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 <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" id="M1"> <a:mtext>aged</a:mtext> <a:mo>≥</a:mo> <a:mn>18</a:mn> <a:mo>−</a:mo> <a:mtext>year</a:mtext> <a:mo>−</a:mo> <a:mtext>old</a:mtext> </a:math> , 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%; <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" id="M2"> <c:mi>p</c:mi> <c:mo><</c:mo> <c:mn>0.001</c:mn> </c:math> ), chronic renal insufficiency (CRI) (73.3% vs. 41.4%; <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" id="M3"> <e:mi>p</e:mi> <e:mo>=</e:mo> <e:mn>0.04</e:mn> </e:math> ), and dyslipidemia (66.7% vs. 34.5%; <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" id="M4"> <g:mi>p</g:mi> <g:mo>=</g:mo> <g:mn>0.04</g:mn> </g:math> ) than those with non-mOHS. The mean forced vital capacity (FVC) in our patients was of <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" id="M5"> <i:mn>59.5</i:mn> <i:mi>%</i:mi> <i:mo>±</i:mo> <i:mn>18.5</i:mn> </i:math> of the predicted value, lower than what is usually reported in stable patients with OHS. At hospital admission, more than two-thirds ( <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" id="M6"> <k:mi>n</k:mi> <k:mo>=</k:mo> <k:mn>34</k:mn> </k:math> , 77.3%) were misdiagnosed as having asthma exacerbation ( <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" id="M7"> <m:mi>n</m:mi> <m:mo>=</m:mo> <m:mn>4</m:mn> </m:math> , 4.9.1%), chronic obstructive pulmonary disease (COPD) exacerbation ( <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" id="M8"> <o:mi>n</o:mi> <o:mo>=</o:mo> <o:mn>12</o:mn> </o:math> , 27.3%) and/or heart failure ( <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" id="M9"> <q:mi>n</q:mi> <q:mo>=</q:mo> <q:mn>29</q:mn> </q:math> , 65.9%). Acute pulmonary oedema (ACPE) ( <s:math xmlns:s="http://www.w3.org/1998/Math/MathML" id="M10"> <s:mi>n</s:mi> <s:mo>=</s:mo> <s:mn>16</s:mn> </s:math> , 36.4%) and acute viral bronchitis ( <u:math xmlns:u="http://www.w3.org/1998/Math/MathML" id="M11"> <u:mi>n</u:mi> <u:mo>=</u:mo> <u:mn>12</u:mn> </u:math> , 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; <w:math xmlns:w="http://www.w3.org/1998/Math/MathML" id="M12"> <w:mi>p</w:mi> <w:mo>=</w:mo> <w:mn>0.01</w:mn> </w:math> ). 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.