Effect of hyperventilation on cerebrospinal fluid acid-base variables after blood alkalosis

AIM: To investigate the effect of hyperventilationon cerebrospinal fluid (CSF) after blood alkalosis. METHODS: Two groups of dogs were studied: ①Metabolic alkalosis and hyperventilation (group Ⅰ, n= 5). ②metabolic alkalosis and normoventilation (group Ⅱ, n= 5). Acute metabolicalkalosis were induced by the intravenous infusion of 50 g/LNaHCO3 in two groups (50 mmol/kg),arterial blood [HCO-3]a was elevated (30. o± 2. 5) mmol/L in one hour. Group Ⅰwas hyperventilation, but group Ⅱ was spontaneous. Thevariables of acid-base in the arterial blood and CSF weremeasured in two groups of dogs in 20, 40, 60 min after hyperventilation. RESULTS: Blood PH shifted in alkalosis directionin both groups after NaHCO3. CSF PH shifted in the same direction as that of blood PH in the group Ⅰ treated with hyperventilation. In the group Ⅱ CSF PH shifted in the direction opposite from that of blood, i. e. to the side. CONCLUSION: The results suggest that the intravenous NaHCO3 infusion can induce the CSF PH shift to the acidoid side in response to acute arterial blood alkalinization, but it will beprevented by using controlled hyperventilation in anesthetineddogs.