Comparing fixed and auto adjusting continuous positive airway pressure (CPAP) amongst symptomatic Obstructive Sleep Apnoea patients - A randomised controlled trial

INTRODUCTION: Continuous Positive Airway Pressure (CPAP) is required for obstructive sleep apnoea (OSA). Thisstudy compares the efficacy between Fixed Pressure CPAP (Fixed CPAP) and Auto-adjusting Pressure (APAP) based on Apnoea Hypopnoea Index (AHI), Epworth Sleepiness Score (ESS) among patients with symptomatic OSA and to ascertain their CPAP preference.

METHODS: This is a prospective, randomised, crossover, single-blinded study conducted from February 2018 to February 2019 among adult subjects attending respiratory clinic Universiti Kebangsaan Malaysia Medical Centre (UKMMC).

RESULTS: Forty-six subjects were recruited with 27 males (58.7%). The mean age was 54 (+11) year old. The baseline median Body Mass Index (BMI) was 34.2 kg/m2 (Interquartile Range IQR: 30.8 kg/m2 -41.7 kg/m2); baseline median AHI 28.8 /hour (IQR 21.2/hour-54.0/hour); andbaseline median ESS 15 (IQR 13-16). After intervention, the median AHI was 5.0 / hour (IQR 4.2/hour-6.0/hour) at fixed CPAP arm; APAP arm was 5.5/ hour (IQR 4.2/hour-6.3/hour); p<0.01. The median ESS at fixed CPAP arm was 2 (IQR 0-3); APAP arm was 2 (IQR 1-3); p < 0.01. Those who preferred APAP were 22 subjects (47.8%) and had median optimal CPAP pressure 13.0 cmH2O (IQR 12.0 cmH2O -13.5 cmH2O); 24 subjects (52.2%) who preferred Fixed CPAP had median optimal CPAP pressure 8.0 cmH2O (IQR 6.3 cmH2O -8.7 cmH2O); p<0.01. Median baseline BMI was 37.6 kg/m2 (IQR 30.8 kg/m2 -43.0 kg/m2) for those who preferred APAP and 32.3 kg/m2 (IQR 30.8 kg/m2 - 38.4 kg/m2) for subjects preferred Fixed CPAP; p=0.03.

DISCUSSION: Fixed CPAP maybe considered as first line therapy for symptomatic moderate and severe OSA with titrated optimal CPAP pressure less than 8 cmH2O and BMI less than 32.3 kg/m2; based on subjects' preference. Baseline AHI and average daily CPAP usage was not statisticallysignificant in affecting patient preference between fixed and auto adjusting CPAP. This is the first study of its kind conducted in Malaysia.