Transient hyperoxia and cerebral blood flow velocity in infants born prematurely and at full term.

Abstract

SUMMARY Little is known about the effects of hyperoxia on the cerebral circulation of human infants. Using duplex Doppler we measured the changes in cerebral blood flow velocity in a group of full term (n=15) and premature infants (n=17, median gestational age 31 weeks) in response to a transient threefold increase in oxygen tension. Measurements of blood gas tensions as well as blood pressure and cerebral blood flow velocity were made over a period of 20 minutes on three occasions for each infant; during normal oxygenation, hyperoxia, and normal oxygenation. There was a fall in cerebral blood flow velocity in 15 of the 17 premature infants with hyperoxia and the median reduction was 0-06 cm/second for every 1 kPa increase in oxygen tension. There was no significant change in either PCO2 or blood pressure during the period of hyperoxia. The cerebral blood flow velocity fell in all 15 infants born at full term during hyperoxia, but there was a simultaneous and significant reduction in PCO2 at the same time as the hyperoxia. Analysis of variance suggested that in the infants born at full term the change in carbon dioxide had most effect in the reduction of cerebral blood flow velocity, rather than the hyperoxia itself. We conclude that in premature infants, cerebral vascular resistance may be altered by a fall in cerebral blood flow velocity in the presence of hyperoxia.Hyperoxia has a consistent and predictable effect on cerebral blood flow in healthy adult brains. Little is known, however, about the effect of hyperoxia on cerebral blood flow in newborn infants, although oxygen is commonly used to treat lung disease in this population. Periods of prolonged hyperoxia cause vasoconstriction of the neonatal retinal circulation (which arises from the internal carotid artery) and so would also be expected to have a similar effect on the cerebral circulation. Whether the central nervous system of the extremely premature newborn infant is also sensitive to the effects of hyperoxia is unknown.We report the use of duplex Doppler ultrasound to study the physiological effect of extremely short periods of hyperoxia on the cerebral circulation in healthy and ill infants born prematurely and at full term. Methods

Tracheal suctioning is associated with prolonged disturbances of cerebral hemodynamics in very low birth weight infants

“…This was also expected since similar changes in PaO 2 have much smaller effects on the cerebral vasculature than changes in PaCO 2 . 34 Despite that a majority of previous studies also observed CBF increases, a few investigators reported decreases, 9,10 or brief decreases followed by increased CBF after suctioning. 15,16 One of the studies reporting CBF decreases had few patients, and the other had a majority of infants with IVH.…”

Effect of oxygen inhalation on cerebral blood flow velocity in premature neonates

“…A couple of studies have documented a fall in CBFV in premature infants with hyperoxemia (24,25). Niijima et al observed a fall in CBFV in 88% premature infants in response to a transient threefold increase in oxygen tension (24). Leahy et al, by using a modified venous occlusion plethysmography technique, observed significant decrease in CBF in premature neonates after inhalation of 100% oxygen (25).…”

Cerebral Blood Flow Velocity Changes After Bovine Natural Surfactant Instillation

“…Excessive hyperoxia can cause a decrease in CBFV in human newborn infants but not with as strong an effect as hypocarbia. 18 We adjusted the inspired oxygen concentration immediately after surfactant administration to prevent an excessively high PAO 2 . Because we obtained measurements at 5 minutes after surfactant, it is possible that we missed significant CBFV changes if they occurred.…”