Noninvasive ventilation for prevention of post-extubation respiratory failure in obese patients

Impact of pressure support ventilation duration after a spontaneous breathing trial on reintubation rates in critically ill subjects: a retrospective study

BACKGROUND

To investigate the effect of different durations of pressure support ventilation (PSV) after a spontaneous breathing trial (SBT) on 48-hour reintubation rates in critically ill subjects.

METHODS

This single-center retrospective cohort study included adult subjects who received mechanical ventilation for over 48 h, successfully completed SBT, and were scheduled for extubation in the intensive care unit of a tertiary hospital between January and December 2023. Subjects were divided into three groups based on PSV duration after SBT: direct extubation (DE, ≤ 30 min), short-term PSV (SP, 30 min-3 h), and long-term PSV (LP, 3-12 h). The primary outcome was the 48-hour reintubation rate. The secondary outcomes included intensive care unit length of stay and 28-day mortality.

RESULTS

A total of 982 subjects were included (638, 235, and 109 in the DE, SP, and LP groups, respectively). The 48-hour reintubation rates were 18.34%, 14.04%, and 16.51% in the DE, SP, and LP groups, respectively (P = 0.298). Multivariate logistic regression showed no significant difference in reintubation risk for SP (OR = 0.73, P = 0.141) and LP groups (OR = 0.88, P = 0.643) compared with the DE group. Age (OR = 1.18, P = 0.003) and APACHE II score (OR = 1.07, P < 0.001) were identified as independent risk factors for reintubation. The median intensive care unit length of stay was 16 days in the DE group, 18 days in the SP group, and 19 days in the LP group (P = 0.033). The 28-day mortality did not differ significantly among groups (12.85%, 11.91%, and 14.68%, respectively; P = 0.690).

CONCLUSIONS

PSV duration after SBT did not significantly affect reintubation rates in the overall population. While short-term PSV showed potential benefits in specific subgroups, particularly COPD patients, direct extubation after successful SBT appears safe for most patients and may reduce ICU length of stay. These findings suggest that extubation strategies should be individualized based on patient characteristics rather than applying extended PSV periods universally.

Noninvasive ventilation for respiratory failure: When does it work and when it does not?

Noninvasive positive pressure ventilation (NIV) is a positive pressure ventilation method employed across various disease processes, utilizing noninvasive interfaces such as helmets and facemasks rather than invasive methods such as endotracheal intubation. The benefits of NIV are significant in both the acute care setting, such as improving work of breathing and avoiding the need for endotracheal intubation, as well as in the chronic care setting, improving quality of life and mortality. While new guidelines broaden the application of NIV across various disease areas and introduce emerging modalities, uncertainty persists regarding the appropriate timing and circumstances for NIV utilization. We present a detailed review of the literature with up-to-date studies assessing the indications and limitations of NIV in a variety of conditions associated with acute and chronic respiratory failure. The review also summarizes the current guidelines on the use of NIV in the acute care setting. Although primarily targeted towards the acute indications of NIV, we believe this review will aid in better understanding and managing noninvasive ventilation for clinicians across both the inpatient and outpatient settings.

Ventilation in the obese: physiological insights and management

Obesity can have profound adverse effects on the respiratory system, including an impact on pulmonary function, respiratory mechanics, respiratory muscle strength and endurance, gas exchange, control of breathing, and exercise capacity. Lung mechanics are modified by increased pleural pressure resulting from increased abdominal mass and subsequent peripheral airway occlusion and worsening of lung compliance due to reduced functional residual capacity without impairment of chest wall compliance. Arterial blood gases are frequently altered in these subjects and these abnormalities are directly proportional to body mass index. Mechanisms that may account for gas exchange abnormalities are multiple: ventilation/perfusion inequality (responsible for isolated hypoxaemia) and alveolar hypoventilation (responsible for so-called "obesity hypoventilation syndrome" (OHS)). Hypoventilation in obese patients results from a diversity of mechanisms, among which the two most frequently raised are mechanical limitation and blunted ventilatory drive. OHS is frequently underappreciated and diagnosis is frequently made during a first acute exacerbation. Obstructive sleep apnoea is a condition frequently associated with obesity and must be systematically screened for in this population because of its impact on morbidity and therapeutic management. Ventilatory management of these patients will depend on the patient's underlying situation, clinical presentation and physiology, including sleep study results; it may include continuous positive airway pressure or non-invasive ventilation. The goal of this narrative review is to provide a physiological-based overview of the impact of obesity on the respiratory system with a special focus on ventilatory management of patients with obesity-related respiratory disturbances.

Humidified Noninvasive Ventilation versus High-Flow Therapy to Prevent Reintubation in Patients with Obesity: A Randomized Clinical Trial

Rationale: The optimal strategy to prevent reintubation in patients with obesity remains uncertain. Objectives: We aimed to determine whether noninvasive ventilation (NIV) with active humidification is superior to a high-flow nasal cannula (HFNC) in preventing reintubation in patients with obesity at intermediate risk. Methods: We conducted a randomized controlled trial in two ICUs in Spain (June 2020-June 2021). We included patients ready for planned extubation with a body mass index >30 and three or fewer risk factors for reintubation. Patients with hypercapnia at the end of the spontaneous breathing trial were excluded. Patients were randomized to undergo NIV with active humidification or HFNC for 48 hours after extubation. The primary outcome was the reintubation rate within 7 days after extubation. As a secondary analysis, we performed a post hoc Bayesian analysis using three different priors. Measurements and Main Results: Of 144 patients (median age, 61 [25th-75th percentile range, 61-67] yr; 65 [45%] men), 72 received NIV and 72 received an HFNC. Reintubation was required in 17 (23.6%) patients receiving NIV and in 24 (33.3%) patients receiving HFNC (difference between groups, 9.7; 95% confidence interval, -4.9, 24.4). All of the secondary analysis showed nonsignificant differences. In the exploratory Bayesian analysis, the probability of a reduction in reintubation with NIV was 99% (data-driven prior), 90% (minimally informative prior), or 89% (skeptical prior). Conclusions: Among adult critically ill patients with obesity at intermediate risk for extubation failure, the rate of reintubation was not significantly lower with NIV than with HFNC. Nevertheless, there is a risk for underpowered results. Clinical trial registered with www.clinicaltrials.gov (NCT04125342).

How to prevent postextubation respiratory failure

PURPOSE OF REVIEW

Postextubation respiratory support treatment approaches, indications, and subgroups of patients with different responses to those therapies are rapidly changing. Planning optimal therapy in terms of choosing devices, timing of application and selecting settings with the goal of minimizing extubation failure is becoming a challenge. This review aims to analyze all the available evidence from a clinical point of view, trying to facilitate decision making at the bedside.

RECENT FINDINGS

There is evidence for high flow nasal cannula support in patients at low risk of extubation failure. Noninvasive ventilation based strategies should be prioritized in patients at very high risk, who are obese or are hypercapnic at the end of a spontaneous breathing trial. Patients not included in the previous groups merit a tailored decision based on more variables.Optimizing the timing of therapy can include facilitation of extubation by transitioning to noninvasive respiratory support or prolonging a planned preventive therapy according to clinical condition.

SUMMARY

Planning postextubatin respiratory support must consider the risk for failing and the presence of some clinical conditions favoring noninvasive ventilation.Extubation can be safely accelerated by modifying screening criteria and spontaneous breathing trial settings, but there is room to increase the role of postextubation noninvasive respiratory support for this indication, always keeping in mind the dangers of delaying a needed intubation.

Incidence, Risk Factors, and Long-Term Outcomes for Extubation Failure in ICU in Patients With Obesity: A Retrospective Analysis of a Multicenter Prospective Observational Study

BACKGROUND

To our knowledge, no large observational study has compared the incidence and risk factors for extubation failure within 48 h and during ICU stay in the same cohort of unselected critically ill patients with and without obesity.

RESEARCH QUESTION

What are the incidence and risk factors of extubation failure in patients with and without obesity?

STUDY DESIGN AND METHODS

In the prospective multicenter observational Practices and Risk Factors for Weaning and Extubation Airway Failure in Adult Intensive Care Unit: A Multicenter Trial (FREEREA) study in 26 ICUs, the primary objective was to compare the incidence of extubation failure within 48 h in patients with and without obesity. Secondary objectives were to describe and to identify the independent specific risk factors for extubation failure using first a logistic regression model and second a decision tree analysis.

RESULTS

Of 1,370 extubation procedures analyzed, 288 (21%) were performed in patients with obesity and 1,082 (79%) in patients without obesity. The incidence of extubation failure within 48 h among patients with or without obesity was 23 of 288 (8.0%) vs 118 of 1,082 (11%), respectively (unadjusted OR, 0.71; 95% CI, 0.45-1.13; P = .15); alongside patients with obesity receiving significantly more noninvasive ventilation [87 of 288 (30%) vs 233 of 1,082 (22%); P = .002] and physiotherapy [165 of 288 (57%) vs 527 of 1,082 (49%); P = .02] than patients without obesity. Risk factors for extubation failure also differed according to obesity status: female sex (adjusted OR, 4.88; 95% CI, 1.61-13.9; P = .002) and agitation before extubation (adjusted OR, 6.39; 95% CI, 1.91-19.8; P = .001) in patients with obesity, and absence of strong cough before extubation (adjusted OR, 2.38; 95% CI, 1.53-3.84; P = .0002) and duration of invasive mechanical ventilation before extubation (adjusted OR, 1.03/d; 95% CI, 1.01-1.06; P = .01) in patients without obesity. The decision tree analysis found similar risk factors.

INTERPRETATION

Our findings indicate that anticipation and application of preventive measures for patients with obesity before and after extubation led to similar rates of extubation failure among patients with and without obesity.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov; No.: NCT02450669; URL: www.

CLINICALTRIALS

gov.

Screening and Perioperative Management of Obesity Hypoventilation Syndrome

Obesity hypoventilation syndrome (OHS) can often be underdiagnosed or misdiagnosed and has been shown to pose significant risks in perioperative situations. Patients with OHS have a higher prevalence of baseline morbid conditions like hypertension, congestive heart failure (CHF), diabetes mellitus, atrial fibrillation, and pulmonary hypertension (PH), which contribute to adverse postoperative outcomes. The potential challenges include difficult intubation and loss of airway, postoperative respiratory failure, worsening heart failure, pulmonary hypertensive crisis, and opioid-induced respiratory depression (OIRD). It is, therefore, important to screen all obese patients for obstructive sleep apnea (OSA) and OHS before elective surgical procedures. The aim of this review is to discuss the preoperative screening and evaluation and safe anesthetic and up-to-date ventilatory management of this complex group of patients. This review also intends to increase the awareness of OHS in the adult population among hospitalists, surgeons, and cardiologists who may find themselves taking care of these patients in complex multidisciplinary settings.

The Buccal Mask: Safe Positive Airway Pressure Delivery for Patients with a Paramedian Forehead Flap

The paramedian forehead flap is commonly performed for the reconstruction of complex nasal defects. It typically requires two separate procedures: flap elevation and inset, and then, 2-3 weeks later, pedicle division. In patients with obesity hypoventilation syndrome, the use of positive airway pressure is often mandatory, especially in the postoperative period. However, the face mask used for positive airway pressure has to apply pressure over the bridge of the nose and may compromise the vascularity of a paramedian forehead flap. We report a case where a buccal mask was used successfully in the postoperative period in a patient who needed positive airway pressure after nasal reconstruction with a paramedian forehead flap.

[Non-invasive Mechanical Ventilation in Acute Respiratory Failure. Clinical Practice Guidelines - on behalf of the German Society of Pneumology and Ventilatory Medicine]

The guideline update outlines the advantages as well as the limitations of NIV in the treatment of acute respiratory failure in daily clinical practice and in different indications.Non-invasive ventilation (NIV) has a high value in therapy of hypercapnic acute respiratory failure, as it significantly reduces the length of ICU stay and hospitalization as well as mortality.Patients with cardiopulmonary edema and acute respiratory failure should be treated with continuous positive airway pressure (CPAP) and oxygen in addition to necessary cardiological interventions. This should be done already prehospital and in the emergency department.In case of other forms of acute hypoxaemic respiratory failure with only mild or moderately disturbed gas exchange (PaO2/FiO2 > 150 mmHg) there is no significant advantage or disadvantage compared to high flow nasal oxygen (HFNO). In severe forms of ARDS NIV is associated with high rates of treatment failure and mortality, especially in cases with NIV-failure and delayed intubation.NIV should be used for preoxygenation before intubation. In patients at risk, NIV is recommended to reduce extubation failure. In the weaning process from invasive ventilation NIV essentially reduces the risk of reintubation in hypercapnic patients. NIV is regarded useful within palliative care for reduction of dyspnea and improving quality of life, but here in concurrence to HFNO, which is regarded as more comfortable. Meanwhile NIV is also recommended in prehospital setting, especially in hypercapnic respiratory failure and pulmonary edema.With appropriate monitoring in an intensive care unit NIV can also be successfully applied in pediatric patients with acute respiratory insufficiency.

Effectiveness of high flow nasal cannula (HFNC) versus bilevel positive airway pressure (BiPAP) in preventing tracheal reintubation in patients with high risk of extubation failure in intensive care unit - A randomised comparative trial

Background and Aims

The incidence of tracheal extubation failure in high-risk patients is higher, and non-invasive ventilation is suggested to avoid tracheal reintubation. This study compares the effectiveness of bilevel positive airway pressure (BiPAP) and high flow nasal cannula (HFNC) to reduce the rate of reintubation in intensive care unit (ICU) patients with increased risk of extubation failure.

Methods

This randomised comparative trial was conducted on 60 high-risk patients on mechanical ventilators admitted to the ICU, ready for weaning after a spontaneous breathing trial. They were randomised to Group H for HFNC and Group B for BiPAP therapy. Designated therapy was administered in these high-risk patients for up to 48 hours after tracheal extubation. Haemodynamic parameters [mean arterial pressure (MAP), heart rate (HR), respiratory rate (RR), a saturation of peripheral oxygen (SpO2), electrocardiogram (ECG)], arterial blood gas analysis (ABG) parameter [potential of hydrogen (pH), partial pressure of carbon dioxide (pCO2), partial pressure of oxygen/fraction of inspired oxygen (paO2/FiO2) ratio], the effectiveness of cough, comfort level was recorded and continuous monitoring for signs of respiratory distress and failure was done.

Results

Most of the patients were obese and had more than two risk factors for extubation failure. Several patients in Group B have significantly higher successful extubation than in Group H (P = 0.044). Most of the reintubation took place within 24 hours. The HFNC therapy was more comfortable and acceptable to patients.

Conclusion

BiPAP therapy was more efficient than HFNC in preventing tracheal reintubation among patients with a high risk of extubation failure.

Optimal positive-end expiratory pressure weaning in acute respiratory distress syndrome patients

PURPOSE OF REVIEW

Positive-end expiratory pressure (PEEP) is a tool in managing acute respiratory distress syndrome (ARDS). In this review, we discuss the various approaches to weaning PEEP after the acute phase of ARDS.

RECENT FINDINGS

There is a paucity of research specifically looking at the differences between PEEP weaning protocols. Data in some populations though, particularly those with elevated BMI, suggest that a physiologic approach to PEEP weaning may be helpful. Use of various tools to optimize PEEP prior to and during spontaneous breathing trials (SBTs) may allow for improved alveolar recruitment and respiratory outcomes.

SUMMARY

Although further prospective studies are warranted, we should consider using a physiologic approach to PEEP weaning in ARDS rather than a one size fits all model, which is currently the standard used in many clinical trials and throughout many ICUs.

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.

Effect of non-invasive ventilation after extubation in critically ill patients with obesity in France: a multicentre, unblinded, pragmatic randomised clinical trial

BACKGROUND

Non-invasive ventilation (NIV) and oxygen therapy (high-flow nasal oxygen [HFNO] or standard oxygen) following extubation have never been compared in critically ill patients with obesity. We aimed to compare NIV (alternating with HFNO or standard oxygen) and oxygen therapy (HFNO or standard oxygen) following extubation of critically ill patients with obesity.

METHODS

In this multicentre, parallel group, pragmatic randomised controlled trial, conducted in 39 intensive care units in France, critically ill patients with obesity undergoing extubation were randomly assigned (1:1) to either the NIV group or the oxygen therapy group. Two randomisations were performed: first, randomisation to either NIV or oxygen therapy, and second, randomisation to either HFNO or standard oxygen (also 1:1), which was nested within the first randomisation. Blinding of the randomisation was not possible, but the statistician was masked to group assignment. The primary outcome was treatment failure within 3 days after extubation, a composite of reintubation for mechanical ventilation, switch to the other study treatment, or premature discontinuation of study treatment. The primary outcome was analysed by intention to treat. Effect of medical and surgical status was assessed. The reintubation within 3 days was analysed by intention to treat and after a post-hoc crossover analysis. This study is registered with ClinicalTrials.gov, number NCT04014920.

FINDINGS

From Oct 2, 2019, to July 17, 2021, of the 1650 screened patients, 981 were enrolled. Treatment failure occurred in 66 (13·5%) of 490 patients in the NIV group and in 130 (26·5%) of 491 patients in the oxygen-therapy group (relative risk 0·43; 95% CI 0·31-0·60, p<0·0001). Medical or surgical status did not modify the effect of NIV group on the treatment-failure rate. Reintubation within 3 days after extubation was similar in the non-invasive ventilation group and in the oxygen therapy group in the intention-to-treat analysis (48 (10%) of 490 patients and 59 (12%) of 491 patients, p=0·26) and lower in the NIV group than in the oxygen-therapy group in the post-hoc cross-over (51 (9%) of 560 patients and 56 (13%) of 421 patients, p=0·037) analysis. No severe adverse events were reported.

INTERPRETATION

Among critically ill adults with obesity undergoing extubation, the use of NIV was effective to reduce treatment-failure within 3 days. Our results are relevant to clinical practice, supporting the use of NIV after extubation of critically ill patients with obesity. However, most of the difference in the primary outcome was due to patients in the oxygen therapy group switching to NIV, and more evidence is needed to conclude that an NIV strategy leads to improved patient-centred outcomes.

FUNDING

French Ministry of Health.

Effect of postextubation noninvasive ventilation with active humidification vs high-flow nasal cannula on reintubation in patients at very high risk for extubation failure: a randomized trial

PURPOSE

High-flow nasal cannula (HFNC) oxygen therapy was noninferior to noninvasive ventilation (NIV) for preventing reintubation in a heterogeneous population at high-risk for extubation failure. However, outcomes might differ in certain subgroups of patients. Thus, we aimed to determine whether NIV with active humidification is superior to HFNC in preventing reintubation in patients with ≥ 4 risk factors (very high risk for extubation failure).

METHODS

Randomized controlled trial in two intensive care units in Spain (June 2020‒June 2021). Patients ready for planned extubation with ≥ 4 of the following risk factors for reintubation were included: age > 65 years, Acute Physiology and Chronic Health Evaluation II score > 12 on extubation day, body mass index > 30, inadequate secretions management, difficult or prolonged weaning, ≥ 2 comorbidities, acute heart failure indicating mechanical ventilation, moderate-to-severe chronic obstructive pulmonary disease, airway patency problems, prolonged mechanical ventilation, or hypercapnia on finishing the spontaneous breathing trial. Patients were randomized to undergo NIV with active humidification or HFNC for 48 h after extubation. The primary outcome was reintubation rate within 7 days after extubation. Secondary outcomes included postextubation respiratory failure, respiratory infection, sepsis, multiorgan failure, length of stay, mortality, adverse events, and time to reintubation.

RESULTS

Of 182 patients (mean age, 60 [standard deviation (SD), 15] years; 117 [64%] men), 92 received NIV and 90 HFNC. Reintubation was required in 21 (23.3%) patients receiving NIV vs 35 (38.8%) of those receiving HFNC (difference -15.5%; 95% confidence interval (CI) -28.3 to -1%). Hospital length of stay was lower in those patients treated with NIV (20 [12‒36.7] days vs 26.5 [15‒45] days, difference 6.5 [95%CI 0.5-21.1]). No additional differences in the other secondary outcomes were observed.

CONCLUSIONS

Among adult critically ill patients at very high-risk for extubation failure, NIV with active humidification was superior to HFNC for preventing reintubation.

Benefit with preventive noninvasive ventilation in subgroups of patients at high-risk for reintubation: a post hoc analysis

BACKGROUND

High-flow nasal cannula (HFNC) was shown to be non-inferior to noninvasive ventilation (NIV) for preventing reintubation in a general population of high-risk patients. However, some subgroups of high-risk patients might benefit more from NIV. We aimed to determine whether the presence of many risk factors or overweight (body mass index (BMI) ≥ 25 kg/m2) patients could have different response to any preventive therapy, NIV or HFNC in terms of reduced reintubation rate.

METHODS

Not pre-specified post hoc analysis of a multicentre, randomized, controlled, non-inferiority trial comparing NFNC and NIV to prevent reintubation in patients at risk for reintubation. The original study included patients with at least 1 risk factor for reintubation.

RESULTS

Among 604 included in the original study, 148 had a BMI ≥ 25 kg/m2. When adjusting for potential covariates, patients with ≥ 4 risk factors (208 patients) presented a higher risk for reintubation (OR 3.4 [95%CI 2.16-5.35]). Patients with ≥ 4 risk factors presented lower reintubation rates when treated with preventive NIV (23.9% vs 45.7%; P = 0.001). The multivariate analysis of overweight patients, adjusted for covariates, did not present a higher risk for reintubation (OR 1.37 [95%CI 0.82-2.29]). However, those overweight patients presented an increased risk for reintubation when treated with preventive HFNC (OR 2.47 [95%CI 1.18-5.15]).

CONCLUSIONS

Patients with ≥ 4 risk factors for reintubation may benefit more from preventive NIV. Based on this result, HFNC may not be the optimal preventive therapy in overweight patients. Specific trials are needed to confirm these results.

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.

: 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.

The Impact of Obesity in Critical Illness

The prevalence of obesity is rising worldwide. Adipose tissue exerts anatomic and physiological effects with significant implications for critical illness. Changes in respiratory mechanics cause expiratory flow limitation, atelectasis, and V̇/Q̇ mismatch with resultant hypoxemia. Altered work of breathing and obesity hypoventilation syndrome may cause hypercapnia. Challenging mask ventilation and peri-intubation hypoxemia may complicate intubation. Patients with obesity are at increased risk of ARDS and should receive lung-protective ventilation based on predicted body weight. Increased positive end expiratory pressure (PEEP), coupled with appropriate patient positioning, may overcome the alveolar decruitment and intrinsic PEEP caused by elevated baseline pleural pressure; however, evidence is insufficient regarding the impact of high PEEP strategies on outcomes. Venovenous extracorporeal membrane oxygenation may be safely performed in patients with obesity. Fluid management should account for increased prevalence of chronic heart and kidney disease, expanded blood volume, and elevated acute kidney injury risk. Medication pharmacodynamics and pharmacokinetics may be altered by hydrophobic drug distribution to adipose depots and comorbid liver or kidney disease. Obesity is associated with increased risk of VTE and infection; appropriate dosing of prophylactic anticoagulation and early removal of indwelling catheters may decrease these risks. Obesity is associated with improved critical illness survival in some studies. It is unclear whether this reflects a protective effect or limitations inherent to observational research. Obesity is associated with increased risk of intubation and death in SARS-CoV-2 infection. Ongoing molecular studies of adipose tissue may deepen our understanding of how obesity impacts critical illness pathophysiology.

Comparison of the effects of 2 ventilatory strategies using tidal volumes of 6 and 8 ml/kg on pulmonary shunt and alveolar dead space volume in upper abdominal cancers surgery

Background: High tidal volume leads to inflammation, and low tidal volume leads to atelectasia and hypoxemia. This study was conducted to compare the effect of 6 mL/kg with positive end-expiratory pressure (PEEP) and 8 mL/kg without PEEP on pulmonary shunt and dead space volume. Methods: This clinical trial was done on 36 patients aged 20 to 65 years old with ASA I-II. They were candidates for upper abdominal surgery and divided randomly into 2 groups. One group were ventilated with the tidal volume = 8 mL/kg without PEEP (TV8). The other group received the tidal volume = 6 mL/kg with low PEEP = 5 cm H2O (TV6). Arterial and central venous blood gases were taken after intubation and 2 hours later. Additionally, the vital signs of the patients were checked every 30 minutes. Data analysis was performed using t test, chi-square test, and repeated measures analysis of variance with SPSS software, version 16 (SPSS Inc). P value less than.05 were meaningful. Results: There was no significant difference on the preanesthesia parameters. The pulmonary shunt was 13.5±0.1% and 18.6±0.2% in the groups TV6 and TV8, respectively (p=0.132), which slightly decreased after 2 hours in both groups without any significant difference (p=0.284). Prior to the ventilation, the ratios of dead space to tidal volume were 0.25±0.2 and 0.14±0.1 in the TV6 and TV8 groups, respectively (p=0.163), and after 2 hours, they were 0.23±0.11 and 0.16±0.1 in the TV6 and TV8 groups, respectively (p=0.271). There was no significant difference between the groups for blood pressure and peripheral and arterial oxygenation changes. Conclusion: The tidal volume of 6 mL/kg with the PEEP of 5 mmHg was similar to the tidal volume of 8 mL/kg without PEEP for hemodynamic and pulmonary changes (oxygenation, shunt, and dead space).

Obesity and Obesity Hypoventilation, Sleep Hypoventilation, and Postoperative Respiratory Failure

Obesity hypoventilation syndrome (OHS) is considered as a diagnosis in obese patients (body mass index [BMI] ≥30 kg/m2) who also have sleep-disordered breathing and awake diurnal hypercapnia in the absence of other causes of hypoventilation. Patients with OHS have a higher burden of medical comorbidities as compared to those with obstructive sleep apnea (OSA). This places patients with OHS at higher risk for adverse postoperative events. Obese patients and those with OSA undergoing elective noncardiac surgery are not routinely screened for OHS. Screening for OHS would require additional preoperative evaluation of morbidly obese patients with severe OSA and suspicion of hypoventilation or resting hypoxemia. Cautious selection of the type of anesthesia, use of apneic oxygenation with high-flow nasal cannula during laryngoscopy, better monitoring in the postanesthesia care unit (PACU) can help minimize adverse perioperative events. Among other risk-reduction strategies are proper patient positioning, especially during intubation and extubation, multimodal analgesia, and cautious use of postoperative supplemental oxygen.

Pleural Pressure Targeted Positive Airway Pressure Improves Cardiopulmonary Function in Spontaneously Breathing Patients With Obesity

BACKGROUND

Increased pleural pressure affects the mechanics of breathing of people with class III obesity (BMI > 40 kg/m²).

RESEARCH QUESTION

What are the acute effects of CPAP titrated to match pleural pressure on cardiopulmonary function in spontaneously breathing patients with class III obesity?

STUDY DESIGN AND METHODS

We enrolled six participants with BMI within normal range (control participants, group I) and 12 patients with class III obesity (group II) divided into subgroups: IIa, BMI of 40 to 50 kg/m²; and IIb, BMI of ≥ 50 kg/m². The study was performed in two phases: in phase 1, participants were supine and breathing spontaneously at atmospheric pressure, and in phase 2, participants were supine and breathing with CPAP titrated to match their end-expiratory esophageal pressure in the absence of CPAP. Respiratory mechanics, esophageal pressure, and hemodynamic data were collected, and right heart function was evaluated by transthoracic echocardiography.

RESULTS

The levels of CPAP titrated to match pleural pressure in group I, subgroup IIa, and subgroup IIb were 6 ± 2 cmH₂O, 12 ± 3 cmH₂O, and 18 ± 4 cmH₂O, respectively. In both subgroups IIa and IIb, CPAP titrated to match pleural pressure decreased minute ventilation (IIa, P = .03; IIb, P = .03), improved peripheral oxygen saturation (IIa, P = .04; IIb, P = .02), improved homogeneity of tidal volume distribution between ventral and dorsal lung regions (IIa, P = .22; IIb, P = .03), and decreased work of breathing (IIa, P < .001; IIb, P = .003) with a reduction in both the work spent to initiate inspiratory flow as well as tidal ventilation. In five hypertensive participants with obesity, BP decreased to normal range, without impairment of right heart function.

INTERPRETATION

In ambulatory patients with class III obesity, CPAP titrated to match pleural pressure decreased work of breathing and improved respiratory mechanics while maintaining hemodynamic stability, without impairing right heart function.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT02523352; URL: www.clinicaltrials.gov.

Post-extubation oxygenation strategies in acute respiratory failure: a systematic review and network meta-analysis

Background

High-flow nasal cannula oxygenation (HFNC) and noninvasive positive-pressure ventilation (NPPV) possibly decrease tracheal reintubation rates better than conventional oxygen therapy (COT); however, few large-scale studies have compared HFNC and NPPV. We conducted a network meta-analysis (NMA) to compare the effectiveness of three post-extubation respiratory support devices (HFNC, NPPV, and COT) in reducing the mortality and reintubation risk.

Methods

The Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, and Ichushi databases were searched. COT, NPPV, and HFNC use were assessed in patients who were aged ≥ 16 years, underwent invasive mechanical ventilation for > 12 h for acute respiratory failure, and were scheduled for extubation after spontaneous breathing trials. The GRADE Working Group Approach was performed using a frequentist-based approach with multivariate random-effect meta-analysis. Short-term mortality and reintubation and post-extubation respiratory failure rates were compared.

Results

After evaluating 4631 records, 15 studies and 2600 patients were included. The main cause of acute hypoxic respiratory failure was pneumonia. Although NPPV/HFNC use did not significantly lower the mortality risk (relative risk [95% confidence interval] 0.75 [0.53–1.06] and 0.92 [0.67–1.27]; low and moderate certainty, respectively), HFNC use significantly lowered the reintubation risk (0.54 [0.32–0.89]; high certainty) compared to COT use. The associations of mortality with NPPV and HFNC use with respect to either outcome did not differ significantly (short-term mortality and reintubation, relative risk [95% confidence interval] 0.81 [0.61–1.08] and 1.02 [0.53–1.97]; moderate and very low certainty, respectively).

Conclusion

NPPV or HFNC use may not reduce the risk of short-term mortality; however, they may reduce the risk of endotracheal reintubation.

Trial registration number and date of registration

PROSPERO (registration number: CRD42020139112, 01/21/2020).

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-021-03550-4.

The Obese Patient: Facts, Fables, and Best Practices

The prevalence of obesity continues to rise worldwide, and anesthesiologists must be aware of current best practices in the perioperative management of the patient with obesity. Obesity alters anatomy and physiology, which complicates the evaluation and management of obese patients in the perioperative setting. Gastric point-of-care ultrasound (PoCUS) is a noninvasive tool that can be used to assess aspiration risk in the obese patient by evaluating the quantity and quality of gastric contents. An important perioperative goal is adequate end-organ perfusion. Standard noninvasive blood pressure (NIBP) is our best available routine surrogate measurement, but is vulnerable to greater inaccuracy in patients with obesity compared to the nonobese population. Current NIBP methodologies are discussed. Obese patients are at risk for wound and surgical site infections, but few studies conclusively guide the exact dosing of intraoperative prophylactic antibiotics for them. We review evidence for low-molecular-weight heparins and weight-based versus nonweight-based administration of vasoactive medications. Finally, intubation and extubation of the patient with obesity can be complicated, and evidence-based strategies are discussed to mitigate danger during intubation and extubation.

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.

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”.

Implications of Obesity for the Management of Severe Coronavirus Disease 2019 Pneumonia

OBJECTIVES

To investigate patients' characteristics, management, and outcomes in the critically ill population admitted to the ICU for severe acute respiratory syndrome coronavirus disease 2019 pneumonia causing an acute respiratory distress syndrome.

DESIGN

Retrospective case-control study.

SETTING

A 34-bed ICU of a tertiary hospital.

PATIENTS

The first 44 coronavirus disease 2019 acute respiratory distress syndrome patients were compared with a historical control group of 39 consecutive acute respiratory distress syndrome patients admitted to the ICU just before the coronavirus disease 2019 crisis.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Obesity was the most frequent comorbidity exhibited by coronavirus disease 2019 patients (n = 32, 73% vs n = 11, 28% in controls; p < 0.001). Despite the same severity of illness and level of hypoxemia at admission, coronavirus disease 2019 patients failed more high flow oxygen via nasal cannula challenges (n = 16, 100% vs n = 5, 45% in controls; p = 0.002), were more often intubated (n = 44, 100% vs n = 22, 56% in controls; p < 0.001) and paralyzed (n = 34, 77% vs n = 3, 14% in controls; p < 0.001), required higher level of positive end-expiratory pressure (15 vs 8 cm H2O in controls; p < 0.001), more prone positioning (n = 33, 75% vs n = 6, 27% in controls; p < 0.001), more dialysis (n = 16, 36% vs n = 3, 8% in controls; p = 0.003), more hemodynamic support by vasopressors (n = 36, 82% vs n = 22, 56% in controls; p = 0.001), and had more often a prolonged weaning from mechanical ventilation (n = 28, 64% vs n = 10, 26% in controls; p < 0.01) resulting in a more frequent resort to tracheostomy (n = 18, 40.9% vs n = 2, 9% in controls; p = 0.01). However, an intensive management requiring more staff per patient for positioning coronavirus disease 2019 subjects (6 [5-7] vs 5 [4-5] in controls; p < 0.001) yielded the same ICU survival rate in the two groups (n = 34, 77% vs n = 29, 74% in controls; p = 0.23).

CONCLUSIONS

In its most severe form, coronavirus disease 2019 pneumonia striked preferentially the vulnerable obese population, evolved toward a multiple organ failure, required prolonged mechanical ventilatory support, and resulted in a high workload for the caregivers.

Comparison of Postextubation Outcomes Associated with High-Flow Nasal Cannula vs. Conventional Oxygen Therapy in Patients at High Risk of Reintubation: a Randomized Clinical Trial

BACKGROUND

Liberation and extubation are important for patients supported by mechanical ventilation. Extubation success is related to the duration of an intensive care unit (ICU) stay and mortality rate. High-flow nasal cannula (HFNC) oxygen therapy has physiological and clinical benefits in respiratory care. The present study compared clinical outcomes associated with HFNC and conventional oxygen therapy (COT) among patients at high risk for reintubation.

METHODS

A single-center randomized clinical trial was conducted between March 2018 and June 2019. Sixty adults admitted to the ICU and who were at high-risk of reintubation and met the inclusion criteria were enrolled in this study. "High risk" for reintubation was defined as having at least one of the following risk factors: age > 65 years, Acute Physiology and Chronic Health Evaluation II score > 12 points on extubation day, obesity, poor expectoration, airway patency problems, difficult or prolonged weaning, and more than one comorbidity. The primary outcome of interest was reintubation within 72 hours. Secondary outcomes included duration of ICU and hospital stay, mortality rate, and time to reintubation.

RESULTS

Of 60 patients, 31 received HFNC and 29 received COT (mean age, 78 ± 7.8 vs. 76 ± 6.5 years, respectively). Reintubation rate within 72 hours did not differ between the groups (3 patients [9.7%] vs. 1 patient [3.4%], respectively). Reintubation time was shorter among patients who received COT than among patients who received HFNC (0.5 hour vs. 25 hours), but this difference was not statistically significant. Duration of ICU did not differ between the groups (14.7 ± 9.6 days vs. 13.8 ± 15.7 days, for HFNC and COT, respectively).

CONCLUSION

Among patients at high risk for reintubation, compared with COT, HFNC did not reduce the risk of reintubation within 72 hours.

Variables predicting weaning outcome in prolonged mechanically ventilated tracheotomized patients: a retrospective study

Background

Several studies have assessed predictors of weaning and extubation outcome in short-term mechanically ventilated patients, but there are only few studies on predictors of weaning from prolonged mechanical ventilation.

Methods

Retrospective, single-center, observational study at a specialized national weaning center in Germany. Patients’ medical records were reviewed to obtain data on demographics, comorbidities, respiratory indices, and the result of a prospectively documented, standardized spontaneous breathing trial (SBT) upon admission to the weaning center. Respiratory indices assessed were the ventilatory ratio (VR) and parameters derived from calculated mechanical power (MP). Predictors associated with failure of prolonged weaning and failure of the SBT were assessed using a binary logistic regression model.

Results

A total of 263 prolonged mechanically ventilated, tracheotomized patients, treated over a 5-year period were analyzed. After 3 weeks of mechanical ventilation, patients with unsuccessful weaning failed a SBT more frequently and showed significantly increased values for inspiratory positive airway pressure, driving pressure, VR, absolute MP, and MP normalized to predicted body weight and dynamic lung-thorax compliance (LTC-MP). In the logistic regression analyses, variables independently correlated with weaning failure were female gender (adjusted odds ratio 0.532 [95% CI 0.291–0.973]; p = 0.040), obesity (body mass index ≥ 30 kg/m²) (2.595 [1.210–5.562]; p = 0.014), COPD (3.209 [1.563–6.589]; p = 0.002), LTC-MP (3.470 [1.067–11.284]; p = 0.039), P_aCO₂ on mechanical ventilation (1.101 [95% CI 1.034–1.173]; p = 0.003), and failure of the SBT (4.702 [2.250–9.825]; p < 0.001). In addition, female gender (0.401 [0.216–0.745]; p = 0.004), LTC-MP (3.017 [1.027–8.862]; p = 0.046), and P_aCO₂ on mechanical ventilation (1.157 [1.083–1.235]; p < 0.001) were independent risk factors for an unsuccessful SBT.

Conclusions

In the present study, the derived predictors of weaning point to a crucial role of the workload imposed on respiratory muscles during spontaneous breathing. Mechanical power normalized to lung-thorax compliance was independently correlated with weaning outcome and may identify patients at high risk for weaning failure.

[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.

Electrical impedance tomography during spontaneous breathing trials and after extubation in critically ill patients at high risk for extubation failure: a multicenter observational study

Background

This study aims to assess the changes in lung aeration and ventilation during the first spontaneous breathing trial (SBT) and after extubation in a population of patients at risk of extubation failure.

Methods

We included 78 invasively ventilated patients eligible for their first SBT, conducted with low positive end-expiratory pressure (2 cm H₂O) for 30 min. We acquired three 5-min electrical impedance tomography (EIT) records at baseline, soon after the beginning (SBT_0) and at the end (SBT_30) of SBT. In the case of SBT failure, ventilation was reinstituted; otherwise, the patient was extubated and two additional records were acquired soon after extubation (SB_0) and 30 min later (SB_30) during spontaneous breathing. Extubation failure was defined by the onset of post-extubation respiratory failure within 48 h after extubation. We computed the changes from baseline of end-expiratory lung impedance (∆EELI), tidal volume (∆Vt%), and the inhomogeneity index. Arterial blood was sampled for gas analysis. Data were compared between sub-groups stratified for SBT and extubation success/failure.

Results

Compared to SBT success (n = 61), SBT failure (n = 17) showed a greater reduction in ∆EELI at SBT_0 (p < 0.001) and SBT_30 (p = 0.001) and a higher inhomogeneity index at baseline (p = 0.002), SBT_0 (p = 0.003) and SBT_30 (p = 0.005). RR/Vt was not different between groups at baseline but was significantly greater at SBT_0 and SBT_30 in SBT failures, compared to SBT successes (p < 0.001 for both). No differences in ∆Vt% and arterial blood gases were observed between SBT success and failure. The ∆Vt%, ∆EELI, inhomogeneity index and arterial blood gases were not different between patients with extubation success (n = 39) and failure (n = 22) (p > 0.05 for all comparisons).

Conclusions

Compared to SBT success, SBT failure was characterized by more lung de-recruitment and inhomogeneity. Whether EIT may be useful to monitor SBT remains to be determined. No significant changes in lung ventilation, aeration or homogeneity related to extubation outcome occurred up to 30 min after extubation.

Trial registration Retrospectively registered on clinicaltrials.gov (Identifier: NCT03894332; release date 27th March 2019).

Electronic supplementary material

The online version of this article (10.1186/s13613-019-0565-0) contains supplementary material, which is available to authorized users.

Obstructive sleep apnoea in adults: peri-operative considerations: A narrative review

: Obstructive sleep apnoea (OSA) is a common breathing disorder of sleep with a prevalence increasing in parallel with the worldwide rise in obesity. Alterations in sleep duration and architecture, hypersomnolence, abnormal gas exchange and also associated comorbidities may all feature in affected patients.The peri-operative period poses a special challenge for surgical patients with OSA who are often undiagnosed, and are at an increased risk for complications including pulmonary and cardiovascular, during that time. In order to ensure the best peri-operative management, anaesthetists caring for these patients should have a thorough understanding of the disorder, and be aware of the individual's peri-operative risk constellation, which depends on the severity and phenotype of OSA, the invasiveness of the surgical procedure, anaesthesia and also the requirement for postoperative opioids.The objective of this review is to educate clinicians in the epidemiology, pathogenesis and diagnosis of OSA in adults and also to highlight specific tasks in the preoperative assessment, namely to select a suitable intra-operative anaesthesia regimen, and manage the extent and duration of postoperative care to facilitate the best peri-operative outcome.

Controversies when using mechanical ventilation in obese patients with and without acute distress respiratory syndrome

INTRODUCTION

As the prevalence of obesity increases, so does the number of obese patients undergoing surgical procedures and being admitted into intensive care units. Obesity per se is associated with reduced lung volume. The combination of general anaesthesia and supine positioning involved in most surgeries causes further reductions in lung volumes, thus resulting in alveolar collapse, decreased lung compliance, increased airway resistance, and hypoxemia. These complications can be amplified by common obesity-related comorbidities. In otherwise healthy obese patients, mechanical ventilation strategies should be optimised to prevent lung damage; in those with acute distress respiratory syndrome (ARDS), strategies should seek to mitigate further lung damage. Areas covered: This review discusses non-invasive and invasive mechanical ventilation strategies for surgical and critically ill adult obese patients with and without ARDS and proposes practical clinical insights to be implemented at bedside both in the operating theatre and in intensive care units. Expert opinion: Large multicentre trials on respiratory management of obese patients are required. Although the indication of lung protective ventilation with low tidal volume is apparently translated to obese patients, optimal PEEP level and recruitment manoeuvres remain controversial. The use of non-invasive respiratory support after extubation must be considered in individual cases.

Joint consensus on anesthesia in urologic and gynecologic robotic surgery: specific issues in management from a task force of the SIAARTI, SIGO, and SIU

INTRODUCTION

Proper management of patients undergoing robotic-assisted urologic and gynecologic surgery must consider a series of peculiarities in the procedures for anesthesiology, critical care medicine, respiratory care, and pain management. Although the indications for robotic-assisted urogynecologic surgeries have increased in recent years, specific guidance documents are still lacking.

EVIDENCE ACQUISITION

A multidisciplinary group including anesthesiologists, gynecologists, urologists, and a clinical epidemiologist systematically reviewed the relevant literature and provided a set of recommendations and unmet needs on peculiar aspects of anesthesia in this field.

EVIDENCE SYNTHESIS

Nine core contents were identified, according to their requirements in urogynecologic robotic-assisted surgery: patient position, pneumoperitoneum and ventilation strategies, hemodynamic variations and fluid therapy, neuromuscular block, renal surgery and prevention of acute kidney injury, monitoring the Department of anesthesia, postoperative delirium and cognitive dysfunction, prevention of postoperative nausea and vomiting, and pain management in endometriosis.

CONCLUSIONS

This consensus document provides guidance for the management of urologic and gynecologic patients scheduled for robotic-assisted surgery. Moreover, the identified unmet needs highlight the requirement for further prospective randomized studies.

Obesity hypoventilation syndrome: a current review

Obesity hypoventilation syndrome (OHS) is defined as the presence of obesity (body mass index ≥ 30 kg/m²) and daytime arterial hypercapnia (PaCO2 ≥ 45 mmHg) in the absence of other causes of hypoventilation. OHS is often overlooked and confused with other conditions associated with hypoventilation, particularly COPD. The recognition of OHS is important because of its high prevalence and the fact that, if left untreated, it is associated with high morbidity and mortality. In the present review, we address recent advances in the pathophysiology and management of OHS, the usefulness of determination of venous bicarbonate in screening for OHS, and diagnostic criteria for OHS that eliminate the need for polysomnography. In addition, we review advances in the treatment of OHS, including behavioral measures, and recent studies comparing the efficacy of continuous positive airway pressure with that of noninvasive ventilation.

Spectrum of postoperative complications in pulmonary hypertension and obesity hypoventilation syndrome

PURPOSE OF REVIEW

The purpose of this review is to identify chronic pulmonary conditions which may often not be recognized preoperatively especially before elective noncardiac surgery and which carry the highest risk of perioperative morbidity and mortality.

RECENT FINDINGS

This review discusses some of the most recent studies that highlight the perioperative complications, and their prevention and management strategies.

SUMMARY

Pulmonary hypertension is a well recognized risk factor for postoperative complications after cardiac surgery but the literature surrounding noncardiac surgery is sparse. Pulmonary hypertension was only recently classified as an independent risk factor for postoperative complications in the American Heart Association/American College of Cardiology Foundation Practice Guideline for noncardiac surgery. Spinal anesthesia should be avoided in most surgeries on patients with pulmonary hypertension because of it's rapid sympatholytic effects. The presence of significant right ventricle dysfunction and marked hypoxemia should prompt re-evaluation of the need for elective surgery. Obesity hypoventilation syndrome is even harder to recognize preoperatively as arterial blood gases are generally not obtained prior to elective noncardiac surgery. Amongst patients with obstructive sleep apnea this group of patients carries much higher risk of postoperative respiratory and congestive heart failure.

Risk factors for noninvasive ventilation failure in patients with post-extubation acute respiratory failure after cardiac surgery

Background

The effect of noninvasive ventilation (NIV) in patients with acute respiratory failure (ARF) after cardiac surgery is controversial. This study identified the feasibility of NIV and assessed the risk factors of NIV failure in patients with ARF after cardiac surgery.

Methods

We retrospectively reviewed data from 112 patients with ARF requiring NIV and categorized them into the NIV failure and success groups. Patient data were extracted for further analysis, the primary outcomes were the need for endotracheal intubation and NIV-related in-hospital mortality. The risk factors for NIV failure in patients with post-extubation ARF was analyzed.

Results

The median time from extubation to NIV was 11 hours. No difference in the EuroSCORE existed between the two groups. NIV failed in 38.4% of the patients. The NIV failure group had a higher in-hospital mortality and stay at the longer intensive care unit (ICU). Most cases of NIV failure occurred within 1-48 hours of the treatment. The main causes of early NIV failure were a weak cough reflex and/or excessive secretions and hemodynamic instability. A Sequential Organ Failure Assessment (SOFA) score ≥10.5, vasoactive-inotropic score ≥6, and pneumonia were predictors of NIV failure, whereas a body mass index (BMI) ≥25.0 kg/m² predicted NIV success.

Conclusions

NIV was effective in the study population. Multiple organ dysfunction, pneumonia, and significant inotropic drug support before NIV were associated with NIV failure, whereas a BMI ≥25 kg/m² was a predictor of NIV success.

Prognostic factors of noninvasive mechanical ventilation in lung cancer patients with acute respiratory failure

Introduction

Few studies have reported outcomes of lung cancer patients with acute respiratory failure (RF) using noninvasive positive pressure ventilation (NIPPV). The aim of this study was to investigate the prognostic factors in these patients.

Materials and methods

This retrospective observational study included all hospitalized lung cancer patients who received NIPPV for acute RF. It was conducted at a tertiary medical center in Taiwan from 2005 to 2010. The primary outcome was all cause mortality at 28 days after the initiation of NIPPV. Secondary outcomes included all-cause in-hospital mortality, weaning from NIPPV, intubation rate, tracheostomy rate, duration of NIPPV, hospital stay and intensive care unit stay.

Results

The all-cause mortality rate at day 28 of the enrolled 58 patients was 39.66%. The 90-day and 1-year mortality rates were 63.79% and 86.21%, respectively. NIPPV as the first line therapy for RF had higher 28-day mortality rate than it used for post-extubation RF (57.6% versus 16.0%, p<0.05). Independent predictors of mortality at 28 days were progressive disease or newly diagnosed lung cancer (OR 14.02 95% CI 1.03–191.59, p = 0.048), combined with other organ failure (OR 18.07 95% CI 1.87–172.7, p = 0.012), and NIPPV as the first line therapy for RF (OR 35.37 95% CI 3.30–378.68, p = 0.003).

Conclusion

Lung cancer patients using NIPPV with progressive or newly diagnosed cancer disease, combined with other organ failure, or NIPPV as the first line therapy for respiratory failure have a poor outcome.

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.

Can high-flow nasal cannula reduce the rate of reintubation in adult patients after extubation? A meta-analysis

BACKGROUND

The effects of high flow nasal cannula (HFNC) on adult patients after extubation remain controversial. We aimed to further determine the effectiveness of HFNC in comparison to noninvasive positive pressure ventilation (NIPPV) and conventional oxygen therapy (COT).

METHODS

The Pubmed, Embase, Medline, Cochrane Central Register of Controlled Trails (CENTRAL) as well as the Information Sciences Institute (ISI) Web of Science were searched for all the controlled study comparing HFNC with NIPPV and COT in adult patients after extubation. The primary outcome was rate of reintubation and the secondary outcomes were intensive care unit (ICU) mortality and length of ICU stay (ICU LOS).

RESULTS

Eight trials with a total of 2936 patients were pooled in our final studies. No significant heterogeneity was found in outcome measures. Compared with COT, HFNC was associated with lower rate of reintubation (Z = 2.97, P = 0.003), and the same result was found in the comparison between HFNC and NIPPV (Z = 0.87, P = 0.38). As for the ICU mortality and ICU LOS, we did not find any advantage of HFNC over COT or NIPPV.

CONCLUSIONS

In patients after extubation, HFNC is a reliable alternative of NIPPV to reduce rate of reintubation compared with COT.

Mechanical ventilation in obese ICU patients: from intubation to extubation

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2017. Other selected articles can be found online at http://ccforum.com/series/annualupdate2017. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901.

Spontaneous breathing trial and post-extubation work of breathing in morbidly obese critically ill patients

Background

Predicting whether an obese critically ill patient can be successfully extubated may be specially challenging. Several weaning tests have been described but no physiological study has evaluated the weaning test that would best reflect the post-extubation inspiratory effort.

Methods

This was a physiological randomized crossover study in a medical and surgical single-center Intensive Care Unit, in patients with body mass index (BMI) >35 kg/m² who were mechanically ventilated for more than 24 h and underwent a weaning test. After randomization, 17 patients were explored using five settings : pressure support ventilation (PSV) 7 and positive end-expiratory pressure (PEEP) 7 cmH2O; PSV 0 and PEEP 7cmH2O; PSV 7 and PEEP 0 cmH2O; PSV 0 and PEEP 0 cmH2O; and a T piece, and after extubation. To further minimize interaction between each setting, a period of baseline ventilation was performed between each step of the study. We hypothesized that the post-extubation work of breathing (WOB) would be similar to the T-tube WOB.

Results

Respiratory variables and esophageal and gastric pressure were recorded. Inspiratory muscle effort was calculated as the esophageal and trans-diaphragmatic pressure time products and WOB. Sixteen obese patients (BMI 44 kg/m² ± 8) were included and successfully extubated. Post-extubation inspiratory effort, calculated by WOB, was 1.56 J/L ± 0.50, not statistically different from the T piece (1.57 J/L ± 0.56) or PSV 0 and PEEP 0 cmH₂O (1.58 J/L ± 0.57), whatever the index of inspiratory effort. The three tests that maintained pressure support statistically underestimated post-extubation inspiratory effort (WOB 0.69 J/L ± 0.31, 1.15 J/L ± 0.39 and 1.09 J/L ± 0.49, respectively, p < 0.001). Respiratory mechanics and arterial blood gases did not differ between the five tests and the post-extubation condition.

Conclusions

In obese patients, inspiratory effort measured during weaning tests with either a T-piece or a PSV 0 and PEEP 0 was not different to post-extubation inspiratory effort. In contrast, weaning tests with positive pressure overestimated post-extubation inspiratory effort.

Trial registration

Clinical trial.gov (reference NCT01616901), 2012, June 4th

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-016-1457-4) contains supplementary material, which is available to authorized users.

Management of acute hypercapnic respiratory failure

PURPOSE OF REVIEW

The objective of this article is to review the most recent literature regarding the management of acute hypercapnic respiratory failure (AHRF).

RECENT FINDINGS

In the field of AHRF management, noninvasive ventilation (NIV) has become the standard method of providing primary mechanical ventilator support. Recently, extracorporeal carbon dioxide removal (ECCO2R) devices have been proposed as new therapeutic option.

SUMMARY

NIV is an effective strategy in specific settings and in selected population with AHRF. To date, evidence on ECCO2R is based only on case reports and case-control trials. Although the preliminary results using ECCO2R to decrease the rate of NIV failure and to wean hypercapnic patients from invasive ventilation are remarkable; further randomized studies are needed to assess the effects of this technique on both short-term and long-term clinical outcomes.

Noninvasive Ventilation in the Critically Ill Patient With Obesity Hypoventilation Syndrome: A Review

Obesity is a global epidemic that adversely affects respiratory physiology. Sleep-disordered breathing and obesity hypoventilation syndrome (OHS) are among the most common pulmonary complications related to obesity class III. Patients with OHS may present with acute hypercapnic respiratory failure (AHRF) that necessitates immediate noninvasive ventilation (NIV) or invasive ventilation and intensive care unit (ICU) monitoring. The OHS is underrecognized as a cause of AHRF. The management of mechanical ventilation in obese ICU patients is one of the most challenging problems facing respirologists, intensivists, and anesthesiologists. The treatment of AHRF in patients with OHS should aim to improve alveolar ventilation with better alveolar gas exchange, as well as maintaining a patent upper airway, which is ideally achieved through NIV. Treatment with NIV is associated with improvement in blood gases and lung mechanics and may reduce hospital admissions and morbidity. In this review, we will address 3 main issues: (1) NIV of critically ill patients with acute respiratory failure and OHS; (2) the indications for postoperative application of NIV in patients with OHS; and (3) the impact of OHS on weaning and postextubation respiratory failure. Additionally, the authors propose an algorithm for the management of obese patients with AHRF.