Chest
Clinical Investigations in Critical CareSodium Bicarbonate for the Treatment of Lactic Acidosis
Section snippets
Is a Low pH Bad?
Proteins, which underlie the function and structure of human cells, contain areas of both positive and negative charge and are thereby sensitive to the pH of the surrounding milieu. One can conceive of innumerable ways in which excess acid could impair protein function and, by extension, the function of the whole body. Yet it is overly simplistic to assume that the clinician's window on acid-base state, the arterial blood pH, reflects accurately the pH at a (likely more important) cellular
Can Sodium Bicarbonate Raise the pH In Vivo?
It seems straightforward that adding a base to acidic blood will raise the pH–the reality is more complex. First, bicarbonate is not one of the independent determinants of the blood pH. Rather, these include the difference between the total concentrations of strong cations and anions (the strong ion difference, [SID]); the total concentration of weak acids; and the Paco2.44 Administration of exogenous sodium bicarbonate increases the SID (which tends to raise the pH) because sodium is a strong
Does Increasing the Blood pH With Sodium Bicarbonate Have any Salutary Effects?
The most direct question to pose regarding sodium bicarbonate therapy is whether it improves the problems that prompt its use. Namely, does it correct hemodynamics, “buy time” for other interventions, or improve outcome?
In isolated rat or rabbit hearts perfused with acidic solutions, bicarbonate fails to augment ventricular contractility.11, 71 In whole animals (including various models of metabolic acidosis), the effects of bicarbonate on ventricular function are more difficult to tease out
Does Sodium Bicarbonate Have Negative Side Effects?
The most obvious side effects of sodium bicarbonate are the fluid and sodium load. This can cause hypervolemia, hyperosmolarity, and hypernatremia.82 Sodium bicarbonate given as a rapid IV bolus can cause a transient fall in mean arterial pressure and a transient rise in intracranial pressure83 that is probably related to its hypertonicity, and this is alleviated when given as a slow IV infusion. Sodium bicarbonate has been shown in three studies to lower Pao2 from 5 to 15 mm Hg in both
Other Alkalinizing Therapies: Carbicarb, Dichloroacetate, Tris-Hydroxymethyl Aminomethane, and Dialysis
Carbicarb is an equimolar mixture of sodium carbonate and sodium bicarbonate. Compared with sodium bicarbonate, Carbicarb raises the SID (thereby the pH) far more45, 4849, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62 and boosts the Pco2 far less48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64 when given IV to animals with metabolic acidosis. To the extent that the failure of sodium bicarbonate to effect hemodynamic improvement is caused by the generation of carbon
Conclusion
Sodium bicarbonate is clearly effective in raising the arterial pH in critically ill patients with lactic acidosis. The impact on intracellular pH is unknown in such patients, but extrapolation from extensive animal studies suggests that it is negative. Despite the correction of arterial acidemia, sodium bicarbonate, like DCA, has no favorable cardiovascular effects, even for patients with severe acidemia and receiving continuous infusions of catecholamines. Although hemodynamic improvement is
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