Sodium bicarbonate and intracellular acidosis: myth or reality?

Sodium bicarbonate administration during ongoing resuscitation is associated with increased return of spontaneous circulation

PURPOSE

Sodium bicarbonate is frequently used for patients unresponsive to cardiopulmonary resuscitation (CPR). Its use may be associated with longer resuscitation duration as well as more severe metabolic acidosis. We applied a new analytical method based on a matched case-control study design to control for the potential confounders.

BASIC PROCEDURES

Out-of-hospital cardiac arrest patients resuscitated in an emergency department for at least 20 minutes, unless there was any return of spontaneous circulation (ROSC) within the time frame, were analyzed. Patients without ROSC for 20 minutes of CPR were matched to those with ROSC based on initial bicarbonate level categorized using cutoff points of 10, 15, 20, 25, and 30 mEq/L, and their observation durations were trimmed to match their pairs. The association between sodium bicarbonate and ROSC was examined using conditional logistic regression analysis.

MAIN FINDINGS

Two matched groups, one with ROSC and the other without (both n = 258), were generated. Sodium bicarbonate administration and its total cumulative dose were significantly associated with an increased ROSC, with odds ratios for ROSC of 1.86 (95% confidence interval [CI], 1.09-3.16; P = .022) and 1.18 (per 20 mEq; 95% CI, 1.04-1.33; P = .008), respectively. The positive associations remained unchanged after multivariable adjustment, with odds ratios for ROSC of 2.49 (95% CI, 1.33-4.65; P = .004) and 1.27 (95% CI, 1.11-1.47; P = .001), respectively.

PRINCIPAL CONCLUSION

Sodium bicarbonate administration during CPR in emergency department was associated with increased ROSC.

The response of the vascular beds to sodium bicarbonate in patients during normothermic bypass

OBJECTIVES

Cardiopulmonary bypass (CPB) provides a unique circumstance to study the effects of drugs on the systemic vasculature. Thus, this study was designed to evaluate the effects of sodium bicarbonate on the systemic circulation during CPB in humans.

DESIGN

Randomized, double-blind study.

SETTING

Tertiary care university hospital.

PARTICIPANTS

Patients presenting for coronary artery bypass graft surgery with CPB.

INTERVENTIONS

In this double-blind study, 22 consecutive adult patients of both sexes undergoing cardiac surgery were randomized into 2 groups. After establishing CPB and cardioplegia, patients in group 1 (n = 11) received saline (0.9%) (1.2 mL/kg), and group 2 received sodium bicarbonate (SB) (7%) (1.2 mL/kg). The blood level in the cardiotomy reservoir, pump flow, and mean arterial pressure were measured for 25 minutes.

MEASUREMENTS AND MAIN RESULTS

The SB-treated patients (group 2) showed significantly greater (p < 0.05) decreases in cardiotomy reservoir blood volume (336 +/- 186 mL) than the saline-treated (140 +/- 97 mL) patients. The mean arterial pressure in group 2 patients significantly (p < 0.05) increased (from 49 +/- 11.9 to 65 +/- 5.3 mmHg) more than in the saline group (from 50 +/- 6.8 to 57 +/- 9.2 mmHg) after 20 minutes. The decrease in reservoir volume significantly (p < 0.05) and inversely correlated (r = -0.61) with the acidotic state of the patients before SB.

CONCLUSIONS

This study found a biphasic response to SB on the systemic circulation during CPB. Early dilation of venous capacitance vessels occurred followed by arteriolar constriction over the 20-minute study interval.

Lactic acidosis: from sour milk to septic shock

Lactic acidosis is frequently encountered in the intensive care unit. It occurs when there is an imbalance between production and clearance of lactate. Although lactic acidosis is often associated with a high anion gap and is generally defined as a lactate level >5 mmol/L and a serum pH <7.35, the presence of hypoalbuminemia may mask the anion gap and concomitant alkalosis may raise the pH. The causes of lactic acidosis are traditionally divided into impaired tissue oxygenation (Type A) and disorders in which tissue oxygenation is maintained (Type B). Lactate level is often used as a prognostic indicator and may be predictive of a favorable outcome if it normalizes within 48 hours. The routine measurement of serum lactate, however, should not determine therapeutic interventions. Unfortunately, treatment options remain limited and should be aimed at discontinuation of any offending drugs, treatment of the underlying pathology, and maintenance of organ perfusion. The mainstay of therapy of lactic acidosis remains prevention.

Uses and abuses of sodium bicarbonate in the neonatal intensive care unit

Despite the lack of evidence for its effectiveness in the treatment of acid-base disturbances in critically ill patients of all ages, and despite several lines of evidence that indicate it might be dangerous, bicarbonate therapy is used routinely in many neonatal intensive care units. The justification for the persistent use of this controversial therapy comes from a variety of sources, many based more in philosophy than in science. Clinicians contemplating the use of bicarbonate therapy should consider what they expect the intervention to accomplish and what evidence exists that their therapeutic objective will be met. Without rigorous scientific support for this therapy, it should be considered of unproven value and, therefore, experimental.