Cerebral vascular resistance in premature infants
J. R. Daven, J. M. Milstein and R. D. Guthrie
The cerebral vascular bed is a low-resistance system in which continuous
forward or advancing diastolic blood flow can be demonstrated. This
advancing flow increases progressively with vasodilation and decreases or
is absent when vessels are constricted. By using the Doppler technique, an
indirect assessment of vascular resistance can be made by comparing
systolic and diastolic flow amplitudes. We examined nine premature infants
and found that respiratory acidosis alone, or hypoxia and acidosis in
combination, resulted in significant vasodilation. This effect was
reversible when arterial blood gas tensions returned to normal. The results
indicate that within a physiologic range of BPs, premature infants with
acute respiratory distress can alter their cerebral vascular resistance in
response to spontaneous changes in blood gas tensions.
