PT  - JOURNAL ARTICLE
AU  - S Mandal
AU  - E S Suh
AU  - E Boleat
AU  - W Asher
AU  - M Kamalanathan
AU  - K Lee
AU  - A Douiri
AU  - P B Murphy
AU  - J Steier
AU  - N Hart
TI  - A cohort study to identify simple clinical tests for chronic respiratory failure in obese patients with sleep-disordered breathing
AID  - 10.1136/bmjresp-2014-000022
DP  - 2014 Apr 01
TA  - BMJ Open Respiratory Research
PG  - e000022
VI  - 1
IP  - 1
4099  - http://bmjopenrespres.bmj.com/content/1/1/e000022.short
4100  - http://bmjopenrespres.bmj.com/content/1/1/e000022.full
SO  - BMJ Open Resp Res2014 Apr 01; 1
AB  - Background Chronic respiratory failure complicating sleep-disordered breathing in obese patients has important adverse clinical implications in terms of morbidity, mortality and healthcare utilisation. Screening strategies are essential to identify obese patients with chronic respiratory failure. Method Prospective data were collected from patients with obesity-related sleep-disordered breathing admitted for respiratory assessment at a UK national sleep and ventilation centre. Hypercapnia was defined as an arterial partial pressure of carbon dioxide of >6kPa. Results 245 obese patients (56±13 years) with a body mass index of 48±12 kg/m2, forced vital capacity (FVC) of 2.1±1.1 L, daytime oximetry (SpO2) of 91±6% and abnormal overnight oximetry were included in the analysis. Receiver operator curve analysis for the whole group showed that an FVC ≤3 L had a sensitivity of 90% and a specificity of 41% in predicting hypercapnia, and an SpO2 ≤95% had a sensitivity of 83% and a specificity of 63% in predicting hypercapnia. Gender differences were observed and receiver operator curve analysis demonstrated ‘cut-offs’ for (1) SpO2 of ≤95% for men and ≤93% for women and (2) FVC of ≤3.5 L for men and ≤2.3 L for women, in predicting hypercapnia. Conclusions The measurement of FVC and clinic SpO2 in obese patients with abnormal overnight limited respiratory studies predicted hypercapnia. This may have clinical utility in stratifying patients attending sleep clinics.