PATTERNED CARDIOVASCULAR-RESPONSES TO SLEEP AND NONRESPIRATORY AROUSALS IN A PORCINE MODEL

Patients with obstructive sleep apnea experience marked cardiovascular changes with apnea termination. Based on this observation, we hypothe sized that sudden sleep disruption is accompanied by a specific, patte rned hemodynamic response, similar to the cardiovascular defense react ion. To test this hypothesis, we recorded mean arterial blood pressure , heart rate, iliac blood flow and vascular resistance, and renal bloo d flow and vascular resistance in five pigs instrumented with chronic sleep electrodes. Cardiovascular parameters were recorded during quiet wakefulness, during non-rapid-eye-movement and rapid-eye-movement sle ep, and during spontaneous and induced arousals. Iliac vasodilation (i liac vascular resistance decreased by - 29.6 +/- 4.1% of baseline) ass ociated with renal vasoconstriction (renal vascular resistance increas ed by 10.3 +/- 4.0%), tachycardia (heart rate increase: + 23.8 +/- 3.1 %), and minimal changes in mean arterial blood pressure were the most common pattern of arousal response, but other hemodynamic patterns wer e observed. Similar findings were obtained in rapid-eye-movement sleep and for acoustic and tactile arousals. In conclusion, spontaneous and induced arousals from sleep may be associated with simultaneous visce ral vasoconstriction and hindlimb vasodilation, but the response is va riable.