CAFFEINE DOES NOT AFFECT CEREBRAL BLOOD FLOW (CBF) IN THE PRETERM INFANT

Abstract

Caffeine (C), used in treating idiopathic apnoe of the preterm newborn, has a presumed negative action on CBF, probably due to C-induced hyperpnea with a corresponding decrease of PaCO2, which way contribute to ischemic events like periventriailar leuconadacia (PVC). We studied changes in CBF in 25 preterm infants by determining CBF velocity (CBFV), using transcutaneous Doppler technique, before and 24 hours after start of C-medication. CBFV was quantitated by the pulsatility index and area under the velocity curve (cm/min) of the anterior cerebral armies. PaCO2, PaO2, blood pH, heart- and respiratory rate, blood pressure and hematocrit were measured simultaneously with the Doppler investigations. In 18/25 infants C-levels were determined which were all in the therapeutic range (10-20) ug/ml). A significant decrease in number of apneic spells occurred (p<.01) and the PaCO2 (mean (SD)) was lower after the start of C-medication (4.7(0.7) vs 5.3(078) kPa, p<.01). CBFV however did not alter during C-medication, In spite of lower PaCO2 values, indicating no gross changes in CBF. It may be that the decrease of PaCO2 after C-medlcation (d(SD): 0.6(0.7) kPa) was not large enough to alter CBFV. Moreover 21/25 infants had already normal PaCO2 values (PaCO2<6.0 kPa) before the start of C; it is reported that in preterm infants only marked hypercarbia (PaCO2 ≥6.7 kPa) and hypocarbia (PaCO2<2.0 kPa) cause significant changes of CBF from baseline values. It is therefore not likely that C, used in the therapeutic range, alters CBF and contributes to the pathogenesis of ischemic brain danage like PVL.