Abstract
It has been suggested that hypocapnia (which normally produces cerebral vasoconstriction) may be a cause of periventricular leukomalacia. This study tested the hypothesis that hypocapnia superimposed upon hypotension produces a further reduction in cerebral blood flow velocity (CBFV).
In 12 newborn piglets, CBFV was measured continuously through an artificial fontanelle. Hypotension was induced by removing 30 ml/kg of blood over 30 minutes. Increasing the ventilator rate from 20 to 100/m min reduced the average pCO2 from above 5.0 to below 2.0 kPa. When mean arterial pressure (MAP) was held steady at 45 mm Hg or above, hypocapnia produced a signficant drop in CBFV but, in all the piglets with a steady MAP below 38 mm Hg, hypocapnia failed to change CBFV. Jugular vein or sagital sinus blood showed no increase in hypoxanthine during hypocapnia. Hyperventilation (without haemorrhage) produced a signficant drop in MAP, preventable by infusing colloid.
Hypocapnia itself does not further reduce CBFV in the hypotensive piglet. However, the pressure effect of hyperventilation may significantly impair the cerebral circulation.
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Whitelaw, A., Karlsen, B., Haaland, K. et al. 10 CEREBROVASCULAR RESPONSE TO HYPOCAPNIA IN HYPOTENSIVE NEWBORN PIGLETS. Pediatr Res 28, 278 (1990). https://doi.org/10.1203/00006450-199009000-00034
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DOI: https://doi.org/10.1203/00006450-199009000-00034