Outcomes of morbidly obese patients requiring mechanical ventilation for acute respiratory failure*

[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.

High Mechanical Power and Driving Pressures are Associated With Postoperative Respiratory Failure Independent From Patients' Respiratory System Mechanics

OBJECTIVES

High mechanical power and driving pressure (ΔP) have been associated with postoperative respiratory failure (PRF) and may be important parameters guiding mechanical ventilation. However, it remains unclear whether high mechanical power and ΔP merely reflect patients with poor respiratory system mechanics at risk of PRF. We investigated the effect of mechanical power and ΔP on PRF in cohorts after exact matching by patients' baseline respiratory system compliance.

DESIGN

Hospital registry study.

SETTING

Academic hospital in New England.

PATIENTS

Adult patients undergoing general anesthesia between 2008 and 2020.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

The primary exposure was high (≥ 6.7 J/min, cohort median) versus low mechanical power and the key-secondary exposure was high (≥ 15.0 cm H 2 O) versus low ΔP. The primary endpoint was PRF (reintubation or unplanned noninvasive ventilation within seven days). Among 97,555 included patients, 4,030 (4.1%) developed PRF. In adjusted analyses, high intraoperative mechanical power and ΔP were associated with higher odds of PRF (adjusted odds ratio [aOR] 1.37 [95% CI, 1.25-1.50]; p < 0.001 and aOR 1.45 [95% CI, 1.31-1.60]; p < 0.001, respectively). There was large variability in applied ventilatory parameters, dependent on the anesthesia provider. This facilitated matching of 63,612 (mechanical power cohort) and 53,260 (ΔP cohort) patients, yielding identical baseline standardized respiratory system compliance (standardized difference [SDiff] = 0.00) with distinctly different mechanical power (9.4 [2.4] vs 4.9 [1.3] J/min; SDiff = -2.33) and ΔP (19.3 [4.1] vs 11.9 [2.1] cm H 2 O; SDiff = -2.27). After matching, high mechanical power and ΔP remained associated with higher risk of PRF (aOR 1.30 [95% CI, 1.17-1.45]; p < 0.001 and aOR 1.28 [95% CI, 1.12-1.46]; p < 0.001, respectively).

CONCLUSIONS

High mechanical power and ΔP are associated with PRF independent of patient's baseline respiratory system compliance. Our findings support utilization of these parameters for titrating mechanical ventilation in the operating room and ICU.

Long-Term Mortality following Acute Noninvasive Ventilation for Obesity-Related Respiratory Failure: A Retrospective Single-Centre Study

Introduction

Determinants of long-term mortality following acute hypercapnic respiratory failure have been extensively studied in patients with chronic obstructive pulmonary disease. However, respiratory failure due to obesity has not been studied to the same extent. This retrospective survey aims to identify whether admission pH is associated with long-term mortality in patients requiring acute noninvasive ventilation (NIV) for obesity-related respiratory failure (ORRF).

Methods

Records from April 2013 to March 2020 were accessed from a NIV quality database at an acute teaching hospital. Adults with hypercapnic ORRF requiring acute NIV were included. pH data were grouped by threshold (pH≤ and >7.25) and correlated with time from presentation to death; multivariable analysis was performed using Cox proportional hazards.

Results

A total of 277 acute NIV episodes were included. Two-year mortality was similar for patients in both pH categories. Univariable analysis identified pH ≤ 7.25 to increase risk of two-year mortality by 43%. However, multivariable analysis identified that pH was not a significant determinant of long-term mortality, although male sex, older age, and higher admission pCO2 increased the risk of death at two years by 76%, 3% per year of age, and 16% per 1 kPa of pCO2 increase, respectively.

Conclusion

Severity of hypercapnia on admission, male sex, and older age are associated with worse two-year mortality in patients requiring acute NIV for ORRF. There is scope for further analyses including investigating the role of domiciliary NIV in ORRF patients.

Acute dyspnea in the emergency department: a clinical review

Acute dyspnea represents one of the most frequent symptoms leading to emergency room evaluation. Its significant prognostic value warrants a careful evaluation. The differential diagnosis of dyspnea is complex due to the lack of specificity and the loose association between its intensity and the severity of the underlying pathological condition. The initial assessment of dyspnea calls for prompt diagnostic evaluation and identification of optimal monitoring strategy and provides information useful to allocate the patient to the most appropriate setting of care. In recent years, accumulating evidence indicated that lung ultrasound, along with echocardiography, represents the first rapid and non-invasive line of assessment that accurately differentiates heart, lung or extra-pulmonary involvement in patients with dyspnea. Moreover, non-invasive respiratory support modalities such as high-flow nasal oxygen and continuous positive airway pressure have aroused major clinical interest, in light of their efficacy and practicality to treat patients with dyspnea requiring ventilatory support, without using invasive mechanical ventilation. This clinical review is focused on the pathophysiology of acute dyspnea, on its clinical presentation and evaluation, including ultrasound-based diagnostic workup, and on available non-invasive modalities of respiratory support that may be required in patients with acute dyspnea secondary or associated with respiratory failure.

Ward-Based Noninvasive Ventilation for Acute Hypercapnic Respiratory Failure Unrelated to Chronic Obstructive Pulmonary Disease

Background

The use of ward-based noninvasive ventilation (NIV) for acute hypercapnic respiratory failure (AHRF) unrelated to chronic obstructive pulmonary disease (COPD) remains controversial. This study evaluated the outcomes and failure rates associated with NIV application in the ward-based setting for patients with AHRF unrelated to COPD.

Methods

A multicentre, retrospective cohort study of patients with AHRF unrelated to COPD was conducted. COPD was not the main reason for hospital admission, treated with ward-based NIV between February 2004 and December 2018. All AHRF patients were eligible; exclusion criteria comprised COPD patients, age < 18 years, pre-NIV pH < 7.35, or a lack of pre-NIV blood gas. In-hospital mortality was the primary outcome; univariable and multivariable models were constructed. The obesity-related AHRF group included patients with AHRF due to obesity hypoventilation syndrome (OHS), and the non-obesity-related AHRF group included patients with AHRF due to pneumonia, bronchiectasis, neuromuscular disease, or fluid overload.

Results

In total, 479 patients were included in the analysis; 80.2% of patients survived to hospital discharge. Obesity-related AHRF was the indication for NIV in 39.2% of all episodes and was the aetiology with the highest rate of survival to hospital discharge (93.1%). In the multivariable analysis, factors associated with a higher risk of in-hospital mortality were increased age (odds ratio, 95% CI: 1.034, 1.017–1.051, P < 0.001) and pneumonia on admission (5.313, 2.326–12.131, P < 0.001). In the obesity-related AHRF group, pre-NIV pH < 7.15 was associated with significantly increased in-hospital mortality (7.800, 1.843–33.013, P=0.005); however, a pre-NIV pH 7.15–7.25 was not associated with increased in-hospital mortality (2.035, 0.523–7.915, P=0.305).

Conclusion

Pre-NIV pH and age have been identified as important predictors of surviving ward-based NIV treatment. Moreover, these data support the use of NIV in ward-based settings for obesity-related AHRF patients with pre-NIV pH thresholds down to 7.15. However, future controlled trials are required to confirm the effectiveness of NIV use outside critical care settings for obesity-related AHRF.

Highlights from the Respiratory Failure and Mechanical Ventilation 2020 Conference

The Respiratory Intensive Care Assembly of the European Respiratory Society organised the first Respiratory Failure and Mechanical Ventilation Conference in Berlin in February 2020. The conference covered acute and chronic respiratory failure in both adults and children. During this 3-day conference, patient selection, diagnostic strategies and treatment options were discussed by international experts. Lectures delivered during the event have been summarised by Early Career Members of the Assembly and take-home messages highlighted.

During #RFMV2020, patient selection, diagnostic strategies and treatment options were discussed by international experts. This review summarises the most important take-home messages.https://bit.ly/3murkoa

Comprehensive rehabilitation treatment for sub-acute COVID-19 patients: an observational study

BACKGROUND

COVID-19 is a respiratory infection, but it should be considered as a systemic illness with increasing interest on the survivors' sequelae and their management. Considering multi-organ disabilities, a comprehensive rehabilitation provided in sub-acute phase could be considered a suitable setting for these patients.

AIM

The aim of this article was to report the features and rehabilitative outcomes of patients requiring rehabilitation due to disabilities related to severe COVID-19 infection.

DESIGN

Longitudinal Observational Study.

SETTING

Department of Rehabilitation in General Hospital.

POPULATION

Patients showing multiple disabilities due to severe COVID-19 infection.

METHODS

Thirty-nine consecutive patients were admitted to a rehabilitation ward transferred from ICU or Medical wards. Barthel Index (BI) and Functional Ambulation Categories (FAC) were scored as disabilities measures. Data regarding comorbidity, rehabilitation course, swabs, procedures in acute phase, non-respiratory manifestations, dysphagia, mental confusion, PaO2/FiO2, oxygen supplementation have been collected to admission and discharge. For all patients a comprehensive rehabilitation treatment have been provided.

RESULTS

Functional outcome is good with a statistically significant improvement in BI and FAC scores. Thirty-eight patients were discharged at their home. Mean lenght of stay (LOS) in acute wards was 46 days. Mean LOS in rehabilitation was 20 day. Eleven patients still had tracheostomy at admission, none at discharge and all dysphagic patients recovered a normal oral feeding. The change in PaO2/FiO2 and the reduction of the oxygen supplementation testify a good recovery of pulmonary function.

CONCLUSIONS

Our results showed a consistent recovery with little caregiver burden at discharge. Fast relocation from ICU makes beds available which are very valuable during pandemic. Comprehensive rehabilitation treatment provided in sub-acute phase for patients still positive for SARS-CoV-2, would be desirable as it seems to be an effective setting. In this setting a strong medical assistance must be ensured.

CLINICAL REHABILITATION IMPACT

The activation of comprehensive rehabilitation settings able to assist sub-acute patients still positive would be desirable as it could be a very efficient Healthcare Systems answer to the catastrophic pandemic, decompressing acute hospital as well. Furthermore, contagious patients with swabs positivity affected by other kind of disabilities (i.e. Stroke, Femur Fracture) can be treated avoiding to lose the early rehabilitation.

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”.

Non-Invasive Ventilation in a Non-Standard Setting – Is it Safe to Ventilate Outside the ICU?

Non-invasive ventilation (NIV) is considered a fundamental method in treating patients with various disorders, requiring respiratory support. Often the lack of beds in the intensive care unit (ICU) and the concomitant medical conditions, which refer patients as unsuitable for aggressive treatment in the ICU, highlight the need of NIV application in general non-monitored wards and unusual settings – most commonly emergency departments, high-dependency units, pulmonary wards, and even ambulances. Recent studies suggest faster improvement of all physiological variables, reduced intubation rates, postoperative pulmonary complications and hospital mortality with better outcome and quality of life by early well-monitored ward-based NIV compared to standard medical therapy in patients with exacerbation of a chronic obstructive pulmonary disease, after a surgical procedure or acute hypoxemic respiratory failure in hematologic malignancies. NIV is a ceiling of treatment and a comfort measure in many patients with do-not-intubate orders due to terminal illnesses. NIV is beneficial only by proper administration with appropriate monitoring and screening for early NIV failure. Successful NIV application in a ward requires a well-equipped area and adequately trained multidisciplinary team. It could be initiated not only by attending physicians, respiratory technicians, and nurses but also by medical emergency teams. Ward-based NIV is supposed to be more cost-effective than NIV in the ICU, but further investigation is required to establish the safety and efficacy in hospital wards with a low nurse to patient ratio.

Obesity and COVID-19 Severity in a Designated Hospital in Shenzhen, China

OBJECTIVE

Patients with obesity are at increased risk of exacerbations from viral respiratory infections. However, the association of obesity with the severity of coronavirus disease 2019 (COVID-19) is unclear. We examined this association using data from the only referral hospital in Shenzhen, China.

RESEARCH DESIGN AND METHODS

A total of 383 consecutively hospitalized patients with COVID-19 admitted from 11 January 2020 to 16 February 2020 and followed until 26 March 2020 at the Third People's Hospital of Shenzhen were included. Underweight was defined as a BMI <18.5 kg/m², normal weight as 18.5-23.9 kg/m², overweight as 24.0-27.9 kg/m², and obesity as ≥28 kg/m².

RESULTS

Of the 383 patients, 53.1% were normal weight, 4.2% were underweight, 32.0% were overweight, and 10.7% were obese at admission. Obese patients tended to have symptoms of cough (P = 0.03) and fever (P = 0.06) compared with patients who were not obese. Compared with normal weight patients, those who were overweight had 1.84-fold odds of developing severe COVID-19 (odds ratio [OR] 1.84, 95% CI 0.99-3.43, P = 0.05), while those who were obese were at 3.40-fold odds of developing severe disease (OR 3.40, 95% CI 1.40-2.86, P = 0.007), after adjusting for age, sex, epidemiological characteristics, days from disease onset to hospitalization, presence of hypertension, diabetes, cardiovascular disease, chronic obstructive pulmonary disease, liver disease, and cancer, and drug used for treatment. Additionally, after similar adjustment, men who were obese versus those who were normal weight were at increased odds of developing severe COVID-19 (OR 5.66, 95% CI 1.80-17.75, P = 0.003).

CONCLUSIONS

In this study, obese patients had increased odds of progressing to severe COVID-19. As the severe acute respiratory syndrome coronavirus 2 may continue to spread worldwide, clinicians should pay close attention to obese patients, who should be carefully managed with prompt and aggressive treatment.

[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.

Obesity hypoventilation syndrome

Obesity hypoventilation syndrome (OHS) is defined as a combination of obesity (body mass index ≥30 kg·m-2), daytime hypercapnia (arterial carbon dioxide tension ≥45 mmHg) and sleep disordered breathing, after ruling out other disorders that may cause alveolar hypoventilation. OHS prevalence has been estimated to be ∼0.4% of the adult population. OHS is typically diagnosed during an episode of acute-on-chronic hypercapnic respiratory failure or when symptoms lead to pulmonary or sleep consultation in stable conditions. The diagnosis is firmly established after arterial blood gases and a sleep study. The presence of daytime hypercapnia is explained by several co-existing mechanisms such as obesity-related changes in the respiratory system, alterations in respiratory drive and breathing abnormalities during sleep. The most frequent comorbidities are metabolic and cardiovascular, mainly heart failure, coronary disease and pulmonary hypertension. Both continuous positive airway pressure (CPAP) and noninvasive ventilation (NIV) improve clinical symptoms, quality of life, gas exchange, and sleep disordered breathing. CPAP is considered the first-line treatment modality for OHS phenotype with concomitant severe obstructive sleep apnoea, whereas NIV is preferred in the minority of OHS patients with hypoventilation during sleep with no or milder forms of obstructive sleep apnoea (approximately <30% of OHS patients). Acute-on-chronic hypercapnic respiratory failure is habitually treated with NIV. Appropriate management of comorbidities including medications and rehabilitation programmes are key issues for improving prognosis.

Non-invasive ventilation in acute respiratory failure of patients with obesity hypoventilation syndrome

INTRODUCTION

Non-invasive ventilation (NIV) has been used successfully for the management of acute respiratory failure (ARF) more often in the last two decades compared to prior decades. There are particular groups of patients that are more likely to benefit from NIV. One of these groups is patients with obesity hypoventilation syndrome (OHS). The aim of this review is to evalue the effectiveness of NIV in acute ARF.

EVIDENCE ACQUISITION

MEDLINE, EMBASE, CINHAIL, Cochrane Central Register of Controlled Trials, DARE, the Cochrane Database of Systematic Reviews, and the ACP Journal Club database were searched from January 2001 to December 2017.

EVIDENCE SYNTHESIS

More than 30% of them have been diagnosed when hospitalized for ARF. NIV rarely failed in reversing ARF. OHS patients who exhibited early NIV failure had a high severity score and a low HCO3 level at admission; more than half of hypercapnic patients with decompensated OHS exhibited a delayed but successful response to NIV.

CONCLUSIONS

Patients with decompensation of OHS have a better prognosis and response to NIV than other hypercapnic patients. They required more aggressive NIV settings, a longer time to reduce paCO2 levels, and showed more frequently a delayed but successful response to NIV.

Benefits of non-invasive ventilation in acute hypercapnic respiratory failure

Non-invasive ventilation (NIV) with bilevel positive airway pressure is a non-invasive technique, which refers to the provision of ventilatory support through the patient's upper airway using a mask or similar device. This technique is successful in correcting hypoventilation. It has become widely accepted as the standard treatment for patients with hypercapnic respiratory failure (HRF). Since the 1980s, NIV has been used in intensive care units and, after initial anecdotal reports and larger series, a number of randomized trials have been conducted. Data from these trials have shown that NIV is a valuable treatment for HRF. This review aims to explore the principal areas in which NIV can be useful, focusing particularly on patients with acute HRF (AHRF). We will update the evidence base with the goal of supporting clinical practice. We provide a practical description of the main indications for NIV in AHRF and identify the group of patients with hypercapnic failure who will benefit most from the application of NIV.

Establishing failure predictors for the planned extubation of overweight and obese patients

We investigated failure predictors for the planned extubation of overweight (body mass index [BMI] = 25.0–29.9) and obese (BMI ≥ 30) patients. All patients admitted to the adult intensive care unit (ICU) of a tertiary hospital in Taiwan were identified. They had all undergone endotracheal intubation for > 48 h and were candidates for extubation. During the study, 595 patients (overweight = 458 [77%]); obese = 137 [23%]) with planned extubation after weaning were included in the analysis; extubation failed in 34 patients (5.7%). Their mean BMI was 28.5 ± 3.8. Only BMI and age were significantly different between overweight and obese patients. The mortality rate for ICU patients was 0.8%, and 2.9% for inpatients during days 1–28; the overall in-hospital mortality rate was 8.4%. Failed Extubation group patients were significantly older, had more end-stage renal disease (ESRD), more cardiovascular system-related respiratory failure, higher maximal inspiratory pressure (MIP), lower maximal expiratory pressure (MEP), higher blood urea nitrogen, and higher ICU- and 28-day mortality rates than did the Successful Extubation group. Multivariate logistic regression showed that cardiovascular-related respiratory failure (odds ratio [OR]: 2.60; 95% [confidence interval] CI: 1.16–5.80), ESRD (OR: 14.00; 95% CI: 6.25–31.35), and MIP levels (OR: 0.94; 95% CI: 0.90–0.97) were associated with extubation failure. We conclude that the extubation failure risk in overweight and obese patients was associated with cardiovascular system-related respiratory failure, ESRD, and low MIP levels.

Body Mass Index and Intensive Care Unit Outcomes in African American Patients

PURPOSE

We sought to determine whether body mass index (BMI) is associated with worse intensive care unit (ICU) outcomes among Black patients.

METHODS

Patients admitted to the medical ICU during 2012 were categorized into six BMI groups based on the World Health Organization criteria. ICU mortality, ICU and hospital length of stay (LOS), need for and duration of mechanical ventilation and organ failure rate were assessed.

RESULTS

A total of 605 patients with mean age 58.9 ± 16.0 years were studied. Compared with those with normal BMI, obese patients had significant higher rates of hypertension, diabetes mellitus and obstructive sleep apnea diagnoses (P<.001 for all). A total of 100 (16.5%) patients died during their ICU stay. Obesity was not associated with increased odds of ICU mortality (OR=.58; 95% CI, .16-2.20). Moreover, improved survival was observed for class II obese patients (OR, .031; 95% CI, .001-.863). There were no differences in the need for and duration of mechanical ventilation between the BMI groups. However, ICU and hospital LOS were significantly longer in patients with obesity.

CONCLUSION

Obesity was not associated with increased ICU mortality; however, obesity was associated with increased comorbid illness and with significant longer ICU and hospital length of stay.

Prospective observational cohort study of patients with weaning failure admitted to a specialist weaning, rehabilitation and home mechanical ventilation centre

OBJECTIVES

According to National Health Service England (NHSE) specialist respiratory commissioning specification for complex home ventilation, patients with weaning failure should be referred to a specialist centre. However, there are limited data reporting the clinical outcomes from such centres.

SETTING

Prospective observational cohort study of patients admitted to a UK specialist weaning, rehabilitation and home mechanical ventilation centre between February 2005 and July 2013.

PARTICIPANTS

262 patients admitted with a median age of 64.2 years (IQR 52.6-73.2 years). 59.9% were male.

RESULTS

39.7% of patients had neuromuscular and/or chest wall disease, 21% were postsurgical, 19.5% had chronic obstructive pulmonary disease (COPD), 5.3% had obesity-related respiratory failure and 14.5% had other diagnoses. 64.1% of patients were successfully weaned, with 38.2% weaned fully from ventilation, 24% weaned to nocturnal non-invasive ventilation (NIV), 1.9% weaned to nocturnal NIV with intermittent NIV during the daytime. 21.4% of patients were discharged on long-term tracheostomy ventilation. The obesity-related respiratory failure group were most likely to wean (relative risk (RR) for weaning success=1.48, 95% CI 1.35 to 1.77; p<0.001), but otherwise weaning success rates did not significantly vary by diagnostic group. The median time-to-wean was 19 days (IQR 9-33) and the median duration of stay was 31 days (IQR 16-50), with no difference observed between the groups. Weaning centre mortality was 14.5%, highest in the COPD group (RR=2.15, 95% CI 1.19 to 3.91, p=0.012) and lowest in the neuromuscular and/or chest wall disease group (RR=0.34, 95% CI 0.16 to 0.75, p=0.007). Of all patients discharged alive, survival was 71.7% at 6 months and 61.8% at 12 months postdischarge.

CONCLUSIONS

Following NHSE guidance, patients with weaning delay and failure should be considered for transfer to a specialist centre where available, which can demonstrate favourable short-term and long-term clinical outcomes.

Determinants of noninvasive ventilation success or failure in morbidly obese patients in acute respiratory failure

PURPOSE

Acute respiratory failure (ARF) is a common life-threatening complication in morbidly obese patients with obesity hypoventilation syndrome (OHS). We aimed to identify the determinants of noninvasive ventilation (NIV) success or failure for this indication.

METHODS

We prospectively included 76 consecutive patients with BMI>40 kg/m2 diagnosed with OHS and treated by NIV for ARF in a 15-bed ICU of a tertiary hospital.

RESULTS

NIV failed to reverse ARF in only 13 patients. Factors associated with NIV failure included pneumonia (n = 12/13, 92% vs n = 9/63, 14%; p<0.0001), high SOFA (10 vs 5; p<0.0001) and SAPS2 score (63 vs 39; p<0.0001) at admission. These patients often experienced poor outcome despite early resort to endotracheal intubation (in-hospital mortality, 92.3% vs 17.5%; p<0.001). The only factor significantly associated with successful response to NIV was idiopathic decompensation of OHS (n = 30, 48% vs n = 0, 0%; p = 0.001). In the NIV success group (n = 63), 33 patients (53%) experienced a delayed response to NIV (with persistent hypercapnic acidosis during the first 6 hours).

CONCLUSIONS

Multiple organ failure and pneumonia were the main factors associated with NIV failure and death in morbidly obese patients in hypoxemic ARF. On the opposite, NIV was constantly successful and could be safely pushed further in case of severe hypercapnic acute respiratory decompensation of OHS.

The effect of obesity on outcomes in mechanically ventilated patients in a medical intensive care unit

BACKGROUND

The effect of obesity on outcomes in critically ill patients requiring invasive mechanical ventilation in a medical intensive care unit (ICU) is uncertain.

OBJECTIVES

This study was intended to further explore the relationship between outcomes and obesity in patients admitted to a medical ICU who required invasive mechanical ventilation.

METHODS

All adult patients admitted to the medical ICU at Washington Hospital Center requiring intubation and invasive mechanical ventilation for at least 24 h between January 1 and December 31, 2009, were retrospectively studied. Patients were categorized as nonobese (BMI <30) and obese (BMI ≥30). The primary outcome measure was 30-day mortality following intubation. Secondary outcomes included ICU length of stay (LOS), hospital LOS and duration of mechanical ventilation.

RESULTS

There were 504 eligible patients: 306 nonobese and 198 (39%) obese. Obese patients had significantly higher rates of diabetes (43 vs. 30%, p = 0.004), hyperlipidemia (32 vs. 24%, p = 0.04), asthma (16 vs. 8%, p = 0.004) and obstructive sleep apnea requiring continuous positive airway pressure treatment (12 vs. 1%, p < 0.001). Nonobese patients had a significantly higher rate of HIV infection (10 vs. 5%, p = 0.05) and malignancy (21 vs. 13%, p = 0.03). There were no significant differences in mortality up to 30 days following intubation and secondary outcomes between obese and nonobese patients. Multivariate analysis using logistic regression showed no significant relationship between mortality rate at 30 days following intubation and obesity. Outcomes were similar for the black obese (n = 153) and nonobese (n = 228) patients and the obese (n = 85) and very obese (n = 113) patients.

CONCLUSIONS

Obesity did not influence outcomes in critically ill patients requiring invasive mechanical ventilation in a medical ICU. Black obese patients had similar outcomes to black nonobese patients, and very obese patients also had similar outcomes to obese patients.

Outcomes of morbidly obese patients receiving invasive mechanical ventilation: a nationwide analysis

BACKGROUND

Critically ill, morbidly obese patients (BMI≥40 kg/m2) are at high risk of respiratory failure requiring invasive mechanical ventilation (IMV). It is not clear if outcomes of critically ill, obese patients are affected by obesity. Due to limited cardiopulmonary reserve, they may have poor outcomes. However, literature to this effect is limited and conflicted.

METHODS

We used the Nationwide Inpatient Sample from 2004 to 2008 to examine the outcomes of morbidly obese people receiving IMV and compared them to nonobese people. We identified hospitalizations requiring IMV and morbid obesity using International Classification of Diseases, 9th Revision, Clinical Modification codes. Primary outcomes studied were inhospital mortality, rates of prolonged mechanical ventilation (≥96 h), and tracheostomy. Multivariable logistic regression was used to adjust for potential confounding variables. We also examined outcomes stratified by number of organs failing.

RESULTS

Of all hospitalized, morbidly obese people, 2.9% underwent IMV. Mean age, comorbidity score, and severity of illness were lower in morbidly obese people. The adjusted mortality was not significantly different in morbidly obese people (OR 0.89; 95% CI, 0.74-1.06). When stratified by severity of disease, there was a stepwise increase in risk for mortality among morbidly obese people relative to nonobese people (range: OR, 0.77; 95% CI, 0.58-1.01 for only respiratory failure, to OR, 4.14; 95% CI, 1.11-15.3 for four or more organs failing). Rates of prolonged mechanical ventilation were similar, but rate of tracheostomy (OR 2.19; 95% CI, 1.77-2.69) was significantly higher in patients who were morbidly obese.

CONCLUSIONS

Morbidly obese people undergoing IMV have a similar risk for death as nonobese people if only respiratory failure is present. When more organs fail, morbidly obese people have increased risk for mortality compared with nonobese people.

Effect of morbid obesity on in-hospital mortality and coronary revascularization outcomes after acute myocardial infarction in the United States

The aim of this study was to investigate the impact of morbid obesity (body mass index ≥40 kg/m(2)) on in-hospital mortality and coronary revascularization outcomes in patients presenting with acute myocardial infarctions (AMI). The Nationwide Inpatient Sample of the Healthcare Cost and Utilization Project was used, and 413,673 patients hospitalized with AMIs in 2009 were reviewed. Morbidly obese patients constituted 3.7% of all patients with AMIs. Analysis of the unadjusted data revealed that morbidly obese patients compared with those not morbidly obese were more likely to undergo any invasive cardiac procedures when presenting with either ST-segment elevation myocardial infarction (97.4% vs 93.8%, p <0.0001) or non-ST-segment elevation myocardial infarction (85.5% vs 80.6%, p <0.0001). The unadjusted mortality rate for morbidly obese patients with AMIs was 3.5%, compared with 5.5% of those not obese (p <0.0001). After adjustment, lower odds of mortality in those morbidly obese compared to those not morbidly remained. In conclusion, patients with morbid obesity had lower odds of in-hospital mortality, compared to those not morbidly obese, consistent with the phenomenon of the "obesity paradox."

Obesity is not associated with increased mortality and morbidity in critically ill children

AIM

To evaluate the effect of obesity on mortality, length of mechanical ventilation, and length of stay (LOS) in critically ill children.

METHODS

Retrospective cohort study in 2- to 18-year-olds, admitted to the pediatric intensive care unit (PICU) at the Children's Hospital of Wisconsin from 2005-2009 who required invasive ventilation. Weight z score was used to categorize patients as normal (-1.89 to 1.04), overweight (1.05-1.65), obese (1.66-2.33), and severely obese (>2.33). Underweight patients were excluded. Age, gender, admission type, Pediatric Index of Mortality 2 score, operative status, trauma status, admission Pediatric Outcome Performance Category, and diagnosis categories were also collected. The outcomes were mortality, total ventilator days, and PICU LOS. Univariate analysis was used to compare the groups, and multivariate logistic regression was used to compare mortality. Total ventilation days and LOS were modeled with linear regression.

RESULTS

In total, 1030 patients were included in the study, with 753 normal weight, 137 overweight, 76 obese, and 64 severely obese. The risk-adjusted mortality rates in overweight (odds ratio [OR], 1.06; 95% confidence interval [CI], 0.62-1.82), obese (OR, 0.68; 95% CI, 0.31-1.48), and severely obese patients (OR, 1.02; 95% CI, 0.45-2.34) were not significantly different compared with the normal-weight group. Total ventilation days (P = .9628) and PICU LOS (P = .8431) were not significantly different between the groups after adjusting for risk factors.

CONCLUSION

Critically ill overweight, obese, and severely obese children who require invasive mechanical ventilation have similar mortality, length of stay in the PICU, and ventilator days as compared with normal-weight children.

Obesity is associated with higher risk of intensive care unit admission and death in influenza A (H1N1) patients: a systematic review and meta-analysis

The aim of this study was to assess the association between obesity and the risk of intensive care unit (ICU) admission and death among patients hospitalized for influenza A (H1N1) viral infection. A systematic review of the Medline and Cochrane databases using 'obesity', 'hospitalization', 'influenza A viral infection', various synonyms, and reference lists of retrieved articles from January 2009 to January 2010. Studies comparing the prevalence of obesity among patients with confirmed infection for influenza A virus and who were either hospitalized or admitted to ICU/died were included. A total of 3059 subjects from six cross-sectional studies, who were hospitalized for influenza A (H1N1) viral infection, were included in this meta-analysis. Severely obese H1N1 patients (body mass index ≥ 40 kg m(-2), n = 804) were as twice as likely to be admitted to ICU or die (odds ration: 2.01, 95% confidence interval: 1.29-3.14, P < 0.002) compared with H1N1 patients who were not severely obese. Having a body mass index ≥ 30 kg m(-2) was similarly associated with a more than twofold increased risk of ICU admission or death although this did not reach statistical significance (2.14, 0.92-4.99, P < 0.07). This meta-analysis supports the view that obesity is associated with higher risks of ICU admission or death in patients with influenza A (H1N1) infection. Therefore, morbid obese patients should be monitored more intensively when hospitalized.

Emergency department management of the airway in obese adults

Airway management in obese adults can be challenging, and much of the literature on this subject focuses on elective surgical cases, rather than acutely ill patients. In this article, we review the emergency department evaluation of the airway in obesity, discussing anatomy, physiology, and pharmacology. In addition, we describe techniques and devices used to improve intubating conditions in the obese patient. After our review of the relevant literature, we conclude that research in this particular area of acute care remains in its infancy.

[Influenza A (H1N1). Experience in the United States]

Pneumonia and seasonal influenza have major repercussions on mortality, morbidity and costs worldwide. At the end of March 2009, an outbreak of influenza A (H1N1) was reported in Mexico that rapidly spread throughout the world, including the United States, reaching pandemic proportions. The activity of influenza A (H1N1) has reached levels higher than those reported in previous years, mainly affecting the pediatric population aged less than 18 years old. In addition, a group of comorbid conditions were more frequently associated in patients with severe influenza A (H1N1), including chronic pulmonary disease, immunosuppression, heart disease, obesity and pregnancy. The current pandemic has had a substantial impact on public health in the United States and in many other countries worldwide. Therefore, the present review aims to examine the North American experience of the influenza A (H1N1) epidemic, focussing chronologically on the epidemiology of the virus, high risk groups, diagnosis, vaccination and management.

Airway management in the obese patient

Airway management is a major factor underlying morbidity and mortality in the obese population. The validity of anthropomorphic prediction model in assessing a difficult airway is less accurate compared with lean subjects. Preoperative evaluation and anticipation of potential complications are critical for safe and successful intubation. Application of noninvasive positive airway pressure can prevent atelectasis and improve oxygenation during the anesthetic induction as well during the postoperative period and after liberation from mechanical ventilation. When performed by trained operators, bedside percutaneous dilatation tracheostomy in obese patients has a safety profile comparable to surgical tracheostomy but provides advantages including ease of performance and lesser cost, and obviates transporting a critically ill patient outside the intensive care unit.

Clinical review: Ventilatory strategies for obstetric, brain-injured and obese patients

The ventilatory management of patients with acute respiratory failure is supported by good evidence, aiming to reduce lung injury by pressure limitation and reducing the duration of ventilatory support by regular assessment for discontinuation. Certain patient groups, however, due to their altered physiology or disease-specific complications, may require some variation in usual ventilatory management. The present manuscript reviews the ventilatory management in three special populations, namely the patient with brain injury, the pregnant patient and the morbidly obese patient.

Obesity and the lung: 3. Obesity, respiration and intensive care

Obesity is a major problem from a public health perspective and a difficult practical matter for intensivists. The obesity pandemic has required treating clinicians to develop an appreciation of the substantial pathophysiological effects of obesity on the various organ systems. The important physiological concepts are illustrated by focusing on obstructive sleep apnoea, obesity hypoventilation syndrome, abdominal compartment syndrome and ventilatory management of the obese patient with acute respiratory distress syndrome.

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

OBJECTIVE

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

DESIGN

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

DATA SOURCE

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

SETTING

Not applicable.

PATIENTS

A total of 62,045 critically ill subjects.

INTERVENTIONS

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

MEASUREMENTS AND MAIN RESULTS

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

CONCLUSION

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