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

Noninvasive ventilation on reintubation in patients with obesity and hypoxemic respiratory failure following abdominal surgery: a post hoc analysis of a randomized clinical trial

PURPOSE

Although noninvasive ventilation (NIV) may reduce reintubation in patients with acute hypoxemic respiratory failure following abdominal surgery, this strategy has not been specifically assessed in patients with obesity.

METHODS

We conducted a post hoc analysis of a multicenter randomized controlled trial comparing NIV delivered via facial mask to standard oxygen therapy among patients with obesity and acute hypoxemic respiratory failure within 7 days after abdominal surgery. The primary outcome was reintubation within 7 days. Secondary outcomes were invasive ventilation-free days at day 30, intensive care unit (ICU)-acquired pneumonia and 30-day survival.

RESULTS

Among 293 patients with hypoxemic respiratory failure following abdominal surgery, 76 (26%) patients had obesity and were included in the intention-to-treat analysis. Reintubation rate was significantly lower with NIV (13/42, 31%) than with standard oxygen therapy (19/34, 56%) within 7 days (absolute difference: - 25%, 95% confidence interval (CI) - 49 to - 1%, p = 0.03). NIV was associated with significantly more invasive ventilation-free days compared with standard oxygen therapy (27.1 ± 8.6 vs 22.7 ± 11.1 days; p = 0.02), while fewer patients developed ICU-acquired pneumonia (1/42, 2% vs 6/34, 18%; p = 0.04). The 30-day survival was 98% in the NIV group (41/42) versus 85% in the standard oxygen therapy (p = 0.08). In patients with body mass index (BMI) < 30 kg/m2, no significant difference was observed between NIV (36/105, 34%) and standard oxygen therapy (47/109, 43%, p = 0.03). An interaction test showed no statistically significant difference between the two subsets (BMI ≥ 30 kg/m2 and BMI < 30 kg/m2).

CONCLUSIONS

Among patients with obesity and hypoxemic respiratory failure following abdominal surgery, use of NIV compared with standard oxygen therapy reduced the risk of reintubation within 7 days, contrary to patients without obesity. However, no interaction was found according to the presence of obesity or not, suggesting either a lack of power to conclude in the non-obese subgroup despite existing differences, or that the statistical difference found in the overall sample was driven by a large effect in the obese subsets.

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.

Emergencies in obese patients: a narrative review

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

Can Alveolar-Arterial Difference and Lung Ultrasound Help the Clinical Decision Making in Patients with COVID-19?

Background: COVID-19 is an emerging infectious disease, that is heavily challenging health systems worldwide. Admission Arterial Blood Gas (ABG) and Lung Ultrasound (LUS) can be of great help in clinical decision making, especially during the current pandemic and the consequent overcrowding of the Emergency Department (ED). The aim of the study was to demonstrate the capability of alveolar-to-arterial oxygen difference (AaDO₂) in predicting the need for subsequent oxygen support and survival in patients with COVID-19 infection, especially in the presence of baseline normal PaO₂/FiO₂ ratio (P/F) values. Methods: A cohort of 223 swab-confirmed COVID-19 patients underwent clinical evaluation, blood tests, ABG and LUS in the ED. LUS score was derived from 12 ultrasound lung windows. AaDO₂ was derived as AaDO₂ = ((FiO₂) (Atmospheric pressure − H₂O pressure) − (PaCO₂/R)) − PaO₂. Endpoints were subsequent oxygen support need and survival. Results: A close relationship between AaDO₂ and P/F and between AaDO₂ and LUS score was observed (R² = 0.88 and R² = 0.67, respectively; p < 0.001 for both). In the subgroup of patients with P/F between 300 and 400, 94.7% (n = 107) had high AaDO₂ values, and 51.4% (n = 55) received oxygen support, with 2 ICU admissions and 10 deaths. According to ROC analysis, AaDO₂ > 39.4 had 83.6% sensitivity and 90.5% specificity (AUC 0.936; p < 0.001) in predicting subsequent oxygen support, whereas a LUS score > 6 showed 89.7% sensitivity and 75.0% specificity (AUC 0.896; p < 0.001). Kaplan–Meier curves showed different mortality in the AaDO₂ subgroups (p = 0.0025). Conclusions: LUS and AaDO₂ are easy and effective tools, which allow bedside risk stratification in patients with COVID-19, especially when P/F values, signs, and symptoms are not indicative of severe lung dysfunction.

Effect of mandibular advancement device treatment on HIF-1α, EPO and VEGF in the myocardium of obstructive sleep apnea-hypopnea syndrome rabbits

The aim of this study was to investigate the effects of mandibular advancement device (MAD) therapy for obstructive sleep apnea-hypopnea syndrome (OSAHS) on hypoxia-inducible factor-1α (HIF-1α), erythropoietin (EPO) and vascular endothelial growth factor (VEGF) in myocardial tissue. New Zealand rabbits were used to develop OSAHS and MAD models. Cone beam computed tomography (CBCT) of the upper airway and polysomnography (PSG) recordings were performed with the animals in the supine position. All of the animals were induced to sleep in a supine position for 4-6 h each day and were observed continuously for 8 weeks. The myocardial tissue of the three groups was dissected to measure the expression of HIF-1α, EPO and VEGF. The results showed that there was higher expression of HIF-1α, EPO and VEGF in the OSAHS group than those in the MAD and control groups. MAD treatment significantly downregulated the expression of HIF-1α, EPO and VEGF in the OSAHS animals. We concluded that MAD treatment could significantly downregulate the increased expression of HIF-1α, EPO and VEGF in OSAHS rabbits, improving their myocardial function.