Circadian Variations of Blood Pressure in Patients With Sequelae of Carbon Monoxide Poisoning

Abstract

It has been shown that carbon monoxide poisoning causes necrosis of the globus pallidum and the cerebral cortex, and a diffuse demyelination of the cerebral subcortical white matter, resulting in the impairment of the higher brain functions manifested as memory disturbances, apraxia, and agnosia. The purpose of the present study was to determine the effects of the lesions in the brain caused by carbon monoxide poisoning on the circadian changes in blood pressure and pulse rate. We measured the ambulatory blood pressure in 15 male patients with the sequelae of acute carbon monoxide poisoning and 16 age- and sex-matched controls. Using either brain computed tomography or brain magnetic resonance imaging, we determined that seven patients had lesions in the globus pallidum bilaterally, four had lesions in the parietotemporooccipital lobe bilaterally, and five had multiple deep white matter lesions. Circadian variations of blood pressure and pulse rate did not show any significant differences in either group. The average 24-h blood pressures were 120.8 +/- 2.2 (systolic)/74.1 +/- 1.5 mm Hg (diastolic) in the patients and 117.4 +/- 2.7/74.5 +/- 2.1 mm Hg in the controls. The daytime (6:00 to 21:00) and nighttime (21:00 to 6:00) blood pressures were 127.3 +/- 2.3/78.0 +/- 1.5 mm Hg and 109.7 +/- 2.4/67.4 +/- 1.7 mm Hg in the patients, and 121.6 +/- 2.9/77.5 +/- 2.2 mm Hg and 110.0 +/- 2.7/69.3 +/- 1.8 mm Hg in the controls, respectively. Furthermore, there were no differences in cardiovascular and plasma catecholamine responses induced by either a head-up tilt or a cold pressor test between the two groups. It is concluded that diffuse or multiple lesions in bilateral cerebral hemispheres caused by carbon monoxide poisoning per se do not affect the circadian changes in blood pressure and pulse rate observed in normotensive subjects.