Prevention and care of respiratory failure in obese patients

The Role of Obstructive Sleep Apnea in Hypercapnic Respiratory Failure Identified in Critical Care, Inpatient, and Outpatient Settings

An emerging body of literature describes the prevalence and consequences of hypercapnic respiratory failure. While device qualifications, documentation practices, and previously performed clinical studies often encourage conceptualizing patients as having a single "cause" of hypercapnia, many patients encountered in practice have several contributing conditions. Physiologic and epidemiologic data suggest that sleep-disordered breathing-particularly obstructive sleep apnea (OSA)-often contributes to the development of hypercapnia. In this review, the authors summarize the frequency of contributing conditions to hypercapnic respiratory failure among patients identified in critical care, emergency, and inpatient settings with an aim toward understanding the contribution of OSA to the development of hypercapnia.

Sleep status of older adults with sleep apnoea syndrome may vary by body mass index

Obesity and ageing are the most important risk factors for sleep apnoea syndrome (SAS); however, the role of body mass index (BMI) on sleep status in healthy older adults is unclear. To explore sleep parameters according to BMI among active older adults, we cross-sectionally examined the relationship between sleep-related parameters and BMI in 32 Japanese adults aged from 83 to 95 years without long-term care who were unaware of having SAS. Correlation and linear regression analyses were performed. Moderate or severe SAS prevalence was high in both those with low (68.8%) and high (68.8%) BMI. A higher increase in apnoea-hypopnoea index (AHI) was negatively correlated with sleep depth in the high-BMI group. In the low-BMI group, the number of awakenings and age were positively correlated with AHI. Older adults may have SAS regardless of their BMI, and the sleep status of patients with SAS may vary by BMI.

The role of fatty acid metabolism in acute lung injury: a special focus on immunometabolism

Reputable evidence from multiple studies suggests that excessive and uncontrolled inflammation plays an indispensable role in mediating, amplifying, and protracting acute lung injury (ALI). Traditionally, immunity and energy metabolism are regarded as separate functions regulated by distinct mechanisms, but recently, more and more evidence show that immunity and energy metabolism exhibit a strong interaction which has given rise to an emerging field of immunometabolism. Mammalian lungs are organs with active fatty acid metabolism, however, during ALI, inflammation and oxidative stress lead to a series metabolic reprogramming such as impaired fatty acid oxidation, increased expression of proteins involved in fatty acid uptake and transport, enhanced synthesis of fatty acids, and accumulation of lipid droplets. In addition, obesity represents a significant risk factor for ALI/ARDS. Thus, we have further elucidated the mechanisms of obesity exacerbating ALI from the perspective of fatty acid metabolism. To sum up, this paper presents a systematical review of the relationship between extensive fatty acid metabolic pathways and acute lung injury and summarizes recent advances in understanding the involvement of fatty acid metabolism-related pathways in ALI. We hold an optimistic believe that targeting fatty acid metabolism pathway is a promising lung protection strategy, but the specific regulatory mechanisms are way too complex, necessitating further extensive and in-depth investigations in future studies.

The impact of obesity on ventilator-associated pneumonia, a US nationwide study

BACKGROUND

Ventilator-associated pneumonia (VAP) is one of the leading causes of mortality in patients with critical care illness. Since obesity is highly prevalent, we wanted to study its impact on the outcomes of patients who develop VAP.

METHODS

Using the National Inpatient Sample (NIS) database from 2017 to 2020, we conducted a retrospective study of adult patients with a principal diagnosis of VAP with a secondary diagnosis with or without obesity according to 10th revision of the International Statistical Classification of Diseases (ICD-10) codes. Several demographics, including age, race, and gender, were analyzed. The primary endpoint was mortality, while the secondary endpoints included tracheostomy, length of stay in days, and patient charge in dollars. Multivariate logistic regression model analysis was used to adjust for confounders, with a p-value less than 0.05 considered statistically significant.

RESULTS

The study included 3832 patients with VAP, 395 of whom had obesity. The mean age in both groups was around 58 years, and 68% of the group with obesity were females compared to 40% in females in the group without obesity. Statistically significant comorbidities in the obesity group included a Charlson Comorbidity Index score of three and above, diabetes mellitus, hypertension, chronic kidney disease, and sleep apnea. Rates and odds of mortality were not significantly higher in the collective obesity group 39 (10%) vs. 336 (8.5%), p-value 0.62, adjusted odds ratio 1.2, p-value 0.61). The rates and odds of tracheostomy were higher in the obesity group but not statistically significant. Obese patients were also found to have a longer hospitalization. Upon subanalysis of the data, no evidence of racial disparities was found in the care of VAP for both the obese and control groups.

CONCLUSIONS

Obesity was not found to be an independent risk factor for worse outcomes in patients who develop VAP in the intensive care unit.

Sepsis and obesity: a scoping review of diet-induced obesity murine models

BACKGROUND

Sepsis, the life-threatening host response to infection, is a major cause of mortality. Obesity increases vulnerability to sepsis; however, some degree of obesity may be protective, called the "obesity paradox". This scoping review systematically maps the literature on outcomes associated with diet-induced obesity and sepsis-induced organ injury, focusing on non-transgenic murine models.

METHODS

A literature search of primary articles was conducted from database inception to June 2023. Eligible articles compared diet-induced obesity to non-obese mice in sepsis models involving live pathogens. Two reviewers screened articles and extracted data on obesogenic and sepsis models utilized, and organ injury outcomes, including physiological dysfunction, histological alterations, and biochemical changes.

RESULTS

Seventeen studies met eligibility criteria; 82% used male C57BL/6 mice, and 88% used cecal ligation and puncture to induce sepsis. Most studies used 60% high-fat diets compared to 10-16% fat in controls. Seven (64%) studies reported increased mortality in obese septic mice, one (9%) observed a decrease, and three (37%) found no significant difference. The liver, lungs, and kidneys were the most studied organs. Alanine transaminase results were inconclusive. Myeloperoxidase levels were increased in the livers of two studies and inconclusive in the lungs of obese septic mice. Creatinine and neutrophil gelatinase-associated lipocalin were elevated in obese septic mice.

CONCLUSIONS

There is variability in the methodology and measured outcomes in murine models of diet-induced obesity and sepsis and a lack of studies in female mice. The absence of standardized models has produced conflicting findings on the impact of obesity on sepsis outcomes.

Multicentre, parallel, open-label, two-arm, randomised controlled trial on the prognosis of electrical impedance tomography-guided versus low PEEP/FiO2 table-guided PEEP setting: a trial protocol

INTRODUCTION

Previous studies suggested that electrical impedance tomography (EIT) has the potential to guide positive end-expiratory pressure (PEEP) titration via quantifying the alveolar collapse and overdistension. The aim of this trial is to compare the effect of EIT-guided PEEP and acute respiratory distress syndrome (ARDS) network low PEEP/fraction of inspired oxygen (FiO2) table strategy on mortality and other clinical outcomes in patients with ARDS.

METHODS

This is a parallel, two-arm, multicentre, randomised, controlled trial, conducted in China. All patients with ARDS under mechanical ventilation admitted to the intensive care unit will be screened for eligibility. The enrolled patients are stratified by the aetiology (pulmonary/extrapulmonary) and partial pressure of arterial oxygen/FiO2 (≥150 mm Hg or <150 mm Hg) and randomised into the intervention group or the control group. The intervention group will receive recruitment manoeuvre and EIT-guided PEEP titration. The EIT-guided PEEP will be set for at least 12 hours after titration. The control group will not receive recruitment manoeuvre routinely and the PEEP will be set according to the lower PEEP/FiO2 table proposed by the ARDS Network. The primary outcome is 28-day survival.

ANALYSIS

Qualitative data will be analysed using the χ2 test or Fisher's exact test, quantitative data will be analysed using independent samples t-test or Mann-Whitney U test. Kaplan-Meier analysis with log-rank test will be used to evaluate the 28-day survival rate between two groups. All outcomes will be analysed based on the intention-to-treat principle.

ETHICS AND DISSEMINATION

The trial is approved by the Institutional Research and Ethics Committee of the Peking Union Medical College Hospital. Data will be published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT05307913.

Obesity and COVID-19 Pandemics: Epidemiology, Mechanisms, and Management

Obesity is a principle causative factor of various metabolic dysfunctions, chronic inflammation, and multi-organ impairment. The global epidemic of obesity has constituted the greatest threat to global health. Emerging evidence has associated obesity with an increased risk of severe infection and poor outcomes from coronavirus disease 2019 (COVID-19). During current COVID-19 pandemic, the interaction between COVID-19 and obesity has exaggerated the disease burden of obesity more than ever before. Thus, there is an urgent need for consideration of universal measures to reduce the risk of complications and severe illness from severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) in obesity population. In this review, we first summarized the clinical evidence on the effect of obesity on susceptibility, severity, and prognosis of COVID-19. Then we discussed and the underlying mechanisms, including respiratory pathophysiology of obesity, dysregulated inflammation, upregulated angiotensin-converting enzyme 2 (ACE2) expression, hyperglycemia, and adipokines. Finally, we proposed recommendations on how to reduce the spread and pandemic of SARS-CoV-2 infection by prevention and treatment of obesity.

Effect of high-flow nasal cannula versus non-invasive ventilation after extubation on successful extubation in obese patients: a retrospective analysis of the MIMIC-IV database

BACKGROUND

The pathophysiological characteristics of the respiratory system of obese patients differ from those of non-obese patients. Few studies have evaluated the effects of high-flow nasal cannula (HFNC) and non-invasive ventilation (NIV) on the prognosis of obese patients. We here compared the effects of these two techniques on the prevention of reintubation after extubation for obese patients.

METHODS

Data were extracted from the Medical Information Mart for Intensive Care database. Patients who underwent HFNC or NIV treatment after extubation were assigned to the HFNC or NIV group, respectively. The reintubation risk within 96 hours postextubation was compared between the two groups using a doubly robust estimation method. Propensity score matching was performed for both groups.

RESULTS

This study included 757 patients (HFNC group: n=282; NIV group: n=475). There was no significant difference in the risk of reintubation within 96 hours after extubation for the HFNC group compared with the NIV group (OR 1.50, p=0.127). Among patients with body mass index ≥40 kg/m2, the HFNC group had a significantly lower risk of reintubation within 96 hours after extubation (OR 0.06, p=0.016). No significant differences were found in reintubation rates within 48 hours (15.6% vs 11.0%, p=0.314) and 72 hours (16.9% vs 13.0%, p=0.424), as well as in hospital mortality (3.2% vs 5.2%, p=0.571) and intensive care unit (ICU) mortality (1.3% vs 5.2%, p=0.108) between the two groups. However, the HFNC group had significantly longer hospital stays (14 days vs 9 days, p=0.005) and ICU (7 days vs 5 days, p=0.001) stays.

CONCLUSIONS

This study suggests that HFNC therapy is not inferior to NIV in preventing reintubation in obese patients and appears to be advantageous in severely obese patients. However, HFNC is associated with significantly longer hospital stays and ICU stays.

Association between obesity and mortality in critically ill COVID-19 patients requiring invasive mechanical ventilation: a multicenter retrospective observational study

This study aimed to determine whether obesity and disease outcomes are associated in patients with critically-ill coronavirus disease 2019 (COVID-19) requiring invasive mechanical ventilation (IMV). This retrospective observational study using Japanese multicenter registry data included COVID-19 patients who required IMV and were discharged between January and September 2020. The patients were divided into the obese (body mass index [BMI] ≥ 25 kg/m²) and nonobese (BMI < 25 kg/m²) groups. Logistic regression models were used to analyze the association between obesity and disease outcomes. The primary outcome was in-hospital mortality; the secondary outcome was venovenous extracorporeal membrane oxygenation (VV-ECMO) implementation. Altogether, 477 patients were enrolled (obese, n = 235, median BMI, 28.2 kg/m²; nonobese, n = 242, median BMI, 22.4 kg/m²). Obesity was significantly associated with lower in-hospital mortality in the unadjusted logistic regression model (odds ratio 0.63; 95% confidence interval, 0.42-0.97; p = 0.033), but not with mortality in the adjusted logistic regression model using age, sex, and Charlson Comorbidity Index as covariates (p = 0.564). Obesity was not associated with VV-ECMO implementation in both unadjusted and adjusted models (unadjusted, p = 0.074; adjusted, p = 0.695). Obesity was not associated with outcomes in COVID-19 patients requiring IMV. Obesity may not be a risk factor for poor outcomes in these patients.

Profiles of Elderly Patients with Obesity Hypoventilation Syndrome in Martinique: A Single-Center Study

Obesity hypoventilation syndrome (OHS) is a form of chronic respiratory insufficiency related to obesity that affects young and old people. Age appears to be associated with poorer response to treatment by nighttime ventilation. This study aimed to describe the characteristics of elderly subjects (>65 years) with OHS compared to younger patients, with a view to adapting therapy in older individuals. We conducted a retrospective study comparing socio-demographic, clinical, functional characteristics as well as treatment and outcomes between young (<65 years) and older (65 years and older) individuals with OHS at the University Hospital of Martinique. We included 143 patients (114 women), of whom 82 were 65 years or older (57%). Charlson index was higher in the older group. Patients in ≥65 years group were less frequently obese, but more frequently had diabetes mellitus, cardiac arrythmia and arterial hypertension compared to younger patients. There was no difference in the circumstances of diagnosis or arterial blood gas at diagnosis. At follow up, partial pressure of carbon dioxide (pCO₂) was higher in ≥65 years group. Despite comparable NIV settings, apart from lower expiratory positive airway pressure (EPAP) with higher apnea-hypopnea index (AHI), patients in the ≥65-year-old group remained more frequently hypercapnic. In conclusion, over half (57%) of patients with OHS in our cohort were aged over 65 years. Older patients developed OHS at lower BMI levels than their younger counterparts, and more frequently, had comorbidities such as diabetes, hypertension and cardiac arrhythmia. Increased Charlson index, lower BMI and female sex were independent factors associated with OHS in the elderly.

The Bordeaux Sleepiness Scale (BOSS): a new questionnaire to measure sleep-related driving risk

STUDY OBJECTIVES

Sleepiness is a well-known risk factor for traffic accidents. Our study presents a new questionnaire, the Bordeaux Sleepiness Scale (BOSS), specifically designed to evaluate sleep-related driving risk in patients with sleep disorders.

METHODS

The BOSS was designed by gathering data on sociodemographics, sleepiness, driving items, and traffic accident exposure (kilometers driven) in the past year of 293 patients followed for sleep disorders at a French sleep clinic. It was then validated on data from a large population-based cohort of 7,296 highway drivers. Its performance was compared to the Epworth sleepiness scale and to self-reported episodes of severe sleepiness at the wheel. Receiver operating characteristic curves were computed.

RESULTS

The sensitivity and specificity of the BOSS (cutoff = 3) to predict sleep-related near-misses or accidents was, respectively, 82% and 74%, with an area under the receiver operating characteristic curve of 0.83. In a cohort of patients and a large population-based cohort, the area under the curve of the BOSS was significantly larger than that of the Epworth sleepiness scale (P < .001). Although the areas under the curve were equivalent between the BOSS and sleepiness at the wheel, the specificity of the BOSS was higher.

CONCLUSIONS

The BOSS scale combining exposure (kilometers driven) and self-perception of situational sleepiness provides a simple and reliable evaluation of sleep-related driving risk. This short, specific questionnaire should be promoted as a first-line tool to evaluate the risk of traffic accidents in sleepy patients.

CITATION

Philip P, Micoulaud-Franchi J-A, Taillard J, et al. The Bordeaux Sleepiness Scale (BOSS): a new questionnaire to measure sleep-related driving risk. J Clin Sleep Med. 2023;19(5):957-965.

Pulmonary Recruitment Prior to Intraoperative Multiple Pulmonary Ground-Glass Nodule Localization Increases the Localization Accuracy-A Retrospective Study

The standard treatment for early-stage lung cancer is complete tumor excision by limited resection of the lung. Preoperative localization is used before video-assisted thoracoscopic surgery (VATS) to improve the accuracy of pulmonary nodule excision. However, lung atelectasis and hypoxia resulting from controlling apnea during the localization procedure may affect the localization accuracy. Pre-procedural pulmonary recruitment may improve the respiratory mechanics and oxygenation during localization. In this study, we investigated the potential benefits of pre-localization pulmonary recruitment prior to pulmonary ground-glass nodule localization in a hybrid operating room. We hypothesized that pre-localization pulmonary recruitment would increase the localization accuracy, improve oxygenation, and prevent the need for re-inflation during the localization procedure. We retrospectively enrolled patients with multiple pulmonary nodule localizations before surgical intervention in our hybrid operating room. We compared the localization accuracy between patients who had undergone pre-procedure pulmonary recruitment and patients who had not. Saturation, re-inflation rate, apnea time, procedure-related pneumothorax, and procedure time were also recorded as secondary outcomes. The patients who had undergone pre-procedure recruitment had better saturation, shorter procedure time, and higher localization accuracy. The pre-procedure pulmonary recruitment maneuver was effective in increasing regional lung ventilation, leading to improved oxygenation and localization accuracy.

Positive end-expiratory pressure and postoperative complications in patients with obesity: a review and meta-analysis

OBJECTIVE

In patients with obesity, use of positive end-expiratory pressure (PEEP) > 5 cm H₂ O (centimeters of water) has been shown to prevent intraoperative atelectasis. This study compares the rate of postoperative pulmonary complications (PPCs) associated with PEEP > 5 cm H₂ O and PEEP ≤ 5 cm H₂ O in patients with obesity who underwent surgery under general anesthesia with mechanical ventilation.

METHODS

This study searched Medline, Embase, the Cochrane Central Register of Controlled Trials (CENTRAL), and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) using the terms "PEEP," "anesthesia," and "ventilation." Cochrane ReviewManager (RevMan) version 5 was used for data analysis. The primary outcome was a composite of PPCs, including atelectasis, pneumonia, pneumothorax, and acute respiratory failure.

RESULTS

The initial search identified 903 titles and abstracts, and 4 randomized controlled trials were included for analysis. We included a total of 2116 participants from four randomized controlled trials that compared PEEP ≤ 5 cm H₂ O with PEEP > 5 cm H₂ O in adult patients with obesity. There was no statistically significant difference in PPCs between the PEEP ≤ 5 cm H₂ O and PEEP > 5 cm H₂ O groups (risk ratio = 2.21, 95% CI: 0.41-11.83; p = 0.35). However, a significant heterogeneity was found within included studies (I²  = 53%).

CONCLUSIONS

It is unclear whether PEEP > 5 cm H₂ O improves the postoperative clinical outcome in patients with obesity, which is in contrast to previously established evidence that it reduces atelectasis in patients with obesity.

The intersection of obesity and (long) COVID-19: Hypoxia, thrombotic inflammation, and vascular endothelial injury

The role of hypoxia, vascular endothelial injury, and thrombotic inflammation in worsening COVID-19 symptoms has been generally recognized. Damaged vascular endothelium plays a crucial role in forming in situ thrombosis, pulmonary dysfunction, and hypoxemia. Thrombotic inflammation can further aggravate local vascular endothelial injury and affect ventilation and blood flow ratio. According to the results of many studies, obesity is an independent risk factor for a variety of severe respiratory diseases and contributes to high mechanical ventilation rate, high mortality, and slow recovery in COVID-19 patients. This review will explore the mechanisms by which obesity may aggravate the acute phase of COVID-19 and delay long COVID recovery by affecting hypoxia, vascular endothelial injury, and thrombotic inflammation. A systematic search of PubMed database was conducted for papers published since January 2020, using the medical subject headings of "COVID-19" and "long COVID" combined with the following keywords: "obesity," "thrombosis," "endothelial injury," "inflammation," "hypoxia," "treatment," and "anticoagulation." In patients with obesity, the accumulation of central fat restricts the expansion of alveoli, exacerbating the pulmonary dysfunction caused by SARS-CoV-2 invasion, inflammatory damage, and lung edema. Abnormal fat secretion and immune impairment further aggravate the original tissue damage and inflammation diffusion. Obesity weakens baseline vascular endothelium function leading to an early injury and pre-thrombotic state after infection. Enhanced procoagulant activity and microthrombi promote early obstruction of the vascular. Obesity also prolongs the duration of symptoms and increases the risk of sequelae after hospital discharge. Persistent viral presence, long-term inflammation, microclots, and hypoxia may contribute to the development of persistent symptoms, suggesting that patients with obesity are uniquely susceptible to long COVID. Early interventions, including supplemental oxygen, comprehensive antithrombotic therapy, and anti-inflammatory drugs, show effectiveness in many studies in the prevention of serious hypoxia, thromboembolic events, and systemic inflammation, and are therefore recommended to reduce intensive care unit admission, mortality, and sequelae.

Arterial bicarbonate is associated with hypoxic burden and uncontrolled hypertension in obstructive sleep apnea - The ESADA cohort

OBJECTIVE

Blood bicarbonate concentration plays an important role for obstructive sleep apnea (OSA) patients to maintain acid-base balance. We investigated the association between arterial standard bicarbonate ([HCO3^-]) and nocturnal hypoxia as well as comorbid hypertension in OSA.

METHODS

A cross-sectional analysis of 3329 patients in the European Sleep Apnea Database (ESADA) was performed. Arterial blood gas analysis and lung function test were performed in conjunction with polysomnographic sleep studies. The 4% oxygen desaturation index (ODI), mean and minimum oxygen saturation (SpO₂), and percentage of time with SpO₂ below 90% (T90%) were used to reflect nocturnal hypoxic burden. Arterial hypertension was defined as a physician diagnosis of hypertension with ongoing antihypertensive medication. Hypertensive patients with SBP/DBP below or above 140/90 mmHg were classified as controlled-, uncontrolled hypertension, respectively.

RESULTS

The [HCO3^-] level was normal in most patients (average 24.0 ± 2.5 mmol/L). ODI, T90% increased whereas mean and minimum SpO₂ decreased across [HCO3^-] tertiles (ANOVA, p = 0.030, <0.001, <0.001, and <0.001, respectively). [HCO3^-] was independently associated with ODI, mean SpO₂, minimum SpO₂, and T90% after adjusting for confounders (β value [95%CI]: 1.21 [0.88-1.54], -0.16 [-0.20 to -0.11], -0.51 [-0.64 to -0.37], 1.76 [1.48-2.04], respectively, all p < 0.001). 1 mmol/L elevation of [HCO3^-] was associated with a 4% increased odds of uncontrolled hypertension (OR: 1.04 [1.01-1.08], p = 0.013).

CONCLUSION

We first demonstrated an independent association between [HCO3^-] and nocturnal hypoxic burden as well as uncontrolled hypertension in OSA patients. Bicarbonate levels as an adjunctive measure provide insight into the pathophysiology of hypertension in OSA.

Cost-effectiveness of outpatient versus inpatient non-invasive ventilation setup in obesity hypoventilation syndrome: the OPIP trial

BACKGROUND

Current guidelines recommend that patients with obesity hypoventilation syndrome (OHS) are electively admitted for inpatient initiation of home non-invasive ventilation (NIV). We hypothesised that outpatient NIV setup would be more cost-effective.

METHODS

Patients with stable OHS referred to six participating European centres for home NIV setup were recruited to an open-labelled clinical trial. Patients were randomised via web-based system using stratification to inpatient setup, with standard fixed level NIV and titrated during an attended overnight respiratory study or outpatient setup using an autotitrating NIV device and a set protocol, including home oximetry. The primary outcome was cost-effectiveness at 3 months with daytime carbon dioxide (PaCO₂) as a non-inferiority safety outcome; non-inferiority margin 0.5 kPa. Data were analysed on an intention-to-treat basis. Health-related quality of life (HRQL) was measured using EQ-5D-5L (5 level EQ-5D tool) and costs were converted using purchasing power parities to £(GBP).

RESULTS

Between May 2015 and March 2018, 82 patients were randomised. Age 59±14 years, body mass index 47±10 kg/m² and PaCO₂ 6.8±0.6 kPa. Safety analysis demonstrated no difference in ∆PaCO₂ (difference -0.27 kPa, 95% CI -0.70 to 0.17 kPa). Efficacy analysis showed similar total per-patient costs (inpatient £2962±£580, outpatient £3169±£525; difference £188.20, 95% CI -£61.61 to £438.01) and similar improvement in HRQL (EQ-5D-5L difference -0.006, 95% CI -0.05 to 0.04). There were no differences in secondary outcomes.

DISCUSSION

There was no difference in medium-term cost-effectiveness, with similar clinical effectiveness, between outpatient and inpatient NIV setup. The home NIV setup strategy can be led by local resource demand and patient and clinician preference.

TRIAL REGISTRATION NUMBERS

NCT02342899 and ISRCTN51420481.

The effect of positive end-expiratory pressure on intracranial pressure in obese and non-obese severe brain injury patients: a retrospective observational study

BACKGROUND

The effect of positive end-expiratory pressure (PEEP) on intracranial pressure (ICP) had never been studied in obese patients with severe brain injury (SBI). The main aim was to evaluate the effect of PEEP on ICP in SBI patients with mechanical ventilation according to obesity status.

METHODS

SBI patients admitted to the ICU with mechanical ventilation between 2014 and 2015 were included. Demographic, hemodynamic, arterial blood gas, and ventilator data at the time of the paired PEEP and ICP observations were recorded and compared between obese (body mass index ≥ 30 kg/m²) and non-obese SBI patients. Generalized estimating equation (GEE) model was used to assess the relationship between PEEP and ICP in obese and non-obese SBI patients, respectively.

RESULTS

Six hundred twenty-seven SBI patients were included, 407 (65%) non-obese and 220 (35%) obese patients. A total of 30,415 paired PEEP and ICP observations were recorded in these patients, 19,566 (64.3%) for non-obese and 10,849 (35.7%) for obese. In the multivariable analysis, a statistically significant relationship between PEEP and ICP was found in obese SBI patients, but not in non-obese ones. For every cmH₂O increase in PEEP, there was a 0.19 mmHg increase in ICP (95% CI [0.05, 0.33], P = 0.007) and a 0.15 mmHg decrease in CPP (95% CI [-0.29, -0.01], P = 0.036) in obese SBI patients after adjusting for confounders.

CONCLUSIONS

The results suggested that, contrary to non-obese SBI patients, the application of PEEP may produce an increase in ICP in obese SBI patients. However, the effect was modest and may be clinically inconsequential.

How to improve intubation in the intensive care unit. Update on knowledge and devices

Tracheal intubation in the critically ill is associated with serious complications, mainly cardiovascular collapse and severe hypoxemia. In this narrative review, we present an update of interventions aiming to decrease these complications. MACOCHA is a simple score that helps to identify patients at risk of difficult intubation in the intensive care unit (ICU). Preoxygenation combining the use of inspiratory support and positive end-expiratory pressure should remain the standard method for preoxygenation of hypoxemic patients. Apneic oxygenation using high-flow nasal oxygen may be supplemented, to prevent further hypoxemia during tracheal intubation. Face mask ventilation after rapid sequence induction may also be used to prevent hypoxemia, in selected patients without high-risk of aspiration. Hemodynamic optimization and management are essential before, during and after the intubation procedure. All these elements can be integrated in a bundle. An airway management algorithm should be adopted in each ICU and adapted to the needs, situation and expertise of each operator. Videolaryngoscopes should be used by experienced operators.

Multidisciplinary residential program for the treatment of obesity: how body composition assessed by DXA and blood chemistry parameters change during hospitalization and which variations in body composition occur from discharge up to 1-year follow-up

PURPOSE

Obesity is a chronic disease characterized by a complex variable clinical presentation with comorbidities. A multidisciplinary residential program (MRP) represents one of the best options for treating obesity. The purpose of this study was to evaluate the effectiveness of 8-week MRP on weight loss, body composition assessed by DXA, and metabolic blood parameters between entry (T0) and discharge (T1). The secondary endpoint was the evaluation of the patients' adherence to diet during the check-up outpatient visits, at 2 (T2), 6 (T3), and 12 (T4) months after discharge.

METHODS

168 subjects were enrolled (61 males and 117 females, aged 58.5 ± 13 years, BMI 41.3 ± 6 kg/m²) in the study. The difference in values ​​(end of hospitalization compared to baseline) was calculated through the univariate analysis procedure, which provides regression analysis and analysis of variance for a variable dependent on one or more variables.

RESULTS

There was a statistically significant improvement of all parameters investigated: total mass (- 5.68 kg), fat mass (- 4416.85 g), fat mass index (- 1724.56), visceral adipose tissue (- 332.76 g), arm circumference (- 1.63 cm) and calf circumference (- 1.16 cm). As it is reasonable to expect, even the fat free mass has been reduced (- 1236.03 g); however, the skeletal muscle index was not affected. Statistically significant improvement in glycaemic and lipid profile were reported. The BMI average reduction continued from discharge until T4. No statistically significant changes in fat free mass and visceral adipose tissue (VAT) were reported during a year of follow-up.

CONCLUSIONS

The present study demonstrated the clinical benefits of 8-week MRP, which includes hypocaloric diet, physical exercise, and psychological support.

LEVEL OF EVIDENCE

III, evidence obtained from cohort or case-control analytic studies.

Application of Inverse-Probability-of-Treatment Weighting to Estimate the Effect of Daytime Sleepiness in Patients with Obstructive Sleep Apnea

Rationale: Continuous positive airway pressure (CPAP), the first line therapy for obstructive sleep apnea (OSA), is considered effective in reducing daytime sleepiness. Its efficacy relies on adequate adherence, often defined as >4 hours per night. However, this binary threshold may limit our understanding of the causal effect of CPAP adherence and daytime sleepiness, and a multilevel approach for CPAP adherence can be more appropriate. Objectives: In this study, we show how two causal inference methods can be applied on observational data for the estimation of the effect of different ranges of CPAP adherence on daytime sleepiness as measured by the Epworth Sleepiness Scale (ESS). Methods: Data were collected from a large prospective observational French cohort for patients with OSA. Four groups of CPAP adherence were considered (0-4, 4-6, 6-7, and 7-10 h per night). Multivariable regression, inverse-probability-of-treatment weighting (IPTW), and inverse propensity weighting with regression adjustment (IPW-RA) were used to assess the impact of CPAP adherence level on daytime sleepiness. Results: In this study, 9,244 patients with OSA treated by CPAP were included. The mean initial ESS score was 11 (±5.2), with a mean reduction of 4 points (±5.1). Overall, there was evidence of the causal effect of CPAP adherence on daytime sleepiness which was mainly observed between the lower CPAP adherence group (0-4 h) compared with the higher CPAP adherence group (7-10 h). There are no differences by considering higher level of CPAP adherence (>4 h). Conclusions: We showed that IPTW and IPW-RA can be easily implemented to answer questions regarding causal effects using observational data when randomized trials cannot be conducted. Both methods give a direct causal interpretation at the population level and allow the assessment of the appropriate consideration of measured confounders.

Adipose Tissue Inflammation and Pulmonary Dysfunction in Obesity

Obesity is a chronic disease caused by an excess of adipose tissue that may impair health by altering the functionality of various organs, including the lungs. Excessive deposition of fat in the abdominal area can lead to abnormal positioning of the diaphragm and consequent reduction in lung volume, leading to a heightened demand for ventilation and increased exposure to respiratory diseases, such as chronic obstructive pulmonary disease, asthma, and obstructive sleep apnoea. In addition to mechanical ventilatory constraints, excess fat and ectopic deposition in visceral depots can lead to adipose tissue dysfunction, which promotes metabolic disorders. An altered adipokine-secretion profile from dysfunctional adipose tissue in morbid obesity fosters systemic, low-grade inflammation, impairing pulmonary immune response and promoting airway hyperresponsiveness. A potential target of these adipokines could be the NLRP3 inflammasome, a critical component of the innate immune system, the harmful pro-inflammatory effect of which affects both adipose and lung tissue in obesity. In this review, we will investigate the crosstalk between adipose tissue and the lung in obesity, highlighting the main inflammatory mediators and novel therapeutic targets in preventing pulmonary dysfunction.

Obesity and COVID-19: Mechanistic Insights From Adipose Tissue

Obesity is associated with an increase in morbidity and mortality from coronavirus disease 2019 (COVID-19). The risk is related to the cytokine storm, a major contributor to multiorgan failure and a pathological character of COVID-19 patients with obesity. While the exact cause of the cytokine storm remains elusive, disorders in energy metabolism has provided insights into the mechanism. Emerging data suggest that adipose tissue in obesity contributes to the disorders in several ways. First, adipose tissue restricts the pulmonary function by generation of mechanical pressures to promote systemic hypoxia. Second, adipose tissue supplies a base for severe acute respiratory syndrome coronavirus 2 entry by overexpression of viral receptors [angiotensin-converting enzyme 2 and dipeptidyl peptidase 4]. Third, impaired antiviral responses of adipocytes and immune cells result in dysfunction of immunologic surveillance as well as the viral clearance systems. Fourth, chronic inflammation in obesity contributes to the cytokine storm by secreting more proinflammatory cytokines. Fifth, abnormal levels of adipokines increase the risk of a hyperimmune response to the virus in the lungs and other organs to enhance the cytokine storm. Mitochondrial dysfunction in adipocytes, immune cells, and other cell types (endothelial cells and platelets, etc) is a common cellular mechanism for the development of cytokine storm, which leads to the progression of mild COVID-19 to severe cases with multiorgan failure and high mortality. Correction of energy surplus through various approaches is recommended in the prevention and treatment of COVID-19 in the obese patients.

Non-invasive ventilation versus oxygen therapy after extubation in patients with obesity in intensive care units: the multicentre randomised EXTUB-OBESE study protocol

INTRODUCTION

Patients with obesity are considered to be at high risk of acute respiratory failure (ARF) after extubation in intensive care unit (ICU). Compared with oxygen therapy, non-invasive ventilation (NIV) may prevent ARF in high-risk patients. However, these strategies have never been compared following extubation of critically ill patients with obesity. Our hypothesis is that NIV is associated with less treatment failure compared with oxygen therapy in patients with obesity after extubation in ICU.

METHODS AND ANALYSIS

The NIV versus oxygen therapy after extubation in patients with obesity in ICUs protocol (EXTUB-obese) trial is an investigator-initiated, multicentre, stratified, parallel-group unblinded trial with an electronic system-based randomisation. Patients with obesity defined as a body mass index ≥30 kg/m² will be randomly assigned in the 'NIV-group' to receive prophylactic NIV applied immediately after extubation combined with high-flow nasal oxygen (HFNO) or standard oxygen between NIV sessions versus in the 'oxygen therapy group' to receive oxygen therapy alone (HFNO or standard oxygen,). The primary outcome is treatment failure within the 72 hours, defined as reintubation for mechanical ventilation, switch to the other study treatment, or premature study-treatment discontinuation (at the request of the patient or for medical reasons such as gastric distention). The single, prespecified, secondary outcome is the incidence of ARF until day 7. Other outcomes analysed will include tracheal intubation rate at day 7 and day 28, length of ICU and hospital stay, ICU mortality, day 28 and day 90 mortality.

ETHICS AND DISSEMINATION

The study project has been approved by the appropriate ethics committee 'Comité-de-Protection-des-Personnes Ile de FranceV-19.04.05.70025 Cat2 2019-A00956-51'. Informed consent is required. The results will be submitted for publication in a peer-reviewed journal and presented at one or more scientific conferences. If use of NIV shows positive effects, teams (medical and surgical) will use NIV following extubation of critically ill patients with obesity.

TRIAL REGISTRATION NUMBER

NCT04014920.

Emergencies in obese patients: a narrative review

Obesity is associated to an increased risk of morbidity and mortality due to respiratory, cardiovascular, metabolic, and neoplastic diseases. The aim of this narrative review is to assess the physio-pathological characteristics of obese patients and how they influence the clinical approach during different emergency settings, including cardiopulmonary resuscitation. A literature search for published manuscripts regarding emergency and obesity across MEDLINE, EMBASE, and Cochrane Central was performed including records till January 1, 2021. Increasing incidence of obesity causes growth in emergency maneuvers dealing with airway management, vascular accesses, and drug treatment due to both pharmacokinetic and pharmacodynamic alterations. Furthermore, instrumental diagnostics and in/out-hospital transport may represent further pitfalls. Therefore, people with severe obesity may be seriously disadvantaged in emergency health care settings, and this condition is enhanced during the COVID-19 pandemic, when obesity was stated as one of the most frequent comorbidity. Emergency in critical obese patients turns out to be an intellectual, procedural, and technical challenge. Organization and anticipation based on the understanding of the physiopathology related to obesity are very important for the physician to be mentally and physically ready to face the associated issues.

: A Post-Hoc Analysis of a Randomized Clinical Trial

RATIONALE

Whereas non-invasive ventilation (NIV) may prevent reintubation in patients at high-risk of extubation failure in intensive care units (ICUs), this oxygenation strategy has not been specifically assessed in obese patients.

OBJECTIVES

We hypothesized that NIV may decrease the risk of reintubation in obese patients compared with high-flow nasal oxygen (HFNO).

METHODS

Post-hoc analysis of a multicenter, randomized, controlled trial (not pre-specified) comparing NIV alternating with HFNO versus HFNO alone after extubation, with the aim of assessing NIV effects according to patient body-mass index (BMI).

MEASUREMENTS AND MAIN RESULTS

Among 623 patients at high-risk of extubation failure, 206 (33%) were obese (BMI≥30 kg/m2), 204 (33%) were overweight (25≤BMI<30), and 213 (34%) were normal or underweight (BMI<25). Significant heterogeneity of NIV effects on the rate of reintubation was found according to BMI (Pinteraction=0.007). Reintubation rates at day 7 were significantly lower with NIV alternating with HFNO than with HFNO alone in obese or overweight patients: 7% (15/204) vs. 20% (41/206); difference, -13%; [95% CI, -19 to -6]; P=0.0002; whereas it did not significantly differ in normal or underweight patients. In-ICU mortality was significantly lower with NIV than with HFNO alone in obese or overweight patients (2% vs. 9%; difference, -6%; [95% CI, -11 to -2]; P=0.006).

CONCLUSIONS

Prophylactic NIV alternating with HFNO immediately after extubation significantly decreased the risk of reintubation and death as compared with HFNO alone in obese or overweight patients at high-risk of extubation failure. By contrast, NIV was not effective in normal or underweight patients.

Malignant Hyperthermia During Cardiac Surgery Successfully Treated by Deep Hypothermia Using Cardiopulmonary Bypass: A Case Report

Malignant hyperthermia (MH) is a life-threatening hypermetabolic disorder triggered by volatile anesthetics and/or succinylcholine. We report a case of a 58-year-old patient with a type-A aortic dissection. After induction of general anesthesia, a hypermetabolic reaction was successfully treated by deep hypothermia using cardiopulmonary bypass. Dantrolene became available in theater after the hypermetabolism was already treated successfully by hypothermia. Because of a low suspicion of MH, dantrolene was not administered when it became available. The patient fully recovered, and MH susceptibility was confirmed. Cardiopulmonary bypass should be considered to treat MH in case dantrolene and conservative therapy are unavailable or insufficient.

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.

Obesity and severe coronavirus disease 2019: molecular mechanisms, paths forward, and therapeutic opportunities

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) appears to have higher pathogenicity among patients with obesity. Obesity, termed as body mass index greater than 30 kg/m2, has now been demonstrated to be important comorbidity for disease severity during coronavirus disease 2019 (COVID-19) pandemic and associated with adverse events. Unraveling mechanisms behind this phenomenon can assist scientists, clinicians, and policymakers in responding appropriately to the COVID-19 pandemic. In this review, we systemically delineated the potential mechanistic links between obesity and worsening COVID-19 from altered physiology, underlying diseases, metabolism, immunity, cytokine storm, and thrombosis. Problematic ventilation caused by obesity and preexisting medical disorders exacerbate organ dysfunction for patients with obesity. Chronic metabolic disorders, including dyslipidemia, hyperglycemia, vitamin D deficiency, and polymorphisms of metabolism-related genes in obesity, probably aid SARS-CoV-2 intrusion and impair antiviral responses. Obesity-induced inadequate antiviral immunity (interferon, natural killer cells, invariant natural killer T cell, dendritic cell, T cells, B cell) at the early stage of SARS-CoV-2 infection leads to delayed viral elimination, increased viral load, and expedited viral mutation. Cytokine storm, with the defective antiviral immunity, probably contributes to tissue damage and pathological progression, resulting in severe symptoms and poor prognosis. The prothrombotic state, driven in large part by endothelial dysfunction, platelet hyperactivation, hypercoagulability, and impaired fibrinolysis in obesity, also increases the risk of severe COVID-19. These mechanisms in the susceptibility to severe condition also open the possibility for host-directed therapies in population with obesity. By bridging work done in these fields, researchers can gain a holistic view of the paths forward and therapeutic opportunities to break the vicious cycle of obesity and its devastating complications in the next emerging pandemic.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Management of Intraoperative Mechanical Ventilation to Prevent Postoperative Complications after General Anesthesia: A Narrative Review

Mechanical ventilation (MV) is still necessary in many surgical procedures; nonetheless, intraoperative MV is not free from harmful effects. Protective ventilation strategies, which include the combination of low tidal volume and adequate positive end expiratory pressure (PEEP) levels, are usually adopted to minimize the ventilation-induced lung injury and to avoid post-operative pulmonary complications (PPCs). Even so, volutrauma and atelectrauma may co-exist at different levels of tidal volume and PEEP, and therefore, the physiological response to the MV settings should be monitored in each patient. A personalized perioperative approach is gaining relevance in the field of intraoperative MV; in particular, many efforts have been made to individualize PEEP, giving more emphasis on physiological and functional status to the whole body. In this review, we summarized the latest findings about the optimization of PEEP and intraoperative MV in different surgical settings. Starting from a physiological point of view, we described how to approach the individualized MV and monitor the effects of MV on lung function.

Obesity is a strong risk factor for short-term mortality and adverse outcomes in Mexican patients with COVID-19: a national observational study

Conflicting results have been obtained through meta-analyses for the role of obesity as a risk factor for adverse outcomes in patients with coronavirus disease-2019 (COVID-19), possibly due to the inclusion of predominantly multimorbid patients with severe COVID-19. Here, we aimed to study obesity alone or in combination with other comorbidities as a risk factor for short-term all-cause mortality and other adverse outcomes in Mexican patients evaluated for suspected COVID-19 in ambulatory units and hospitals in Mexico. We performed a retrospective observational analysis in a national cohort of 71 103 patients from all 32 states of Mexico from the National COVID-19 Epidemiological Surveillance Study. Two statistical models were applied through Cox regression to create survival models and logistic regression models to determine risk of death, hospitalisation, invasive mechanical ventilation, pneumonia and admission to an intensive care unit, conferred by obesity and other comorbidities (diabetes mellitus (DM), chronic obstructive pulmonary disease, asthma, immunosuppression, hypertension, cardiovascular disease and chronic kidney disease). Models were adjusted for other risk factors. From 24 February to 26 April 2020, 71 103 patients were evaluated for suspected COVID-19; 15 529 (21.8%) had a positive test for SARS-CoV-2; 46 960 (66.1%), negative and 8614 (12.1%), pending results. Obesity alone increased adjusted mortality risk in positive patients (hazard ratio (HR) = 2.7, 95% confidence interval (CI) 2.04-2.98), but not in negative and pending-result patients. Obesity combined with other comorbidities further increased risk of death (DM: HR = 2.79, 95% CI 2.04-3.80; immunosuppression: HR = 5.06, 95% CI 2.26-11.41; hypertension: HR = 2.30, 95% CI 1.77-3.01) and other adverse outcomes. In conclusion, obesity is a strong risk factor for short-term mortality and critical illness in Mexican patients with COVID-19; risk increases when obesity is present with other comorbidities.

Nasal versus oronasal masks for home non-invasive ventilation in patients with chronic hypercapnia: a systematic review and individual participant data meta-analysis

BACKGROUND

The optimal interface for the delivery of home non-invasive ventilation (NIV) to treat chronic respiratory failure has not yet been determined. The aim of this individual participant data (IPD) meta-analysis was to compare the effect of nasal and oronasal masks on treatment efficacy and adherence in patients with COPD and obesity hypoventilation syndrome (OHS).

METHODS

We searched Medline and Cochrane Central Register of Controlled Trials for prospective randomised controlled trials (RCTs) of at least 1 month's duration, published between January 1994 and April 2019, that assessed NIV efficacy in patients with OHS and COPD. The main outcomes were diurnal PaCO₂, PaO₂ and NIV adherence (PROSPERO CRD42019132398).

FINDINGS

Of 1576 articles identified, 34 RCTs met the inclusion criteria and IPD were obtained for 18. Ten RCTs were excluded because only one type of mask was used, or mask data were missing. Data from 8 RCTs, including 290 IPD, underwent meta-analysis. Oronasal masks were used in 86% of cases. There were no differences between oronasal and nasal masks for PaCO₂ (0.61 mm Hg (95% CI -2.15 to 3.38); p=0.68), PaO₂ (-0.00 mm Hg (95% CI -4.59 to 4.58); p=1) or NIV adherence (0·29 hour/day (95% CI -0.74 to 1.32); p=0.58). There was no interaction between the underlying pathology and the effect of mask type on any outcome.

INTERPRETATION

Oronasal masks are the most used interface for the delivery of home NIV in patients with OHS and COPD; however, there is no difference in the efficacy or tolerance of oronasal or nasal masks.

Obesity and risk of catheter-related infections in the ICU. A post hoc analysis of four large randomized controlled trials

PURPOSE

Obesity increases the risk of nosocomial infection, but data regarding the role of body mass index (BMI) in catheter related infections are scarce. We used the data gathered from four randomized, controlled trials (RCTs) to investigate the association between body mass index (BMI) and intravascular catheter infections in critically ill obese patients.

METHODS

Adult obese patients who required short-term central venous, arterial or dialysis catheter insertion in the intensive care unit (ICU) were analyzed. The association between BMI and major catheter-related infection (MCRI), catheter-related bloodstream infection (CRBSI) and catheter tip colonization was estimated using univariate and multivariate marginal Cox models. Exploratory analysis using dressing disruptions was added.

RESULTS

A total of 2282 obese patients and 4275 catheters from 32 centers were included in this post-hoc analysis. Overall, 66 (1.5%) MCRI, 43 (1%) CRBSI and 399 (9.3%) catheter colonizations were identified. The hazard ratio (HR) for MCRI, CRBSI and colonization increased with BMI. After adjustment for well-known infection risk factors, the BMI ≥ 40 group had an increased risk for MCRI (HR 1.88, 95% CI 1.13-3.12, p = 0.015), CRBSI (HR 2.19, 95% CI 1.19-4.04, p = 0.012) and colonization (HR 1.44, 95% CI 1.12-1.84, p = 0.0038) compared to the BMI < 40 group. The mean dressing disruption per catheter was increased in the BMI ≥ 40 group (2.03 versus 1.68 in the BMI < 40 group, p = 0.05).

CONCLUSIONS

Using the largest dataset ever collected from large multicentric RCTs, we showed that patients with BMI ≥ 40 had an increased risk for intravascular catheter infections. Targeted prevention measures should focus on this population with a particular attention to catheter care and dressing disruption.

Sleep-Related Breathing Disorders: When CPAP Is Not Enough

Three decades ago, continuous positive airway pressure (CPAP) was introduced to treat obstructive sleep apnea (OSA). Shortly after, bilevel positive airway pressure devices (BPAP) that independently adjusted inspiratory and expiratory positive airway pressure were developed to treat complex sleep-related breathing disorders unresponsive to CPAP. Based on the bilevel positive airway pressure platform (hardware) governed by propriety algorithms (software), advanced modes of noninvasive ventilation (NIV) were developed to address complex cardiorespiratory pathophysiology beyond OSA. This review summarizes key aspects of different bilevel PAP therapies (BPAP with/without backup rate, adaptive servoventilation, and volume-assured pressure support) to treat common sleep-related hypoventilation disorders, treatment-emergent central sleep apnea, and central sleep apnea syndromes.

The Effect of Bariatric Surgery Volume on General Surgery Outcomes for Morbidly Obese Patients

INTRODUCTION

Bariatric surgery performed at high volume centers decreases length of stay, cost, and morbidity and mortality. The effect of a high volume of bariatric surgery procedures on outcomes may extend not just to bariatric surgery but to any general surgical procedure in morbidly obese patients. We hypothesized that patients with morbid obesity (body mass index >40 kg/m²) undergoing common, nonbariatric general surgery would have decreased morbidity and mortality at centers performing high volumes of bariatric surgery.

METHODS

The 2016 National Inpatient Sample (NIS) was used to identify the number of laparoscopic gastric bypass and sleeve gastrectomy performed at each hospital. Hospitals were classified as high volume bariatric hospitals (HVBH) ≥10 reported cases (50 actual)/year or low volume bariatric hospitals (LVBH) <10 reported cases (50 actual)/year, as NIS reports a 20% sample of actual cases. Patients with morbid obesity undergoing laparoscopic or open appendectomy, cholecystectomy, or ventral hernia repair were included for analysis. Propensity scores were developed based on available demographics, comorbidities, and hospital procedure volume. Postoperative complications during the index hospital admission, determined by ICD-10 code, were compared using inverse propensity weights. Differences were considered significant with a p value of <0.05.

RESULTS

The total number of general surgery patient cases analyzed was 14,028 from 2,482 hospitals, representing 70,140 admissions. The cohort of patients undergoing operations treated at HVBH were younger (p=0.03) with higher rates of COPD (p=0.04). Patients at LVBH had higher rates of nicotine dependence (p=0.0001) and obstructive sleep apnea (p < 0.001). On propensity-weighted analysis adjusting for preoperative comorbidities and hospital procedure volume, there were significantly higher rates of multiple postprocedure complications at LVBH, specifically, postprocedure respiratory failure for patients undergoing elective laparoscopic cholecystectomy, elective ventral hernia repair with mesh and appendectomy.

CONCLUSION

Patients with morbid obesity may have an advantage in having general surgery procedures at HVBH. HVBH may have a volume-outcomes relationship where the hospital and staff familiarity with the management principles required to minimize the postoperative risk associated with morbid obesity and improve patient outcomes.

Obesity Hypoventilation: Traditional Versus Nontraditional Populations

Obesity hypoventilation syndrome is the most frequent cause of chronic hypoventilation and is increasingly more common with rising obesity rates. It leads to considerable morbidity and mortality, particularly when not recognized and treated adequately. Long-term nocturnal noninvasive ventilation is the mainstay of treatment but evidence suggests that CPAP may be effective in stable patients. Specific perioperative management is required to reduce complications. Some unique syndromes associated with obesity and hypoventilation include rapid-onset obesity with hypoventilation, hypothalamic, autonomic dysregulation (ROHHAD), and Prader-Willi syndrome. Congenital central hypoventilation syndrome (early or late-onset) is a genetic disorder resulting in hypoventilation. Several acquired causes of chronic central hypoventilation also exist. A high level of clinical suspicion is required to appropriately diagnose and manage affected patients.

Continuous positive airway pressure-treated patients' behaviours during the COVID-19 crisis

Obstructive sleep apnoea (OSA) is one of the most prevalent chronic diseases, affecting nearly one billion people worldwide [1]. Continuous positive airway pressure (CPAP) is the first-line therapy for OSA [2], and is currently used by over one million people throughout France. A focus on the OSA population during the COVID-19 outbreak is of particular interest for the following two main reasons. 1) OSA is a multi-morbid disease with up to 70% of patients being obese [3] and exhibiting a high prevalence of cardiometabolic comorbidities. Such a clinical context is expected to be associated with a higher risk of severe forms of COVID-19 and a higher mortality rate [4]. 2) CPAP treatment is considered a high-risk aerosol-generating procedure potentially facilitating viral dispersion into the environment and transmission of infection [5–7].

The #COVID19 pandemic has had limited impact on CPAP use by obstructive sleep apnoea patients. Mainly only those with suspected or proven COVID-19 stopped CPAP use, sometimes without a physician's advice, and were more likely to move to a separate bedroom.https://bit.ly/2RxQDZO

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”.

The use of intraoperative bedside lung ultrasound in optimizing positive end expiratory pressure in obese patients undergoing laparoscopic bariatric surgeries

BACKGROUND

Anesthetic management of patients with obesity undergoing laparoscopic abdominal surgeries requires careful plan for intraoperative mechanical ventilation aiming to avoid lung atelectasis and/or overdistention. There are conflicting data on the optimum positive end expiratory pressure (PEEP) during these surgeries. We hypothesized that lung ultrasound could be used for PEEP titration during laparoscopic surgery.

OBJECTIVE

The purpose of this study is to evaluate the effectiveness of intraoperative individualized lung ultrasound-guided PEEP in obese patients undergoing laparoscopic bariatric surgery on intraoperative partial arterial oxygen tension (PaO₂) and early postoperative pulmonary complications.

METHODS

A randomized controlled trial included 40 adult patients with body mass index (BMI) > 35 kg/m² undergoing laparoscopic bariatric surgery. Patients were randomized into: control group (n = 20) who received PEEP 4 cm.H₂ O and ultrasound-guided group (n = 20) who received individualized lung ultrasound stepwise PEEP. All patients received volume-controlled ventilation with a tidal volume of 6 mL/kg of ideal weight and a fraction of inspired oxygen of .5. The primary outcome was the difference in partial arterial oxygen tension (PaO₂) between the control group and the ultrasound-guided group. The secondary outcomes included the incidence of early postoperative pulmonary atelectasis, respiratory failure, bronchospasm, hypoxia or pneumothorax.

SETTINGS

General surgery operating theatre at Cairo University hospitals.

RESULTS

Ultrasound-guided group showed higher PO₂ after PEEP optimization and postoperatively compared with control group (P = .005, and P = .01 respectively). Also, ultrasound-guided group showed no postoperative complications compared with control group that had 5 cases who developed postoperative pulmonary complications in the form of hypoxia and basal collapse in the first 24 hour postoperatively chest x ray (0% versus 25%, P = .047).

CONCLUSION

In patients with obesity undergoing laparoscopic bariatric surgery, the use of lung ultrasound individualized stepwise PEEP approach improved oxygenation, compliance and reduced the incidence of postoperative pulmonary atelectasis and hypoxia without causing hemodynamic instability.

Sleep-related breathing disorders and pulmonary hypertension

Sleep-related breathing disorders (SBDs) include obstructive apnoea, central apnoea and sleep-related hypoventilation. These nocturnal events have the potential to increase pulmonary arterial pressure (PAP) during sleep but also in the waking state. "Pure" obstructive sleep apnoea syndrome (OSAS) is responsible for a small increase in PAP whose clinical impact has not been demonstrated. By contrast, in obesity hypoventilation syndrome (OHS) or overlap syndrome (the association of chronic obstructive pulmonary disease (COPD) with obstructive sleep apnoea (OSA)), nocturnal respiratory events contribute to the development of pulmonary hypertension (PH), which is often severe. In the latter circumstances, treatment of SBDs is essential in order to improve pulmonary haemodynamics.Patients with pulmonary arterial hypertension (PAH) or chronic thromboembolic pulmonary hypertension (CTEPH) are at risk of developing SBDs. Obstructive and central apnoea, as well as a worsening of ventilation-perfusion mismatch, can be observed during sleep. There should be a strong suspicion of SBDs in such a patient population; however, the precise indications for sleep studies and the type of recording remain to be specified. The diagnosis of OSAS in patients with PAH or CTEPH should encourage treatment with continuous positive airway pressure (CPAP). The presence of isolated nocturnal hypoxaemia should also prompt the initiation of long-term oxygen therapy. These treatments are likely to avoid worsening of PH; however, it is prudent not to treat central apnoea and Cheyne-Stokes respiration (CSR) with adaptive servo-ventilation in patients with chronic right-heart failure because of a potential risk of serious adverse effects from such treatment.In this review we will consider the current knowledge of the consequences of SBDs on pulmonary haemodynamics in patients with and without chronic respiratory disease (group 3 of the clinical classification of PH) and the effect of treatments of respiratory events during sleep on PH. The prevalence and consequences of SBDs in PAH and CTEPH (groups 1 and 4 of the clinical classification of PH, respectively), as well as therapeutic options, will also be discussed.

Long-term variations of arterial stiffness in patients with obesity and obstructive sleep apnea treated with continuous positive airway pressure

BACKGROUND

Obstructive sleep apnea (OSA) is associated with cardiovascular co-morbidities and mortality. Arterial stiffness is an independent predictor of cardiovascular risk and mortality, and is influenced by the presence of OSA and related comorbidities. There is a paucity of data regarding long-term evolution of arterial stiffness in CPAP-treated OSA patients. We aimed to prospectively study long term PWV variations and determinants of PWV deterioration.

METHODS

In a prospective obese OSA cohort, at time of diagnosis and after several years of follow-up we collected arterial stiffness measured by carotid-femoral pulse wave velocity (PWV), clinical and metabolic parameters, and CPAP adherence. Univariate and multivariate analyses were performed in order to determine contributing factors.

RESULTS

Seventy two OSA patients (men: 52.8%, median age: 55.8 years and median BMI of 38.5 kg/m2) with a prevalence of hypertension: 58.3%, type 2 diabetes: 20.8%, hypercholesterolemia: 33.3%, current or past smoking: 59.7%, were evaluated after a median follow-up of 7.4 [5.8; 8.3] years. Over the period of follow-up, the median increase in PWV was 1.34 [0.10; 2.37] m/s. In multivariate analysis, the increase in PWV was associated with older age (10 extra years was associated with a 5.24 [1.35; 9.12] % increase in PWV) and hypertension (a significant increase in PWV of 8.24 [1.02; 15.57] %). No impact of CPAP adherence on PWV evolution was found.

CONCLUSION

PWV progression in CPAP-treated OSA patients is mainly related to pre-existing cardio-metabolic comorbidities and not influenced by CPAP adherence. In this high cardiovascular risk population, it is crucial to associated weight management and exercise with CPAP treatment.

Easier access to mechanical ventilation worldwide: an urgent need for low income countries, especially in face of the growing COVID-19 crisis

That positive pressure mechanical ventilation can save lives was proved during the poliomyelitis epidemics of the 1950s. Since that time there has been a growing increase in the use of ventilatory support, and it has been closely associated with the development of critical care medicine [1]. Positive pressure ventilation can be life-saving in patients with acute severe hypoxaemia that is refractory to more conservative measures. In patients with severe cardiopulmonary distress for whom the effort of breathing is intolerable, mechanical ventilation substitutes for the action of the respiratory muscles [1].

Combining easy-to-build noninvasive ventilator and open-source hardware description, may allow for adequate availability of ventilators to patients in low- and middle-income countries. This is urgently needed in the growing COVID-19 epidemic. https://bit.ly/3f8ZkUR

Impact of obstructive sleep apnea on the obesity paradox in critically ill patients

OBJECTIVE

Patients admitted to an intensive care unit (ICU) frequently suffer from multiple chronic diseases, including obstructive sleep apnea (OSA). Until recently OSA was not considered as a key determinant in an ICU patient's prognosis. The objective of this study was to document the impact of OSA on the prognosis of ICU patients.

METHODS

Data were retrospectively collected concerning adult patients admitted to ICU at two university hospitals. In a nested study OSA status was checked using the hospital electronic medical records to identify exposed and unexposed cases. The following outcomes were considered: length of stay in the ICU, ICU mortality, in-hospital mortality, ventilator-associated pneumonia (VAP).

RESULTS

Out of 5146 patients included in the study, 289 had OSA at ICU admission (5.6%). After matching, the overall impact of OSA on length of ICU stay was not significant (p = .24). In a predefined subgroup analysis, there was a significant impact of OSA on the length of ICU stay for patients with BMI over 40 kg/m² (IRR: 1.56 [1.05; 2.32], p = .03). OSA status had no impact on ICU or hospital mortality and VAP.

CONCLUSION

In general, known OSA did not increase the ICU stay except for patients with both OSA and morbid obesity.

Obesity hypoventilation syndrome treated with non-invasive ventilation: Is a switch to CPAP therapy feasible?

BACKGROUND AND OBJECTIVE

Obesity hypoventilation syndrome (OHS) can be treated with either continuous positive airway pressure (CPAP) or non-invasive ventilation (NIV) therapy; the device choice has important economic and operational implications.

METHODS

This multicentre interventional trial investigated the safety and short-term efficacy of switching stable OHS patients who were on successful NIV therapy for ≥3 months to CPAP therapy. Patients underwent an autotitrating CPAP night under polysomnography (PSG); if the ensuing parameters were acceptable, they were sent home on a fixed CPAP for a 4-6-week period. It was hypothesized that blood gas analysis, PSG parameters and lung function tests would remain unchanged.

RESULTS

A total of 42 OHS patients were recruited, of whom 37 patients were switched to CPAP therapy. All patients had a history of severe obstructive sleep apnoea syndrome; chronic obstructive pulmonary disease (COPD) (Global Initiative for Obstructive Lung Disease (GOLD) I/II) was present in 52%. Regarding the primary outcome, 30 of 42 patients (71%, 95% CI: 55-84%) maintained daytime partial pressure of carbon dioxide (PaCO₂ ) levels ≤45 mm Hg after the home CPAP period. There was no further impairment in quality of life, sleep parameters or lung function. Interestingly, 24 patients (65%) preferred CPAP as their long-term therapy, despite the high pressure levels used (mean: 13.8 ± 1.8 mbar). After the CPAP period, 7 of 37 patients were categorized as CPAP failure, albeit only due to mild hypercapnia (mean: 47.9 ± 2.7 mm Hg).

CONCLUSION

It is feasible to switch most stable OHS patients from NIV to CPAP therapy, a step that could significantly reduce health-related costs. The auto-adjusted CPAP device, used in combination with the analysis of the PSG and capnometry, is a valid titration method in OHS patients.

Partial failure of CPAP treatment for sleep apnoea: Analysis of the French national sleep database

BACKGROUND AND OBJECTIVE

Continuous positive airway pressure (CPAP) is the first-line therapy for obstructive sleep apnoea (OSA). Residual apnoea and/or hypopnoea events, that is an apnoea-hypopnoea index (AHI) > 5, during CPAP contribute to treatment drop-out. The clinical scenarios triggering residual events during CPAP use are poorly described. Underlying co-morbidities, especially cardiovascular diseases, lifestyle factors, OSA characteristics at diagnosis and type of mask have been suggested as potential contributors.

METHODS

Patients from the prospective French sleep apnoea registry diagnosed with OSA (AHI ≥ 15 events/h) treated with CPAP were included. Logistic regression analysis identified factors associated with a risk of residual AHI > 5 events/h on CPAP.

RESULTS

The 12 285 OSA patients were predominantly men (n = 8715, 70.9%), middle-aged (58.2 (49.8; 66.1) years) and obese (median body mass index: 31.3 (27.7; 35.6) kg/m² ). Most had an AHI ≤ 5 events/h (n = 9573, 77.9%) versus 22.1% with AHI > 5/h. The latter were less CPAP adherent (5.75 (4.01; 7.00) vs 6.00 (4.53; 7.00) h/night). In multivariable analysis, factors associated with residual AHI >5/h were male sex, age, sedentary lifestyle, OSA severity, cardiovascular co-morbidities (heart failure and arrhythmia) and type of interface (orofacial mask versus nasal mask: OR = 2.15 (95%CI: 1.95; 2.37)). A subgroup analysis found that patients using pressures above 10 cm H₂ O were 1.43 (95% CI: 1.3; 1.57) times more likely to have residual AHI > 5/h.

CONCLUSION

Knowing about risk factors for residual apnoeic-hypopnoeic events may assist in the timely provision of personalized care including the type of PAP therapy, attention to co-morbidities and choice of interface.

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.