Abstract
A reciprical relationship exists between CBF and arterial O2 content (CaO2) during hypoxic hypoxia. Prolonged hypoxia may be complicated by metabolic acidosis further decreasing CaO2. To investigate if NaHCO3 lowers CBF by increasing pH and CaO2 CBF (microspheres), osmolarity, and arteriovenous differences of O2 content and blood gases were obtained in 14 ventilated piglets. Measurements were obtained during control (C), prolonged isocapnic hypoxia (50 min) to produce metabolic acidosis (H+A), and following infusion of saline (Grl, n=6) or 2mEq/kg NaHCO3 (Gr2, n=8) during hypoxia. At C pH was 7.44±.01(X±SE) in Grl and 7.41±.01 in Gr2. H+A resulted in similar reductions in pH (Grl=7.21±.02 and Gr2=7.21±.03), but differences occurred after the infusions, (Grl=7.15±.03 vs. Gr2=7.30±.03, p<.05). In each Gr CaO2 paralleled pH but did not differ between Gr. CBF (ml/min·100g) in Grl was 120±17 at C, increased to 287±60* during H+A and 259±31* during saline. Similarly, CBF rose in Gr2 from C of 116±12 to 251±23* during H+A, and 221±34* with NaHCO3. Although cerebral O2 delivery, extraction, and uptake changed (due to the extent of CaO2 reduction), both Gr were comparable. No changes in osmolarity occurred. It appears that the magnitude of change in pH induced by 2 mEq/kg NaHCO3 does not alter CBF. It is speculated that even larger increases in pH produced by NaHCO3 may not affect CBF due to changes in O2 affinity. (*p<.05 vs. control).
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Laptook, A. EFFECTS OF NaHCO3 ON CEREBRAL BLOOD FLOW (CBF) DURING HYPOXIA AND ACIDOSIS IN NEWBORN PIGLETS. Pediatr Res 18 (Suppl 4), 331 (1984). https://doi.org/10.1203/00006450-198404001-01431
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DOI: https://doi.org/10.1203/00006450-198404001-01431