Sodium bicarbonate versus Carbicarb in canine myocardial hypercarbic acidosis

Effect of Intravenously Administered Crystalloid Solutions on Acid-Base Balance in Domestic Animals

Intravenous fluid therapy can alter plasma acid-base balance. The Stewart approach to acid-base balance is uniquely suited to identify and quantify the effects of the cationic and anionic constituents of crystalloid solutions on plasma pH. The plasma strong ion difference (SID) and weak acid concentrations are similar to those of the administered fluid, more so at higher administration rates and with larger volumes. A crystalloid's in vivo effects on plasma pH are described by 3 general rules: SID > [HCO3-] increases plasma pH (alkalosis); SID < [HCO3-] decreases plasma pH (alkalosis); and SID = [HCO3-] yields no change in plasma pH. The in vitro pH of commercially prepared crystalloid solutions has little to no effect on plasma pH because of their low titratable acidity. Appreciation of IV fluid composition and an understanding of basic physicochemical principles provide therapeutically valuable insights about how and why fluid therapy can produce and correct alterations of plasma acid-base equilibrium. The ideal balanced crystalloid should (1) contain species-specific concentrations of key electrolytes (Na+ , Cl- , K+ , Ca++ , Mg++ ), particularly Na+ and Cl- ; (2) maintain or normalize acid-base balance (provide an appropriate SID); and (3) be isosmotic and isotonic (not induce inappropriate fluid shifts) with normal plasma.

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.

Hemodynamic consequences of severe lactic acidosis in shock states: from bench to bedside

Lactic acidosis is a very common biological issue for shock patients. Experimental data clearly demonstrate that metabolic acidosis, including lactic acidosis, participates in the reduction of cardiac contractility and in the vascular hyporesponsiveness to vasopressors through various mechanisms. However, the contributions of each mechanism responsible for these deleterious effects have not been fully determined and their respective consequences on organ failure are still poorly defined, particularly in humans. Despite some convincing experimental data, no clinical trial has established the level at which pH becomes deleterious for hemodynamics. Consequently, the essential treatment for lactic acidosis in shock patients is to correct the cause. It is unknown, however, whether symptomatic pH correction is beneficial in shock patients. The latest Surviving Sepsis Campaign guidelines recommend against the use of buffer therapy with pH ≥7.15 and issue no recommendation for pH levels <7.15. Furthermore, based on strong experimental and clinical evidence, sodium bicarbonate infusion alone is not recommended for restoring pH. Indeed, bicarbonate induces carbon dioxide generation and hypocalcemia, both cardiovascular depressant factors. This review addresses the principal hemodynamic consequences of shock-associated lactic acidosis. Despite the lack of formal evidence, this review also highlights the various adapted supportive therapy options that could be putatively added to causal treatment in attempting to reverse the hemodynamic consequences of shock-associated lactic acidosis.

Comparison of sodium bicarbonate and carbicarb for the treatment of metabolic acidosis in newborn calves

Carbicarb (an equimolar mixture of sodium bicarbonate and sodium carbonate) was compared with sodium bicarbonate alone for the treatment of acidosis in newborn calves: 25 of 49 calves with a blood pH at birth of less than 7-2 and a base deficit of less than -3 mmol/litre were treated intravenously with sodium bicarbonate and 24 were treated with carbicarb. The doses were calculated on the basis of the base deficit in a blood sample taken 10 minutes after birth, and further blood samples were taken immediately after the treatment and 30 and 60 minutes after the treatment for the determination of acid-base status, blood gases and haematological and biochemical variables. Both treatments resulted in a significant increase in blood pH, but there was no difference between them. The mean (sd) blood pH before treatment was 7.09 (0.02) and after treatment it was 7.28 (0.01). There was no increase in the partial pressure of carbon dioxide after treatment with either sodium bicarbonate or carbicarb. Both treatments were associated with an increase in sodium concentration and decreases in the total erythrocyte count, haematocrit and haemoglobin concentration.

Does bicarbonate therapy improve the management of severe diabetic ketoacidosis?

OBJECTIVE

The use of bicarbonates in the treatment of severe diabetic ketoacidosis remains controversial, especially regarding the benefit/risk ratio. The aim of this study was to assess the efficacy of bicarbonate therapy during severe diabetic ketoacidosis (pH <7.10).

DESIGN

Retrospective study.

SETTING

The emergency unit of a teaching hospital.

PATIENTS

The records of 39 patients consecutively admitted for severe diabetic ketoacidosis were analyzed (pH <7.10). The patients were divided into two groups: group 1 (n = 24; patients with bicarbonate treatment) and group 2 (n = 15; patients without bicarbonate treatment).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We compared two groups of patients presenting with severe diabetic ketoacidosis (pH values between 6.83 and 7.08) treated with or without bicarbonate. A group of 24 patients received 120+/-40 mmol sodium bicarbonate. The two groups were similar at admission with regard to clinical and biological parameters. No difference could be demonstrated between the two groups concerning the clinical parameters or the normalization time of biochemical parameters. If the number of patients with hypokalemia was comparable between the two groups, the potassium supply was significantly more important in group 1 compared with group 2 (366+/-74 mmol/L vs. 188+/-109 mmol/L, respectively; p < .001).

CONCLUSIONS

Data from the literature and this study are not in favor of the use of bicarbonate in the treatment of diabetic ketoacidosis with pH values between 6.90 and 7.10.

Postinjury multiple organ failure: a bimodal phenomenon

To better define the epidemiology of postinjury multiple organ failure (MOF), we prospectively evaluated 457 high-risk trauma patients who survived more than 48 hours. Overall, 70 (15%) developed MOF. In 27 (39%) patients, the occurrence was early, while in 43 (61%) patients the presentation was delayed. At presentation, early MOF had more cardiac dysfunction, while late MOF had greater hepatic failure. Indices of shock were more critical risk factors for early MOF, while advanced age was more important for late MOF. While early and late MOF had a similar high incidence of major infections, these appeared to be more important in precipitating late MOF. Finally, while mortality is similar, early MOF patients appear to succumb faster. In conclusion, postinjury MOF remains a significant challenge and appears to present in at least two patterns (i.e., early versus late). Better understanding of the relative roles of the dysfunctional inflammation and infections in early MOF versus late MOF may facilitate the development of new strategies for the prevention and treatment of morbid syndrome.

Mechanisms of myocardial depression after bolus injection of sodium bicarbonate

PURPOSE

The classic model for the effects of NaHCO3 on myocardial function predicts transient myocardial depression after an intravenous bolus of sodium bicarbonate in association with myocardial acidosis.

METHODS

Five anesthetized, paralyzed, and ventilated dogs underwent midline sternotomy. Myocardial global function was assessed by cardiac output, left ventricular (LV) dp/dt, LV end-systolic, and LV end-diastolic pressures. Regional myocardial function assessed by measuring the LV regional end-systolic, LV end-diastolic lengths, and LAD coronary blood flow. Coronary sinus, intramyocardial and arterial pH were measured as was free serum Ca++. Animals were made acidemia by infusion of 0.3 N HCl and then given a bolus of sodium bicarbonate. This produced transient depression followed by recovery of myocardial function.

RESULTS

During the depression phase there was no significant decrease in interstitial pH or an increase in A-VCO2 difference as predicted by the current model. However, there was a significant decrease in the serum free Ca++ that coincided with myocardial depression.

CONCLUSION

We could not confirm the predictions of the classic model and hypothesize that myocardial depression may be caused by decreased availability of free Ca++ of decreased Ca++ flux rather than intracellular acidosis.