Acute Respiratory Failure in Obesity-Hypoventilation Syndrome Managed in the ICU

Abstract

BACKGROUND: Obesity-hypoventilation syndrome (OHS) is defined as the combination of obesity (body mass index > 30 kg/m 2) and daytime arterial hypercapnia (P aCO 2 > 45 mm Hg) in the absence of other causes of hypoventilation, and can lead to acute hypercapnic respiratory failure in the ICU. Our objective was to describe the ventilatory management and outcomes of subjects with OHS who were admitted to the ICU for acute hypercapnic respiratory failure. METHODS: We retrospectively built a cohort of subjects with OHS who were admitted for acute hypercapnic respiratory failure in 4 ICUs of the university teaching hospital in Lyon, France, between 2013 and 2017. The main end point was the rate of success of noninvasive ventilation (NIV). Secondary end points were survival from OHS diagnosis to the last follow-up and risk factors for ICU admission and long-term survival. RESULTS: One hundred fifteen subjects with OHS were included. Thirtyseven subjects (32.1%) were admitted to the ICU for acute hypercapnic respiratory failure. Congestive heart failure was the leading cause of acute hypercapnic respiratory failure (54%). At ICU admission, pH before NIV use was median (range) 7.26 (7.22-7.31) and P aCO 2 was 70 (61-76) mm Hg. NIV was used as first-line ventilatory support in 36 subjects (97.2%) and was successful in 33 subjects (91.7%). ICU mortality was low (2.7%). The subjects admitted to the ICU were significantly older and had a lower FEV 1 and vital capacity at the time of an OHS diagnosis. The difference in the restricted mean survival time was 663 d in favor of subjects not admitted to the ICU. Multivariate analysis showed that lower vital capacity at an OHS diagnosis was significantly associated with a higher risk of ICU admission. No factor was independently associated with long-term overall mortality in multivariate analysis. CONCLUSIONS: Acute hypercapnic respiratory failure in subjects with OHS was generally responsive to NIV and was frequently associated with congestive heart failure.

Characteristics of Obese Patients with Acute Hypercapnia Respiratory Failure Admitted in the Department of Pneumology: An Observational Study of a North African Population

“…The mean FVC in our patients was of 59.5% ±18.5 of the predicted value, lower than what is usually reported in stable patients with OHS [ 36 ]. Similarly, in a study by Chebib et al [ 26 ], patients with OHS who were admitted to the ICU for AHRF had significantly lower baseline FVC than those not admitted to the ICU (72% vs. 80%, respectively; p = 0.01). Moreover, a cut-off of FVC < 3.5 L in men and 2.3 l in women could predict chronic daytime hypercapnia in obese subjects, as was shown by Mandal et al [ 37 ].…”

“…This fact suggests that OHS remains widely unknown even among specialists. Thus, it is frequently missed or neglected during hospitalization as well as during outpatient follow-up after hospital discharge [ 26 ]. Moreover, more than two-thirds of patients had been erroneously diagnosed on admission with COPD/asthma exacerbation and/or congestive heart failure.…”

“…In contrast, pleural effusion ( n = 2, %) and extra respiratory infection ( n = 1; %) were rarely involved. In a study by Chebib et al [ 26 ], congestive heart failure was responsible for AHRF in more than half of patients (54%), followed by acute pulmonary embolism (10.8%), and in slightly less than one-third of patients, no cause could be identified. Carrillo et al [ 30 ] found that most of AHRF episodes were triggered by respiratory infections, while cardiac origin was much less involved than was reported in our study.…”

“…Overall, the common causes of AHRF in patients with OHS are respiratory infections, ACPE, and sepsis [ 42 ], but idiopathic forms are also frequent. Therefore, OHS patients with AHRF need to be meticulously assessed for infection, with a careful examination of heart function and loading condition [ 26 ]. Other less common causes include pleural effusion, pulmonary embolism, depressants, surgery, rib contusion and fractures, supine immobilization, and thoracic bracing [ 43 ] [ 30 ] [ 28 ].…”

Impact of obesity on outcome of severe bacterial infections

“…This is consistent with a greater chance of survival in cases of severe bacterial infections but is contradictory to the higher mortality rates in cases of severe viral infections. The alveolar hypoventilation that is common in obese patients could explain the worse outcome of lung infections related to influenza and COVID-19 in this group of patients but is not consistent with their greater chance of survival in cases of severe bacterial infections [ 25 ].…”