.8 days, P = .59). Malnourished patients had a longer LOS in hospital than well-nourished patients (24 vs 17 days, P = .03).

CONCLUSION

Malnutrition is an independent risk factor for increased hospital LOS.

Is There an Obesity Paradox in Critical Illness? Epidemiologic and Metabolic Considerations

PURPOSE OF REVIEW

Obesity represents a global epidemic with serious implications in public health due to its increasing prevalence and its known association with a high morbidity and mortality burden. However, a growing number of data support a survival benefit of obesity in critical illness. This review summarizes current evidence regarding the obesity paradox in critical illness, discusses methodological issues and metabolic implications, and presents potential pathophysiologic mechanisms.

RECENT FINDINGS

Data from meta-analyses and recent studies corroborate the obesity-related survival benefit in critically ill patients as well as in selected populations such as patients with sepsis and acute respiratory distress syndrome, but not trauma. However, this finding warrants a cautious interpretation due to certain methodological limitations of these studies, such as the retrospective design, possible selection bias, the use of BMI as an obesity index, and inadequate adjustment for confounding variables. Main pathophysiologic mechanisms related to obesity that could explain this phenomenon include higher energy reserves, inflammatory preconditioning, anti-inflammatory immune profile, endotoxin neutralization, adrenal steroid synthesis, renin-angiotensin system activation, cardioprotective metabolic effects, and prevention of muscle wasting. The survival benefit of obesity in critical illness is supported from large meta-analyses and recent studies. Due to important methodological limitations, more prospective studies are needed to further elucidate this finding, while future research should focus on the pathophysiologic role of adipose tissue in critical illness.

Dose-Response Meta-Analysis of the Impact of Body Mass Index on Mortality in the Intensive Care Unit

INTRODUCTION

Both low and high body mass index (BMI) are associated with mortality in the intensive care unit (ICU). Although many studies have been done to determine the relationship between BMI and risk of mortality in the ICU, their results were inconsistent. This study aimed to conduct a dose-response meta-analysis of published observational studies to assess the effect of BMI on the risk of mortality in patients admitted to the ICU.

METHODS

PubMed, Scopus, and Google Scholar were searched to identify articles up to May 2019. A total of 31 relevant articles, with 238,961 patients and a follow-up period of 1 month to 11 years, were analyzed.

RESULTS

Linear analysis showed a 0.6% decrease in mortality rate per unit (kg/m² ) increase in BMI (odds ratio: 0.99; 95% CI, 0.98-0.99). In addition, nonlinear analysis showed a decrease in risk of mortality for a BMI of 35 (P < .001) and then increased the risk of mortality with a BMI > 35 (P < .001).

CONCLUSION

This dose-response meta-analysis revealed that a BMI ≤ 35 can be a protective agent against mortality, but a BMI > 35 is a life-threatening factor in patients admitted to the ICU.

Searching for the Best Way to Assess the Risk of Thrombosis in Aesthetic Plastic Surgery; The Role of the Caprini/Pannucci Score

INTRODUCTION

There is concern regarding the high incidence of thrombosis in plastic surgery patients. For this reason, we wanted to compare the results of the Caprini/Pannucci score in patients with and without a past history of thrombosis admitted for aesthetic plastic surgery.

METHODS

This was a case-control study of 152 patients undergoing aesthetic plastic surgery procedures. We formed two groups: Group I had 70 patients who had thrombosis after aesthetic plastic surgery and group II had 82 patients without thrombosis. We studied the considered risk factors for thrombosis. We weighted the factors according to the OR and linear regressions. We then related them to the Caprini/Pannucci score.

RESULTS

Patients in group I had a score of 5.68 versus 3.45 in group II (p < 0.001). There was a 9.86% increase in thrombosis for each increased point in the rating. A higher effectiveness of the Caprini score was found in the high-score group; the greatest flaw was in the low-scoring group. The sensitivity was 75.71%, and the specificity was 70.73%. The factors with the greatest impact were the infiltration of fat in the buttocks, degree of obesity and time of surgery. There was an increased risk of thrombosis in patients with gluteal fat injections, varicose veins, obesity and immune disorders as well as those who had previously given birth.

CONCLUSION

To increase the effectiveness of the score and to use the score as a basis on which to decide upon prophylactic care, it is necessary to modify the score and add some factors.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Genomic Circuitry Underlying Immunological Response to Pediatric Acute Respiratory Infection

Acute respiratory tract viral infections (ARTIs) cause significant morbidity and mortality. CD8 T cells are fundamental to host responses, but transcriptional alterations underlying anti-viral mechanisms and links to clinical characteristics remain unclear. CD8 T cell transcriptional circuitry in acutely ill pediatric patients with influenza-like illness was distinct for different viral pathogens. Although changes included expected upregulation of interferon-stimulated genes (ISGs), transcriptional downregulation was prominent upon exposure to innate immune signals in early IFV infection. Network analysis linked changes to severity of infection, asthma, sex, and age. An influenza pediatric signature (IPS) distinguished acute influenza from other ARTIs and outperformed other influenza prediction gene lists. The IPS allowed a deeper investigation of the connection between transcriptional alterations and clinical characteristics of acute illness, including age-based differences in circuits connecting the STAT1/2 pathway to ISGs. A CD8 T cell-focused systems immunology approach in pediatrics identified age-based alterations in ARTI host response pathways.

Fatty acid synthase downregulation contributes to acute lung injury in murine diet-induced obesity

The prevalence of obesity is rising worldwide and obese patients comprise a specific population in the intensive care unit. Acute respiratory distress syndrome (ARDS) incidence is increased in obese patients. Exposure of rodents to hyperoxia mimics many of the features of ARDS. In this report, we demonstrate that high fat diet induced obesity increases the severity of hyperoxic acute lung injury in mice in part by altering fatty acid synthase (FASN) levels in the lung. Obese mice exposed to hyperoxia had significantly reduced survival and increased lung damage. Transcriptomic analysis of lung homogenates identified Fasn as one of the most significantly altered mitochondrial associated genes in mice receiving 60% compared to 10% fat diet. FASN protein levels in the lung of high fat diet mice were lower by immunoblotting and immunohistochemistry. Depletion of FASN in type II alveolar epithelial cells resulted in altered mitochondrial bioenergetics and more severe lung injury with hyperoxic exposure, even upon the administration of a 60% fat diet. This is the first study to show that a high fat diet leads to altered FASN expression in the lung and that both a high fat diet and reduced FASN expression in alveolar epithelial cells promote lung injury.

The impact of body mass index on resource utilization and outcomes of children admitted to a pediatric intensive care unit

Introduction:

Obesity is associated with poor health outcomes but may be protective in intensive care unit patients. The objective of this study is to describe the characteristics of underweight, normal weight, and obese children, and to compare their length of stay, resource utilization, and mortality.

Methods:

The charts of 1447 patients who were admitted to a tertiary-level pediatric intensive care unit during 1 calendar year were reviewed. Patients were divided into three groups: underweight (<5th percentile), normal (5th–95th percentiles), and obese (>95th percentile). Body mass index for age percentile was used for children older than age 2 years, and weight-for-height percentile was used for children younger than age 2 years. Demographic data, Pediatric Index of Mortality 2 score, Pediatric Index of Mortality 2 risk of mortality, hospital mortality, hospital length of stay, the use and duration of ventilator support, hemodynamic support, and dialysis were determined.

Results:

Fifteen percent of children were underweight, while 61.5% were normal weight and 23.5% were obese; 54.9% of the patients were male. The overall mortality was 1.87%, with no significant difference between the three weight groups. The racial distribution, prevalence, and duration of invasive and noninvasive ventilation, and the use of vasopressors, central venous lines, and dialysis were similar between three groups. Tube feeding and parenteral nutrition were used more often in the underweight group. Pediatric intensive care unit and hospital lengths of stays were higher in underweight children. Underweight children were younger when compared to normal or obese children. Pediatric Index of Mortality 2 scores and Pediatric Index of Mortality 2 risk of mortality scores were higher in underweight children.

Conclusion:

There were no significant differences between the three weight groups in mortality. Underweight children were younger and sicker, and received tube feeding and parenteral nutrition more frequently.

Functional Status in Older Intensive Care Unit Survivors

Older ICU survivors are often challenged with clusters of geriatric syndromes and functional decline. The purpose of this study was (a) to assess patterns of geriatric syndromes and functional status from admission to 6 months post discharge and (b) to examine the predictors of longitudinal functional status. This is a prospective cohort study. Demographic information, clinical variables, geriatric syndromes, and functional status were collected longitudinally. A total of 192 medical ICU older adult survivors were included in the analysis. Factors associated with reductions in functional status over 6 months were (a) institutionalized prior to hospitalization, (b) pressure sore before admission, (c) existing delirium, (d) impaired mobility at baseline, (e) increased APACHE II score upon ICU admission, and (f) use of mechanical ventilation during the ICU stay. Importantly, overweight was the only factor that was associated with increased functional level over 6 months.

Is body mass index associated with outcomes of mechanically ventilated adult patients in intensive critical units? A systematic review and meta-analysis

BACKGROUND

Obesity paradox refers to lower mortality in subjects with higher body mass index (BMI), and has been documented under a variety of condition. However, whether obesity paradox exists in adults requiring mechanical ventilation in intensive critical units (ICU) remains controversial.

METHODS

MEDLINE, EMBASE, China Biology Medicine disc (CBM) and CINAHL electronic databases were searched from the earliest available date to July 2017, using the following search terms: "body weight", "body mass index", "overweight" or "obesity" and "ventilator", "mechanically ventilated", "mechanical ventilation", without language restriction. Subjects were divided into the following categories based on BMI (kg/m2): underweight, < 18.5 kg/m2; normal, 18.5-24.9 kg/m2; overweight, BMI 25-29.9 kg/m2; obese, 30-39.9 kg/m2; and severely obese > 40 kg/m2. The primary outcome was mortality, and included ICU mortality, hospital mortality, short-term mortality (<6 months), and long-term mortality (6 months or beyond). Secondary outcomes included duration of mechanical ventilation, length of stay (LOS) in ICU and hospital. A random-effects model was used for data analyses. Risk of bias was assessed using the Newcastle-Ottawa quality assessment scale.

RESULTS

A total of 15,729 articles were screened. The final analysis included 23 articles (199,421 subjects). In comparison to non-obese patients, obese patients had lower ICU mortality (odds ratio (OR) 0.88, 95% CI 0.0.84-0.92, I2 = 0%), hospital mortality (OR 0.83, 95% CI 0.74-0.93, I2 = 52%), short-term mortality (OR 0.81, 95% CI 0.74-0.88, I2 = 0%) as well as long-term mortality (OR 0.69, 95% CI 0.60-0.79, I2 = 0%). In comparison to subjects with normal BMI, obese patients had lower ICU mortality (OR 0.88, 95% CI 0.82-0.93, I2 = 5%). Hospital mortality was lower in severely obese and obese subjects (OR 0.71, 95% CI 0.53-0.94, I2 = 74%, and OR 0.80, 95% CI 0.73-0.89, I2 = 30%). Short-term mortality was lower in overweight and obese subjects (OR 0.82, 95% CI 0.75-0.90, I2 = 0%, and, OR 0.75, 95% CI 0.66-0.84, I2 = 8%, respectively). Long-term mortality was lower in severely obese, obese and overweight subjects (OR 0.39, 95% CI 0.18-0.83, and OR 0.63, 95% CI 0.46-0.86, I2 = 56%, and OR 0.66, 95% CI 0.57-0.77, I2 = 0%). All 4 mortality measures were higher in underweight subjects than in subjects with normal BMI. Obese subjects had significantly longer duration on mechanical ventilation than non-obese group (mean difference (MD) 0.48, 95% CI 0.16-0.80, I2 = 37%), In comparison to subjects with normal BMI, severely obese BMI had significantly longer time in mechanical ventilation (MD 1.10, 95% CI 0.38-1.83, I2 = 47%). Hospital LOS did not differ between obese and non-obese patients (MD 0.05, 95% CI -0.52 to 0.50, I2 = 80%). Obese patients had longer ICU LOS than non-obese patients (MD 0.38, 95% CI 0.17-0.59, I2 = 70%). Hospital LOS and ICU LOS did not differ significantly in subjects with different BMI status.

CONCLUSIONS

In ICU patients receiving mechanical ventilation, higher BMI is associated with lower mortality and longer duration on mechanical ventilation.

Body mass index and mortality in patients with and without diabetes mellitus

OBJECTIVE

Investigate the association between body mass index (BMI), length of stay (LOS), and mortality in hospitalized patients with and without diabetes mellitus (DM).

METHODS

Historical prospectively collected data of adult patients hospitalized between 2011 and 2013. Body mass index was calculated according to measurement or self-report on admission and classified as follows: underweight (<18.5), normal weight (18.5-24.9), overweight (25-29.9), obese (30-34.9), and severely obese (≥35). The main outcomes were LOS, in-hospital, and end-of-follow-up mortality.

RESULTS

Cohort included 24 233 patients (53% male; mean age ± SD, 65 ± 18), including 7397 patients with DM (31%). Among patients with normal BMI, LOS was shorter compared with underweight patients, but it was longer compared with overweight and obese patients. Following multivariate adjustment, this difference remained significant only for patients with DM. There was a significant interaction between DM status and BMI group, in the models for in-hospital and end-of-follow-up mortality. Compared with normal BMI, in-hospital mortality risk was increased by 80% and 100% for the underweight with and without DM, respectively. For patients with and without DM, in-hospital mortality risk was 30% to 40% lower among overweight and obese patients, and there was no difference between severely obese and normal weight patients. At the end-of-follow-up, mortality risk was 1.6-fold and 1.7-fold higher among underweight patients with and without DM, respectively. For overweight, obese, and severely obese patients, mortality risk was decreased by 30% to 40% in those with DM and by 20% to 30% in those without DM.

CONCLUSIONS

In hospitalized patients with and without DM, there was an inverse association between BMI and mortality.

Super Obesity in the Medical Intensive Care Unit

BACKGROUND

Studies exploring the effect of body mass index (BMI) on outcomes in the intensive care unit (ICU) have yielded mixed results, with few studies assessing patients at the extremes of obesity. We sought to understand the clinical characteristics and outcomes of patients with super obesity (BMI > 50 kg/m²) as compared to morbid obesity (BMI > 40 kg/m²) and obesity (BMI > 30 kg/m²).

METHODS

A retrospective review of patients admitted to the Los Angeles County + University of Southern California medical intensive care unit (MICU) service between 2008 and 2013 was performed. The first 150 patients with BMI 30 to 40, 40 to 50, and 50+ were separated into groups. Demographic data, comorbid conditions, reason for admission, Acute Physiology and Chronic Health Evaluation II (APACHE II) scores, serum bicarbonate, and arterial carbon dioxide pressure (Pco ₂) at admission were collected. Hospital and ICU length of stay (LOS), discharge disposition, mortality, use of mechanical ventilation (invasive and noninvasive), use of radiography, and other clinical outcomes were also recorded.

RESULTS

There was no difference in age, sex, and APACHE II score among the 3 groups. A pulmonary etiology was the most common reason for admission in the higher BMI categories (P < .001). There was no difference in mortality among the groups. Intensive care unit and hospital LOS rose with increasing BMI (P < .001). Patients admitted for pulmonary etiologies and higher BMIs had an increased ICU and hospital LOS (P < .001). Super obese patients used significantly more noninvasive mechanical ventilation (NIMV, P < .001). There were no differences in the use of invasive mechanical ventilation across the groups.

CONCLUSION

Super obese patients are most commonly admitted to the MICU with pulmonary diagnoses and have an increased use of noninvasive ventilation. Super obesity was not associated with increased ICU mortality. Clinicians should be prepared to offer NIMV to super obese patients and anticipate a longer LOS in this group.

The impact of disease severity on paradoxical association between body mass index and mortality in patients with acute kidney injury undergoing continuous renal replacement therapy

BACKGROUND

Association between high body mass index (BMI) and survival benefit is confounded by comorbid conditions such as nutritional status and inflammation. Patients with acute kidney injury (AKI), particularly those receiving continuous renal replacement therapy (CRRT), are highly catabolic and more susceptible to loss of energy. Herein, we evaluated whether disease severity can modify the relationship between BMI and mortality.

METHODS

We conducted an observational study in 1144 patients who had undergone CRRT owing to various causes of AKI between 2010 and 2014. Patients were categorized into four groups; underweight (< 18.5 kg/m²), normal (18.5-22.99 kg/m²), overweight (23.0-24.99 kg/m²), and obesity (≥25 kg/m²) according to BMI classification by the Committee of Clinical Practice Guidelines and Korean Society for the Study of Obesity. More severe disease was defined as sepsis-related organ failure assessment (SOFA) score of ≥ a median value of 12. The study endpoint was death that occurred within 30 days after the initiation of CRRT.

RESULTS

The mean age was 63.2 years and 439 (38.4%) were females. The median BMI was 23.6 (20.9-26.2) kg/m². The obese group were younger and higher SOFA score than normal BMI group. In a multivariable Cox regression analysis, we found a significant interaction between BMI and SOFA score (P <  0.001). Furthermore, obese patients were significantly associated with a lower risk of death as compared to normal BMI group after adjusting confounding factors [hazard ratio (HR), 0.81; 95% confidence interval (CI), 0.68-0.97; P = 0.03]. This association was only evident among patients with high severity (HR, 0.61; 95% CI, 0.48-0.76, P <  0.001). In contrast, in those with low severity, survival benefit of high BMI was lost, whereas underweight was associated with an increased risk of death (HR, 1.74; 95% CI, 1.16-2.60; P = 0.007).

CONCLUSION

In this study, we found a survival benefit of high BMI in AKI patients undergoing CRRT, particularly in those with more disease severity; the effect was not observed in those with less disease severity.

Acute lung injury induced by intestinal ischemia and reperfusion is altered in obese female mice

RATIONAL

Acute lung injury (ALI) is a common complication after intestinal ischemia and reperfusion (I/R) injury that can lead to acute respiratory distress syndrome (ARDS). We have previously demonstrated that females are protected against lung damage induced by intestinal I/R through an estrogen mediated mechanism.

OBJECTIVES

To investigate the effect of obesity on ALI induced by intestinal I/R in female mice.

METHODS

C57Bl/6 female mice were fed with a standard low-fat diet (SD) or a high-fat diet (HFD) for 9 weeks. Intestinal I/R injury was induced by a 45 min occlusion of the mesenteric artery followed by 2 and 24 h of reperfusion.

RESULTS

Significant increase in lung myeloperoxidase expression (MPO) and neutrophil numbers of SD and HFD mice occurred at 2 h and 24 h of reperfusion. Furthermore, HFD mice presented a significant increase in lung eosinophil peroxidase (EPO) expression and eosinophil numbers compared to SD mice. Lung wet/dry weight ratio was significantly greater in HFD mice at 2 and 24 h of reperfusion, accompanied by a significant increase in the expression of inducible NO in the lung tissue and a significant decrease in arterial oxygen saturation at 24 h of reperfusion relative to SD mice.

CONCLUSION

Obesity predisposes female mice to increased pulmonary oedema and deterioration in gas exchange, which is accompanied by an increase in iNOS expression in the lung.

Can body mass index predict clinical outcomes for patients with acute lung injury/acute respiratory distress syndrome? A meta-analysis

BACKGROUND

The effects of body mass index (BMI) on the prognosis of acute respiratory distress syndrome (ARDS) are controversial. We aimed to further determine the relationship between BMI and the acute outcomes of patients with ARDS.

METHODS

We searched the Pubmed, Embase, Medline, Cochrane Central Register of Controlled Trials (CENTRAL), and ISI Web of Science for trials published between 1946 and July 2016, using "BMI" or "body mass index" or "overweight" or "obese" and "ARDS" or "ALI" or "acute respiratory distress syndrome" or "acute lung injury", without limitations on publication type or language. Heterogeneity and sensitivity analyses were conducted, and a random-effects model was applied to calculate the odds ratio (OR) or mean difference (MD). Review Manager (RevMan) was used to test the hypothesis using the Mann-Whitney U test. The primary outcome was unadjusted mortality, and secondary outcomes included mechanical ventilation (MV)-free days and length of stay (LOS) in the intensive care unit (ICU) and in hospital.

RESULTS

Five trials with a total of 6268 patients were pooled in our final analysis. There was statistical heterogeneity between normal-weight and overweight patients in LOS in the ICU (I ² = 71%, χ ² = 10.27, P = 0.02) and in MV-free days (I ² = 89%, χ ² = 18.45, P < 0.0001). Compared with normal weight, being underweight was associated with higher mortality (OR 1.59, 95% confidence interval (CI) 1.22, 2.08, P = 0.0006), while obesity and morbid obesity were more likely to result in lower mortality (OR 0.68, 95% CI 0.57, 0.80, P < 0.00001; OR 0.72, 95% CI 0.56, 0.93, P = 0.01). MV-free days were much longer in patients with morbid obesity (MD 2.64, 95% CI 0.60, 4.67, P = 0.01), but ICU and hospital LOS were not influenced by BMI. An important limitation of our analysis is the lack of adjustment for age, sex, illness severity, comorbid illness, and interaction of outcome parameters.

CONCLUSIONS

Obesity and morbid obesity are associated with lower mortality in patients with ARDS.

A gradient-boosted model analysis of the impact of body mass index on the short-term outcomes of critically ill medical patients

Objective

To evaluate the impact of body mass index on the short-term prognosis of non-surgical critically ill patients while controlling for performance status and comorbidities.

Methods

We performed a retrospective analysis on a two-year single-center database including 1943 patients. We evaluated the impact of body mass index on hospital mortality using a gradient-boosted model that also included comorbidities and was assessed by Charlson’s comorbidity index, performance status and illness severity, which was measured by the SAPS3 score. The SAPS3 score was adjusted to avoid including the same variable twice in the model. We also assessed the impact of body mass index on the length of stay in the hospital after intensive care unit admission using multiple linear regressions.

Results

A low value (< 20kg/m²) was associated with a sharp increase in hospital mortality. Mortality tended to subsequently decrease as body mass index increased, but the impact of a high body mass index in defining mortality was low. Mortality increased as the burden of comorbidities increased and as the performance status decreased. Body mass index interacted with the impact of SAPS3 on patient outcome, but there was no significant interaction between body mass index, performance status and comorbidities. There was no apparent association between body mass index and the length of stay at the hospital after intensive care unit admission.

Conclusion

Body mass index does appear to influence the shortterm outcomes of critically ill medical patients, who are generally underweight. This association was independent of comorbidities and performance status.

Impact of Weight Extremes on Clinical Outcomes in Pediatric Acute Respiratory Distress Syndrome

OBJECTIVES

To determine whether weight extremes impact clinical outcomes in pediatric acute respiratory distress syndrome.

DESIGN

Post hoc analysis of a cohort created by combining five multicenter pediatric acute respiratory distress syndrome studies.

SETTING

Forty-three academic PICUs worldwide.

PATIENTS

A total of 711 subjects prospectively diagnosed with pediatric acute respiratory distress syndrome.

INTERVENTION

Subjects more than 2 years were included and categorized by Center for Disease Control and Prevention body mass index z score criteria: underweight (< -1.89), normal weight (-1.89 to +1.04), overweight (+1.05 to +1.64), and obese (≥ +1.65). Subjects were stratified by direct versus indirect lung injury leading to pediatric acute respiratory distress syndrome. The primary outcome was in-hospital mortality. In survivors, secondary analyses included duration of mechanical ventilation and ICU length of stay.

MEASUREMENTS AND MAIN RESULTS

A total of 331 patients met inclusion criteria; 12% were underweight, 50% normal weight, 11% overweight, and 27% obese. Overall mortality was 20%. By multivariate analysis, body mass index category was independently associated with mortality (p = 0.004). When stratified by lung injury type, there was no mortality difference between body mass index groups with direct lung injury; however, in the indirect lung injury group, the odds of mortality in the obese were significantly lower than normal weight subjects (odds ratio, 0.11; 95% CI, 0.02-0.84). Survivors with direct lung injury had no difference in the duration of mechanical ventilation or ICU length of stay; however, those with indirect lung injury, the overweight required longer duration of mechanical ventilation than other groups (p < 0.001).

CONCLUSIONS

These data support the obesity paradox in pediatric acute respiratory distress syndrome. Obese children with indirect lung injury pediatric acute respiratory distress syndrome have a lower risk of mortality. Importantly, among survivors, the overweight with indirect lung injury requires longer duration of mechanical ventilation. Our data require prospective validation to further elucidate the pathobiology of this phenomenon.

The Critical Care Obesity Paradox and Implications for Nutrition Support

Obesity is a leading cause of preventable death worldwide. The prevalence of obesity has been increasing and is associated with an increased risk for other co-morbidities. In the critical care setting, nearly one third of patients are obese. Obese critically ill patients pose significant physical and on-physical challenges to providers, including optimization of nutrition therapy. Intuitively, obese patients would have worse critical care-related outcome. On the contrary, emerging data suggests that critically ill obese patients have improved outcomes, and this phenomenon has been coined "the obesity paradox." The purposes of this review will be to outline the historical views and pathophysiology of obesity and epidemiology of obesity, describe the challenges associated with obesity in the intensive care unit setting, review critical care outcomes in the obese, define the obesity-critical care paradox, and identify the challenges and role of nutrition support in the critically ill obese patient.

Prevalence of obesity and the effect on length of mechanical ventilation and length of stay in intensive care patients: A single site observational study

OBJECTIVES

To provide a snapshot of the prevalence of abnormal body mass index (BMI) in a sample of intensive care unit (ICU) patients; to identify if any medical specialty was associated with abnormal BMI and to explore associations between BMI and ICU-related outcomes.

BACKGROUND

Obesity is an escalating public health issue across developed nations but there is little data pertaining to critically ill patients who require care that is expensive.

METHODS

Retrospective observational audit of 735 adult patients (median age 58 years) admitted to the Sir Charles Gairdner Hospital 23 bed tertiary ICU between November 2012 and June 2014. Primary outcome measure was patient BMI: underweight (<18.5kg/m²), normal weight (18.5-24.99kg/m²), overweight (25-29.99kg/m²), obese (30-39.99kg/m²) or extreme obese (40kg/m² or above). Other measures included gender, acute physiology and chronic health evaluation II score, admission specialty, length of mechanical ventilation (MV), length of stay (LOS) and mortality.

RESULTS

Compared to the general population there was a higher proportion of obese patients within the cohort with the majority of patients overweight (33.9%) or obese (36.5%) and median BMI of 27.9 (IQR 7.9). There were no significant differences between specialties for BMI (p=0.103) and abnormal BMI was not found to impact negatively on mortality (ICU, p=0.373; hospital, p=0.330). Normal BMI patients had shorter length of MV than other BMI categories and the impact of BMI on ICU LOS was dependent on length of MV. Overweight patients ventilated for five days or more had a shorter LOS, and extremely obese non-ventilated patients had a longer LOS, compared to normal weight patients.

CONCLUSIONS

Although the obesity-disease relationship is increasingly complex and data presented reflects categorical BMI for patients admitted to a single ICU site it may be important to consider the cost implications of caring for this cohort especially with regard to MV and LOS.

Factors associated with length of stay in intensive care after bariatric surgery

BACKGROUND

Although uncommon, admission to the intensive care unit (ICU) after bariatric surgery may be necessary. This study evaluates characteristics of bariatric surgery patients that are admitted to the ICU, and identifies possible risk factors for increased ICU length of stay (LOS).

SETTING

Academic hospital, United States.

METHODS

A retrospective review of all ICU admissions after bariatric surgery from 2006 to 2013 was performed. Demographic characteristics and perioperative data were extracted, and risk factors for the LOS and mortality in the ICU were analyzed.

RESULTS

In total, 124 out of 4398 (2.8%) patients were admitted to the ICU after bariatric surgery. The mean age of these patients was 52.7±11.8 years and included 79 female patients (64%). There were 19 nonemergent or planned admissions (15.3%) and 105 unplanned admissions (84.7%). Mean body mass index was 47.8±12.2 kg/m², and mean American Society of Anesthesiology (ASA) score was 3.1±0.6. Roux-en-Y gastric bypass, sleeve gastrectomy, and adjustable gastric banding were performed in 80 (65%), 18 (15%), and 6 (5%) patients, respectively. Revisional procedures were performed in 15 (12%) patients. Respiratory failure was the most common cause for admission, occurring in 35 (28.2%) patients. The most common surgical complications requiring ICU admission were bleeding (n = 27) and anastomotic leak (n = 21). Mean ICU LOS was 6.0±9.6 (1-65) days. Mortality occurred in 5 (4.0%) patients. Based on univariate analysis, risk factors associated with ICU LOS were conversion from laparoscopic to open approach, anastomotic leak, time from operation to ICU admission, and reoperation. Higher ASA score was a significant risk factor for mortality.

CONCLUSION

ICU admission after bariatric surgery is uncommon but is associated with a significantly increased mortality. Anastomotic leak, conversions, time from operation to ICU admission, and reoperation have the greatest impact in determining the LOS in the ICU after bariatric surgery.

The outcome of acute respiratory distress syndrome in relation to body mass index and diabetes mellitus

OBJECTIVE

To determine the 28 day mortality of patients with ARDS in relation to body mass index (BMI) and presence diabetes mellitus (DM).

DESIGN

Retrospective cohort study of patients enrolled in the ARDS Network randomized controlled trials.

RESULTS

2914 patients were enrolled in these trials. 112 patients were underweight (BMI < 18.5), 948 patients were normal range (18.5 ≤ BMI < 25.0), 801 patients were overweight (25.0 ≤ BMI < 30.0), 687 patients were obese (30.0 ≤ BMI < 40.0), and 175 patients were severely obese (BMI ≥ 40.0). 469 patients had DM. There was no significant difference in the 28 day mortality in relation to BMI or presence of DM (underweight adjusted OR, 1.217; 95% CI, 0.749-1.979; overweight adjusted OR, 0.887; 95% CI, 0.696-1.131; obese adjusted OR, 0.812; 95% CI, 0.624-1.056; severely obese adjusted OR, 1.102; 95% CI, 0.716-1.695; and DM adjusted OR, 0.938; 95% CI, 0.728-1.208).

CONCLUSIONS

The short term mortality in patients with ARDS is not affected by BMI or the presence of DM.

A retrospective cohort study examining the association between body mass index and mortality in severe sepsis

Body mass index (BMI) is an easily calculated indicator of a patient's body mass including muscle mass and body fat percentage and is used to classify patients as underweight or obese. This study is to determine if BMI extremes are associated with increased 28-day mortality and hospital length of stay (LOS) in emergency department (ED) patients presenting with severe sepsis. We performed a retrospective chart review at an urban, level I trauma center of adults admitted with severe sepsis between 1/2005 and 10/2007, and collected socio-demographic variables, comorbidities, initial and most severe vital signs, laboratory values, and infection sources. The primary outcome variables were mortality and LOS. We performed bivariable analysis, logistic regression and restricted cubic spline regression to determine the association between BMI, mortality, and LOS. Amongst 1,191 severe sepsis patients (median age, 57 years; male, 54.7%; median BMI, 25.1 kg/m(2)), 28-day mortality was 19.9% (95% CI 17.8-22.4) and 60-day mortality was 24.4% (95% CI 21.5-26.5). Obese and morbidly obese patients were younger, less severely ill, and more likely to have soft tissue infections. There was no difference in adjusted mortality for underweight patients compared to the normal weight comparator (OR 0.74; CI 0.42-1.39; p = 0.38). The obese and morbidly obese experienced decreased mortality risk, vs. normal BMI; however, after adjustment for baseline characteristics, this was no longer significant (OR 0.66; CI 0.42-1.03; p = 0.06). There was no significant difference in LOS across BMI groups. Neither LOS nor adjusted 28-day mortality was significantly increased or decreased in underweight or obese patients with severe sepsis. Morbidly obese patients may have decreased 28-day mortality, partially due to differences in initial presentation and source of infection. Larger, prospective studies are needed to validate these findings related to BMI extremes in patients with severe sepsis.

Impact of endotoxin challenge in obese pigs

Studies exploring the influence of obesity on septic shock remain limited and controversial. Pigs were chosen as a clinically relevant species, resembling to humans in various functions. We hypothesize obesity may impair porcine acute endotoxic shock. Four groups of five "Yucatan" minipigs were studied: lean and obese control groups, lean lipopolysaccharide (LPS) group receiving Escherichia coli endotoxin (LPS) and obese LPS group receiving the same endotoxin dose. We measured hemodynamic and oxygenation parameters, skin microvascular blood flow at rest and during reactive hyperemia, von Willebrand factor, tumor necrosis factor α, and interleukin 6. All measurements were performed at baseline and at 30, 60, 90, 150, and 300 min. Results were given as median with 25th to 75th interquartile range. Control groups remained stable during the study period. In LPS groups, administration of endotoxin resulted in a typical hypokinetic shock. In obese LPS group at 300 min, we observed a significant impairment of cardiac index (1.2 [1.06-1.45] vs. 1.7 [1.57-1.97] L/min per m, P = 0.008) compared with the lean LPS group; moreover, pulmonary hypertension (mean arterial pressure: 42 [39-47] vs. 32 [28-34] mmHg, P = 0.008), hypoxemia (partial pressure of oxygen: 216 [178-262] vs. 325 [285-414] mmHg, P = 0.02), and lactate levels (5.8 [4.2-6.8] vs. 3.9 [2.2-5.5] mmol/L, P = 0.04) were significantly higher compared with the lean LPS group. Throughout the study, rest flow and peak flow during reactive hyperemia were more decreased in the obese LPS group. Compared with the lean LPS group, tumor necrosis factor α levels at 60 min (269 [178-428] vs. 126 [105-166] ng/mL, P = 0.03) and interleukin 6 levels at 300 min (101 [61-142] vs. 52 [36-64] ng/mL, P = 0.03) were significantly higher in the obese LPS group. In our model of endotoxic shock, obese pigs developed a more severe hemodynamic failure with pronounced microcirculatory dysfunction and proinflammatory response.

The association between obesity and outcomes in critically ill patients

BACKGROUND

Obesity rates are increasing worldwide, particularly in North America. The impact of obesity on the outcome of critically ill patients is unclear.

METHODS

A prospective observational cohort study of consecutive patients admitted to a tertiary critical care unit in Canada between January 10, 2008 and March 31, 2009 was conducted. Exclusion criteria were age <18 years, admission <24 h, planned cardiac surgery, pregnancy, significant ascites, unclosed surgical abdomen and brain death on admission. Height, weight and abdominal circumference were measured at the time of intensive care unit (ICU) admission. Coprimary end points were ICU mortality and a composite of ICU mortality, reintubation, ventilator-associated pneumonia, line sepsis and ICU readmission. Subjects were stratified as obese or nonobese, using two separate metrics: body mass index (BMI) ≥ 30 kg/m(2) and a novel measurement of 75th percentile for waist-to-height ratio (WHR).

RESULTS

Among 449 subjects with a BMI ≥ 18.5 kg/m(2), both BMI and WHR were available for comparative analysis in 348 (77.5%). Neither measure of obesity was associated with the primary end points. BMI ≥ 3 0 kg/m(2) was associated with a lower odds of six-month mortality than the BMI <30 kg/m(2) group (adjusted OR 0.59 [95% CI 0.36 to 0.97]; P=0.04) but longer intubation times (adjusted RR 1.56 [95% CI 1.17 to 2.07]; P=0.003) and longer ICU length of stay (adjusted RR 1.67 [95% CI 1.21 to 2.31]; P=0.002). Conversely, measurement of 75th percentile for WHR was associated only with decreased ICU readmission (OR 0.23 [95% CI 0.07 to 0.79]; P=0.02).

CONCLUSIONS

Obesity was not necessarily associated with worse outcomes in critically ill patients.

Intensive care unit and hospital mortality in patients with obstructive sleep apnea

INTRODUCTION

Obstructive sleep apnea (OSA) is a common disorder affecting between 5% and 24% of men and women. The prevalence of OSA in the intensive care unit (ICU) population is unknown. This study was undertaken to determine the prevalence of OSA in patients admitted to the ICU and to determine if OSA is an independent predictor of mortality.

METHODS

This is a retrospective study using an Acute Physiology and Chronic Health Evaluation III database cross-referenced to a comprehensive clinical database to identify patients with and without OSA admitted to medical, surgical, and mixed ICUs at a large academic medical center.

RESULTS

Between January 2003 and December 2005, 15077 patients were admitted to the ICUs; and of these, 1183 (7.8%) had a physician-documented diagnosis of OSA. Eight hundred thirty-five (71%) patients had polysomnographic testing at our institution with a documented apnea-hypopnea index more than 5 per hour. Patients with OSA were younger (59.1 ± 14.0 vs 62.3 ± 18.0), male (58.9% vs 53.7%), and had lower Acute Physiology and Chronic Health Evaluation III scores (45.3 ± 24.1 vs 54.9 ± 27.7). Predicted mortality (10.3% ± 16.4% vs 16.3 ± 21.7), median ICU length of stay (1.13 vs 1.50 days), ICU mortality (2.4% vs 6.2%), and hospital mortality (3.9% vs 11.4%) were all reduced in patients with OSA, P values < .001. When adjusted for the severity of illness, OSA was independently associated with decreased hospital mortality, (0.408; 95% confidence interval, 0.298-0.557).

CONCLUSIONS

Obstructive sleep apnea is common in patients admitted to the ICU. Obstructive sleep apnea was associated with a reduction in both ICU and hospital mortality.

Obesity and nutrition in acute respiratory distress syndrome

This article discusses obesity, its contribution to clinical outcomes, and the current literature on nutrition. More than one third of Americans are obese. Literature suggests that, among critically ill patients, the relationship between obesity and outcomes is complex. Obese patients may be at greater risk of developing acute respiratory distress syndrome (ARDS) than normal weight patients. Although obesity may confer greater morbidity in intensive care, it seems to decrease mortality. ARDS is a catabolic state; patients demonstrate a profound inflammatory response, multiple organ dysfunction, and hypermetabolism, often with malnutrition. The concept of pharmaconutrition has emerged.

Obesity-induced hyperleptinemia improves survival and immune response in a murine model of sepsis

BACKGROUND

Obesity is a growing health problem and associated with immune dysfunction. Sepsis is defined as systemic inflammatory response syndrome that occurs during infection. Excessive inflammation combined with immune dysfunction can lead to multiorgan damage and death.

METHODS

The authors investigated the influence of a class 1 obesity (body mass index between 30 and 34.9) on immune function and outcome in sepsis and the role of leptin on the immune response. The authors used a long-term high-fat-diet feeding model (12 weeks) on C57Bl/6 mice (n = 100) and controls on standard diet (n = 140) followed by a polymicrobial sepsis induced by cecal ligation and puncture.

RESULTS

The authors show that class 1 obesity is connected to significant higher serum leptin levels (data are mean ± SEM) (5.7 ± 1.2 vs. 2.7 ± 0.2 ng/ml; n = 5; P = 0.033) and improved innate immune response followed by significant better survival rate in sepsis (71.4%, n = 10 vs. 10%, n = 14; P < 0.0001). Additional sepsis-induced increases in leptin levels stabilize body temperature and are associated with a controlled immune response in a time-dependent and protective manner. Furthermore, leptin treatment of normal-weight septic mice with relative hypoleptinemia (n = 35) also significantly stabilizes body temperature, improves cellular immune response, and reduces proinflammatory cytokine response resulting in improved survival (30%; n = 10).

CONCLUSIONS

Relative hyperleptinemia of class 1 obesity or induced by treatment is protective in sepsis. Leptin seems to play a regulatory role in the immune system in sepsis, and treatment of relative hypoleptinemia could offer a new way of an individual sepsis therapy.

Contrasting effects of preexisting hyperglycemia and higher body size on hospital mortality in critically ill patients: a prospective cohort study

BACKGROUND

Obesity and diabetes mellitus are well-defined risk factors for cardiovascular mortality. The impact of antecedent hyperglycemia and body size on mortality in critical ill patients in intensive care units (ICUs) may vary across their range of values. Therefore, we prospectively analyzed the relationship between in-hospital mortality and preexisting hyperglycemia and body size in critically ill ICU patients to understand how mortality varied among normal, overweight, and obese patients and those with low, intermediate, and high glycated hemoglobin (HbA1c) levels.

METHODS

Medical history, weight, height, physiologic variables, and HbA1c were obtained during the first 24 h for patients who were consecutively admitted to the high complexity ICU of Hospital de Clínicas de Porto Alegre, Brazil, from April to August 2011. The relationships between mortality and obesity and antecedent hyperglycemia were prospectively analyzed by cubic spline analysis and a Cox proportional hazards model.

RESULTS

The study comprised 199 patients. The overall hospital mortality rate was 43.2% during a median 16 (8-28) days of follow-up. There was a progressive risk of in-hospital mortality with higher HbA1c levels, with the relationship becoming significant at HbA1c >9.3% compared with lower levels (hazard ratio 1.74; 95% confidence interval with Bonferroni correction 1.49-2.80). In contrast, mean body mass index (BMI) was higher in survivors than in nonsurvivors (27.2 kg/m2 ± 7.3 vs. 24.7 kg/m2 ± 5.0 P = 0.031, respectively). Cubic spline analysis showed that these relationships differed nonlinearly through the spectrum of BMI values. In a Cox proportional hazards model adjusted for Acute Physiology and Chronic Health Evaluation II score and HbA1c, the risk of in-hospital mortality progressively decreased with increasing BMI (BMI <20 vs. 20-23.9 kg/m2, P = 0.032; BMI <20 vs. 24-34.9 kg/m2, P = 0.010; BMI <20 vs. ≥35 kg/m2, P = 0.032).

CONCLUSIONS

Our findings suggest that significant hyperglycemia prior to ICU admission is a risk factor for in-hospital mortality. Conversely, increasing BMI may confer an advantageous effect against mortality in critical illness independently of previous glycemic control.

Clinical Outcomes in Critically Ill Patients Associated With the Use of Complex vs Weight-Only Predictive Energy Equations

BACKGROUND

The energy intake goal is important to achieving energy intake in critically ill patients, yet clinical outcomes associated with energy goals have not been reported.

METHODS

This secondary analysis used the Improving Nutrition Practices in the Critically III International Nutrition Surveys database from 2007-2009 to evaluate whether mortality or time to discharge alive is related to use of complex energy prediction equations vs weight only. The sample size was 5672 patients in the intensive care unit (ICU) ≥ 4 days and a subset of 3356 in the ICU ≥ 12 days. Mortality and time to discharge alive were compared between groups by regression, controlling for age, sex, admission type, Acute Physiology and Chronic Health Evaluation II score, ICU geographic region, actual energy intake, and obesity.

RESULTS

There was no difference in mortality between the use of complex and weight-only equations (odds ratio [OR], 0.90; 95% confidence interval [CI], 0.86-1.15), but obesity (OR, 0.83; 95% CI, 0.71-0.96) and higher energy intake (OR, 0.65; 95% CI, 0.56-0.76) had lower odds of mortality. Time to discharge alive was shorter in patients fed using weight-only equations (hazard ratio [HR], 1.11; 95% CI, 1.01-1.23) in patients staying ≥ 4 days and with greater energy intake (HR, 1.19; 95% CI, 1.06-1.34) in patients in the ICU ≥ 12 days.

CONCLUSION

These data suggest that higher energy intake is important to survival and time to discharge alive. However, the analysis was limited by actual energy intake <70% of goal. Delivery of full goal intake will be needed to determine the relationship between the method of determining energy goal and clinical outcomes.

Body mass index and mortality in Korean intensive care units: a prospective multicenter cohort study

Background

The level of body mass index (BMI) that is associated with the lowest mortality in critically ill patients in Asian populations is uncertain. We aimed to examine the association of BMI with hospital mortality in critically ill patients in Korea.

Methods

We conducted a prospective multicenter cohort study of 3,655 critically ill patients in 22 intensive care units (ICUs) in Korea. BMI was categorized into five groups: <18.5, 18.5 to 22.9, 23.0 to 24.9 (the reference category), 25.0 to 29.9, and ≥30.0 kg/m².

Results

The median BMI was 22.6 (IQR 20.3 to 25.1). The percentages of patients with BMI<18.5, 18.5 to 22.9, 23.0 to 24.9, 25.0 to 29.9, and ≥30.0 were 12, 42.3, 19.9, 22.4, and 3.3%, respectively. The Cox-proportional hazard ratios with exact partial likelihood to handle tied failures for hospital mortality comparing the BMI categories <18.5, 18.5 to 22.9, 25.0 to 29.9, and ≥30.0 with the reference category were 1.13 (0.88 to 1.44), 1.03 (0.84 to 1.26), 0.96 (0.76 to 1.22), and 0.68 (0.43 to 1.08), respectively, with a highly significant test for trend (p = 0.02).

Conclusions

A graded inverse association between BMI and hospital mortality with a strong significant trend was found in critically ill patients in Korea.

Effect of body mass index on stroke rehabilitation

OBJECTIVE

To investigate the association between body mass index (BMI) and the functional progress of patients with stroke, admitted to a rehabilitation hospital.

DESIGN

A retrospective cohort study.

SETTING

A freestanding university rehabilitation hospital stroke unit.

PARTICIPANTS

All patients (N=819) admitted to the stroke unit of a rehabilitation hospital during the study.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

The primary study outcome measure was the FIM efficiency of patients by BMI category.

RESULTS

For the 819 patients admitted during the observation period, BMI was compared with FIM score changes per day (FIM efficiency). After adjusting for age and sex, the FIM efficiency differed by BMI. The underweight group had the lowest FIM efficiency, followed by the obese and normal-weight subgroups. The overweight group had the highest FIM efficiency (P=.05) when compared with the obese subgroup.

CONCLUSIONS

Among patients admitted to an acute rehabilitation hospital for stroke rehabilitation, overweight patients had better functional progress than did patients in the other weight categories.

The effect of obesity on outcomes in mechanically ventilated patients in a medical intensive care unit

BACKGROUND

The effect of obesity on outcomes in critically ill patients requiring invasive mechanical ventilation in a medical intensive care unit (ICU) is uncertain.

OBJECTIVES

This study was intended to further explore the relationship between outcomes and obesity in patients admitted to a medical ICU who required invasive mechanical ventilation.

METHODS

All adult patients admitted to the medical ICU at Washington Hospital Center requiring intubation and invasive mechanical ventilation for at least 24 h between January 1 and December 31, 2009, were retrospectively studied. Patients were categorized as nonobese (BMI <30) and obese (BMI ≥30). The primary outcome measure was 30-day mortality following intubation. Secondary outcomes included ICU length of stay (LOS), hospital LOS and duration of mechanical ventilation.

RESULTS

There were 504 eligible patients: 306 nonobese and 198 (39%) obese. Obese patients had significantly higher rates of diabetes (43 vs. 30%, p = 0.004), hyperlipidemia (32 vs. 24%, p = 0.04), asthma (16 vs. 8%, p = 0.004) and obstructive sleep apnea requiring continuous positive airway pressure treatment (12 vs. 1%, p < 0.001). Nonobese patients had a significantly higher rate of HIV infection (10 vs. 5%, p = 0.05) and malignancy (21 vs. 13%, p = 0.03). There were no significant differences in mortality up to 30 days following intubation and secondary outcomes between obese and nonobese patients. Multivariate analysis using logistic regression showed no significant relationship between mortality rate at 30 days following intubation and obesity. Outcomes were similar for the black obese (n = 153) and nonobese (n = 228) patients and the obese (n = 85) and very obese (n = 113) patients.

CONCLUSIONS

Obesity did not influence outcomes in critically ill patients requiring invasive mechanical ventilation in a medical ICU. Black obese patients had similar outcomes to black nonobese patients, and very obese patients also had similar outcomes to obese patients.

Outcomes of morbidly obese patients receiving invasive mechanical ventilation: a nationwide analysis

BACKGROUND

Critically ill, morbidly obese patients (BMI≥40 kg/m2) are at high risk of respiratory failure requiring invasive mechanical ventilation (IMV). It is not clear if outcomes of critically ill, obese patients are affected by obesity. Due to limited cardiopulmonary reserve, they may have poor outcomes. However, literature to this effect is limited and conflicted.

METHODS

We used the Nationwide Inpatient Sample from 2004 to 2008 to examine the outcomes of morbidly obese people receiving IMV and compared them to nonobese people. We identified hospitalizations requiring IMV and morbid obesity using International Classification of Diseases, 9th Revision, Clinical Modification codes. Primary outcomes studied were inhospital mortality, rates of prolonged mechanical ventilation (≥96 h), and tracheostomy. Multivariable logistic regression was used to adjust for potential confounding variables. We also examined outcomes stratified by number of organs failing.

RESULTS

Of all hospitalized, morbidly obese people, 2.9% underwent IMV. Mean age, comorbidity score, and severity of illness were lower in morbidly obese people. The adjusted mortality was not significantly different in morbidly obese people (OR 0.89; 95% CI, 0.74-1.06). When stratified by severity of disease, there was a stepwise increase in risk for mortality among morbidly obese people relative to nonobese people (range: OR, 0.77; 95% CI, 0.58-1.01 for only respiratory failure, to OR, 4.14; 95% CI, 1.11-15.3 for four or more organs failing). Rates of prolonged mechanical ventilation were similar, but rate of tracheostomy (OR 2.19; 95% CI, 1.77-2.69) was significantly higher in patients who were morbidly obese.

CONCLUSIONS

Morbidly obese people undergoing IMV have a similar risk for death as nonobese people if only respiratory failure is present. When more organs fail, morbidly obese people have increased risk for mortality compared with nonobese people.

Critical illness induces nutrient-independent adipogenesis and accumulation of alternatively activated tissue macrophages

INTRODUCTION

We previously reported that in artificially-fed critically ill patients, adipose tissue reveals an increase in small adipocytes and accumulation of M2-macrophages. We hypothesized that nutrient-independent factors of critical illness explain these findings, and that the M2-macrophage accumulation may not be limited to adipose tissue.

METHODS

In a long-term cecal ligation and puncture (CLP) mouse model of sepsis, we compared the effect of parenteral nutrition (CLP-fed, n = 13) with nutrient restriction (CLP-restricted, n = 11) on body composition, adipocyte size and macrophage accumulation in adipose tissue, liver and lungs. Fed healthy mice (n = 11) were studied as controls. In a human study, in vivo adipose tissue biopsies were studied from ICU patients (n = 40) enrolled in a randomized control trial which compared early initiation of parenteral nutrition (PN) versus tolerating nutrient restriction during the first week of ICU stay. Adipose tissue morphology was compared with healthy human controls (n = 13).

RESULTS

Irrespective of nutritional intake, critically ill mice lost weight, fat and fat-free mass. Adipocyte number, proliferation marker Proliferating Cell Nuclear Antigen (PCNA) and adipogenic markers PPARγ and CCAAT/enhancer binding protein-β (C/EBPβ) increased with illness, irrespective of nutritional intake. M2-macrophage accumulation was observed in adipose tissue, liver and lungs of critically ill mice. Macrophage M2-markers correlated with CCL2 expression. In adipose tissue biopsies of critically ill patients, increased adipogenic markers and M2 macrophage accumulation were present irrespective of nutritional intake.

CONCLUSIONS

Adipogenesis and accumulation of tissue M2-macrophages are hallmarks of prolonged critical illness, irrespective of nutritional management. During critical illness, M2-macrophages accumulate not only in adipose tissue, but also in the liver and lungs.

Relação do estado nutricional e dependência de ventilação mecânica em pacientes críticos oncológicos

O estado de má nutrição está ligado com a perda de massa muscular que, por sua vez, pode ser responsável pelo mal prognóstico de pacientes internados em unidade de terapia intensiva (UTI). A relação entre câncer e estado nutricional tem sido amplamente estudada. No entanto, a relação entre estado nutricional e tempo de permanência em ventilação mecânica invasiva (VMI) em pacientes oncológicos ainda não está totalmente esclarecida. O objetivo do estudo foi verificar a relação do estado nutricional dos pacientes oncológicos em UTI com o tempo de permanência em VMI. Participaram do estudo 57 pacientes que estiveram internados na UTI do Hospital Erasto Gaertner e necessitaram de suporte ventilatório invasivo por no mínimo 48 horas. Foram coletados dados referentes ao gênero, à idade, ao índice de massa corporal (IMC), à localização topográfica do câncer, ao estádio clínico (EC) da doença, ao exame anatomopatológico (AP), ao tratamento realizado, ao motivo de internamento na UTI e ao APACHE II. O diagnóstico de desnutrição encontrado foi de 22,81%, 50,88% eram eutróficos, 14,04% tinham sobrepeso e 12,28% eram obesos. O escore de APACHE II obteve média de 26,4 pontos e taxa prevista de mortalidade de 60%. A média geral de tempo sob VMI foi de 11,2 dias. A correlação entre índice de massa corporal e tempo de permanência sob VMI foi de r=0,076 e p=0,575. Concluímos que a maior parte dos pacientes possui classificação nutricional de eutrofia e tempo de permanência sob VMI elevado. Ainda, o estado nutricional avaliado isoladamente não está relacionado com o tempo de permanência em VMI.

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.

Not all critically ill obese patients are the same: the influence of prior comorbidities

Purpose. Data suggest that obesity in critical illness is associated with improved outcomes. We postulate that these findings may be influenced by preillness comorbidities. We sought to determine if critically ill obese patients without significant comorbidity had improved mortality compared to obese patients with multiple comorbidities. Materials and Methods. We analyzed data from a prospective observational study conducted in 3 tertiary ICUs. Severely obese (body mass index ≥30) adults in the ICU for ≥24 hours were identified and classified into limited comorbid illnesses (0-1) or multiple comorbidities (≥2). The primary outcome was the odds ratio (OR) of mortality at day 28. Important secondary outcomes were ICU length of stay and ICU free days in the first 28 days. Results. 598 patients were enrolled; 183 had BMI ≥30. Of these, 38 had limited comorbidities and 145 had multiple comorbidities. In unadjusted analyses, obese patients with multiple comorbidities were 4.70 times (95% CI 1.07–20.6) as likely to die by day 28 compared to patients with limited comorbidities (P = 0.04). After stratifying by admission diagnosis and adjusting for APACHE II score, the influence of comorbidities remained large and trended toward significance (OR 4.28, 95% CI 0.92–20.02, P = 0.06). In adjusted analyses, obese patients with multiple comorbidities tended to have longer ICU duration (3.06 days, SE 2.28, P = 0.18) and had significantly fewer ICU free days in the first 28 days (−3.92 days, SE 1.83, P = 0.03). Conclusions. Not all critically ill obese patients are the same. Those with less comorbidity may have better outcomes than those with multiple comorbidities. This may be important when considering prognosis and discussing care with patients and families.

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.

Obesity is associated with reduced brain tissue oxygen tension after severe brain injury

BACKGROUND

Obesity has been associated with compromised tissue oxygenation and reduced organ perfusion. The brain is critically dependent on oxygen delivery, and reduced brain tissue oxygen tension (P(bt)O(2)) may result in poor outcome after brain injury. We tested the hypothesis that obesity is associated with compromised P(bt)O(2) after severe brain injury.

METHODS

Patients with severe brain injury (GCS score ≤ 8) who underwent continuous P(bt)O(2) monitoring were retrospectively identified from a prospective single-center database. Patients, were classified by body mass index (BMI = weight (kg)/m(2)) and were included if they were obese (BMI ≥ 30) or non-obese (BMI = < 30).

RESULTS

Sixty-nine patients (mean age 46.4 ± 17.0 years) were included. Mean daily P(bt)O(2) was 25.8 (9.6) mmHg for the 28 obese and 31.8 (12.3) mmHg for the 41 non-obese patients (P = 0.03). Initial P(bt)O(2) and mean daily maximum P(bt)O(2) measurements also were significantly lower in obese patients than in non-obese patients. Univariate predictors of compromised P(bt)O(2) (defined as minutes P(bt)O(2) < 20 mmHg) included elevated BMI (P = 0.02), presence of ARDS (P < 0.01), mean PaO(2) (P < 0.01), maximum FiO(2) (P < 0.01), mean PaO(2):FiO(2) (P < 0.01), and mean CVP (P < 0.01). In multivariable analysis, BMI was significantly associated with compromised P(bt)O(2) (P = 0.02). Sex, age, and mean CVP were also identified as significant predictors of compromised P(bt)O(2); ARDS and PF ratio were not.

CONCLUSIONS

In patients with severe brain injury, obesity was found to be an independent predictor of compromised P(bt)O(2). This effect may be mediated through obesity-related pulmonary dysfunction and inadequate compensatory mechanisms.