HEMODYNAMIC-CHANGES ASSOCIATED WITH OBSTRUCTIVE SLEEP-APNEA FOLLOWED BY AROUSAL IN A PORCINE MODEL

To study the effects of airway obstruction (AWO) and arousal on corona ry blood flow, mean arterial pressure (MAP), and heart rate, pigs were chronically instrumented with arterial catheters, Doppler flow probes on the left circumflex coronary artery, and electrodes for determinat ion of sleep stages. A modified tracheostomy tube was placed in the tr achea to obstruct the upper airway during sleep sessions. In control s tudies during non-rapid-eye-movement (NREM) sleep, MAP was 84 +/- 2 mm Hg before AWO and increased by 5 +/- 2 mmHg on arousal. MAP was lower during rapid-eye-movement (REM) sleep (62 +/- 2 mmHg), and the increas e on arousal was fourfold greater (22 +/- 2 mmHg). Heart rate was simi lar in both sleep stages (NREM: 120 +/- 4 beats/min; REM: 124 +/- 5 be ats/min) and increased significantly on arousal (NREM: 12 +/- 2 beats/ min; REM: 18 +/- 1 beats/min). Coronary blood flow was similar during both stages (NREM: 43 +/- 4 ml/min; REM: 46 +/- 8 ml/min) and increase d by 12-15% on arousal. Coronary vascular resistance index increased s ignificantly by 24% on arousal from AWO during REM sleep. All increase s and decreases were significant at P < 0.05. Receptor blockade studie s were performed to assess a-adrenergic receptor involvement.