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Three Part Question

In [adult patients with severe metabolic acidosis during prolonged cardiopulmonary resuscitation], does the [administration of sodium bicarbonate] lead to [higher sustained return of spontaneous circulation]?

Clinical Scenario

A 67-year-old male with a history of type II diabetes and hypertension presents following an out-of-hospital cardiac arrest. Bystander CPR was initiated immediately. His initial rhythm was ventricular fibrillation and ACLS protocol was followed by EMS prior to arrival. Upon arrival, he remains in refractory ventricular fibrillation. A stat venous blood gas is obtained which reveals a pH of 6.8. You consider whether sodium bicarbonate would significantly increase the chances of obtaining return of spontaneous circulation in this patient.

Search Strategy

Medline 1966-09/19 using PubMed, Cochrane Library (2019), and Embase
[(exp cardiopulmonary resuscitation OR exp cardiac arrest) AND (exp metabolic acidosis) AND (sodium bicarbonate)]. Limit to English language.

Search Outcome

26 studies were identified; two addressed the clinical question.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Kim J, et al. February 2016 Republic of Korea	599 adult patients presenting after cardiac arrest with ongoing CPR	Single-center matched case-control observational study	Return of spontaneous circulation within 20 minutes of arrival	Patients with acidosis had 2.78 times the odds of ROSC when sodium bicarbonate is administered	Observational study; significant baseline differences between two groups; unmeasured variables may affect results; neurologically intact survival not analyzed.
Ahn S, et al. April 2018 Republic of Korea	50 adult patients with out of hospital arrest	RCT	Change in acidosis (pH)	Change in pH from 6.90 to 6.99 at 20 minutes (p=0.038)	Empiric rather than weight-based bicarbonate dosing; primary endpoint is not a patient-centered outcome; likely underpowered study for their secondary outcomes.
			Secondary endpoints: ROSC, survival to hospital admission, and good neurologic outcome at 1 month	No change in sustained ROSC, survival to hospital admission, or good neurological at 1 month

Comment(s)

The routine administration of sodium bicarbonate in cardiac arrest has not been shown to improve outcomes in cardiac arrest. In fact, the generation of excess CO2 may lead to the adverse effects of inducing respiratory acidosis and causing acidosis in the cerebrospinal fluid, with subsequent cerebral edema. However, the role of sodium bicarbonate in mitigating severe metabolic acidosis is less clear. These two studies sought to answer this question, and their results are mixed. The larger study found an increase in retrun of spontaneous circulation (ROSC) after controlling for multiple confounders, and the other, smaller study found no significant change using simpler statistical methods. This limited data suggests that rates of ROSC may marginally improve with sodium bicarbonate administration in patients with severe acidosis; however, the patient-centered outcome of neurologically intact survival remains unclear.

Clinical Bottom Line

In adult patients with severe metabolic acidosis during prolonged cardiopulmonary resuscitation, the administration of sodium bicarbonate may lead to a slightly higher sustained return of spontaneous circulation; however, the effect on neurologically intact survival appears to be limited.

References

1. Kim J, Kim K, Park J, Jo YH, Lee JH, Hwang JE, Ha C, Ko YS, Jung E. Sodium bicarbonate administration during ongoing resuscitation is associated with increased return of spontaneous circulation Am J Emerg Med 2016; 34(2): 225-229
2. Ahn S, Kim YJ, Sohn CH, Seo DW, Lim KS, Donnino MW, Kim, WY. Sodium bicarbonate on severe metabolic acidosis during prolonged cardiopulmonary resuscitation: a double-blind, randomized placebo-controlled pilot study J Thorac Dis 2018;10(4): 2295-2302.