Different Hypothermic Acid-Base Regulatory Strategies

Table 5.2	Different Hypothermic Acid-Base Regulatory Strategies
Strategy	Aim	Total CO₂ Content	pH and PaCO₂ Maintenance	Intracellular State	-Imidazole and Buffering	Enzyme Structure and Function	Cerebral Blood Flow and Coupling	Effect on Ischemic Tissue
pH-stat	Constant pH	Increases	Normal corrected values	Acidotic (excess H⁺)	Excess (+) charge	Altered and activity decreased	Flow close to normothermic	? Lessens hypothermic protection
pH-stat	Constant pH	Increases	Normal corrected values	Acidotic (excess H⁺)	Buffering decreased		? Flow and metabolism uncoupled
-Stat	Constant OH^-/H⁺	Constant	Normal uncorrected values	Neutral (H^- = OH^-)	Constant net charge	Normal and activity maximal	Flow decreases (appropriate)	? Allows full hypothermic protection
-Stat	Constant OH^-/H⁺	Constant	Normal uncorrected values	Neutral (H^- = OH^-)	Buffering constant		? Flow and metabolism coupled

?, questionable.

From

TinkerJH, ed. Cardiopulmonary Bypass: Current Concepts and Controversies. Philadelphia, PA: JB Lippincott; 1989:16