Influence of body mass index on outcome of the mechanically ventilated patients

Obesity Surgery Mortality Risk Score as a Predictor for Intensive Care Unit Admission in Patients Undergoing Laparoscopic Bariatric Surgery

Background: Laparoscopic bariatric surgery provides many benefits including lower postoperative pain scores, reduced opioid consumption, shorter hospital stays, and improved quality of recovery. However, the anaesthetic management of obese patients requires caution in determining postoperative risk and in planning adequate postoperative pathways. Currently, there are no specific indications for intensive care unit (ICU) admission in this surgical population and most decisions are made on a case-by-case basis. The aim of this study is to investigate whether Obesity Surgery Mortality Risk Score (OS-MRS) is able to predict ICU admission in patients undergoing laparoscopic bariatric surgery (LBS). Methods: We retrospectively reviewed data of patients who underwent LBS during a 2-year period (2017-2019). The collected data included demographics, comorbidities and surgery-related variables. Postoperative ICU admission was decided via bariatric anaesthesiologists' evaluations, based on the high risk of postoperative cardiac or respiratory complications. Anaesthesia protocol was standardized. Logistic regression was used for statistical analysis. Results: ICU admission was required in 2% (n = 15) of the 763 patients. The intermediate risk group of the OS-MRS was detected in 84% of patients, while the American Society of Anaesthesiologists class III was reported in 80% of patients. A greater OS-MRS (p = 0.01), advanced age (p = 0.04), male gender (p = 0.001), longer duration of surgery (p = 0.0001), increased number of patient comorbidities (p = 0.002), and previous abdominal surgeries (p = 0.003) were predictive factors for ICU admission. Conclusions: ICU admission in obese patients undergoing LBS is predicted by OS-MRS together with age, male gender, number of comorbidities, previous abdominal surgeries, and duration of surgery.

Mortality in Patients with Obesity and Acute Respiratory Distress Syndrome Receiving Extracorporeal Membrane Oxygenation: The Multicenter ECMObesity Study

Rationale: Patients with obesity are at increased risk for developing acute respiratory distress syndrome (ARDS). Some centers consider obesity a relative contraindication to receiving extracorporeal membrane oxygenation (ECMO) support, despite growing implementation of ECMO for ARDS in the general population. Objectives: To investigate the association between obesity and mortality in patients with ARDS receiving ECMO. Methods: In this large, international, multicenter, retrospective cohort study, we evaluated the association of obesity, defined as body mass index ⩾ 30 kg/m2, with ICU mortality in patients receiving ECMO for ARDS by performing adjusted multivariable logistic regression and propensity score matching. Measurements and Main Results: Of 790 patients with ARDS receiving ECMO in our study, 320 had obesity. Of those, 24.1% died in the ICU, compared with 35.3% of patients without obesity (P < 0.001). In adjusted models, obesity was associated with lower ICU mortality (odds ratio, 0.63 [95% confidence interval, 0.43-0.93]; P = 0.018). Examined as a continuous variable, higher body mass index was associated with decreased ICU mortality in multivariable regression (odds ratio, 0.97 [95% confidence interval, 0.95-1.00]; P = 0.023). In propensity score matching of 199 patients with obesity to 199 patients without, patients with obesity had a lower probability of ICU death than those without (22.6% vs. 35.2%; P = 0.007). Conclusions: Among patients receiving ECMO for ARDS, those with obesity had lower ICU mortality than patients without obesity in multivariable and propensity score matching analyses. Our findings support the notion that obesity should not be considered a general contraindication to ECMO.

Epidemiological profile and risk factors associated with death in patients receiving invasive mechanical ventilation in an adult intensive care unit from Brazil: a retrospective study

Introduction

Understanding the epidemiological profile and risk factors associated with invasive mechanical ventilation (IMV) is essential to manage the patients better and to improve health services. Therefore, our objective was to describe the epidemiological profile of adult patients in intensive care that required IMV in-hospital treatment. Also, to evaluate the risks associated with death and the influence of positive end-expiratory pressure (PEEP) and arterial oxygen pressure (PaO2) at admission in the clinical outcome.

Methods

We conducted an epidemiological study analyzing medical records of inpatients who received IMV from January 2016 to December 2019 prior to the Coronavirus Disease (COVID)-19 pandemic in Brazil. We considered the following characteristics in the statistical analysis: demographic data, diagnostic hypothesis, hospitalization data, and PEEP and PaO2 during IMV. We associated the patients' features with the risk of death using a multivariate binary logistic regression analysis. We adopted an alpha error of 0.05.

Results

We analyzed 1,443 medical records; out of those, 570 (39.5%) recorded the patients' deaths. The binary logistic regression was significant in predicting the patients' risk of death [X2(9) = 288.335; p < 0.001]. Among predictors, the most significant in relation to death risk were: age [elderly ≥65 years old; OR = 2.226 (95%CI = 1.728-2.867)]; male sex (OR = 0.754; 95%CI = 0.593-0.959); sepsis diagnosis (OR = 1.961; 95%CI = 1.481-2.595); need for elective surgery (OR = 0.469; 95%CI = 0.362-0.608); the presence of cerebrovascular accident (OR = 2.304; 95%CI = 1.502-3.534); time of hospital care (OR = 0.946; 95%CI = 0.935-0.956); hypoxemia at admission (OR = 1.635; 95%CI = 1.024-2.611), and PEEP >8 cmH2O at admission (OR = 2.153; 95%CI = 1.426-3.250).

Conclusion

The death rate of the studied intensive care unit was equivalent to that of other similar units. Regarding risk predictors, several demographic and clinical characteristics were associated with enhanced mortality in intensive care unit patients under mechanical ventilation, such as diabetes mellitus, systemic arterial hypertension, and older age. The PEEP >8 cmH2O at admission was also associated with increased mortality since this value is a marker of initially severe hypoxia.

Biomarkers as predictors of mortality in critically ill obese patients with COVID-19 at high altitude

BACKGROUND

Obesity is a common chronic comorbidity of patients with COVID-19, that has been associated with disease severity and mortality. COVID-19 at high altitude seems to be associated with increased rate of ICU discharge and hospital survival than at sea-level, despite higher immune levels and inflammation. The primary aim of this study was to investigate the survival rate of critically ill obese patients with COVID-19 at altitude in comparison with overweight and normal patients. Secondary aims were to assess the predictive factors for mortality, characteristics of mechanical ventilation setting, extubation rates, and analytical parameters.

METHODS

This is a retrospective cohort study in critically ill patients with COVID-19 admitted to a hospital in Quito-Ecuador (2,850 m) from Apr 1, 2020, to Nov 1, 2021. Patients were cathegorized as normal weight, overweight, and obese, according to body mass index [BMI]).

RESULTS

In the final analysis 340 patients were included, of whom 154 (45%) were obese, of these 35 (22.7%) were hypertensive and 25 (16.2%) were diabetic. Mortality in obese patients (31%) was lower than in the normal weight (48%) and overweight (40%) groups, but not statistically significant (p = 0.076). At multivariable analysis, in the overall population, older age (> 50 years) was independent risk factor for mortality (B = 0.93, Wald = 14.94, OR = 2.54 95%CI = 1.58-4.07, p < 0.001). Ferritin and the neutrophil/lymphocyte ratio were independent predictors of mortality in obese patients. Overweight and obese patients required more positive and-expiratory pressure compared to normal-weight patients. In obese patients, plateau pressure and mechanical power were significantly higher, whereas extubation failure was lower as compared to overweight and normal weight.

CONCLUSIONS

This preliminary study suggests that BMI was not associated with mortality in critically ill patients at high altitude. Age was associated with an increase in mortality independent of the BMI. Biomarkers such as ferritin and neutrophils/lymphocytes ratio were independent predictors of mortality in obese patients with COVID-19 at high altitude.

The Impact of BiLevel Positive Airway Pressure (BiPAP) Application Timing on Emergency Room Length of Stay in Patients With Pulmonary Edema: A Single-Center, Retrospective Cohort Study

BACKGROUND

 Bilevel positive airway pressure (BiPAP) is a form of non-invasive ventilation (NIV) that is used to help and facilitate breathing. Our objective is to evaluate the impact of BiPAP application time on the length of emergency room (ER) stay in pulmonary edema patients.

METHOD

This is a retrospective cohort study that included patients who presented to the ER at King Abdullah Medical City (KAMC) from June 2019 to June 2021. The eligibility criteria for BiPAP application were congestive heart failure (CHF) and type 1 and type 2 respiratory failure, The data were collected from the Track Care system. We defined early BiPAP as BiPAP application time within one hour from admission, and late BiPAP more than one hour and we calculated the percentage of discharge within four hours in each group.

RESULT

 Out of 147 fulfilling study eligibility, 64% had CHF, 23% had type 2 respiratory failure and 13% had type 1 respiratory failure. For patients discharged within four hours, 85% were in the early BiPAP and 15% were in the late BiPAP groups (p = 0.001 as compared to the late discharge group). Discharge within four hours was observed with the following percentages in the study subgroups: CHF early BiPAP (84%), late BiPAP (16%) (p = 0.004), type 1 respiratory failure early BiPAP (79%), late BiPAP (21%) (p = 0.71) and type 2 respiratory failure early BiPAP (94%), late BiPAP (6%) (p = 0.89).

CONCLUSION

 Our results show that there is a significant outcome in early BiPAP application in decreasing the length of ER stay only in patients with pulmonary edema.

Domiciliary noninvasive ventilation for chronic respiratory diseases

Patients with chronic respiratory diseases, including chronic obstructive pulmonary disease (COPD), neuromuscular diseases, kyphoscoliosis and obstructive sleep apnoea-obesity hypoventilation syndrome (OSA-OHS), are at a higher risk of decompensation in the form of hypercapnic respiratory failure leading to intensive care unit (ICU) admission and increased mortality. This article reviews the evidence of role of domiciliary noninvasive ventilation (NIV) in patients with diseases with chronic ventilatory failure, including the mechanism of the effect of (NIV).

Influence of the Driving Pressure on Mortality in ARDS Patients with or without Abdominal Obesity: A Retrospective Cohort Study

Objective. This study sets out to explore if the relationship between the driving pressure and hospital mortality in ARDS patients is influenced by body mass index (BMI) level or the presence of abdominal obesity. Methods. Data were extracted from an online database named “Multiparameter Intelligent Monitoring in Intensive Care III.” A total of 1556 patients were included and divided into four subgroups based on both BMI level (BMI ≥30 kg/m2 or BMI ＜30 kg/m2) and abdominal assessment. Driving pressure [i.e., the difference between plateau pressure and positive end-expiratory pressure (PEEP)] within 24 h of invasive mechanical ventilation was compared between survivors and nonsurvivors during hospitalization in each group. A logistic regression model was used for hospital mortality. Results. There were 1556 patients with mild-to-severe ARDS, 666 (42.80%) nonobese patients with nonabdominal obesity, 259 (16.65%) nonobese patients with abdominal obesity, 97 (6.23%) obese patients with nonabdominal obesity, and 534 (34.32%) obese patients with abdominal obesity. Driving pressure in nonobese patients with nonabdominal obesity was significantly lower in survivors (12.77 ± 4.53 cm H2O) than in nonsurvivors (14.26 ± 5.52 cm H2O, $p<0.01$ ). On the contrary, in the other three groups, driving pressure was not significantly different between survivors and nonsurvivors. After a logistic multivariable regression analysis, in nonobese (BMI<30 kg/m2) patients with nonabdominal obesity, the driving pressure was independently associated with increased hospital mortality (OR: 1.04, 95% CI 1.00–1.09, $p<0.05$ ) but not in the other three subgroups. Conclusion. Driving pressure is associated with increase in hospital mortality only in nonobese (BMI <30 kg/m2) patients with nonabdominal obesity.

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.

A trauma-related survival predictive model of acute respiratory distress syndrome

Purpose

The purpose of this study was to construct and validate a simple model for the prediction of survival in patients with trauma‐related ARDS.

Methods

This is a single‐center, retrospective cohort study using MIMIC‐III Clinical Database.

Results

842 patients were included in this study. 175 (20.8%) died in‐hospital, whereas 215 (25.5%) died within 90 days. The deceased group had higher Acute Physiology Score (APS III), Sequential Organ Failure Assessment (SOFA), and Simplified Acute Physiology Score II (SAPS II). In multivariate logistic regression model, independent risk factors for mortality in ARDS patients included age ([odds ratio] OR, 1.035; 95% confidence interval [CI], 1.020–1.049), body mass index (OR, 0.957; 95% CI, 0.926–0.989), red blood cell distribution width (OR, 1.283; 95% CI, 1.141–1.443), hematocrit (OR, 1.055; 95% CI, 1.017–1.095), lactate (OR, 1.226; 95% CI, 1.127–1.334), blood urea nitrogen (OR, 1.025; 95% CI, 1.007–1.044), acute kidney failure (OR, 1.875; 95% CI, 1.188–2.959), sepsis (OR, 1.917; 95% CI, 1.165–3.153), type of admission (emergency vs. elective [OR, 2.822; 95% CI, 1.647–4.837], and urgent vs. elective [OR, 5.156; 95% CI, 1.896–14.027]). The area under the curve (AUC) of the model was 0.826, which was superior than the SAPS II (0.776), APS III (0.718), and SOFA (0.692). In the cross‐validation model, the accuracy of the test set was 0.823, the precision was 0.643, and the AUC was 0.813.

Conclusions

We established a prediction model using data commonly used in the clinic, which has high accuracy and precision and is worthy of use in clinical practice.

Utilization Trends and Predictors of Non-invasive and Invasive Ventilation During Hospitalization Due to Community-Acquired Pneumonia

BACKGROUND

Community-acquired pneumonia (CAP) is associated with significant morbidity and mortality. Non-invasive ventilation (NIV) and invasive mechanical ventilation (IMV) are most important interventions for patients with severe CAP associated with respiratory failure. We analysed utilization trends and predictors of non-invasive and invasive ventilation in patients hospitalized with CAP.

METHODS

 Nationwide Inpatient Sample and Healthcare Cost and Utilization Project data for years 2008-2017 were analysed. Adult hospitalizations due to CAP were identified by previously validated International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) and International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10-CM) codes. We then utilized the Cochran-Armitage trend test and multivariate survey logistic regression models to analyse temporal incidence trends, predictors, and outcomes. We used SAS 9.4 software (SAS Institute Inc., Cary, NC, USA) for analysing data.

RESULTS

Out of a total of 8,385,861 hospitalizations due to CAP, ventilation assistance was required in 552,395 (6.6%). The overall ventilation use increased slightly; however, IMV utilization decreased, while NIV utilization increased. In multivariable regression analysis, males, Asian/others and weekend admissions were associated with higher odds of any ventilation utilization. Concurrent diagnoses of septicemia, congestive heart failure, alcoholism, chronic lung diseases, pulmonary circulatory diseases, diabetes mellitus, obesity and cancer were associated with increased odds of requiring ventilation assistance. Ventilation requirement was associated with high odds of in-hospital mortality and discharge to facility.

CONCLUSION

The use of NIV among CAP patients has increased while IMV use has decreased over the years. We observed numerous factors linked with a higher use of ventilation support. The requirement of ventilation support is also associated with very high chances of mortality and morbidity.

Practical Review of Mechanical Ventilation in Adults and Children in The Operating Room and Emergency Department

BACKGROUND

During general anesthesia, mechanical ventilation can cause pulmonary damage through mechanism of ventilator-induced lung injury which is a major cause of postoperative pulmonary complications, which varies between 5 and 33% and increases significantly the 30-day mortality of the surgical patient.

OBJECTIVE

The aim of this review is to analyze different variables which played key role in safe application of mechanical ventilation in the operating room and emergency setting.

METHOD

Also, we wanted to analyze different types of population that underwent intraoperative mechanical ventilation like obese patients, pediatric and adult population and different strategies such as one lung ventilation and ventilation in trendelemburg position. The peer-reviewed articles analyzed were selected according to PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) from Pubmed/Medline, Ovid/Wiley and Cochrane Library, combining key terms such as: "pulmonary post-operative complications", "protective ventilation", "alveolar recruitment maneuvers", "respiratory compliance", "intraoperative paediatric ventilation", "best peep", "types of ventilation". Among the 230 papers identified, 150 articles were selected, after title - abstract examination and removing the duplicates, resulting in 94 articles related to mechanical ventilation in operating room and emergency setting that were analyzed.

RESULTS

Careful preoperative patient's evaluation and protective ventilation (i.e. use of low tidal volumes, adequate PEEP and alveolar recruitment maneuvers) has been shown to be effective not only in limiting alveolar de-recruitment, alveolar overdistension and lung damage, but also in reducing the onset of pulmonary post-operative complications (PPCs).

CONCLUSION

Mechanical ventilation is like "Janus Bi-front" because it is essential for surgical procedures, for the care of critical care patients and in life-threatening conditions but it can be harmful to the patient if continued for a long time and where an excessive dose of oxygen is administered into the lungs. Low tidal volume is associated with minor rate of PPCs and other complications and every complication can increase length of Stay, adding cost to NHS between 1580 € and 1650 € per day in Europe and currently the prevention of PPCS is only weapon that we possess.

Association of body mass index with morbidity in patients hospitalised with COVID-19

PURPOSE

To evaluate the association between body mass index (BMI) and clinical outcomes other than death in patients hospitalised and intubated with COVID-19.

METHODS

This is a single-centre cohort study of adults with COVID-19 admitted to New York Presbyterian Hospital-Weill Cornell Medicine from 3 March 2020 through 15 May 2020. Baseline and outcome variables, as well as lab and ventilatory parameters, were generated for the admitted and intubated cohorts after stratifying by BMI category. Linear regression models were used for continuous, and logistic regression models were used for categorical outcomes.

RESULTS

The study included 1337 admitted patients with a subset of 407 intubated patients. Among admitted patients, hospital length of stay (LOS) and home discharge was not significantly different across BMI categories independent of demographic characteristics and comorbidities. In the intubated cohort, there was no difference in in-hospital events and treatments, including renal replacement therapy, neuromuscular blockade and prone positioning. Ventilatory ratio was higher with increasing BMI on days 1, 3 and 7. There was no significant difference in ventilator free days (VFD) at 28 or 60 days, need for tracheostomy, hospital LOS, and discharge disposition based on BMI in the intubated cohort after adjustment.

CONCLUSIONS

In our COVID-19 population, there was no association between obesity and morbidity outcomes, such as hospital LOS, home discharge or VFD. Further research is needed to clarify the mechanisms underlying the reported effects of BMI on outcomes, which may be population dependent.

Extracellular vesicle therapeutics from plasma and adipose tissue

Extracellular vesicles (EVs) are cell-released lipid-bilayer nanoparticles that contain biologically active cargo involved in physiological and pathological intercellular communication. In recent years, the therapeutic potential of EVs has been explored in various disease models. In particular, mesenchymal stromal cell-derived EVs have been shown to exert anti-inflammatory, anti-oxidant, anti-apoptotic, and pro-angiogenic properties in cardiovascular, metabolic and orthopedic conditions. However, a major drawback of EV-based therapeutics is scale-up issues due to extensive cell culture requirements and inefficient isolation protocols. An emerging alternative approach to time-consuming and costly cell culture expansion is to obtain therapeutic EVs directly from the body, for example, from plasma and adipose tissue. This review discusses isolation methods and therapeutic applications of plasma and adipose tissue-derived EVs, highlighting advantages and disadvantages compared to cell culture-derived ones.

The triumvirate: why hypertension, obesity, and diabetes are risk factors for adverse effects in patients with COVID-19

The outbreak of coronavirus disease 2019 (COVID-19) caused by a novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has become a pandemic. The cellular receptor for SARS-CoV-2 entry is the angiotensin-converting enzyme 2, a membrane-bound homolog of angiotensin-converting enzyme. Henceforth, this has brought the attention of the scientific community to study the interaction between COVID-19 and the renin-angiotensin system (RAS), as well as RAS inhibitors. However, these inhibitors are commonly used to treat hypertension, chronic kidney disorder, and diabetes. Obesity is a known risk factor for heart disease, diabetes, and hypertension, whereas diabetes and hypertension may be indirectly related to each other through the effects of obesity. Furthermore, people with hypertension, obesity, diabetes, and other related complications like cardiovascular and kidney diseases have a higher risk of severe COVID-19 infection than the general population and usually exhibit poor prognosis. This severity could be due to systemic inflammation and compromised immune response and RAS associated with these comorbid conditions. Therefore, there is an urgent need to develop evidence-based treatment methods that do not affect the severity of COVID-19 infection and effectively manage these chronic diseases in people with COVID-19.

Body Mass Index Is Associated with the Severity and All-Cause Mortality of Acute Kidney Injury in Critically Ill Patients: An Analysis of a Large Critical Care Database

Background

Acute kidney injury (AKI) is a common clinical syndrome carrying high morbidity and mortality. Body mass index (BMI) is a common health indicator, and a high BMI value-obesity has been shown to be associated with the outcomes of several diseases. However, the relationship between different BMI categories and mortality in all critically ill patients with AKI is unclear and needs further investigation. Therefore, we evaluated the ability of BMI to predict the severity and all-cause mortality of AKI in critically ill patients.

Methods

We extracted clinical data from the MIMIC-III v1.4 database. All adult patients with AKI were initially screened. The baseline data extracted within 24 hours after ICU admission were presented according to WHO BMI categories. Logistic regression models and the Cox proportional hazards models were, respectively, constructed to assess the relationship between BMI and the severity and all-cause mortality of AKI. The generalized additive model (GAM) was used to identify nonlinear relationships as BMI was a continuous variable. The subgroup analyses were performed to further analyze the stability of the association between BMI category and 365-day all-cause mortality of AKI.

Result

A total of 15,174 patients were extracted and were divided into four groups according to BMI. Obese patients were more likely to be young and male. In the fully adjusted logistic regression model, we found that overweight and obesity were significant predictors of AKI stage III (OR, 95 CI: 1.17, 1.05-1.30; 1.32, 1.18-1.47). In the fully adjusted Cox proportional hazards model, overweight and obesity were associated with significantly lower 30-day, 90-day, and 365-day all-cause mortality. The corresponding adjusted HRs (95 CIs) for overweight patients were 0.87 (0.77, 0.99), 0.84 (0.76, 0.93), and 0.80 (0.74, 0.88), and for obese patients, they were 0.87 (0.77, 0.98), 0.79 (0.71, 0.88), and 0.73 (0.66, 0.80), respectively. The subgroup analyses further presented a stable relationship between BMI category and 365-day all-cause mortality.

Conclusions

BMI was independently associated with the severity and all-cause mortality of AKI in critical illness. Overweight and obesity were associated with increased risk of AKI stage III; however, they were predictive of a relatively lower mortality risk in these patients.

The association between outcomes and body mass index in patients with acute respiratory distress syndrome

INTRODUCTION

Limited information exists about the relationship between body mass index (BMI) and the outcome of acute respiratory distress syndrome (ARDS).

OBJECTIVE

To evaluate the hospital mortality of patients with ARDS in relation to BMI.

MATERIALS AND METHODS

We conducted a retrospective, multicenter study including patients with ARDS. ARDS was defined according to the Berlin criteria. Body weight and height were obtained to calculate BMI. The primary outcome was in-hospital mortality. Secondary outcomes were intensive care unit (ICU) mortality, invasive positive pressure ventilation (IPPV) free days within 28 days and length of stays in the ICU and hospital.

RESULTS

Among 523 patients, 28 (5%) were underweight (BMI <18.5 kg/m² ), 299 (57%) were normal weight (BMI 18.5-24.9 kg/m² ), 159 (30%) were overweight (BMI 25-29.9 kg/m² ) and 37 (7%) were obese (BMI ≥30 kg/m² ). Increasing BMI was associated with younger age (P = 0.017), hypertension (P = 0.003) and diabetes (P = 0.02). Compared with normal weight, being overweight and obese resulted in lower mortality regardless of whether in the hospital (P = 0.019) or ICU (P = 0.044). However, after risk adjustment, only obesity was associated with lower hospital mortality (OR 0.393, 95% CI 0.169-0.914, P = 0.030). With the increase of BMI, the in-hospital mortality and ICU mortality of ARDS dropped gradually (from 57.1% to 24.3%, P = 0.021, and from 53.6% to 24.3%, P = 0.035).

CONCLUSIONS

Obesity is associated with lower mortality in patients with ARDS. With the increase of BMI, the mortality of ARDS drops gradually.

Obesity and Critical Illness in COVID-19: Respiratory Pathophysiology

OBJECTIVE

Recent cohort studies have identified obesity as a risk factor for poor outcomes in coronavirus disease 2019 (COVID-19). To further explore the relationship between obesity and critical illness in COVID-19, the association of BMI with baseline demographic and intensive care unit (ICU) parameters, laboratory values, and outcomes in a critically ill patient cohort was examined.

METHODS

In this retrospective study, the first 277 consecutive patients admitted to Massachusetts General Hospital ICUs with laboratory-confirmed COVID-19 were examined. BMI class, initial ICU laboratory values, physiologic characteristics including gas exchange and ventilatory mechanics, and ICU interventions as clinically available were measured. Mortality, length of ICU admission, and duration of mechanical ventilation were also measured.

RESULTS

There was no difference found in respiratory system compliance or oxygenation between patients with and without obesity. Patients without obesity had higher initial ferritin and D-dimer levels than patients with obesity. Standard acute respiratory distress syndrome management, including prone ventilation, was equally distributed between BMI groups. There was no difference found in outcomes between BMI groups, including 30- and 60-day mortality and duration of mechanical ventilation.

CONCLUSIONS

In this cohort of critically ill patients with COVID-19, obesity was not associated with meaningful differences in respiratory physiology, inflammatory profile, or clinical outcomes.

Body mass index and leptin levels in serum and cerebrospinal fluid in relation to delayed cerebral ischemia and outcome after aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is associated with a high mortality rate and may leave surviving patients severely disabled. After the initial hemorrhage, clinical outcome is further compromised by the occurrence of delayed cerebral ischemia (DCI). Overweight and obesity have previously been associated with protective effects in the post-bleeding phase. The aim of this study was to assess the effects of a patient’s body mass index (BMI) and leptin levels on the occurrence of DCI, DCI-related cerebral infarction, and clinical outcome. In total, 263 SAH patients were included of which leptin levels were assessed in 24 cases. BMI was recorded along disease severity documented by the Hunt and Hess and modified Fisher scales. The occurrence of clinical or functional DCI (neuromonitoring, CT Perfusion) was assessed. Long-term clinical outcome was documented after 12 months (extended Glasgow outcome scale). A total of 136 (51.7%) patients developed DCI of which 72 (27.4%) developed DCI-related cerebral infarctions. No association between BMI and DCI occurrence (P = .410) or better clinical outcome (P = .643) was identified. Early leptin concentration in serum (P = .258) and CSF (P = .159) showed no predictive value in identifying patients at risk of unfavorable outcomes. However, a significant increase of leptin levels in CSF occurred from 326.0 pg/ml IQR 171.9 prior to DCI development to 579.2 pg/ml IQR 211.9 during ongoing DCI (P = .049). In our data, no association between obesity and clinical outcome was detected. After DCI development, leptin levels in CSF increased either by an upsurge of active transport or disruption of the blood-CSF barrier. This trial has been registered at ClinicalTrials.gov (NCT02142166) as part of a larger-scale prospective data collection. BioSAB: https://clinicaltrials.gov/ct2/show/NCT02142166

Susceptibility and Severity of Viral Infections in Obesity: Lessons from Influenza to COVID-19. Does Leptin Play a Role?

The recent pandemic Sars-CoV2 infection and studies on previous influenza epidemic have drawn attention to the association between the obesity and infectious diseases susceptibility and worse outcome. Metabolic complications, nutritional aspects, physical inactivity, and a chronic unbalance in the hormonal and adipocytokine microenvironment are major determinants in the severity of viral infections in obesity. By these pleiotropic mechanisms obesity impairs immune surveillance and the higher leptin concentrations produced by adipose tissue and that characterize obesity substantially contribute to such immune response dysregulation. Indeed, leptin not only controls energy balance and body weight, but also plays a regulatory role in the interplay between energy metabolism and immune system. Since leptin receptor is expressed throughout the immune system, leptin may exert effects on cells of both innate and adaptive immune system. Chronic inflammatory states due to metabolic (i.e., obesity) as well as infectious diseases increase leptin concentrations and consequently lead to leptin resistance further fueling inflammation. Multiple factors, including inflammation and ER stress, contribute to leptin resistance. Thus, if leptin is recognized as one of the adipokines responsible for the low grade inflammation found in obesity, on the other hand, impairments of leptin signaling due to leptin resistance appear to blunt the immunologic effects of leptin and possibly contribute to impaired vaccine-induced immune responses. However, many aspects concerning leptin interactions with inflammation and immune system as well as the therapeutical approaches to overcome leptin resistance and reduced vaccine effectiveness in obesity remain a challenge for future research.

Associations of Body Mass Index with Ventilation Management and Clinical Outcomes in Invasively Ventilated Patients with ARDS Related to COVID-19-Insights from the PRoVENT-COVID Study

We describe the practice of ventilation and mortality rates in invasively ventilated normal-weight (18.5 ≤ BMI ≤ 24.9 kg/m²), overweight (25.0 ≤ BMI ≤ 29.9 kg/m²), and obese (BMI > 30 kg/m²) COVID-19 ARDS patients in a national, multicenter observational study, performed at 22 intensive care units in the Netherlands. The primary outcome was a combination of ventilation variables and parameters over the first four calendar days of ventilation, including tidal volume, positive end–expiratory pressure (PEEP), respiratory system compliance, and driving pressure in normal–weight, overweight, and obese patients. Secondary outcomes included the use of adjunctive treatments for refractory hypoxaemia and mortality rates. Between 1 March 2020 and 1 June 2020, 1122 patients were included in the study: 244 (21.3%) normal-weight patients, 531 (47.3%) overweight patients, and 324 (28.8%) obese patients. Most patients received a tidal volume < 8 mL/kg PBW; only on the first day was the tidal volume higher in obese patients. PEEP and driving pressure were higher, and compliance of the respiratory system was lower in obese patients on all four days. Adjunctive therapies for refractory hypoxemia were used equally in the three BMI groups. Adjusted mortality rates were not different between BMI categories. The findings of this study suggest that lung-protective ventilation with a lower tidal volume and prone positioning is similarly feasible in normal-weight, overweight, and obese patients with ARDS related to COVID-19. A patient’s BMI should not be used in decisions to forgo or proceed with invasive ventilation.

Overweight and Obesity Are Associated With Acute Kidney Injury and Acute Respiratory Distress Syndrome, but Not With Increased Mortality in Hospitalized COVID-19 Patients: A Retrospective Cohort Study

OBJECTIVE

To evaluate the association between overweight and obesity on the clinical course and outcomes in patients hospitalized with COVID-19.

DESIGN

Retrospective, observational cohort study.

METHODS

We performed a multicenter, retrospective, observational cohort study of hospitalized COVID-19 patients to evaluate the associations between overweight and obesity on the clinical course and outcomes.

RESULTS

Out of 1634 hospitalized COVID-19 patients, 473 (28.9%) had normal weight, 669 (40.9%) were overweight, and 492 (30.1%) were obese. Patients who were overweight or had obesity were younger, and there were more women in the obese group. Normal-weight patients more often had pre-existing conditions such as malignancy, or were organ recipients. During admission, patients who were overweight or had obesity had an increased probability of acute respiratory distress syndrome [OR 1.70 (1.26-2.30) and 1.40 (1.01-1.96)], respectively and acute kidney failure [OR 2.29 (1.28-3.76) and 1.92 (1.06-3.48)], respectively. Length of hospital stay was similar between groups. The overall in-hospital mortality rate was 27.7%, and multivariate logistic regression analyses showed that overweight and obesity were not associated with increased mortality compared to normal-weight patients.

CONCLUSION

In this study, overweight and obesity were associated with acute respiratory distress syndrome and acute kidney injury, but not with in-hospital mortality nor length of hospital stay.

Factors Associated with In-Hospital Mortality after Continuous Renal Replacement Therapy for Critically Ill Patients: A Systematic Review and Meta-Analysis

Continuous renal replacement therapy (CRRT) is a broadly-accepted treatment for critically ill patients with acute kidney injury to optimize fluid and electrolyte management. Despite intensive dialysis care, there is a high mortality rate among these patients. There is uncertainty regarding the factors associated with in-hospital mortality among patients requiring CRRT. This review evaluates how various risk factors influence the in-hospital mortality of critically ill patients who require CRRT. Five databases were surveyed to gather relevant publications up to 30 June 2020. We identified 752 works, of which we retrieved 38 in full text. Finally, six cohort studies that evaluated 1190 patients were eligible. The in-hospital mortality rate in these studies ranged from 38.6 to 62.4%. Our meta-analysis results showed that older age, lower body mass index, higher APACHE II and SOFA scores, lower systolic and diastolic blood pressure, decreased serum creatinine level, and increased serum sodium level were significantly associated with increased in-hospital mortality in critically ill patients who received CRRT. These results suggest that there are multiple modifiable factors that influence the risk of in-hospital mortality in critically ill patients undergoing CRRT. Further, healthcare professionals should take more care when CRRT is performed on older adults.

How to ventilate obese patients in the ICU

Obesity is an important risk factor for major complications, morbidity and mortality related to intubation procedures and ventilation in the intensive care unit (ICU). The fall in functional residual capacity promotes airway closure and atelectasis formation. This narrative review presents the impact of obesity on the respiratory system and the key points to optimize airway management, noninvasive and invasive mechanical ventilation in ICU patients with obesity. Non-invasive strategies should first optimize body position with reverse Trendelenburg position or sitting position. Noninvasive ventilation (NIV) is considered as the first-line therapy in patients with obesity having a postoperative acute respiratory failure. Positive pressure pre-oxygenation before the intubation procedure is the method of reference. The use of videolaryngoscopy has to be considered by adequately trained intensivists, especially in patients with several risk factors. Regarding mechanical ventilation in patients with and without acute respiratory distress syndrome (ARDS), low tidal volume (6 ml/kg of predicted body weight) and moderate to high positive end-expiratory pressure (PEEP), with careful recruitment maneuver in selected patients, are advised. Prone positioning is a therapeutic choice in severe ARDS patients with obesity. Prophylactic NIV should be considered after extubation to prevent re-intubation. If obesity increases mortality and risk of ICU admission in the overall population, the impact of obesity on ICU mortality is less clear and several confounding factors have to be taken into account regarding the “obesity ICU paradox”.

Obesity is a risk factor for developing critical condition in COVID-19 patients: A systematic review and meta-analysis

The disease course of COVID-19 varies from asymptomatic infection to critical condition leading to mortality. Identification of prognostic factors is important for prevention and early treatment. We aimed to examine whether obesity is a risk factor for the critical condition in COVID-19 patients by performing a meta-analysis. The review protocol was registered onto PROSPERO (CRD42020185980). A systematic search was performed in five scientific databases between 1 January and 11 May 2020. After selection, 24 retrospective cohort studies were included in the qualitative and quantitative analyses. We calculated pooled odds ratios (OR) with 95% confidence intervals (CIs) in meta-analysis. Obesity was a significant risk factor for intensive care unit (ICU) admission in a homogenous dataset (OR = 1.21, CI: 1.002-1.46; I2 = 0.0%) as well as for invasive mechanical ventilation (IMV) (OR = 2.05, CI: 1.16-3.64; I2 = 34.86%) in COVID-19. Comparing body mass index (BMI) classes with each other, we found that a higher BMI always carries a higher risk. Obesity may serve as a clinical predictor for adverse outcomes; therefore, the inclusion of BMI in prognostic scores and improvement of guidelines for the intensive care of patients with elevated BMI are highly recommended.

Respiratory Muscle Performance Screening for Infectious Disease Management Following COVID-19: A Highly Pressurized Situation

The 2019-2020 coronavirus pandemic elucidated how a single highly infectious virus can overburden health care systems of even highly economically developed nations. A leading contributor to these concerning outcomes is a lack of available intensive care unit (ICU) beds and mechanical ventilation support. Poorer health is associated with a higher risk for severe respiratory complications from the coronavirus. We hypothesize that impaired respiratory muscle performance is an underappreciated factor contributing to poor outcomes unfolding during the coronavirus pandemic. Although impaired respiratory muscle performance is considered to be rare, it is more frequently encountered in patients with poorer health, in particular obesity. However, measures of respiratory muscle performance are not routinely performed in clinical practice, including those with symptoms such as dyspnea. The purpose of this article is to discuss the potential role of respiratory muscle performance from the perspective of the coronavirus pandemic. We also provide a theoretical patient management model to screen for impaired respiratory muscle performance and intervention, if identified, with the goal of unburdening health care systems during future pandemic crises.

Obesity, the most common comorbidity in SARS-CoV-2: is leptin the link?

Overweight and obesity are major risk factors for diabetes, cardiovascular disease, and lung disease. These diseases are the most commonly reported health conditions that predispose individuals with SARS-CoV-2 infection to require hospitalization including intensive care unit admissions. The innate immune response is the host’s first line of defense against a human coronavirus infection. However, most coronaviruses are armed with one strategy or another to overcome host antiviral defense, and the pathogenicity of the virus is related to its capacity to suppress host immunity. The multifaceted nature of obesity including its effects on immunity can fundamentally alter the pathogenesis of acute respiratory distress syndrome and pneumonia, which are the major causes of death due to SARS-CoV-2 infection. Elevated circulating leptin concentrations are a hallmark of obesity, which is associated with a leptin-resistant state. Leptin is secreted by adipocytes in proportion to body fat and regulates appetite and metabolism through signaling in the hypothalamus. However, leptin also signals through the Jak/STAT and Akt pathways, among others, to modulate T cell number and function. Thus, leptin connects metabolism with the immune response. Therefore, it seems appropriate that its dysregulation would have serious consequences during an infection. We propose that leptin may be the link between obesity and its high prevalence as a comorbidity of the SARS-CoV-2 infection. In this article, we present a synthesis of the mechanisms underpinning susceptibility to respiratory viral infections and the contribution of the immunomodulatory effects of obesity to the outcome.

Obesity as a risk factor for COVID-19: an overview

The current coronavirus disease-2019 (COVID-19) pandemic presents a huge challenge for health-care systems worldwide. Many different risk factors are associated with disease severity, such as older age, diabetes, hypertension, and most recently obesity. The incidence of obesity has been on the rise for the past 25 years, reaching over 2 billion people throughout the world, and obesity itself could be considered a pandemic. In this review, we summarize aspects involved with obesity, such as changes in the immune response, nutritional factors, physiological factors, and the gut-lung axis, that impact the viral response and the COVID-19 prognosis.

The acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a prevalent cause of acute respiratory failure with high rates of mortality, as well as short- and long-term complications, such as physical and cognitive impairment. Therefore, early recognition of this syndrome and application of well-demonstrated therapeutic interventions are essential to change the natural course of this entity and bring about positive clinical outcomes. In this article, we review updated concepts in ARDS. Specifically, we discuss the current definition of ARDS, its risk factors, and the evidence supporting ventilation management, adjunctive therapies, and interventions required in refractory hypoxemia.

Lung Recruitment in Obese Patients with Acute Respiratory Distress Syndrome

BACKGROUND

Obese patients are characterized by normal chest-wall elastance and high pleural pressure and have been excluded from trials assessing best strategies to set positive end-expiratory pressure (PEEP) in acute respiratory distress syndrome (ARDS). The authors hypothesized that severely obese patients with ARDS present with a high degree of lung collapse, reversible by titrated PEEP preceded by a lung recruitment maneuver.

METHODS

Severely obese ARDS patients were enrolled in a physiologic crossover study evaluating the effects of three PEEP titration strategies applied in the following order: (1) PEEPARDSNET: the low PEEP/FIO2 ARDSnet table; (2) PEEPINCREMENTAL: PEEP levels set to determine a positive end-expiratory transpulmonary pressure; and (3) PEEPDECREMENTAL: PEEP levels set to determine the lowest respiratory system elastance during a decremental PEEP trial following a recruitment maneuver on respiratory mechanics, regional lung collapse, and overdistension according to electrical impedance tomography and gas exchange.

RESULTS

Fourteen patients underwent the study procedures. At PEEPARDSNET (13 ± 1 cm H2O) end-expiratory transpulmonary pressure was negative (-5 ± 5 cm H2O), lung elastance was 27 ± 12 cm H2O/L, and PaO2/FIO2 was 194 ± 111 mmHg. Compared to PEEPARDSNET, at PEEPINCREMENTAL level (22 ± 3 cm H2O) lung volume increased (977 ± 708 ml), lung elastance decreased (23 ± 7 cm H2O/l), lung collapse decreased (18 ± 10%), and ventilation homogeneity increased thus rising oxygenation (251 ± 105 mmHg), despite higher overdistension levels (16 ± 12%), all values P < 0.05 versus PEEPARDSnet. Setting PEEP according to a PEEPDECREMENTAL trial after a recruitment maneuver (21 ± 4 cm H2O, P = 0.99 vs. PEEPINCREMENTAL) further lowered lung elastance (19 ± 6 cm H2O/l) and increased oxygenation (329 ± 82 mmHg) while reducing lung collapse (9 ± 2%) and overdistension (11 ± 2%), all values P < 0.05 versus PEEPARDSnet and PEEPINCREMENTAL. All patients were maintained on titrated PEEP levels up to 24 h without hemodynamic or ventilation related complications.

CONCLUSIONS

Among the PEEP titration strategies tested, setting PEEP according to a PEEPDECREMENTAL trial preceded by a recruitment maneuver obtained the best lung function by decreasing lung overdistension and collapse, restoring lung elastance, and oxygenation suggesting lung tissue recruitment.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

Adipose-derived exosomes protect the pulmonary endothelial barrier in ventilator-induced lung injury by inhibiting the TRPV4/Ca2+ signaling pathway

Mechanical ventilation (MV) is the main supportive treatment of acute respiratory distress syndrome (ARDS), but it may lead to ventilator-induced lung injury (VILI). Large epidemiological studies have found that obesity was associated with lower mortality in mechanically ventilated patients with acute lung injury, which is known as “obesity paradox.” However, the effects of obesity on VILI are unknown. In the present study, wild-type mice were fed a high-fat diet (HFD) and ventilated with high tidal volume to investigate the effects of obesity on VILI in vivo, and pulmonary microvascular endothelial cells (PMVECs) were subjected to 18% cyclic stretching (CS) to further investigate its underlying mechanism in vitro. We found that HFD protects mice from VILI by alleviating the pulmonary endothelial barrier injury and inflammatory responses in mice. Adipose-derived exosomes can regulate distant tissues as novel adipokines, providing a new mechanism for cell-cell interactions. We extracted three adipose-derived exosomes, including HFD mouse serum exosome (S-Exo), adipose tissue exosome (AT-Exo), and adipose-derived stem cell exosome (ADSC-Exo), and further explored their effects on MV or 18% CS-induced VILI in vivo and in vitro. Administration of three exosomes protected against VILI by suppressing pulmonary endothelial barrier hyperpermeability, repairing the expression of adherens junctions, and alleviating inflammatory response in vivo and in vitro, accompanied by transient receptor potential vanilloid 4 (TRPV4)/Ca²⁺ pathway inhibition. Collectively, these data indicated that HFD-induced obesity plays a protective role in VILI by alleviating the pulmonary endothelial barrier injury and inflammatory response via adipose-derived exosomes, at least partially, through inhibiting the TRPV4/Ca²⁺ pathway.

Higher body mass index is not a protective risk factor for 28-days mortality in critically ill patients with acute kidney injury undergoing continuous renal replacement therapy

Background: Acute kidney injury (AKI) requiring continuous renal replacement therapy (CRRT) is a fatal and common clinical disorder in critically ill patients. Recent studies have shown that the relationship between BMI and the outcome of patients with AKI undergoing CRRT is conflicting.

Methods: A retrospective cohort study based on data reuse. Univariate analysis, multi-factor regression analysis and subgroup analyses were used to explore the association of the BMI with the 28-days mortality risk in patients with AKI undergoing CRRT.

Results: From January 2009 to September 2016, a total of 1120 cases met the inclusion criteria and were enrolled in this study. The univariate analysis showed that BMI was associated with 28-days mortality of patients with AKI undergoing CRRT, its HR value was 0.98 (0.96, 0.99). The multi-factor regression analysis showed that BMI was not associated with 28-days mortality of patients with AKI undergoing CRRT in the four models, the adjusted HR value of four models were 1.00 (0.96, 1.04), 1.01 (0.97, 1.04), 1.00 (0.96, 1.04) and 1.00 (0.96, 1.04), respectively. The subgroups analyses showed that the BMI was a risk factor of the 28-days mortality in patients with AKI undergoing CRRT when GFR ≥30 mL/min, its HR value was 1.04 (1.01, 1.09).

Conclusion: Higher BMI was not a protective risk of 28-day mortality in patients with AKI undergoing CRRT. Especially, when GFR ≥30 mL/min, higher BMI increased the risk of the 28-day mortality rate in patients with AKI undergoing CRRT.

Temporal Changes in Ventilator Settings in Patients With Uninjured Lungs: A Systematic Review

In patients with uninjured lungs, increasing evidence indicates that tidal volume (VT) reduction improves outcomes in the intensive care unit (ICU) and in the operating room (OR). However, the degree to which this evidence has translated to clinical changes in ventilator settings for patients with uninjured lungs is unknown. To clarify whether ventilator settings have changed, we searched MEDLINE, Cochrane Central Register of Controlled Trials, and Web of Science for publications on invasive ventilation in ICUs or ORs, excluding those on patients <18 years of age or those with >25% of patients with acute respiratory distress syndrome (ARDS). Our primary end point was temporal change in VT over time. Secondary end points were changes in maximum airway pressure, mean airway pressure, positive end-expiratory pressure, inspiratory oxygen fraction, development of ARDS (ICU studies only), and postoperative pulmonary complications (OR studies only) determined using correlation analysis and linear regression. We identified 96 ICU and 96 OR studies comprising 130,316 patients from 1975 to 2014 and observed that in the ICU, VT size decreased annually by 0.16 mL/kg (-0.19 to -0.12 mL/kg) (P < .001), while positive end-expiratory pressure increased by an average of 0.1 mbar/y (0.02-0.17 mbar/y) (P = .017). In the OR, VT size decreased by 0.09 mL/kg per year (-0.14 to -0.04 mL/kg per year) (P < .001). The change in VTs leveled off in 1995. Other intraoperative ventilator settings did not change in the study period. Incidences of ARDS (ICU studies) and postoperative pulmonary complications (OR studies) also did not change over time. We found that, during a 39-year period, from 1975 to 2014, VTs in clinical studies on mechanical ventilation have decreased significantly in the ICU and in the OR.

Association Between Obesity and Short-And Long-Term Mortality in Patients With Acute Respiratory Distress Syndrome Based on the Berlin Definition

PURPOSE

Acute respiratory distress syndrome (ARDS) is one of the most common causes of death in intensive care units (ICU). Previous studies have reported the potential protective effect of obesity on ARDS patients. However, these findings are inconsistent, in which less was reported on long-term prognosis and diagnosed ARDS by Berlin definition. This study aimed to investigate the relationship between obesity and short-term and long-term mortality in patients with ARDS based on the Berlin Definition.

METHODS

This is a retrospective cohort study from the Medical Information Mart for Intensive Care III (MIMIC-III) database, in which all the patients were diagnosed with ARDS according to the Berlin definition. The patients were divided into four groups according to the WHO body mass index (BMI) categories. The multivariable logistic regression and Cox regression analysis were used to investigate the relationship between BMI and short-term and long-term mortality.

RESULT

A total of 2,378 patients with ARDS were enrolled in our study. In-hospital mortality was 27.92%, and 1,036 (43.57%) patients had died after 1-year follow-up. After adjusting for confounders, the in-hospital and 1-year mortality risks of obese patients were significantly lower than those of normal weight (OR 0.72, 95%CI 0.55-0.94, P=0.0168; HR 0.80, 95%CI 0.68-0.94 P=0.0084; respectively), while those mortality risks of underweight patients were higher than normal weight patients (P=0.0102, P=0.0184; respectively). The smooth curve showed that BMI, which was used as a continuous variable, was negatively correlated with in-hospital and 1-year mortality. The results were consistent after being stratified by age, gender, race, type of admission, severity of organ dysfunction, and severity of ARDS. The Kaplan-Meier survival curves showed that obese patients had significant lower 1-year mortality than normal weight patients.

CONCLUSION

We found that obesity was associated with decreased risk of short-term and long-term mortality in patients with ARDS.

[Preoperative risk and perioperative management of obese patients]

The obese patient is at an increased risk of perioperative complications. Most importantly, these include difficult access to the airways (intubation, difficult or impossible ventilation), and post-extubation respiratory distress secondary to the development of atelectasis or obstruction of the airways, sometimes associated with the use of morphine derivatives. The association of obstructive sleep apnea syndrome (OSA) with obesity is very common, and induces a high risk of peri- and postoperative complications. Preoperative OSA screening is crucial in the obese patient, as well as its specific management: use of continuous positive pre, per and postoperative pressure. For any obese patient, the implementation of protocols for mask ventilation and/or difficult intubation and the use of protective ventilation, morphine-sparing strategies and a semi-seated positioning throughout the care, is recommended, combined with close monitoring postoperatively. The dosage of anesthetic drugs should be based on the theoretical ideal weight and then titrated, rather than dosed to the total weight. Monitoring of neuromuscular blocking should be used where appropriate, as well as monitoring of the depth of anesthesia. The occurrence of intraoperative recall is indeed more frequent in the obese patient than in the non-obese patient. Appropriate prophylaxis against venous thromboembolic disease and early mobilization are recommended, as thromboembolic disease is increased in the obese patient. The use of non-invasive ventilation to prevent the occurrence of acute post-operative respiratory failure and for its treatment is particularly effective in obese patients. In case of admission to ICU, an individualized ventilatory management based on pathophysiology and careful monitoring should be initiated.

[The obese patient and acute respiratory failure, a challenge for intensive care]

As a result of the constantly increasing epidemic of obesity, it has become a common problem in the intensive care unit. Morbid obesity has numerous consequences for the respiratory system. It affects both respiratory mechanics and pulmonary gas exchange, and dramatically impacts on the patient's management and outcome. With the potential for causing devastating respiratory complications, the particular anatomical and physiological characteristics of the respiratory system of the morbidly obese subject should be carefully taken into consideration. The present article reviews the management of obese patients in respiratory failure, from noninvasive ventilation to tracheostomy, including postural and technical issues, and explains the physiologically based ventilatory strategy both for NIV and invasive mechanical ventilation up to the weaning from the ventilatory support.

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

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

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.

Intubation, tracheostomy, and decannulation in patients with Guillain-Barré-syndrome-does dysphagia matter?

INTRODUCTION

Although patients with Guillain-Barré syndrome frequently require orotracheal intubation and tracheostomy, the incidence and relevance of neurogenic dysphagia prior to intubation and risk factors for prolonged requirement for a tracheal cannula have not yet been identified.

METHODS

Retrospective analysis of the medical records of 88 patients was performed. Clinical characteristics were compared between intubated and nonintubated patients and between immediately decannulated and not immediately decannulated patients.

RESULTS

Thirty-five (39.7%) patients required tracheostomy. Neuromuscular weakness and related respiratory insufficiency were the main reasons for intubation. In the subgroup of tracheotomized patients, immediate decannulation after completed respiratory weaning was possible in 14 (40%) patients. The severity of dysphagia, in particular pharyngolaryngeal hypesthesia, was related to the length of cannulation.

DISCUSSION

Respiratory muscle weakness is the main reason for intubation, whereas neurogenic dysphagia is the main risk factor for persisting cannulation. Dysphagia after weaning is most frequently characterized by severe laryngeal sensory deficit. Muscle Nerve 59:194-200, 2019.

Body Mass Index as a Predictor of Acute Kidney Injury in Critically Ill Patients: A Retrospective Single-Center Study

Background

The aim of this study was to examine the influence of body mass index (BMI) on the development of acute kidney injury (AKI) in critically ill patients in intensive care unit (ICU).

Methods

Data of patients admitted to medical ICU from December 2011 to May 2014 were retrospectively analyzed. Patients were classified into three groups according to their BMI: underweight (<18.5 kg/m²), normal (18.5–24.9 kg/m²), and overweight (≥25 kg/m²). The incidence of AKI was compared among these groups and factors associated with the development of AKI were analyzed. AKI was defined according to the Risk, Injury, Failure, Loss of kidney function, and End-stage (RIFLE) kidney disease criteria.

Results

A total of 468 patients were analyzed. Their mean BMI was 21.5±3.9 kg/m², including 102 (21.8%) underweight, 286 (61.1%) normal-weight, and 80 (17.1%) overweight patients. Overall, AKI occurred in 82 (17.5%) patients. The overweight group had significantly (p<0.001) higher incidence of AKI (36.3%) than the underweight (9.8%) or normal group (15.0%). In addition, BMI was significantly higher in patients with AKI than that in those without AKI (23.4±4.2 vs. 21.1±3.7, p<0.001). Multivariate analysis showed that BMI was significantly associated with the development of AKI (odds ratio, 1.893; 95% confidence interval, 1.224–2.927).

Conclusion

BMI may be associated with the development of AKI in critically ill patients.

Impact of the driving pressure on mortality in obese and non-obese ARDS patients: a retrospective study of 362 cases

PURPOSE

The relation between driving pressure (plateau pressure-positive end-expiratory pressure) and mortality has never been studied in obese ARDS patients. The main objective of this study was to evaluate the relationship between 90-day mortality and driving pressure in an ARDS population ventilated in the intensive care unit (ICU) according to obesity status.

METHODS

We conducted a retrospective single-center study of prospectively collected data of all ARDS patients admitted consecutively to a mixed medical-surgical adult ICU from January 2009 to May 2017. Plateau pressure, compliance of the respiratory system (Crs) and driving pressure of the respiratory system within 24 h of ARDS diagnosis were compared between survivors and non-survivors at day 90 and between obese (body mass index ≥ 30 kg/m²) and non-obese patients. Cox proportional hazard modeling was used for mortality at day 90.

RESULTS

Three hundred sixty-two ARDS patients were included, 262 (72%) non-obese and 100 (28%) obese patients. Mortality rate at day 90 was respectively 47% (95% CI, 40-53) in the non-obese and 46% (95% CI, 36-56) in the obese patients. Driving pressure at day 1 in the non-obese patients was significantly lower in survivors at day 90 (11.9 ± 4.2 cmH₂O) than in non-survivors (15.2 ± 5.2 cmH₂O, p < 0.001). Contrarily, in obese patients, driving pressure at day 1 was not significantly different between survivors (13.7 ± 4.5 cmH₂O) and non-survivors (13.2 ± 5.1 cmH₂O, p = 0.41) at day 90. After three multivariate Cox analyses, plateau pressure [HR = 1.04 (95% CI 1.01-1.07) for each point of increase], Crs [HR = 0.97 (95% CI 0.96-0.99) for each point of increase] and driving pressure [HR = 1.07 (95% CI 1.04-1.10) for each point of increase], respectively, were independently associated with 90-day mortality in non-obese patients, but not in obese patients.

CONCLUSIONS

Contrary to non-obese ARDS patients, driving pressure was not associated with mortality in obese ARDS patients.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Update: non-invasive ventilation in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) remains a common cause of morbidity and mortality worldwide. Patients with COPD and respiratory failure, whether acute or chronic have a poorer prognosis than patients without respiratory failure. Non-invasive ventilation (NIV) has been shown to be a useful tool in both the acute hospital and chronic home care setting. NIV has been well established as the gold standard therapy for acute decompensated respiratory failure complicating an acute exacerbation of COPD with reduced mortality and intubation rates compared to standard therapy. However, NIV has been increasingly used in other clinical situations such as for weaning from invasive ventilation and to palliate symptoms in patients not suitable for invasive ventilation. The equivocal evidence for the use of NIV in chronic hypercapnic respiratory failure complicating COPD has recently been challenged with data now supporting a role for therapy in selected subgroups of patients. Finally the review will discuss the emerging role of high flow humidified therapy to support or replace NIV in certain clinical situation.

Prevention and care of respiratory failure in obese patients

With the increase in the global prevalence of obesity, there is a parallel rise in the proportion of obese patients admitted to intensive care units, referred for major surgery or requiring long-term non-invasive ventilation (NIV) at home for chronic respiratory failure. We describe the physiological effect of obesity on the respiratory system mainly in terms of respiratory mechanics, respiratory drive, and patency of the upper airways. Particular attention is given to the prevention and the clinical management of respiratory failure in obese patients with a main focus on invasive and NIV in intensive care during the perioperative period and long-term use of NIV on return home. We also address other aspects of care of obese patients, including antibiotic dosing and catheter-related infections.