Outcome of Morbid Obesity in the Intensive Care Unit

Body composition (sarcopenia) in obese patients: implications for care in the intensive care unit

The study of body composition is a rapidly evolving science. In today's environment, there is a great deal of interest in assessing body composition, especially in the obese subject, as a guide to clinical and nutrition interventions. There are some strikingly different compartments of body composition between the obese and the lean patient. We do have the ability to measure body composition accurately, although these techniques can be labor intensive and expensive. The recognition of patients with sarcopenic obesity has identified a potential high-risk patient population. These body composition abnormalities may have even greater importance in the intensive care patient.

Critically ill patients with 2009 H1N1 infection in an Indian ICU

Background and Aims:

The 2009 pandemic influenza A (H1N1) has taken its toll across most parts of India. We aimed to study its epidemiology, clinical characteristics and outcomes from an Indian multidisciplinary intensive care unit (ICU).

Materials and Methods:

All patients admitted to our ICU with a flu-like illness and who tested positive for the 2009 H1N1 by reverse -transcriptase polymerase- chain -reaction assay during a 3 month period were prospectively studied.

Results:

Thirty one patients were admitted to the ICU during the study period. Patients were in the younger age group with a median age of 35 years (IQR: 28.2-42.8). Obesity was the commonest risk factor. Twenty six patients (83.9%) required ventilator support; the median duration of ventilator support was 10 days (IQR: 4-22). Severe hypoxemia was the predominant feature in all patients. Circulatory failure requiring vasopressors occurred in 18 (58.1%) patients and acute kidney injury in 6 (3.2%) patients. Twenty six patients were alive at the end of 28 days; subsequently all except one were discharged. The median duration of hospital stay was 15 (IQR: 8-22.5) days. Increasing APACHE II scores were associated with an increased risk of death (Hazard Ratio: 1.1; CI: 1.08 -1.2; P = 0.04). Mean tidal volumes in non-survivors were significantly lower; this was related to poor lung compliance in this group.

Conclusions:

2009 H1N1 infection caused severe disease in relatively young patients without significant co-morbidities, characterized by severe hypoxemia and the requirement for prolonged mechanical ventilation. Extra-pulmonary organ failure included circulatory and renal failure.

The impact of obesity on critical care resource use and outcomes

Obese patients in the ICU present unique challenges to the health care team and specific challenges to nurses. This article reviews the science and art of resource use for obese patients in the ICU. Staff nurses and advanced practice nurses can make important contributions in evaluating optimal resource use and improving outcomes in this population of vulnerable patients.

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.

Metabolic support of the obese intensive care unit patient: a current perspective

PURPOSE OF REVIEW

Obesity is a widespread condition associated with a variety of mechanical, metabolic, and physiologic changes that affect both health outcomes and delivery of care. Nutrition support is a key element of management during critical illness known to improve outcomes favorably, but is likewise complicated in the presence of obesity. This review serves to discuss the challenges unique to management of critically ill obese patients and an evidence-based approach to nutrition support in this patient population.

RECENT FINDINGS

High-protein, hypocaloric feeding has emerged as a nutrition support strategy capable of reducing hyperglycemia and protein catabolism, while promoting favorable changes in body composition and fluid mobilization. Recent data have shown a protective effect of mild-moderate obesity (BMI 30-39.9 kg/m2), with improved morbidity and mortality outcomes in this subgroup. Therefore, it is unclear whether hypocaloric feeding represents an inferior approach in this subgroup in which weight maintenance may be preferable.

SUMMARY

There are many obstacles that limit provision of nutrition support in the obese ICU patient. Calculating energy needs accurately is extremely problematic due to a lack of reliable prediction equations and a wide variability in body composition among the obese patients. Further research is needed to determine a better approach to estimating energy needs in this population, in addition to validating hypocaloric feeding as the standard approach to nutrition support in the obese patients.

Short- and medium-term survival following coronary artery bypass surgery in British Indo-Asian and white Caucasian individuals: impact of diabetes mellitus

Previous studies have suggested that South Asian (SA) ethnicity is a predictor of poorer outcome after coronary artery bypass grafting (CABG). Our aim was to identify potential reasons for the higher postoperative mortality in SA patients and investigate all these reasons. All individuals undergoing isolated CABG in a tertiary cardiac centre from April 2002 to September 2007. In total, there were 2897 subjects (2623 white subjects; 274 SA subjects) who were included in an observational study showing the effect of ethnicity on the medium-term survival following CABG. Survival at 30 days and survival up to five years (median 2.7 years) were measured. SA subjects undergoing CABG were younger (62+/-9 vs. 66+/-9 years, P<0.001), less obese [body mass index (BMI) 26+/-4 vs. 28+/-4 kg/m(2), P<0.001] and had a higher prevalence of diabetes mellitus (58% vs. 33%, P<0.001) compared with white subjects. Thirty-day mortality was higher in SA subjects (2.6% vs. 1.0%, P=0.02). Non-diabetic SA had similar 30-day mortality, five-year survival and life expectancy compared to non-diabetic white subjects. In contrast, diabetic SA had a higher 30-day mortality (3.8% vs. 1.4%, P=0.01) and worse life expectancy compared to diabetic white subjects. The higher early postoperative mortality observed in SA patients is related to higher incidence of diabetes among them. SA diabetics have a significantly higher postoperative mortality and worse overall life expectancy. Ethnicity per se is not an independent predictor of short- or medium-term survival after CABG.

Obesity and lung inflammation

The prevalence of obesity has increased dramatically worldwide, predisposing individuals to an increased risk of morbidity and mortality due to cardiovascular disease and type 2 diabetes. Less recognized is the fact that obesity may play a significant role in the pathogenesis of pulmonary diseases through mechanisms that may involve proinflammatory mediators produced in adipose tissue that contribute to a low-grade state of systemic inflammation. In animal models, inflammatory responses in the lung have been shown to influence the production of the adipocytokines, leptin and adiponectin, cytokines, acute phase proteins, and other mediators produced by adipose tissue that may participate in immune responses of the lung. An increased adipose tissue mass may also influence susceptibility to pulmonary infections, enhance pulmonary inflammation associated with environmental exposures, and exacerbate airway obstruction in preexisting lung disease. An increased understanding of the mechanisms by which obesity influences pulmonary inflammation may facilitate the development of novel therapeutic interventions for the treatment of lung disease.

Body mass index is associated with the development of acute respiratory distress syndrome

BACKGROUND

The relationship between body mass index (BMI) and development of acute respiratory distress syndrome (ARDS) is unknown.

METHODS

A cohort study of critically ill patients at risk for ARDS was carried out. BMI was calculated from admission height and weight. Patients were screened daily for AECC (American European Consensus Committee)-defined ARDS and 60-day ARDS mortality.

RESULTS

Of 1795 patients, 83 (5%) patients were underweight (BMI <18.5 kg/m(2)), 627 (35%) normal (BMI 18.5-24.9), 605 (34%) overweight (BMI 25-29.9), 364 (20%) obese (BMI 30-39.9) and 116 (6%) severely obese (BMI > or =40). Increasing weight was associated with younger age (p<0.001), diabetes (p<0.0001), higher blood glucose (p<0.0001), lower prevalence of direct pulmonary injury (p<0.0001) and later development of ARDS (p = 0.01). BMI was associated with ARDS on multivariate analysis (OR(adj) 1.24 per SD increase; 95% CI 1.11 to 1.39). Similarly, obesity was associated with ARDS compared with normal weight (OR(adj) 1.66; 95% CI 1.21 to 2.28 for obese; OR(adj) 1.78; 95% CI 1.12 to 2.92 for severely obese). Exploratory analysis in a subgroup of intubated patients without ARDS on admission (n = 1045) found that obese patients received higher peak (p<0.0001) and positive end-expiratory pressures (p<0.0001) than non-obese patients. Among patients with ARDS, increasing BMI was associated with increased length of stay (p = 0.007) but not with mortality (OR(adj) 0.89 per SD increase; 95% CI 0.71 to 1.12).

CONCLUSION

BMI was associated with increased risk of ARDS in a weight-dependent manner and with increased length of stay, but not with mortality. Additional studies are needed to determine whether differences in initial ventilator settings may contribute to ARDS development in the obese.

Dangers, and benefits of the cytokine mediated response to injury and infection

The inflammatory response is essential for survival in an environment where continuous exposure to noxious events threaten the integrity of the organism. However, the beneficial effects of the response are influenced by factors, which disadvantage individuals within a population. These factors include malnutrition, infection, genotype, gender, pre-existing inflammation, and chronic intoxication. Although the inflammatory response is generally successful in dealing with noxious events, life-long exposure to these events takes its toll on the integrity of the body and becomes apparent as chronic disease, atherosclerosis, organ failure, and frailty. Progress in ameliorating the consequences of lifetime exposure to inflammatory events can only occur if a fuller understanding can be obtained of the factors, which influence the persistence and outcome of the inflammatory response at an individual level. A multitude of studies has shown that specific nutrients, diets, and dietary restriction are able to modulate the inflammatory response in the population as a whole. To advance in this area, precise knowledge is needed of how the disadvantageous factors, mentioned above, affect the individual's response to anti-inflammatory nutrients.

Sepsis-induced intestinal microvascular and inflammatory responses in obese mice

Although clinical obesity is associated with increases in the morbidity and mortality of sepsis, little is known about the mechanisms that underlie the influence of obesity on sepsis. The objective of this study was to determine (a) whether obesity is associated with exaggerated inflammatory and thrombogenic responses in the intestinal microvasculature of septic mice and (b) whether these microvascular alterations are related to changes in the serum levels of cytokines that are produced by adipose tissue. Intravital microscopy was used to quantify leukocyte and platelet adhesion in intestinal postcapillary venules of lean wild-type (WT) mice, and two murine models of obesity, that is, ob/ob and db/db mice. Sepsis was induced by cecal ligation and perforation (CLP). Serum cytokine levels were measured using a cytometric bead assay, whereas adipokines were quantified using enzyme-linked immunosorbent assay. Cecal ligation and perforation elicited significant increases in the adhesion of leukocytes and platelets in venules of lean WT mice. These CLP-induced adhesive interactions were much more pronounced in the microvasculature of both ob/ob and db/db mice. Cecal ligation and perforation was associated with significant increases in serum cytokines in both WT and ob/ob mice, but such changes were not detected in db/db mice. However, db/db (but not WT or ob/ob) mice did exhibit significant increases in serum leptin and adiponectin levels after CLP. Sepsis promotes more intense inflammatory and thrombogenic responses in the gut microcirculation of obese mice than in their lean counterparts. The obesity-enhanced microvascular dysfunction in septic mice shows no consistent correlation with serum cytokines or adipokines.

Impact of obesity on hospitalized patients

Obesity is increasing at an alarming rate worldwide and is a risk factor for cardiac disease, diabetes, and stroke. This provides a challenge for the physicians caring for this patient population in the hospital. Skin integrity, medication dosing, testing, and nutrition are all altered by obesity. We summarize some of the current data on caring for the obese inpatient. Unfortunately, few data on this unique inpatient population exist.

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.

Characteristics and outcome of patients admitted to the ICU following bariatric surgery

BACKGROUND

This study evaluates the characteristics and outcome of patients admitted to the ICU following bariatric surgery.

METHODS

Descriptive study. A review of a prospectively collected database of our bariatric surgery procedures from 2003 until 2006 was performed. The study was performed in a tertiary level, mixed medical and surgical, adult ICU of a large referral hospital.

RESULTS

Of the 265 patients undergoing bariatric surgery (mainly gastroplasties and Roux-en-Y gastric bypasses), 22 (8%) were admitted to the ICU, of which 14 (64%) were on an elective basis and eight (36%) emergently. Hospital length of stay (LOS) for all patients was 4.5 days and ICU LOS was 12 days. Most elective admissions were standard procedure because of obstructive sleep apnea (OSA) or super obesity, with a median ICU stay of 1 day. Emergent admissions were mainly done after emergent surgery due to surgical complications and had a median ICU stay of 8 days. Only two patients needed intensive care for more than 3 days. There were no deaths during ICU stay.

CONCLUSIONS

The ICU admission rate in our report is 8%. This study showed that 32 ICU days are needed per 100 diverse bariatric procedures. Most patients are admitted to the ICU for only a few days and the majority of the admissions is planned.

Endotoxaemia leads to major increases in inflammatory adipokine gene expression in white adipose tissue of mice

The proposition that white adipose tissue is involved in the inflammatory response and metabolic dysregulation of endotoxaemia has been examined. Mice were injected with lipopolysaccharide (LPS; 25 mg/kg) and epididymal, perirenal and subcutaneous adipose tissue removed 4 or 24 h later. The expression of genes encoding key inflammation-related adipokines was measured by real-time polymerase chain reaction. At 24 h after the administration of LPS, there was no change in leptin mRNA level, and adiponectin mRNA fell. However, major increases in TNFalpha, MCP-1 (up to 40-fold) and IL-6 (up to 250-fold) mRNA levels were evident; a substantial elevation in these mRNAs occurred by 4 h, and adipose tissue IL-6 protein also increased (three- to eightfold). At 24 h, the responses in the subcutaneous depot were much lower than in epididymal and perirenal adipose tissue, but at 4 h, the subcutaneous tissue showed major increases in IL-6, MCP-1 and TNFalpha gene expression. In contrast to the inflammatory adipokines, the mRNA level of two macrophage markers, F4/80 and MAC-1, was unaltered in adipose tissue during endotoxaemia. Expression of the hypoxia-sensitive transcription factor, HIF-1alpha, gene was increased at both 4 and 24 h, and HIF-1alpha protein was elevated at 4 h, suggesting that the tissue was hypoxic. It is concluded that white adipose tissue may play an important role in the production of inflammatory mediators in endotoxaemia.

Influence of obesity on sepsis

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

Successful cardiopulmonary resuscitation in a morbidly obese patient with airway obstruction 10 days after tracheostomy

Tracheostomy is often performed in patients requiring prolonged ventilatory support. Tracheostomy tube obstruction caused either by blood clots, mucous plugs, tube malposition and tissue granulation can lead to life-threatening complications. The risk of such complications is markedly increased in morbidly obese individuals. Here we report an incident in an 81-year-old, morbidly obese, male patient who sustained airway obstruction which resulted in cardiac arrest 10 days after tracheostomy. A 17-cm 10-ng blood clot in a tracheobronchial configuration was found to cause the obstruction. It was removed and the patient recovered after resuscitation. The etiology of the obstruction, specific management, and recommendations are discussed.

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

OBJECTIVE

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

DESIGN

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

DATA SOURCE

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

SETTING

Not applicable.

PATIENTS

A total of 62,045 critically ill subjects.

INTERVENTIONS

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

MEASUREMENTS AND MAIN RESULTS

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

CONCLUSION

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

Obesity and immune cell counts in women

Obesity is common in women and is associated with a number of adverse health outcomes including cardiovascular disease, infectious diseases, and cancer. We explore the relationship between obesity and immune cell counts in women in a longitudinal study of 322 women from 1999 through 2003 enrolled as HIV-negative comparators in the Women's Interagency HIV Study. Body mass index (BMI, kg/m(2)) was categorized as normal weight (BMI 18.5-24.9), overweight (BMI 25-29.9), obese (BMI 30-34.9), and morbidly obese (BMI >/=35). CD4 and CD8 counts and percents and total lymphocyte and white blood cell (WBC) counts were measured annually using standardized techniques. A mixed model repeated measures analysis was performed using an autoregressive correlation matrix. At the index visit, 61% of women were African American; mean age was 35 years, and median BMI was 29 kg/m(2). Immunologic parameters were in the reference range (median CD4 count, 995 cells/mm(3); CD8 count, 488 cells/mm(3); total lymphocyte count, 206 cells/mm(3); median WBC, 6 x 10(3) cells/mm(3)). In multivariate analyses, being overweight, obese, or morbidly obese were independently associated with higher CD4, total lymphocyte, and WBC counts than being normal weight; morbid obesity was associated with a higher CD8 count. The strongest associations between body weight and immune cell counts were demonstrated in the morbidly obese. Increasing body weight is associated with higher CD4, CD8, total lymphocyte, and WBC counts in women. Investigation into the impact of obesity on immune function and long-term adverse outcomes is needed.

Anesthetic management of the morbidly obese parturient

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Impaired Mononuclear Cell Immune Function in Extreme Obesity Is Corrected by Weight Loss

BACKGROUND

Obesity is associated with an increased prevalence and severity of infections. The mechanism(s) responsible for the increased risk of infections is unclear. We evaluated the effects of excessive adiposity and weight loss on peripheral blood mononuclear cell (PBMC) chemokine (macrophage chemoattractant protein-1 [MCP-1) and cytokine (interferon-gamma [IFNgamma]) production, which is an important component of the immune response to infectious pathogens.

METHODS

Lipopolysaccharide (LPS)and phorbol 12-myristate 13-acetate plus ionomycin (PMA + I)-stimulated PBMC MCP-1 and IFNgamma production were determined in six extremely obese subjects (body mass index [BMI] = 62.4 +/- 8.6 kg/m(2)) before and 1 year after gastric bypass surgery and in six age-matched lean subjects (BMI = 22.7 +/- 1.4 kg/m(2)).

RESULTS

At baseline, LPS-stimulated MCP-1 production and PMAI-stimulated IFNgamma production by PBMCs were 93.6% +/- 4.9% and 88.8% +/- 9.6% lower, respectively, in obese than in lean subjects (p < 0.03). Obese subjects lost 30.3% +/- 10.6% of their body weight at 1 year after gastric bypass surgery (p < 0.001). Weight loss completely restored LPS-stimulated MCP-1 production and PMA+I-stimulated IFNgamma production in obese subjects to normal.

CONCLUSIONS

Agonist-stimulated production of IFNgamma and MCP-1 are markedly suppressed in subjects with extreme obesity. Weight loss completely normalizes the ability of stimulated PBMCs to produce MCP-1 and IFNgamma. These findings could have important implications in understanding the increased risk of infections associated with obesity, and demonstrate a unique beneficial effect of weight loss on immune function.

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

Introduction

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

Methods

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

Results

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

Conclusion

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

Leptin: at the crossroads of energy balance and systemic inflammation

In addition to playing a central role in energy homeostasis, leptin is also an important player in the inflammatory response. Systemic inflammation is accompanied by fever (less severe cases) or hypothermia (more severe cases). In leptin-irresponsive mutants, the hypothermia of systemic inflammation is exaggerated, presumably due to the enhanced production and cryogenic action of tumor necrosis factor (TNF)-alpha. Mechanisms that exaggerate hypothermia can also attenuate fever, particularly in a cool environment. Another common manifestation of systemic inflammation is behavioral depression. Along with the production of interleukin (IL)-1beta, this manifestation is exaggerated in leptin-irresponsive mutants. The enhanced production of TNF-alpha and IL-1beta may be due, at least in part, to insufficient activation of the anti-inflammatory hypothalamo-pituitary-adrenal axis by immune stimuli in the absence of leptin signaling. In experimental animals and humans that are responsive to leptin, suppression of leptin production under conditions of negative energy balance (e.g., fasting) can exaggerate both hypothermia and behavioral depression. Since these manifestations aid energy conservation, exaggeration of these manifestations under conditions of negative energy balance is likely to be beneficial.

Obesity and infection

Obesity increases morbidity and mortality through its multiple effects on nearly every human system. However, the various aspects of the association between obesity and infection have not been reviewed. Thus, we reviewed the relevant literature focusing on clinical aspects of this association. Obesity has a clear but not yet precisely defined effect on the immune response through a variety of immune mediators, which leads to susceptibility to infections. Data on the incidence and outcome of specific infections, especially community-acquired infections, in obese people are so far limited. The available data suggest that obese people are more likely than people of normal weight to develop infections of various types including postoperative infections and other nosocomial infections, as well to develop serious complications of common infections. Large prospective studies are required to further define the burden of infectious morbidity and mortality conferred by obesity.

Circulating concentrations of adiponectin, an endogenous lipopolysaccharide neutralizing protein, decrease in rats with polymicrobial sepsis

BACKGROUND

Adiponectin is an anti-inflammatory cytokine that is specifically and abundantly produced by adipocytes as a secretory protein. A direct interaction between adiponectin and lipopolysaccharide (LPS) is not fully understood. To elucidate the effects of adiponectin on LPS, we first investigated interactions between recombinant adiponectin and LPS.

MATERIALS AND METHODS

Various concentrations of LPS (50, 500, and 5000 pg/ml) and recombinant adiponectin (1, 10, and 100 microg/ml) were incubated for 1 h. The limulus amoebocyte lysate (LAL) activities in the mixture were measured. Interactions between adiponectin (100 microg/ml) and LPS (100 and 300 microg/ml) were also analyzed in Western blotting. Next, we determined plasma adiponectin, tumor necrosis factor-alpha (TNF-alpha), and endotoxin levels at 1.5, 3, and 24 h after onsets of rodent polymicrobial sepsis induced by cecal ligation and puncture (CLP).

RESULTS

The incubation with adiponectin significantly and dose-dependently suppressed LAL activity in the mixture compared to control. Western blotting revealed that adiponectin incubated with LPS shifted to a higher mass. In the animal model of sepsis, both plasma endotoxin and TNF-alpha levels after CLP gradually increased and were significantly higher at 3, 24 h compared to those after sham operation. On the contrary, plasma adiponectin levels after CLP gradually decreased and were significantly lower at 3, 24 h compared to those after sham operation. Plasma adiponectin levels were negatively correlated with plasma endotoxin levels (r = -0.77, P < 0.01).

CONCLUSIONS

Our results indicate that adiponectin might neutralize LPS in vitro and diminish LPS activity in rats with polymicrobial sepsis. These findings suggest that the anti-inflammatory effects of adiponectin are in part likely because of neutralization of LPS activity.