Introduction Obesity hypoventilation syndrome (OHS) is increasingly common but data detailing the prevalence, outcome and long-term management, in patients admitted to the ICU, are limited. Indeed, we aimed to assess the prevalence of persistent hypercapnia in obese patients admitted to ICU and subsequent referral rate for specialist long-term management of sleep disordered breathing.
Methods A retrospective analysis of data that was prospectively entered into an electronic patient record was conducted, from May 2011 to May 2014, at a University Hospital. Obesity was defined as a body mass index (BMI) (>35 kg/m2) and hypercapnia as an arterial partial pressure of carbon dioxide (PaCO2) >6 kPa. All patients meeting both criteria were reviewed to assess whether these patients were referred to the regional sleep and ventilation unit.
Results A total of 5014 patients were ventilated in critical care of which 240 (5%) had obesity with persistent hypercapnia (age 49 ± 14 years, BMI 41.5 ± 6.7 kg/m2, PaCO2 7.5 kPa). 27% percent (65/240) were referred for assessment of sleep disordered breathing. Referred patients were more likely to have respiratory comorbidity (p < 0.001) and were more obese (ΔBMI 3.1 kg/m2, p < 0.001) but of similar age (p = 0.977) and degree of hypercapnia (p = 0.474). Patients referred for assessment of sleep disordered breathing had improved survival compared to those who were not referred (980 days v 1271 days, log rank test p = 0.004, Figure 1).
Conclusions Rates of obesity and persistent hypercapnia are high in survivors of critical illness. However, patients are frequently not referred for specialist respiratory assessment. Survival is increased in patients referred for long-term management, although this data needs to be interpreted with caution as this could be the result of referral bias and a prospective study is now required.