Date Published: October 25, 2018
Publisher: Public Library of Science
Author(s): Dan Adler, Elise Dupuis-Lozeron, Jean Paul Janssens, Paola M. Soccal, Frédéric Lador, Laurent Brochard, Jean-Louis Pépin, Pei-Lin Lee.
Acute hypercapnic respiratory failure (AHRF) treated with non-invasive ventilation in the ICU is frequently caused by chronic obstructive pulmonary disease (COPD) exacerbations and obesity-hypoventilation syndrome, the latter being most often associated with obstructive sleep apnea. Overlap syndrome (a combination of COPD and obstructive sleep apnea) may represent a major burden in this population, and specific diagnostic pathways are needed to improve its detection early after ICU discharge.
To evaluate whether pulmonary function tests can identify a high probability of obstructive sleep apnea in AHRF survivors and outperform common screening questionnaires to identify the disorder.
Fifty-three patients surviving AHRF (31 males; median age 67 years (interquartile range: 62–74) participated in the study. Anthropometric data were recorded and body plethysmography was performed 15 days after ICU discharge. A sleep study was performed 3 months after ICU discharge.
The apnea-hypopnea index was negatively associated with static hyperinflation as measured by the residual volume to total lung capacity ratio in the % of predicted (coefficient = -0.64; standard error 0.17; 95% CI -0.97 to -0.31; p<0.001). A similar association was observed in COPD patients only: coefficient = -0.65; standard error 0.19; 95% CI -1.03 to -0.26; p = 0.002. Multivariate analysis with penalized maximum likelihood confirmed that the residual volume to total lung capacity ratio was the main contributor for apnea-hypopnea index variance in addition to classic predictors. Screening questionnaires to select patients at risk for sleep-disordered breathing did not perform well. In AHRF survivors, static hyperinflation is negatively associated with the apnea-hypopnea index in both COPD and non-COPD patients. Measuring static hyperinflation in addition to classic predictors may help to increase the recognition of obstructive sleep apnea as common screening tools are of limited value in this specific population.
Chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA) are highly prevalent chronic diseases and represent a considerable economic burden for health care systems worldwide [1–3]. Acute hypercapnic respiratory failure (AHRF) in patients admitted to the intensive care unit (ICU) is mainly due to COPD exacerbation or obesity-hypoventilation syndrome. In a high proportion of these individuals, non-invasive ventilation treatment is successful [4–7]. OSA is a component of the obesity-hypoventilation syndrome in more than 85% of cases and most patients with a clinical diagnosis of this syndrome remain treated in the long term with non-invasive positive airway pressure [5, 8, 9]. Conversely, only selected subgroups of COPD patients with persistent hypercapnia after AHRF benefit from home non-invasive ventilation as evidenced by recent high-quality randomized controlled trials [10, 11]. Cohort studies also suggest that untreated COPD patients with co-morbid OSA are at increased risk for repeated exacerbations and death [12, 13].
Baseline characteristics of the study population are shown in Table 1. Fifty-three patients surviving AHRF were enrolled in the study (31 males; median age 67 years [IQR 62–74]; BMI 33 [26–41] kg/m2). The prevalence of COPD was high with no difference between patients with or without significant OSA (64% versus 82% respectively; p = 0.296).
Our study expands current knowledge of interactions between lung mechanics and sleep-disordered breathing and shows that the severity of static hyperinflation is negatively associated with the AHI in both COPD and non-COPD patients surviving AHRF. Classic screening tools for OSA did not perform well and are of limited interest in this specific population.