Journal of critical care
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Journal of critical care · Mar 1993
Comparative StudySodium bicarbonate versus Carbicarb in canine myocardial hypercarbic acidosis.
The objective of this study was to compare the in vivo effects of sodium bicarbonate (NaHCO3) and Carbicarb infusion on regional contractile performance and acid-base status in the setting of hypercarbic acidosis. Animals (N = 9) were anesthetized and paralyzed using sodium pentothal, halothane, and pancuronium bromide, and mechanically ventilated with an air-O2 mixture so that arterial PO2 was > or = 300 mm Hg. Following beta-adrenergic blockade, alveolar ventilation was gradually reduced over a 50-minute period to increase arterial PCO2 to 60 to 80 mm Hg. ⋯ End-diastolic length was inversely proportional to changes in stroke work, and coronary blood flow varied directly with changes in coronary venous Pco2. Myocardial O2 consumption decreased (P < .05) during Carbicarb infusion, but changes during NaHCO3 did not reach statistical significance. Our findings lend support to the hypothesis that intramyocardial pH determines myocardial function independent of CO2 production by buffer therapy.(ABSTRACT TRUNCATED AT 400 WORDS)
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Journal of critical care · Mar 1993
Oxygen kinetics during liver transplantation: the relationship between delivery and consumption.
In anesthetized humans, oxygen consumption is independent of oxygen delivery above a critical threshold. Below this critical level, lactic acid is a marker of anaerobic metabolism and tissue oxygen debt, and heralds a supply dependency of oxygen consumption. The goal of this study was to determine whether a threshold value for oxygen delivery below which oxygen consumption becomes supply dependent can be identified in patients with normal, impaired, or absent liver function. ⋯ Lactate increased in both groups during surgery, but was significantly higher in nonsurvivors (6.6 +/- 0.4 mmol/L) than in survivors (4.6 +/- 0.1 mmol/L) (P < .05). With similar changes for oxygen delivery and oxygen consumption during increased lactate levels we could not identify a clear supply dependency of oxygen consumption in survivors and nonsurvivors during liver transplantation. We conclude that the interpretation of blood lactate levels during circulatory shock can be biased due to a reduced lactate clearance in patients with impaired liver function, unrelated to the status of the relationship between oxygen delivery and consumption.(ABSTRACT TRUNCATED AT 250 WORDS)
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Journal of critical care · Mar 1993
Effect of the pericardium on systolic ventricular interdependence in the dog.
Systolic ventricular interdependence, whereby changes in left ventricular (LV) ejection alter right ventricular (RV) ejection, has been described. It is unclear, however, whether this interaction is influenced by pericardial volume constraint or by myocardial mechanical coupling. We hypothesized that if mechanical coupling were the primary factor determining systolic ventricular interdependence then it should be unaltered by the presence or absence of an intact pericardium, but affected by changes in LV end-systolic volume. ⋯ However, PSPrv increased more when the pericardium was intact (P < .05). These data suggest that LV ejection can enhance SVrv and that this interaction is not appreciably altered by volume loading or the presence of an intact pericardium. Pericardial interactions may alter PSPrv but do not affect SVrv.