HEMODYNAMIC EFFECTS OF METABOLIC ACIDOSIS IN CHOLERA: IMPLICATIONS FOR FLUID REPLETION IN SEVERE BURNS

To summarize the train of events in cholera as we visualize them: Severe dehydration results in hypovolemia, and cardiac output and all pressures fall. Acidosis causes peripheral venous constriction, thereby reducing the capacity of the venous reservoirs and maintaining, to some extent, venous return to the heart. Fluid administration without correction of acidosis favors a disproportionate venous return to the heart and pulmonary circulation. Alleviation of acidosis during fluid replacement results in a more even distribution of the circulating blood volume and reduces the possibility of engorgement of the pulmonary bed. This mechanism may also explain the occasional appearance of pulmonary congestion in patients with severe burns and metabolic acidosis. Fluid therapy without correction of acidosis in such patients may also favor a disproportionate venous return to the heart and pulmonary circulation. Treatment of the acidosis may be expected to reduce, in these patients as well, the possibility of pulmonary engorgement. In conclusion, these data indicate that the blood pH affects the distribution of the circulating blood volume and thereby influences the volume of blood returning to the heart, and through it, the central blood volume, ventricular filling pressures and cardiac output. We suggest that the site of action is in the peripheral venous bed.