Evaluation of obstructive sleep apnoea in Singapore using computerised polygraphic monitoring

There is no information of the prevalence and severity of obstructive sleep apnoea (OSA) in Asian snorers. One reason is the complexity and cost of a full polysomnographic recording. We have studied 37 snorers using an ambulatory recording system (Vitalog CA). Overnight recordings for seven hours were made of: 1) Respiratory pattern using respiratory inductance plethysmography; 2) Heart rate from the electrocardiograph (ECG); 3) Body position; 4) Body movements; 5) Oxygen saturation using finger-probe oximetry. The data were stored and analysed and scored using a dedicated microcomputer. Twenty-eight patients had OSA based on polygraphic criteria. The most consistent clinical findings in these patients were daytime somnolence and short thick necks. Respiratory events, oximetry and arousals during sleep showed a graded response according to the severity of excessive daytime somnolence. We conclude that OSA may not be uncommon in Asian patients and that the clinical severity can be confirmed by simplified polygraphic recordings using microcomputer analysis.