SLEEP-APNEA IN PATIENTS WITH QUADRIPLEGIA

Background - This study was undertaken to establish the prevalence of, and the factors contributing towards, sleep disordered breathing in p atients with quadriplegia. Methods - Forty representative quadriplegic patients (time since injury >6 months, injury level C8 and above, Fra nkel category A, B, or C; mean (SE) age 35.0 (1.7) years) had home sle ep studies in which EEG, EGG, submental EMG, body movement, nasal airf low, respiratory effort, and pulse oximetry (SpO(2)) were measured. Pa tients reporting post traumatic amnesia of >24 hours, drug or alcohol abuse or other major medical illness were excluded from the study. A q uestionnaire on medications and sleep was administered and supine bloo d pressure, awake SpO(2), spirometric values, height, and neck circumf erence were measured.Results - A pattern of sustained hypoventilation was not observed in any of the patients. Sleep apnoeas and hypopnoeas were, however, common. Eleven patients (27.5%) had a respiratory distu rbance index (RDI, apnoeas plus hypopnoeas per hour of sleep) of great er than or equal to 15, with nadir SpO(2) ranging from 49% to 95%. Twe lve of the 40 (30%) had an apnoea index (AI) of greater than or equal to 5 and, of these, nine (75%) had predominantly obstructive apnoeas - that is, >80% of apnoeas were obstructive or mixed. This represents a prevalence of sleep disordered breathing more than twice that observe d in normal populations. For the study population RDI correlated with systolic and diastolic blood pressure and neck circumference. RDI was higher in patients who slept supine compared with those in other postu res. Daytime sleepiness was a common complaint in the study population and sleep architecture was considerably disturbed with decreased REM sleep and increased stage 1 non-REM sleep. Conclusions - Sleep disorde red breathing is common in quadriplegic patients and sleep disturbance is significant. The predominant type of apnoea is obstructive. As wit h non-quadriplegic patients with sleep apnoea, sleep disordered breath ing in quadriplegics is associated with increased neck circumference a nd the supine sleep posture.