Abstract

OBJECTIVES: There is no designated pressure level for continuous positive airway pressure (CPAP) and there are many factors that affect pressure level. In our study, we aimed to assess factors that affect CPAP pressure level on titration night.

MATERIAL AND METHODS: Patients who were diagnosed with obstructive sleep apnoea syndrome (OSAS) and who were recommended to use CPAP between January 2005 and June 2011 were included in the study. The files of the patients were investigated retrospectively. All the patients were diagnosed with OSAS by polysomnography (PSG) conducted on the first night and their auto-CPAP titrations were made on a second night by full-night PSG. The patients whose CPAP and BIPAP titrations made manually were excluded. The CPAP pressure level for each patient was set at the minimum pressure needed to abolish all respiratory events in the supine position and at the rapid eye movement (REM) stage.

RESULTS: Five hundred and twenty-five patients were included in the study. Three hundred and seventy (70.5%) were men and 155 (29.5%) were women. Mean age was 50.4±9.8 years, body mass index (BMI) was 32.2±5.7, Epworth Sleepiness Scale (ESS) score was 10.6±6, and CPAP pressure level was 10.5±2.1. In the first-night PSG, mean apnoea hypopnoea index (AHI) was 50.1±23.7, oxygen desaturation index (ODI) was 42.7±24.8, minimum oxygen saturation (min SpO2) was 75.6±10.9%, and periodic leg movement index (PLMI) was 19.6±21.3. No correlation was found between CPAP pressure and age or gender. A positive correlation was found with BMI and ESS score. In the first-night PSG, a positive correlation was found with AHI, AI, ODI, and PLMI, and a negative correlation with min SpO2%. In the last-night PSG, a positive correlation was found with sleep latency, full-face mask usage, and PLMI, and a negative correlation with sleep efficiency and nasal mask usage. In multivariate analysis, longer sleep latency and higher PLMI were found to be independent effective factors.

CONCLUSION: Although age and gender do not affect CPAP pressure level, higher BMI and ESS and severe OSAS require higher levels of CPAP pressure. Longer sleep latency, lower sleep efficiency, shorter REM latency, and higher PLMI and full-face mask usage on the last night also lead to higher levels of CPAP pressure.