Cardiovascular responses to nonrespiratory and respiratory arousals in a porcine model

1 Charles A. Dana Research Institute and Harvard-Thorndike Laboratory of Beth Israel Deaconess Medical Center and Harvard Center on Sleep Neurobiology and Sleep Apnea, 2 Beth Israel Deaconess Medical Center Sleep Disorders Center, 3 Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston 02215; and 4 Harvard Medical School and Veterans Affairs Medical Center, Brockton/West Roxbury Division, West Roxbury, Massachusetts 02132 Spontaneous and provoked nonrespiratory arousals can be accompanied by a patterned hemodynamic response. To investigate whether a patterned response is also elicited by respiratory arousals, we compared nonrespiratory arousals (NRA) to respiratory arousals (RA) induced by airway occlusion during non-rapid eye movement sleep. We monitored mean arterial blood pressure (MAP), heart rate, iliac and renal blood flow, and sleep stage in 7 pigs during natural sleep. Iliac and renal vascular resistance were calculated. Airway occlusions were obtained by manually inflating a chronically implanted tracheal balloon during sleep. The balloon was quickly deflated as soon as electroencephalogram arousal occurred. As previously reported, NRA generally elicited iliac vasodilation, renal vasoconstriction, little change in MAP, and tachycardia. In contrast, RA generally elicited iliac and renal vasoconstriction, an increase in MAP and tachycardia. The frequent occurrence of iliac vasoconstriction and arterial pressure elevation following RA but not NRA suggests that sleep state change alone does not account for the hemodynamic response to airway occlusion during sleep. sleep apnea; swine; regional blood flow; vascular resistance; blood pressure