The Janus faces of bicarbonate therapy in the ICU: not sure!

Effect of early clinical management on metabolic acidemia in neonates with hypoxic-ischemic encephalopathy

OBJECTIVE

To determine the safety and effectiveness of sodium bicarbonate administration in the management of metabolic acidemia and short-term outcomes in neonates with hypoxic-ischemic encephalopathy (HIE).

STUDY DESIGN

Retrospective cohort study of neonates born at ≥35 weeks of gestation and receiving therapeutic hypothermia. Demographics, pH, lactate, base deficit, treatment, MRI findings, seizure incidence, death prior to discharge were collected.

RESULTS

There was higher mortality (p = 0.010) and injury on MRI (p = 0.008)-primarily deep gray matter (p < 0.001) and cortical injury (p = 0.003)-in the bicarbonate group compared to controls in univariate analysis. The combined outcome of death or abnormal MRI was not significantly associated (OR 1.97, 95% CI 0.80-4.87, p = 0.141) with bicarbonate administration when adjusting for sex, 5-minute Apgar, and initial base deficit.

CONCLUSION

This study demonstrated association between bicarbonate use after HIE and negative short-term outcomes. Future prospective trials could overcome the treatment bias limitation demonstrated in this retrospective study.

Metabolic Acidosis in Children: A Literature Review

Metabolic acidosis is characterised by a primary decrease in the serum bicarbonate concentration, a secondary decrease in the arterial partial pressure of CO­2, and a reduction in blood pH. Metabolic acidosis, acute or chronic, may have deleterious effects on cellular function and cause increased morbidity and mortality. A systematic review of the available literature was performed to identify data on the prevalence, manifestations, cause, outcomes, and treatment of metabolic acidosis in children. Online databases (Ovid Medline, Embase, and PubMed), commercial search engines (including Google), and chapters on metabolic acidosis in the standard textbooks of paediatrics and medicine were reviewed. Systematic approach to acute metabolic acidosis starts with proper history taking and examination. This is followed by assessment of acid-base parameters, including pH, partial pressure of CO2, and bicarbonate concentration in arterial blood. Blood gas is needed to differentiate primary metabolic acidosis from compensated respiratory alkalosis. Once the diagnosis of a metabolic acidosis has been confirmed, serum electrolyte values are used to determine the serum anion gap. The various causes of increased and normal anion gap metabolic acidosis have been discussed in the article. The main aim of treatment in metabolic acidosis is to reverse the primary pathophysiology. In acute metabolic acidosis, sodium bicarbonate therapy is not beneficial due to potential complications and is reserved for specific situations. Base therapy is used in chronic metabolic acidosis where it ameliorates many of its untoward effects. Other modalities of treatment of metabolic acidosis include peritoneal or haemodialysis and tris-hydroxymethyl aminomethane.

Sodium Bicarbonate in Different Critically Ill Conditions: From Physiology to Clinical Practice

Intravenous sodium bicarbonate is commonly used in several critically ill conditions for the management of acute acidemia independently of the etiology, and for the prevention of acute kidney injury, although this is still controversial from a physiologic point of view.

Sodium bicarbonate in 5% dextrose: can clinicians tell the difference?

BACKGROUND

Due to the lack of double-blind randomised controlled trials, the true effect of intravenous sodium bicarbonate therapy in ICU patients with metabolic acidosis remains unclear.

METHODS

We diluted 100 mL 8.4% sodium bicarbonate in 150 mL 5% dextrose (D5W) within a 250 mL polyolefin bag after removing 100 mL. We asked ICU clinicians to inspect a 250 mL bag containing sodium bicarbonate or a 250 mL bag where 100 mL of D5W had been removed and then returned. The bags were attached to intravenous giving sets. We asked participants to identify the contents of the bags.

RESULTS

Among 60 participants (39 nursing staff [65%], 20 medical staff [33.3%] and one pharmacist), 36 (60%) answered correctly. The Cohen κ for agreement between test bag content and participants' answers was 0.20 (95% CI, -0.05 to 0.45; P = 0.12), implying the answers were correct by chance. In the group of 28 participants who indicated they used a clue to help them decide their answer, 15 (53.6%) answered correctly, whereas in the remainder (n = 32), 21 (65.6%) answered correctly (P = 0.49).

CONCLUSION

When 100 mL of 8.4% sodium bicarbonate were diluted in 150 mL of D5W within a 250 mL polyolefin bag, clinicians were unable to correctly identify the contents of the bags. Our findings imply that sodium bicarbonate therapy can be successfully blinded.