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

Background: Acute hypercapnic respiratory failure (AHRF) is a common life-threatening event in patients with obesity hypoventilation syndrome (OHS).

Objectives: To study the clinical pattern, noninvasive ventilatory support, as well as the short- and long-term outcomes of patients with OHS admitted in a ward because of AHRF.

Methods: We conducted a retrospective cohort study including all adults with OHS aged ≥ 18 - year - old, admitted in a 90-bed-ward for AHRF.

Results: A total of 44 patients were included. Fifteen (34.1%) and 29 (65.9%) patients were diagnosed with malignant OHS (mOHS) and nonmalignant OHS (non-mOHS), respectively, while 36 (81.8%) had coexisting obstructive sleep apnea hypopnea syndrome (OSAHS). Patients with mOHS had a significantly higher rate of heart failure (100% vs. 31%; < 0.001), chronic renal insufficiency (CRI) (73.3% vs. 41.4%; = 0.04), and dyslipidemia (66.7% vs. 34.5%; = 0.04) than those with non-mOHS. The mean forced vital capacity (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. At hospital admission, more than two-thirds ( = 34, 77.3%) were misdiagnosed as having asthma exacerbation ( = 4, 4.9.1%), chronic obstructive pulmonary disease (COPD) exacerbation ( = 12, 27.3%) and/or heart failure ( = 29, 65.9%). Acute pulmonary oedema (ACPE) ( = 16, 36.4%) and acute viral bronchitis ( = 12, 27.3%) were the main identified causal factors, while no cause could be determined in 5 (11.4%) patients. Noninvasive positive pressure ventilation (NIPPV) using bilevel positive airway pressure (BIPAP) was very highly effective to treat AHRF, with only 2.27% of patients failing the modality. Median overall duration of ventilation was 9 hours per day (1.3-20) and was significantly longer in patients with mOHS than in those with non-mOHS (10 [6-18] vs. 8 [1.3-20], respectively; = 0.01). Forty two of the forty-three patients discharged alive were treated with BIPAP or continuous positive airway pressure (CPAP) in 26 and 16 patients, respectively. The probability of survival was 90% at 12 months, while the probability of readmission for a new episode of AHRF was 56% at 6 months and 22% at 12 months, respectively.

Conclusion: AHRF in OHS patients is a life-threatening event which can be successfully and safely treated with BIPAP, with a low long-term mortality even in patients with mOHS.