Comparative effects of bicarbonate, tris-(hydroxymethyl)aminomethane and dichloroacetate in newborn swine with normoxic lactic acidosis.

A total of 20 newborn piglets age 11.5 +/- 0.3 days and weighing 3.7 +/- 0.1 kg were studied under pentobarbital anesthesia. After stabilization following surgical procedures, baseline values for blood gases, base excess (BE), heart rate (HR), aortic pressure (AoP), left-ventricular contractility (LV dP/dtmax), carotid artery flow (CarF) and renal artery flow (RenF) were measured and normal lactic acid 0.2 ml/kg was infused over 1 h and the same parameters repeated. Then sodium bicarbonate (BC, n = 8), Tris-(hydroxymethyl)aminomethane (THAM, n = 6) or dichloroacetate (DCA, n = 6) were infused over 1 h. The doses of BC and THAM were calculated from the standard formula: Mmol = Base deficit x kg x 0.3. DCA was given at a dose of 300 mg/kg. Following lactic acid infusion, pH was 7.00 +/- 0.4 and BE was -20.6 +/- 1.2. Acidosis was associated with a significant (p < 0.05) increase in AoP (+18.6 +/- 7.4%) and decreases in HR (-13.9 +/- 2.7%) and RenF (-43.8 +/- 10.4%). Values of dP/dtmax and CarF were higher during acidosis in all but 3 animals. Following infusion of alkalizing agents pH and BE values were highest with BC and lowest with DCA and the differences were statistically significant (p < or = 0.05). In general, all three alkalizing agents reversed, in part or completely, the changes in cardiovascular parameters associated with acidosis so that following alkali infusion the changes were not statistically significant when compared to baseline values.(ABSTRACT TRUNCATED AT 250 WORDS)