Cerebrovascular hemodynamics during and after recovery from acute asphyxia in the newborn dog.

Cerebrovascular volume and transmural pressure loads accompanying acute increases in cerebral blood flow are implicated in the pathogenesis of periventricular-intraventricular hemorrhage in preterm infants. An acute increase in cerebral blood flow would be expected during acute recovery from asphyxia. Therefore, cerebrovascular hemodynamics, including flow (microspheres), were studied during and after acute recovery from asphyxia in seven newborn dogs in order to study the determinants of these volume and pressure loads. During the acute recovery phase, cerebral hemispheric blood flow was 69.6 +/- 10 ml/100 g/min (mean +/- SEM) representing a 250% increase from baseline values of 19.9 +/- 1.8 ml/100 g/min (p less than 0.005), while combined cerebellar-brainstem flow was 204.3 +/- 19.3 ml/100 g/min representing a 536% increase from baseline values of 32.0 +/- 1.5 ml/100 g/min (p less than 0.005). Blood flow to both areas had returned to baseline levels 20 min after the onset of recovery. Associated with this cerebral hyperemia was an acute increase in mean arterial pressure from 21.3 +/- 4.5 mm Hg at end asphyxia to 69.5 +/- 6.0 mm Hg at peak recovery (p less than 0.01), and parallel acute increases in sagittal sinus pressure (from 4.0 +/- 0.4 to 14.6 +/- 1.9 mm Hg, p less than 0.01) and cerebrospinal fluid pressure (from 3.8 +/- 0.4 to 14.3 +/- 1.9 mm Hg, p less than 0.01). Central venous pressure fell from 4.3 +/- 0.6 mm Hg at end asphyxia to 1.6 +/- 0.5 mm Hg, and thus is not a determinant of the elevation in sagittal sinus pressure.(ABSTRACT TRUNCATED AT 250 WORDS)