Physiological and management implications of obesity in critical illness

Machine learning models and nomogram based on clinical, laboratory profiles and skeletal muscle index to predict pancreatic fistula after pancreatoduodenectomy

Background

Postoperative pancreatic fistula (POPF) is a perilous complication that may arise subsequent to pancreaticoduodenectomy (PD). In recent times, there has been an escalating interest in employing machine learning (ML) techniques to aid in treatment decision-making. The purpose of this research is to assess the effectiveness of ML in comparison to conventional models, while also conducting an initial evaluation of the predictive capability of skeletal muscle index (SMI) concerning POPF.

Methods

This retrospective observational study was carried out at The First Affiliated Hospital of Wenzhou Medical University from January 2012 to January 2021, encompassing data from 269 patients who underwent PD. After identifying independent factors associated with the condition, a logistic regression model was employed to construct a nomogram, alongside the establishment of five ML models. To assess their effectiveness, the best-performing ML model and nomogram were evaluated on a separate test group comprising 77 additional patients. The evaluation involved comparing the area under the curve (AUC) and Brier score.

Results

Among the 269 patients studied, the incidence of POPF was found to be 56.9%, with 106 patients (69.3%) experiencing clinically-relevant POPF. We identified six independent factors associated with POPF, including body mass index (BMI), SMI, pancreatic duct dilatation, tumor size, triglyceride levels, and the ratio of aspartate aminotransferase to alanine aminotransferase (AST/ALT) on the first postoperative day. When evaluated on the test set, the Gaussian Naive Bayes (GNB) model, which was the best-performing ML model, achieved an AUC of 0.824 and a Brier score of 0.175. The corresponding performance indicators for the nomogram were 0.844 for AUC and 0.165 for the Brier score.

Conclusions

This study found that there is minimal difference between ML and the nomogram based on logistic regression in predicting POPF. Additionally, SMI shows promise as a potential and practical tool for assessing the risk of POPF.

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.

Approach to the Physiologically Challenging Endotracheal Intubation in the Intensive Care Unit

Endotracheal intubation for airway management is a common procedure in the ICU. Intubation may be difficult due to anatomic airway abnormalities but also due to physiologic derangements that predispose patients to cardiovascular collapse during the procedure. Results of studies demonstrate a high incidence of morbidity and mortality associated with airway management in the ICU. To reduce the likelihood of complications, medical teams must be well versed in the general principles of intubation and be prepared to manage physiologic derangements while securing the airway. In this review, we present relevant literature on the approach to endotracheal intubation in the ICU and provide pragmatic recommendations relevant to medical teams performing intubations in patients who are physiologically unstable.

Identifying Comorbid Subtypes of Patients With Acute Respiratory Failure

BACKGROUND

Patients with acute respiratory failure have multiple risk factors for disability following their intensive care unit stay. Interventions to facilitate independence at hospital discharge may be more effective if personalized for patient subtypes.

OBJECTIVES

To identify subtypes of patients with acute respiratory failure requiring mechanical ventilation and compare post-intensive care functional disability and intensive care unit mobility level among subtypes.

METHODS

Latent class analysis was conducted in a cohort of adult medical intensive care unit patients with acute respiratory failure receiving mechanical ventilation who survived to hospital discharge. Demographic and clinical medical record data were collected early in the stay. Clinical characteristics and outcomes were compared among subtypes by using Kruskal-Wallis tests and χ2 tests of independence.

RESULTS

In a cohort of 934 patients, the 6-class model provided the optimal fit. Patients in class 4 (obesity and kidney impairment) had worse functional impairment at hospital discharge than patients in classes 1 through 3. Patients in class 3 (alert patients) had the lowest magnitude of functional impairment (P < .001) and achieved the earliest out-of-bed mobility and highest mobility level of all subtypes (P < .001).

CONCLUSIONS

Acute respiratory failure survivor subtypes identified from clinical data available early in the intensive care unit stay differ in post-intensive care functional disability. Future research should target high-risk patients in early rehabilitation trials in the intensive care unit. Additional investigation of contextual factors and mechanisms of disability is critical to improving quality of life in acute respiratory failure survivors.

Low preoperative serum fibrinogen level is associated with postoperative acute kidney injury in patients with in acute aortic dissection

OBJECTIVE

Acute kidney injury (AKI) after cardiac surgery is associated with serious complication and high risk of mortality. The relationship between hemostatic system and the prognosis of patients with acute type A aortic dissection (ATAAD) has not been evaluated. The purpose of this study was to investigate the association between preoperative serum fibrinogen level and risk of postoperative AKI in patients with ATAAD.

METHODS

A total of 172 consecutive patients undergoing urgent aortic arch surgery for ATAAD between April 2020 and December 2021 were identified from Beijing Anzhen Hospital aortic surgery database. The primary outcome was postoperative AKI as defined by the Kidney Disease Improving Global Outcomes (KDIGO) criteria. The univariate and multivariate logistic regression analysis were done to assess the independent predictors of risk for postoperative AKI. Receiver operating characteristic (ROC) curve was generated to evaluate the predictive probabilities of risk factors for AKI.

RESULTS

In our study, 51.2% (88/172) patients developed postoperative AKI. Multivariate logistic regression analysis identified low preoperative serum fibrinogen level (OR, 1.492; 95% CI, 1.023 to 2.476; p = 0.021) and increased body mass index (BMI) (OR, 1.153; 95% CI, 1.003 to 1.327; p = 0.046) as independent predictors of postoperative AKI in patients with ATAAD. A mixed effect analysis of variance modeling revealed that obese patients with low preoperative serum fibrinogen level had higher incidence of postoperative AKI (p = 0.04). The ROC curve indicated that low preoperative serum fibrinogen level was a significant predictor of AKI [area under the curve (AUC), 0.771; p < 0.001].

CONCLUSIONS

Low preoperative serum fibrinogen level and obesity were associated with the risk of postoperative AKI in patients with ATAAD. These data suggested that low preoperative serum fibrinogen level was preferred marker for predicting the postoperative AKI, especially in obese patients with ATAAD.

The association between BMI trajectories and bronchopulmonary dysplasia among very preterm infants

OBJECTIVE

To investigate the association between change in body mass index (BMI) from birth to 36 weeks gestation (ΔBMI) and bronchopulmonary dysplasia (BPD) among infants born <30 weeks gestation.

METHODS

This was a multicenter retrospective cohort study (2015-2018) of infants born <30 weeks gestation and alive at ≥34 weeks corrected. Main exposure was a change in BMI z score from birth to 36 weeks corrected age grouped into quartiles of change. Association between ΔBMI z scores and BPD was assessed using generalized linear mixed models.

RESULTS

Among 772 included infants, 51% developed BPD. From birth to 36 weeks CGA, the weight z score of infants with BPD decreased less than for BPD-free infants, despite a greater decrease in length z score and similar caloric intake resulting in increases in BMI z score (median [IQR], 0.16 [-0.64; 1.03] vs -0.29 [-1.03; 0.49]; P < 0.01). In the adjusted analysis, higher ΔBMI z score quartiles were associated with higher odds of BPD (Q3 vs Q2, AOR [95% CI], 2.02 [1.23; 3.31] and Q4 vs Q2, AOR [95% CI], 2.00 [1.20; 3.34]).

CONCLUSION

Among preterm infants, an increase in BMI z score from birth to 36 weeks corrected is associated with higher odds of BPD.

IMPACT

Preterm infants with evolving lung disease often experience disproportionate growth in the neonatal period. In this multicenter cohort study, increases in BMI z score from birth to 36 weeks CGA were associated with higher odds of BPD. Despite similar caloric intake, infants with BPD had a higher weight- but lower length-for-age, resulting in higher BMI z score compared to BPD-free infants. This suggests that infants with evolving BPD may require different growth and nutritional targets compared to BPD-free infants.

Drug dosing in hospitalized obese patients with COVID-19

Obesity is highly prevalent in hospitalized patients admitted with COVID-19. Evidence based guidelines are available for COVID-19-related therapies but dosing information specific to patients with obesity is lacking. Failure to account for the pharmacokinetic alterations that exist in this population can lead to underdosing, and treatment failure, or overdosing, resulting in an adverse effect. The objective of this manuscript is to provide clinicians with guidance for making dosing decisions for medications used in the treatment of patients with COVID-19. A detailed literature search was conducted for medications listed in evidence-based guidelines from the National Institutes of Health with an emphasis on pharmacokinetics, dosing and obesity. Retrieved manuscripts were evaluated and the following prioritization strategy was used to form the decision framework for recommendations: clinical outcome data > pharmacokinetic studies > adverse effects > physicochemical properties. Most randomized controlled studies included a substantial number of patients who were obese but few had large numbers of patients more extreme forms of obesity. Pharmacokinetic data have described alterations with volume of distribution and clearance but this variability does not appear to warrant dosing modifications. Future studies should provide more information on size descriptors and stratification of data according to obesity and body habitus.

Management of Respiratory Distress and Failure in Morbidly and Super Obese Patients During Critical Care Transport

Morbidly and super obese patients are a unique patient population that presents critical care transport providers with unique clinical and logistical challenges in the setting of respiratory distress and failure. These patients are more likely to have chronic respiratory issues at baseline, unique anatomic and physiologic abnormalities, and other comorbidities that leave them poorly able to tolerate respiratory illness or injury. This requires specialized understanding of their respiratory mechanics as well as how to tailor standard treatment modalities, such as noninvasive ventilation, to meet their needs. Also, careful and deliberate planning is required to address the specific anatomic and physiologic characteristics of this population if intubation and mechanical ventilation are needed. Finally, their dimensions and weight also have distinct consequences on transport vehicle considerations. This article reviews the pathophysiology, management, and critical care transport considerations for this unique patient population in respiratory distress and failure.

Cardiovascular disease and COVID-19: a consensus paper from the ESC Working Group on Coronary Pathophysiology & Microcirculation, ESC Working Group on Thrombosis and the Association for Acute CardioVascular Care (ACVC), in collaboration with the European Heart Rhythm Association (EHRA)

The cardiovascular system is significantly affected in coronavirus disease-19 (COVID-19). Microvascular injury, endothelial dysfunction, and thrombosis resulting from viral infection or indirectly related to the intense systemic inflammatory and immune responses are characteristic features of severe COVID-19. Pre-existing cardiovascular disease and viral load are linked to myocardial injury and worse outcomes. The vascular response to cytokine production and the interaction between severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and angiotensin-converting enzyme 2 receptor may lead to a significant reduction in cardiac contractility and subsequent myocardial dysfunction. In addition, a considerable proportion of patients who have been infected with SARS-CoV-2 do not fully recover and continue to experience a large number of symptoms and post-acute complications in the absence of a detectable viral infection. This conditions often referred to as 'post-acute COVID-19' may have multiple causes. Viral reservoirs or lingering fragments of viral RNA or proteins contribute to the condition. Systemic inflammatory response to COVID-19 has the potential to increase myocardial fibrosis which in turn may impair cardiac remodelling. Here, we summarize the current knowledge of cardiovascular injury and post-acute sequelae of COVID-19. As the pandemic continues and new variants emerge, we can advance our knowledge of the underlying mechanisms only by integrating our understanding of the pathophysiology with the corresponding clinical findings. Identification of new biomarkers of cardiovascular complications, and development of effective treatments for COVID-19 infection are of crucial importance.

Population Pharmacokinetics of Polymyxin B in Obese Patients for Resistant Gram-Negative Infections

Polymyxin B is an effective but potentially nephrotoxic antibiotic that is commonly used to treat resistant Gram-negative infections. As a weight-based dosing drug, obese patients may be at a high risk of nephrotoxicity. However, the pharmacokinetics and dosing recommendations for this population are currently lacking. This study aimed to describe the polymyxin B population pharmacokinetics and to evaluate pharmacokinetic/pharmacodynamics (PK/PD) target attainment for obese patients. This study included 26 patients (body mass index, BMI >30) who received polymyxin B for ≥3 days. The total body weight (TBW) ranged from 75 to 125 kg, and the BMI ranged from 30.04 to 40.35. A two-compartment model adequately described the data using Phoenix NLME software. Monte Carlo simulation was used to assess polymyxin B exposure and the probability of target attainment (PTA). As a result, body weight had no significant effect on polymyxin B pharmacokinetics. According to model-based simulation, adjusted body weight (ABW)-based regimens had a high probability of achieving optimal exposure with minimal toxicity risk by comparing TBW and ideal body weight (IBW)-based regimens. The fixed dose of 125 mg or 150 mg q12h had a high toxicity risk. PTA results showed that TBW, IBW, and ABW-based regimens had similar PTA values. Therefore, for obese patients, ABW-based regimens but with a daily dose <250 mg have a high likelihood of achieving an AUC_ss,24h of 50-100 mg h/L and attaining PK/PD targets with the MIC ≤0.5 mg/L.

The effect of body mass index on the development of acute kidney injury and mortality in intensive care unit: is obesity paradox valid?

BACKGROUND

The conflicting results of studies on intensive care unit (ICU) mortality of obese patients and obese patients with acute kidney injury (AKI) reveal a paradox within a paradox. The aim of this study was to determine the effects of body mass index and obesity on AKI development and ICU mortality.

METHODS

The 4,459 patients treated between January 2015 and December 2019 in the ICU at a Tertiary Care Center in Turkey were analyzed retrospectively.

RESULTS

AKI developed more in obese patients with 69.8% (620). AKI development rates were similar in normal-weight (65.1%; 1172) and overweight patients (64.9%; 1149). The development of AKI in patients who presented with cerebrovascular diseases was higher in obese patients (81; 76.4%) than in normal-weight (158; 62.7%) and overweight (174; 60.8%) patients (p < 0.05). The risk of developing AKI was approximately 1.4 times (CI 95% = 1.177-1.662) higher in obese patients than in normal-weight patients. Dialysis was used more frequently in obese patients (24.3%, p < 0.001), who stayed longer in the ICU (p < 0.05). It was determined that the development of AKI in normal-weight and overweight patients increased mortality (p < 0.001) and that there was not a difference in mortality rates between obese patients with and without AKI.

CONCLUSION

The risk of AKI development was higher in obese patients but not in those who were in serious conditions. Another paradox was that the development of AKI was associated with a higher mortality rate in normal-weight and overweight patients, but not in obese patients. Cerebrovascular diseases as a cause of admission pose additional risks for AKI.

Obesity in the Critical Care Setting

The prevalence of obesity continues to rise and is caused by many factors. Obesity places patients at risk for high blood pressure, diabetes, heart disease, and cancer. Although obesity in the normal population is associated with increased morbidity and mortality, obesity in critically ill patients has lower mortality. This is referred to as the obesity paradox, and although not fully understood, involves several mechanisms that demonstrate a protective factor in critically ill obese patients. However, despite the benefit, the management of critically ill obese patients faces many challenges.

Association between admission body mass index and outcomes in critically ill children: A systematic review and meta-analysis

BACKGROUND & AIMS

The association between nutritional status at pediatric intensive care unit (PICU) admission with clinical outcomes remains unclear. We conducted this systematic review to summarize the overall impact of PICU admission body mass index (BMI) on clinical outcomes.

METHODS

We searched the following medical databases from inception through May 2020: PubMed, Excerpta Medica database (Embase), Cumulative Index of Nursing and Allied Health Literature (CINAHL), Cochrane Library, and Web of Science. We included studies on patients ≤18 years old admitted to a PICU that investigated the effect of BMI on mortality, PICU or hospital length of stay (LOS), or duration of mechanical ventilation (MV). Classification of underweight, overweight, and obese were based on each study's criteria.

RESULTS

There was a total of 21,558 patients from 20 included studies. 12,936 (60.0%), 2965 (13.8%), 2182 (10.1%), 3348 (15.5%) were normal weight, underweight, overweight, and obese patients, respectively. Relative to normal weight patients, underweight (OR 1.32, 95% CI 0.89-1.98; p = 0.171) and overweight/obese patients (OR 1.10, 95% CI 0.86-1.42; p = 0.446) did not have an increase risk in mortality. There was also no difference in duration of MV, PICU and hospital LOS between all three weight categories. Included studies were heterogeneous and lacked standardized nutritional categorization. Sensitivity analysis including only studies that used BMI z-scores as nutritional classification (n = 5) revealed that underweight patients had higher odds of mortality compared to patients with normal weight (OR 1.61, 95% CI 1.35-1.92; p < 0.001); studies that used percentiles as classification did not reveal any differences in mortality. Sensitivity analysis including only studies containing mixed PICU cohorts (i.e., excluding specialized cohorts e.g., congenital heart surgeries, burns) revealed higher mortality odds in underweight patients (OR 1.53, 95% CI 1.25-1.87; p < 0.001) and overweight/obese patients (OR 1.51, 95% CI 1.14-2.01; p = 0.004) relative to normal weight patients.

CONCLUSIONS

Our systematic review did not reveal any association between PICU admission BMI status and outcomes in critically ill children. Further investigation with standardized nutrition status classification on admission, stratified by patient subgroups, is needed to clarify the association between nutritional status and clinical outcomes of PICU patients.

The Protective Effects of Butorphanol on Pulmonary Function of Patients with Obesity Undergoing Laparoscopic Bariatric Surgery: a Double-Blind Randomized Controlled Trial

BACKGROUND

Obesity is a risk factor for postoperative pulmonary complications (PPCs). Recent studies have reported the pulmonary protective role of the kappa opioid receptor (KOR). Butorphanol is a narcotic with strong KOR agonist action, and the role in pulmonary protection is uncertain. Here, we hypothesized that butorphanol exerts protective effects on pulmonary function in patients with obesity undergoing laparoscopic bariatric surgery.

METHODS

Patients with a body mass index ≥ 30 kg/m² scheduled for laparoscopic bariatric surgery were randomized to receive butorphanol or normal saline. Butorphanol was administered as an initial loading dose of 10 μg/kg at 5 min before induction followed by 5 μg/(kg h) during surgery. The primary outcome was arterial-alveolar oxygen tension ratio (a/A ratio). Secondary outcomes included other pulmonary variables, biomarkers reflecting pulmonary injury, and incidence of PPCs within 7 days after surgery.

RESULTS

Patients in the butorphanol group had a significantly higher a/A ratio at 1 h after the operation began (68 ± 7 vs. 55 ± 8, P < 0.001), end of the operation (73 ± 8 vs. 59 ± 7, P < 0.001), and 1 h after extubation (83 ± 9 vs. 70 ± 5, P < 0.001) compared with those in the control group. In addition, in the butorphanol group, dead space to tidal volume ratios were significantly lower than those in the control group at the same time points (all P < 0.001). In the control group, the levels of biomarkers reflecting pulmonary injury were significantly higher than those in the butorphanol group at 3 h, 6 h, 12 h, and 24 h postoperatively (P < 0.001). The incidence of PPCs was similar in both groups.

CONCLUSION

Butorphanol administration protected pulmonary function by improving oxygenation and reducing dead space ventilation in patients with obesity undergoing laparoscopic bariatric surgery. Butorphanol may therefore provide clinical benefits in patients with obesity.

Sex Differences in the Association of Body Composition and Cardiovascular Mortality

Background To determine whether differences in body composition contribute to sex differences in cardiovascular disease (CVD) mortality, we investigated the relationship between components of body composition and CVD mortality in healthy men and women. Methods and Results Dual energy x-ray absorptiometry body composition data from the National Health and Nutrition Examination Survey 1999-2004 and CVD mortality data from the National Health and Nutrition Examination Survey 1999-2014 were evaluated in 11 463 individuals 20 years of age and older. Individuals were divided into 4 body composition groups (low muscle mass-low fat mass-the referent; low muscle-high fat; high muscle-low fat, and high muscle-high fat), and adjusted competing risks analyses were performed for CVD versus non-CVD mortality. In women, high muscle/high fat mass was associated with a significantly lower adjusted CVD mortality rate (hazard ratio [HR], 0.58; 95% CI, 0.39-0.86; P=0.01), but high muscle/low fat mass was not. In men, both high muscle-high fat (HR, 0.74; 95% CI, 0.53-1.04; P=0.08) and high muscle-low fat mass (HR, 0.40; 95% CI, 0.21-0.77; P=0.01) were associated with lower CVD. Further, in adjusted competing risks analyses stratified by sex, the CVD rate in women tends to significantly decrease as normalized total fat increase (total fat fourth quartile: HR, 0.56; 95% CI, 0.34-0.94; P<0.03), whereas this is not noted in men. Conclusions Higher muscle mass is associated with lower CVD and mortality in men and women. However, in women, high fat, regardless of muscle mass level, appears to be associated with lower CVD mortality risk. This finding highlights the importance of muscle mass in healthy men and women for CVD risk prevention, while suggesting sexual dimorphism with respect to the CVD risk associated with fat mass.

Obesity and impaired barrier function after shock: A biomimetic in vitro model using microfluidics

BACKGROUND

Impaired microvascular perfusion in the obese patient has been linked to chronic adverse health consequences. The impact on acute illnesses including trauma, sepsis, and hemorrhagic shock (HS) is uncertain. Studies have shown that endothelial glycocalyx and vascular endothelial derangements are causally linked to perfusion abnormalities. Trauma and HS are also associated with impaired microvascular perfusion in which glycocalyx injury and endothelial dysfunction are sentinel events. We postulate that obesity may impact the adverse consequences of HS on the vascular barrier. This was studied in vivo in a biomimetic model of HS using microfluidic technology.

METHODS

Human umbilical vein endothelial cell monolayers were established in a microfluidic device. Cells were exposed to standard or biomimetic shock conditions (hypoxia plus epinephrine) followed by perfusion from plasma obtained from obese or nonobese subjects. Endothelial glycocalyx and endothelial cellular injury were then determined.

RESULTS

Plasma from nonobese patients completely reversed glycocalyx and endothelial vascular barrier injury. Plasma from obese patients was only partially protective and was associated with differences in adipokines and other substances in the plasma of these patients.

CONCLUSION

Our study supports that obesity impairs HS resuscitation. This may be due to microrheological differences between nonobese and obese individuals and may contribute to the poorer outcome in this patient population.

Factors associated with shockable versus non-shockable rhythms in patients with in-hospital cardiac arrest

AIM

To identify factors associated with the initial rhythm in patients with in-hospital cardiac arrest and to assess whether potential differences in outcomes based on the initial rhythm can be explained by patient and event characteristics.

METHODS

Adult patients (≥18 years old) with in-hospital cardiac arrest in 2017 and 2018 were included from the Danish In-Hospital Cardiac Arrest Registry (DANARREST). We used population-based registries to obtain data on comorbidities, cardiac procedures, and medications. Unadjusted and adjusted risk ratios (RRs) for initial rhythm, return of spontaneous circulation (ROSC), and survival were estimated in separate models including an incremental number of prespecified variables.

RESULTS

A total of 3422 patients with in-hospital cardiac arrest were included, of which 639 (19%) had an initial shockable rhythm. Monitored cardiac arrest, witnessed cardiac arrest, and specific cardiac diseases (i.e. ischemic heart disease, dysrhythmias, and valvular heart disease) were associated with initial shockable rhythm. Conversely, higher age, female sex, and specific non-cardiovascular comorbidities (e.g. overweight and obesity, renal disease, and pulmonary cancer) were associated with an initial non-shockable rhythm. Initial shockable rhythm remained strongly associated with increased ROSC (RR = 1.63, 95%CI 1.51-1.76), 30-day survival (RR = 2.31, 95%CI 2.02-2.64), and 1-year survival (RR = 2.36, 95%CI 2.02-2.76) compared to initial non-shockable rhythm in the adjusted analyses.

CONCLUSION

In this study, specific patient and cardiac arrest characteristics were associated with initial rhythm in patients with in-hospital cardiac arrest. However, differences in patient and cardiac arrest characteristics did not fully explain the association with survival for initial shockable rhythm compared to a non-shockable rhythm.

ICU admission body composition: skeletal muscle, bone, and fat effects on mortality and disability at hospital discharge-a prospective, cohort study

Background

Reduced body weight at the time of intensive care unit (ICU) admission is associated with worse survival, and a paradoxical benefit of obesity has been suggested in critical illness. However, no research has addressed the survival effects of disaggregated body constituents of dry weight such as skeletal muscle, fat, and bone density.

Methods

Single-center, prospective observational cohort study of medical ICU (MICU) patients from an academic institution in the USA. Five hundred and seven patients requiring CT scanning of chest or abdomen within the first 24 h of ICU admission were evaluated with erector spinae muscle (ESM) and subcutaneous adipose tissue (SAT) areas and with bone density determinations at the time of ICU admission, which were correlated with clinical outcomes accounting for potential confounders.

Results

Larger admission ESM area was associated with decreased odds of 6-month mortality (OR per cm², 0.96; 95% CI, 0.94–0.97; p < 0.001) and disability at discharge (OR per cm², 0.98; 95% CI, 0.96–0.99; p = 0.012). Higher bone density was similarly associated with lower odds of mortality (OR per 100 HU, 0.69; 95% CI, 0.49–0.96; p = 0.027) and disability at discharge (OR per 100 HU, 0.52; 95% CI, 0.37–0.74; p < 0.001). SAT area was not significantly associated with these outcomes’ measures. Multivariable modeling indicated that ESM area remained significantly associated with 6-month mortality and survival after adjusting for other covariates including preadmission comorbidities, albumin, functional independence before admission, severity scores, age, and exercise capacity.

Conclusion

In our cohort, ICU admission skeletal muscle mass measured with ESM area and bone density were associated with survival and disability at discharge, although muscle area was the only component that remained significantly associated with survival after multivariable adjustments. SAT had no association with the analyzed outcome measures.

Complications and Failure to Rescue After Abdominal Surgery for Trauma in Obese Patients

BACKGROUND

Although obesity is considered an epidemic in the United States, there is mixed evidence regarding the impact of obesity on outcomes after traumatic injury and major surgery. We hypothesized that obese patients undergoing trauma laparotomy would be at increased risk of failure to rescue (FTR), defined as death after a complication.

METHODS

We analyzed trauma registry data for adult patients who underwent abdominal exploration for trauma at all 30 level I and II Pennsylvania trauma centers, 2011-2014. We used competing risks regression to identify significant risk factors for complications. We used multivariable logistic regression to identify significant risk factors for FTR.

RESULTS

Of 95,806 admitted patients, 15,253 (15.9%) were categorized as obese. Overall, 3228 (3.4%) underwent laparotomy, including 2681 (83.1%) nonobese and 547 (17.0%) obese patients. Among obese patients, 47.2% had at least one complication and 28.7% had two or more complications, compared with 33.5% and 18.7% of nonobese patients, respectively. The most common complication was pneumonia (15.0% of obese and 10.5% of nonobese patients; P = 0.003), followed by sepsis (8.8% versus 4.2%; P < 0.001) and deep vein thrombosis (8.4% versus 5.9%; P < 0.001). Obesity was independently associated with complications (hazard ratio, 1.4; 95% confidence interval, 1.2-1.6). In multivariable analysis, obesity was not associated with FTR (odds ratio, 1.3; 95% confidence interval, 0.9-2.0).

CONCLUSIONS

Obesity is a risk factor for complications after traumatic injury but not for FTR. The increased risk of complications may reflect processes of care that are not attuned to the needs of this population, offering opportunities for improvement in care.

Obesity and the Survival of Critically Ill Patients with Acute Kidney Injury: A Paradox within the Paradox?

The obesity epidemic is reflected by the rising number of obese patients requiring intensive care. Obesity is a recognized risk factor for the development of acute kidney injury (AKI) in critically ill patients. Both acute critical illness and AKI are associated with higher in-hospital mortality rates, and intensive care unit (ICU) patients suffering from AKI have an elevated risk of death. The relationships between obesity and mortality in critically ill paediatric and adult patients with or without AKI are less clear. Conflicting evidence exists regarding the potential impact of body mass index on the mortality of ICU patients with AKI. Some studies looking at the ICU outcomes of critically ill obese patients with AKI show reduced mortality and others show either no association or elevated mortality. Despite a high biologic plausibility of the proposed causal mechanisms, such as a greater haemodynamic stability and the protective cytokine, adipokine, and lipoprotein defence profiles associated with obesity, the inconsistency of the data suggests that the obesity paradox is a statistical fallacy and the result of chance, bias, and residual confounding variables in retrospective cohort analyses. Further prospective randomized trials are essential to elucidate the role of obesity and the mechanisms underlying a potential survival benefit of obesity in critically ill patients with AKI.

The value of a bariatric specific chart to initiate resuscitation of adult bariatric burns

INTRODUCTION

The prevalence of obese adults is rising across the world with a tripling of rates since 1975. The resuscitation of large burns in obese patients brings unique challenges leading some to advocate the use of a bariatric specific burn chart.

AIMS

We sought to determine whether bariatric burn specific charts can better estimate burn percentage to prevent under resuscitation. We also reviewed the impact of obesity upon the length of hospital stay, morbidity and mortality at our institution.

METHODS

A retrospective case note review, of patients identified from the prospective International Burns Injury Database (iBID), was undertaken of patients' ≥18 years of age with burns ≥15% of their total body surface area.

RESULTS

There were 79 overweight and 53 bariatric patients from a total of 232 patients identified. There was no statistical difference in burn percentage or fluid input estimation between the Lund & Browder and Neaman charts. Complications were seen in 51% of the normal weight patients. Obese patients had a similar incidence of death (24%) compared to the normal weight group (26%). The class I obese had the lowest complication rate at 28% and lowest mortality rate at 11%.

CONCLUSIONS

Bariatric specific charts did not demonstrate any benefits in optimising bariatric resuscitation. There appears to be a 'physiological benefit' in the class I obese who sustained burns undergoing resuscitation.

The immunological roles in acute-on-chronic liver failure: An update

BACKGROUND

Acute-on-chronic liver failure (ACLF) refers to the acute deterioration of liver function that occurs in patients with chronic liver disease. ACLF is characterized by acute decompensation, organ failure and high short-term mortality. Numerous studies have been conducted and remarkable progress has been made regarding the pathophysiology and pathogenesis of this disease in the last decade. The present review was to summarize the advances in this field.

DATA SOURCES

A comprehensive search in PubMed and EMBASE was conducted using the medical subject words "acute-on-chronic liver failure", "ACLF", "pathogenesis", "predictors", and "immunotherapy" combined with free text terms such as "systemic inflammation" and "immune paralysis". Relevant papers published before October 31, 2018, were included.

RESULTS

ACLF has two marked pathophysiological features, namely, excessive systemic inflammation and susceptibility to infection. The systemic inflammation is mainly manifested by a significant increase in the levels of plasma pro-inflammatory factors, leukocyte count and C-reactive protein. The underlying mechanisms are unclear and may be associated with decreased immune inhibitory cells, abnormal expression of cell surface molecules and intracellular regulatory pathways in immune cells and increased damage-associated molecular patterns in circulation. However, the main cause of susceptibility to infection is immune paralysis. Immunological paralysis is characterized by an attenuated activity of immune cells. The mechanisms are related to elevations of immune inhibitory cells and the concentration of plasma anti-inflammatory molecules. Some immune biological indicators, such as soluble CD163, are used to explore the pathogenesis and prognosis of the disease, and some immunotherapies, such as glucocorticoids and granulocyte colony-stimulating factor, are effective on ACLF.

CONCLUSIONS

Overwhelming systemic inflammation and susceptibility to infection are two key features of ACLF. A better understanding of the state of a patient's immune system will help to guide immunotherapy for ACLF.

Metabolic support in the critically ill: a consensus of 19

Metabolic alterations in the critically ill have been studied for more than a century, but the heterogeneity of the critically ill patient population, the varying duration and severity of the acute phase of illness, and the many confounding factors have hindered progress in the field. These factors may explain why management of metabolic alterations and related conditions in critically ill patients has for many years been guided by recommendations based essentially on expert opinion. Over the last decade, a number of randomized controlled trials have been conducted, providing us with important population-level evidence that refutes several longstanding paradigms. However, between-patient variation means there is still substantial uncertainty when translating population-level evidence to individuals. A cornerstone of metabolic care is nutrition, for which there is a multifold of published guidelines that agree on many issues but disagree on others. Using a series of nine questions, we provide a review of the latest data in this field and a background to promote efforts to address the need for international consistency in recommendations related to the metabolic care of the critically ill patient. Our purpose is not to replace existing guidelines, but to comment on differences and add perspective.

ARDS in Obese Patients: Specificities and Management

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2019. Other selected articles can be found online at https://www.biomedcentral.com/collections/annualupdate2019. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901.

Association of obesity with morbidity and mortality in critically ill children: a systematic review and meta-analysis of observational studies

Recent studies have suggested that obesity might be protective in specific conditions such as critical illness; however, there are controversial data in critically ill children with obesity. The aim of this study was to investigate the association of obesity with mortality and other outcomes in these patients. We conducted a systematic review of observational studies investigating obesity in critically ill children, published by August 2017 in PubMed and Scopus. After screening documents, 15 articles with 142119 patients were included in the systematic review and meta-analysis. The results were reported with odds ratio (OR) or standard mean difference (SMD). The primary outcome was mortality and the secondary outcomes were length of ICU stay (ICU LOS), length of hospital stay (hospital LOS), and duration of mechanical ventilation (MV). The analysis showed that critically ill children without obesity had lower risk of mortality compared to patients with obesity (OR 0.79, 95% CI 0.64 to 0.97, P = 0.025, I² = 35.2%). Hospital LOS was also significantly lower in children without obesity (pooled SMD -0.12, 95% CI -0.21 to -0.04, P = 0.004, I² = 8.1%). There were no differences in ICU LOS (95% CI -0.19 to 0.01, P = 0.083) and duration of MV (95% CI -0.22 to 0.03, P = 0.136) between critically ill children with and without obesity. In conclusion, the current systematic review and meta-analysis revealed that critically ill children with obesity have higher risk of mortality and length of hospital stay compared to the group without obesity. Further prospective studies are essential to elucidate the role of obesity and underlying mechanisms in predicting outcomes of critically ill children.

Impact of Non-cardiac Comorbidities in Adults with Congenital Heart Disease: Management of Multisystem Complications

The prevalence and impact of non-cardiac comorbidities in adult patients with congenital heart disease increase over time, and these complications are often specifically a consequence of the long-term altered cardiovascular physiology or sequelae of previous therapies. For the ACHD patient admitted to the intensive care unit (ICU) for either surgical or medical treatment, an assessment of the burden of multisystem disease, as well as an understanding of the underlying cardiovascular pathophysiology, is essential for optimal management of these complex patients. This chapter takes an organ-system-based approach to reviewing common comorbidities in the ACHD patient, focusing on conditions that are directly related to ACHD status and may significantly impact ICU care.

Effects of postmortem positional changes on conjunctival petechiae

The present study aimed to determine whether postmortem period, physical constitution, cause of death, and cardiopulmonary resuscitation are associated with positional changes in the postmortem appearance of conjunctival petechiae. We retrospectively investigated serial forensic autopsies from 6 h to 6 days postmortem (n = 442; male, 303; female, 139; median age, 62 years; range, 0–100 years). The causes of death were sharp instrument injury, blunt force trauma, fire, intoxication, asphyxia, drowning, hypothermia, hyperthermia, acute heart failure, and natural causes. Of these, 28 (male, n = 18; female, n = 10) were aged ≤5 years. Palpebral conjunctival petechiae were initially assessed at autopsy in supine bodies, then reassessed in prone bodies after 30 min. Among 414 bodies, 291 (70.2%) and 123 (29.7%) who were aged between 6 and 100 years, and 18 (64.2%) and 10 (35.7%) aged <5 years at the time of death, were discovered in the supine and prone positions, respectively. The amounts of petechiae increased within 1.5 days postmortem, but not in those discovered in the prone position. The rates at which petechiae increased were higher in supine overweight bodies (BMI ≥ 25.0) and in those who were discovered supine and had died of asphyxia or drowning (37.5%). Cardiopulmonary resuscitation for bodies discovered in the supine and prone positions did not statistically affect the occurrence of petechiae. Several postmortem factors can cause hypostatic blood redistribution that manifests as increased amounts of petechiae in the palpebral conjunctivae.

The Association of Nutrition Status Expressed as Body Mass Index z Score With Outcomes in Children With Severe Sepsis: A Secondary Analysis From the Sepsis Prevalence, Outcomes, and Therapies (SPROUT) Study

OBJECTIVES

The impact of nutrition status on outcomes in pediatric severe sepsis is unclear. We studied the association of nutrition status (expressed as body mass index z score) with outcomes in pediatric severe sepsis.

DESIGN

Secondary analysis of the Sepsis Prevalence, Outcomes, and Therapies study. Patient characteristics, ICU interventions, and outcomes were compared across nutrition status categories (expressed as age- and sex-adjusted body mass index z scores using World Health Organization standards). Multivariable regression models were developed to determine adjusted differences in all-cause ICU mortality and ICU length of stay by nutrition status.

SETTING

One-hundred twenty-eight PICUs across 26 countries.

PATIENTS

Children less than 18 years with severe sepsis enrolled in the Sepsis Prevalence, Outcomes, and Therapies study (n = 567).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Nutrition status data were available for 417 patients. Severe undernutrition was seen in Europe (25%), Asia (20%), South Africa (17%), and South America (10%), with severe overnutrition seen in Australia/New Zealand (17%) and North America (14%). Severe undernutrition was independently associated with all-cause ICU mortality (adjusted odds ratio, 3.0; 95% CI, 1.2-7.7; p = 0.02), whereas severe overnutrition in survivors was independently associated with longer ICU length of stay (1.6 d; p = 0.01).

CONCLUSIONS

There is considerable variation in nutrition status for children with severe sepsis treated across this selected network of PICUs from different geographic regions. Severe undernutrition was independently associated with higher all-cause ICU mortality in children with severe sepsis. Severe overnutrition was independently associated with greater ICU length of stay in childhood survivors of severe sepsis.

ICU Admission Muscle and Fat Mass, Survival, and Disability at Discharge: A Prospective Cohort Study

BACKGROUND

Skeletal muscle dysfunction occurring as a result of ICU admission associates with higher mortality. Although preadmission higher BMI correlates with better outcomes, the impact of baseline muscle and fat mass has not been defined. We therefore investigated the association of skeletal muscle and fat mass at ICU admission with survival and disability at hospital discharge.

METHODS

This single-center, prospective, observational cohort study included medical ICU (MICU) patients from an academic institution in the Unites States. A total of 401 patients were evaluated with pectoralis muscle area (PMA) and subcutaneous adipose tissue (SAT) determinations conducted by CT scanning at the time of ICU admission, which were later correlated with clinical outcomes accounting for potential confounders.

RESULTS

Larger admission PMA was associated with better outcomes, including higher 6-month survival (OR, 1.03; 95% CI, 1.01-1.04; P < .001), lower hospital mortality (OR, 0.96; 95% CI, 0.93-0.98; P < .001), and more ICU-free days (slope, 0.044 ± 0.019; P = .021). SAT was not significantly associated with any of the measured outcomes. In multivariable analyses, PMA association persisted with 6 months and hospital survival and ICU-free days, whereas SAT remained unassociated with survival or other outcomes. PMA was not associated with regaining of independence at the time of hospital discharge (OR, 0.99; 95% CI, 0.98-1.01; P = .56).

CONCLUSIONS

In this study cohort, ICU admission PMA was associated with survival during and following critical illness; it was unable to predict regaining an independent lifestyle following discharge. ICU admission SAT mass was not associated with survival or other measured outcomes.

Class III obesity is a risk factor for the development of acute-on-chronic liver failure in patients with decompensated cirrhosis

BACKGROUND & AIMS

Acute-on-chronic liver failure (ACLF) is a syndrome of systemic inflammation and organ failures. Obesity, also characterized by chronic inflammation, is a risk factor among patients with cirrhosis for decompensation, infection, and mortality. Our aim was to test the hypothesis that obesity predisposes patients with decompensated cirrhosis to the development of ACLF.

METHODS

We examined the United Network for Organ Sharing (UNOS) database, from 2005-2016, characterizing patients at wait-listing as non-obese (body mass index [BMI] <30), obese class I-II (BMI 30-39.9) and obese class III (BMI ≥40). ACLF was determined based on the CANONIC study definition. We used Cox proportional hazards regression to assess the association between obesity and ACLF development at liver transplantation (LT). We confirmed our findings using the Nationwide Inpatient Sample (NIS), years 2009-2013, using validated diagnostic coding algorithms to identify obesity, hepatic decompensation and ACLF. Logistic regression evaluated the association between obesity and ACLF occurrence.

RESULTS

Among 387,884 patient records of decompensated cirrhosis, 116,704 (30.1%) were identified as having ACLF in both databases. Multivariable modeling from the UNOS database revealed class III obesity to be an independent risk factor for ACLF at LT (hazard ratio 1.24; 95% CI 1.09-1.41; p <0.001). This finding was confirmed using the NIS (odds ratio 1.30; 95% CI 1.25-1.35; p <0.001). Regarding specific organ failures, analysis of both registries demonstrated patients with class I-II and class III obesity had a greater prevalence of renal failure.

CONCLUSION

Class III obesity is a newly identified risk factor for ACLF development in patients with decompensated cirrhosis. Obese patients have a particularly high prevalence of renal failure as a component of ACLF. These findings have important implications regarding stratifying risk and preventing the occurrence of ACLF.

LAY SUMMARY

In this study, we identify that among patients with decompensated cirrhosis, class III obesity (severe/morbid obesity) is a modifiable risk factor for the development of acute-on-chronic liver failure (ACLF). We further demonstrate that regarding the specific organ failures associated with ACLF, renal failure is significantly more prevalent in obese patients, particularly those with class III obesity. These findings underscore the importance of weight management in cirrhosis, to reduce the risk of ACLF. Patients with class III obesity should be monitored closely for the development of renal failure.

Optimizing Care for Trauma Patients with Obesity

Obesity is a growing epidemic that has been contributing to the increasing cost of healthcare. Its prevalence is now approximately 37%. Morbid obesity is associated with increased morbidity and mortality in trauma patients. An increased recognition of obesity as a chronic disease and a better understanding of its pathophysiology can allow for proper preparation and accommodative measures to improve resuscitation and subsequent care, thereby improving trauma outcomes. The aim of this review is to provide an overview of the scope of the problem. This review also provides evidence-based recommendations for the optimal resuscitation sequence for obese patients.

Morbid obesity impairs adequacy of thoracic compressions in a simulation-based model

Adequate cardiopulmonary resuscitation is an important predictor of survival, however, obesity provides a significant physical barrier to thoracic compressions. This study explores the effect of morbid obesity on compression adequacy. We performed a prospective randomised controlled crossover study, assessing the adequacy of thoracic compressions on a manikin modified to emulate a morbidly obese patient. Participants recruited from critical care departments were randomised to perform continuous compressions for two minutes on each manikin. Accelerometers were used to measure thoracic wall movement. The primary endpoint was a composite measure of compression adequacy (rate, depth and recoil). Secondary endpoints were the individual components of the composite outcome and measures of perceived effectiveness, fatigue, and pain. One hundred and one participants were recruited. There was a significant difference between the obese and control groups in the composite endpoint (4% versus 30%, <i>P</i> <0.001), as well as the individual components of adequacy (<i>P</i> <0.01 for all). Quartile data showed significant deterioration in adequacy of depth and recoil in both groups, and this occurred significantly earlier in the obese group (<i>P</i> ≤0.001). Participants' perception of effectiveness was significantly lower (<i>P</i> ≤0.001) in the obese group, and levels of fatigue (<i>P</i> ≤0.001) and pain (<i>P</i> ≤0.001) significantly higher. Morbid obesity impairs the adequacy of thoracic compressions for trained rescuers in a simulation-based model. Participants were not fully aware of how ineffective compressions were. There is evidence of earlier fatigue further reducing effectiveness. These findings have significant implications for the training of rescuers in a clinically relevant population and the planning of future research.

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.

Feeding the critically ill obese patient: a systematic review protocol

REVIEW QUESTION/OBJECTIVE

The objective of this review is to identify effective enteral nutritional regimens targeting protein and calorie delivery for the critically ill obese patient on morbidity and mortality.More specifically, the review question is:In the critically ill obese patient, what is the optimal enteral protein and calorie target that improves mortality and morbidity?

BACKGROUND

The World Health Organization (WHO) defines obesity as abnormal or excessive fat accumulation that may impair health, or, empirically, as a body mass index (BMI) ≥ 30 kg/m. Twenty-eight percent of the Australian population is obese with the prevalence rising to 44% in rural areas, and there is evidence that rates of obesity are increasing. The prevalence of obese patients in intensive care largely mirrors that of the general population. There is concern, however, that this may also be rising. A recently published multi-center nutritional study of critically ill patients reported a mean BMI of 29 in their sample, suggesting that just under 50% of their intensive care population is obese. It is inevitable, therefore, that the intensivist will care for the critically ill obese patient.Managing the critically ill obese patient is challenging, not least due to the co-morbid diseases frequently associated with obesity, including diabetes mellitus, cardiovascular disease, dyslipidaemia, sleep disordered breathing and respiratory insufficiency, hepatic steatohepatitis, chronic kidney disease and hypertension. There is also evidence that metabolic processes differ in the obese patient, particularly those with underlying insulin resistance, itself a marker of the metabolic syndrome, which may predispose to futile cycling, altered fuel utilization and protein catabolism. These issues are compounded by altered drug pharmacokinetics, and the additional logistical issues associated with prophylactic, therapeutic and diagnostic interventions.It is entirely plausible that the altered metabolic processes observed in the obese intensify and compound the metabolic changes that occur during critical illness. The early phases of critical illness are characterized by an increase in energy expenditure, resulting in a catabolic state driven by the stress response. Activation of the stress response involves up-regulation of the sympathetic nervous system and the release of pituitary hormones resulting in altered cortisol metabolism and elevated levels of endogenous catecholamines. These produce a range of metabolic disturbances including stress hyperglycemia, arising from both peripheral resistance to the effects of anabolic factors (predominantly insulin) and increased hepatic gluconeogenesis. Proteolysis is accelerated, releasing amino acids that are thought to be important in supporting tissue repair, immune defense and the synthesis of acute phase reactants. There is also altered mobilization of fuel stores, futile cycling, and evidence of altered lipoprotein metabolism. In the short term this is likely to be an adaptive response, but with time and ongoing inflammation this becomes maladaptive with a concomitant risk of protein-calorie malnutrition, immunosuppression and wasting of functional muscle tissue resulting from protein catabolism, and this is further compounded by disuse atrophy. Muscle atrophy and intensive care unit (ICU) acquired weakness is complex and poorly understood, but it is postulated that the provision of calories and sufficient protein to avoid a negative nitrogen balance mitigates this process. Avoiding lean muscle mass loss in the obese intuitively has substantial implications, given the larger mass that is required to be mobilized during their rehabilitation phase.There is, in addition, evolving evidence that hormones derived from both the gut and adipose tissue are also involved in the response to stress and critical illness, and that adipose tissue in particular is not a benign tissue bed, but rather should be considered an endocrine organ. Some of these hormones are thought to be pro-inflammatory and some anti-inflammatory; however both the net result and clinical significance of these are yet to be fully elucidated.The provision of adequate nutrition has become an integral component of supportive ICU care, but is complex. There is ongoing debate within critical care literature regarding the optimal route of delivery, the target dose, and the macronutrient components (proportion of protein and non-protein calories) of nutritional support. A number of studies have associated caloric deficit with morbidity and mortality, with the resultant assumption that prescribing sufficient calories to match energy expenditure will reduce morbidity and mortality, although the evidence base underpinning this assumption is limited to observational studies and small, randomized trials.There is research available that suggests hyper-caloric feeding or hyper-alimentation, particularly of carbohydrates, may result in increased morbidity including hyperglycemia, liver steatosis, respiratory insufficiency with prolonged duration of mechanical ventilation, re-feeding syndrome and immune suppression. But the results from studies of hypo-caloric and eucaloric feeding regimens in critically ill patients are conflicting, independent of the added metabolic complexities observed in the critically ill obese patient.Notwithstanding the debate regarding the dose and components of nutritional therapy, there is consensus that nutrition should be provided, preferably via the enteral route, and preferably initiated early in the ICU admission. The enteral route is preferred for a variety of reasons, not the least of which is cost. In addition there is evidence to suggest the enteral route is associated with the maintenance of gut integrity, a reduction in bacterial translocation and infection rates, a reduction in the incidence of stress ulceration, attenuation of oxidative stress, release of incretins and other entero-hormones, and modulation of systemic immune responses. Yet there is evidence that the initiation of enteral nutritional support for the obese critically ill patient is delayed, and that when delivered is at sub-optimal levels. The reasons for this remain obscure, but may be associated with the false assumption that every obese patient has nutritional reserves due to their adipose tissues, and can therefore withstand longer periods with no, or reduced nutritional support. In fact obesity does not necessarily protect from malnutrition, particularly protein and micronutrient malnutrition. It has been suggested by some authors that the malnutrition status of critically ill patients is a stronger predictor of mortality than BMI, and that once malnutrition status is controlled for, the apparent protective effects of obesity observed in several epidemiological studies dissipate. This would be consistent with the large body of evidence that associates malnutrition (BMI < 20 kg/m) with increased mortality, and has led some authors to postulate that the weight-mortality relationship is U-shaped. This has proven difficult to demonstrate, however, due to recognized confounding influences such as chronic co-morbidities, baseline nutritional status and the nature of the presenting critical illness.This has led to interest in nutritional regimens targeting alternative calorie and protein goals to protect the obese critically ill patient from complications arising from critical illness, and particularly protein catabolism. However, of the three major nutritional organizations, the American Society of Parenteral and Enteral Nutrition (ASPEN) is the only professional organization to make specific recommendations about providing enteral nutritional support to the critically ill obese patient, recommending a regimen targeting a hypo-caloric, high-protein goal. It is thought that this regimen, in which 60-70% of caloric requirements are provided promotes steady weight loss, while providing sufficient protein to achieve a neutral, or slightly positive, nitrogen balance, mitigating lean muscle mass loss, and allowing for wound healing. Targeting weight loss is proposed to improve insulin sensitivity, improve nursing care and reduce the risk of co-morbidities, although how this occurs and whether it can occur over the relatively short time frame of an intensive care admission (days to weeks) remains unclear. Despite these recommendations observational data of international nutritional practice suggest that ICU patients are fed uniformly low levels of calories and protein across BMI groups.Supporting the critically ill obese patient will become an increasingly important skill in the intensivist's armamentarium, and enteral nutritional therapy forms a cornerstone of this support. Yet, neither the optimal total caloric goal nor the macronutrient components of a feeding regimen for the critically ill obese patient is evident. Although the suggestion that altering the macronutrient goals for this vulnerable group of patients appears to have a sound physiological basis, the level of evidence supporting this remains unclear, and there are no systematic reviews on this topic. The aim of this systematic review is to evaluate existing literature to determine the best available evidence describing a nutritional strategy that targets energy and protein delivery to reduce morbidity and mortality for the obese patient who is critically ill.

Body mass index and thoracic subcutaneous adipose tissue depth: possible implications for adequacy of chest compressions

Objective

Adequacy of cardiopulmonary resuscitation relies on compression of the thoracic cage to produce changes in intra-thoracic pressures sufficient to generate a pressure gradient. In order to evaluate the efficacy of cardiopulmonary resuscitation in morbid obesity, it is first necessary to determine the depth of thoracic subcutaneous adipose tissue (SAT) and to correlate this with body mass index (BMI).

Results

Computerised-tomography images of the thorax of 55 patients with a diagnosis of obesity or morbid obesity (mean BMI 45.95 kg/m²) were evaluated to determine the depth of SAT at the level at which chest compressions would be applied by a trained rescuer, and correlated with BMI. Mean anterior SAT was 36.53 mm, and mean posterior SAT was 50.73 mm. There was a significant correlation between BMI and anterior and posterior SAT for males (p < 0.05 for both), and females (p < 0.05 for both). The slope of the functions was considered sufficiently close to allow combining the data. This also showed a significant correlation between SAT and BMI (p < 0.01 for both). Both anterior and posterior SAT is correlated with BMI. This data allows development of a model to explore the efficacy of chest compressions in morbid obesity.

Electronic supplementary material

The online version of this article (10.1186/s13104-017-2918-9) contains supplementary material, which is available to authorized users.

Repeated Piperacillin-Tazobactam Plasma Concentration Measurements in Severely Obese Versus Nonobese Critically Ill Septic Patients and the Risk of Under- and Overdosing

OBJECTIVE

Obesity and critical illness modify pharmacokinetics of antibiotics, but piperacillin-tazobactam continuous IV infusion pharmacokinetics has been poorly studied in obese critically ill patients. We aimed to compare pharmacokinetics of piperacillin in severely obese and nonobese patients with severe sepsis or septic shock. We hypothesized that plasma concentration variability would expose the critically ill to both piperacillin under and overdosing.

METHODS

Prospective comparative study. Consecutive critically ill severely obese (body mass index, > 35 kg/m) and nonobese patients (body mass index, < 30 kg/m) were treated with 16 g/2 g/24 hr continuous piperacillin-tazobactam infusion. Piperacillin plasma concentration was measured every 12 hours over a 7-day period by high-pressure liquid chromatography. Unbound piperacillin plasma concentration and fractional time of plasma concentration spent over 64 mg/L (4-fold the minimal inhibitory concentration for Pseudomonas aeruginosa) were compared between the two groups. We performed 5,000 Monte Carlo simulations for various dosing regimens and minimal inhibitory concentration and calculated the probability to spend 100% of the time over 64 mg/L.

RESULTS

We enrolled 11 severely obese and 12 nonobese patients and obtained 294 blood samples. We did not observe a statistically significant difference in piperacillin plasma concentrations over time between groups. The fractional time over 64 mg/L was 64% (43-82%) and 93% (85-100%) in obese and nonobese patients, respectively, p = 0.027 with intra- and intergroup variability. Five nonobese and two obese patients experienced potentially toxic piperacillin plasma concentrations. When 64 mg/L was targeted, Monte Carlo simulations showed that 12 g/1.5 g/24 hr was inadequate in both groups and 16 g/2 g/24 hr was adequate only in nonobese patients.

CONCLUSION

Using a conventional dosing of 16 g/2 g/24 hr continuous infusion, obese patients were more likely than nonobese patients to experience piperacillin underdosing when facing high minimal inhibitory concentration pathogens. The present study suggests that piperacillin drug monitoring might be necessary in the sickest patients who are at the highest risk of unpredictable plasma concentration exposing them to overdose, toxicity, underdosing, and treatment failure.

Precocious obesity predisposes the development of more severe cisplatin-induced acute kidney injury in young adult mice

Obesity and its consequences can damage the kidney over time. However, less is known about the impact of developing overweight/obesity during childhood on the kidney in adulthood and the renal impact of a superimposed acute kidney injury (AKI). This study evaluated the effect of obesity induced by a high-fat diet initiated soon after weaning on the adult life of mice and their response to superimposed nephrotoxic effects of cisplatin. C57BL/6 post-weaning mice (3 weeks old) were divided into a control group (CT, n = 12) and a high-fat diet group (HF, n = 12). After 9 weeks, animals were further divided into the following groups: CT, CT treated with a single dose of cisplatin (CTCis, 20 mg/kg, i.p.), HF and HF treated with cisplatin (HFCis). The HF group exhibited higher body weight gain compatible with a moderate obesity. Obese mice presented increased visceral adiposity, hyperkalemia, sodium retention, glomerular hyperfiltration and proteinuria, without any significant changes in blood pressure and glycemia. AKI induced by cisplatin was exacerbated in obese animals with a 92% reduction in the GFR versus a 31% decrease in the CTCis group; this sharp decline resulted in severely elevated serum creatinine and urea levels. Acute tubular necrosis induced by cisplatin was worsened in obese mice. The HFCis group exhibited robust systemic and intrarenal inflammation that was significantly higher than that in the CTCis group; the HFCis group also showed a higher degree of renal oxidative stress. In conclusion, the moderate degree of obesity induced shortly after weaning resulted in mild early renal alterations, however, obese young animals were prone to develop a much more severe AKI induced by cisplatin.

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.

Multicentre prospective cohort study of body mass index and postoperative complications following gastrointestinal surgery

Background

There is currently conflicting evidence surrounding the effects of obesity on postoperative outcomes. Previous studies have found obesity to be associated with adverse events, but others have found no association. The aim of this study was to determine whether increasing body mass index (BMI) is an independent risk factor for development of major postoperative complications.

Methods

This was a multicentre prospective cohort study across the UK and Republic of Ireland. Consecutive patients undergoing elective or emergency gastrointestinal surgery over a 4-month interval (October–December 2014) were eligible for inclusion. The primary outcome was the 30-day major complication rate (Clavien–Dindo grade III–V). BMI was grouped according to the World Health Organization classification. Multilevel logistic regression models were used to adjust for patient, operative and hospital-level effects, creating odds ratios (ORs) and 95 per cent confidence intervals (c.i.).

Results

Of 7965 patients, 2545 (32·0 per cent) were of normal weight, 2673 (33·6 per cent) were overweight and 2747 (34·5 per cent) were obese. Overall, 4925 (61·8 per cent) underwent elective and 3038 (38·1 per cent) emergency operations. The 30-day major complication rate was 11·4 per cent (908 of 7965). In adjusted models, a significant interaction was found between BMI and diagnosis, with an association seen between BMI and major complications for patients with malignancy (overweight: OR 1·59, 95 per cent c.i. 1·12 to 2·29, P = 0·008; obese: OR 1·91, 1·31 to 2·83, P = 0·002; compared with normal weight) but not benign disease (overweight: OR 0·89, 0·71 to 1·12, P = 0·329; obese: OR 0·84, 0·66 to 1·06, P = 0·147).

Conclusion

Overweight and obese patients undergoing surgery for gastrointestinal malignancy are at increased risk of major postoperative complications compared with those of normal weight.

Impact of Obesity on Outcomes in a Multiethnic Cohort of Medical Intensive Care Unit Patients

PURPOSE

To examine the association of obesity with in-hospital mortality and complications during critical illness.

METHODS

We performed a retrospective analysis of a multiethnic cohort of 699 patients admitted to medical intensive care unit between January 2010 and May 2011 at Mount Sinai St. Luke's and Mount Sinai West Hospitals, tertiary care centers in New York City. Multivariate logistic regression analysis was used to evaluate the association between obesity (body mass index [BMI] ≥ 30] and in-hospital mortality. Subgroup analysis was performed in elderly patients (age ≥65 years).

RESULTS

Compared to normal BMI, obese patients had lower in-hospital mortality (24.4% vs 17.6%, P = .04). On multivariate analysis, obesity was independently associated with lower in-hospital mortality (odds ratio [OR]: 0.49, 95% confidence interval [CI]: 0.27-0.89, P = .018). There was no significant difference in rates of mechanical ventilation, reintubation, and vasopressor requirement across BMI categories. In subgroup analysis, elderly obese patients did not display lower in-hospital mortality (adjusted OR: 0.85, 95% CI: 0.40-1.82, P = .68).

CONCLUSION

Our study supports the hypothesis that obesity is associated with decreased mortality during critical illness. However, this finding was not observed among elderly obese patients. Further studies should explore the interaction between age, obesity, and outcomes in critical illness.

Low Plasma Levels of Adiponectin Do Not Explain Acute Respiratory Distress Syndrome Risk: a Prospective Cohort Study of Patients with Severe Sepsis

BACKGROUND

Obesity is associated with the development of acute respiratory distress syndrome (ARDS) in at-risk patients. Low plasma levels of adiponectin, a circulating hormone-like molecule, have been implicated as a possible mechanism for this association. The objective of this study was to determine the association of plasma adiponectin level at ICU admission with ARDS and 30-day mortality in patients with severe sepsis and septic shock.

METHODS

This is a prospective cohort study of patients admitted to the medical ICU at the Hospital of the University of Pennsylvania. Plasma adiponectin was measured at the time of ICU admission. ARDS was defined by Berlin criteria. Multivariable logistic regression was used to determine the association of plasma adiponectin with the development of ARDS and mortality at 30 days.

RESULTS

The study included 164 patients. The incidence of ARDS within 5 days of admission was 45%. The median initial plasma adiponectin level was 7.62 mcg/ml (IQR: 3.87, 14.90) in those without ARDS compared to 8.93 mcg/ml (IQR: 4.60, 18.85) in those developing ARDS. The adjusted odds ratio for ARDS associated with each 5 mcg increase in adiponectin was 1.12 (95% CI 1.01, 1.25), p-value 0.025). A total of 82 patients (51%) of the cohort died within 30 days of ICU admission. There was a statistically significant association between adiponectin and mortality in the unadjusted model (OR 1.11, 95% CI 1.00, 1.23, p-value 0.04) that was no longer significant after adjusting for potential confounders.

CONCLUSIONS

In this study, low levels of adiponectin were not associated with an increased risk of ARDS in patients with severe sepsis and septic shock. This argues against low levels of adiponectin as a mechanism explaining the association of obesity with ARDS. At present, it is unclear whether circulating adiponectin is involved in the pathogenesis of ARDS or simply represents an epiphenomenon of other unknown functions of adipose tissue or metabolic alterations in sepsis.