Sodium Bicarbonate for Critically Ill Patients With Metabolic Acidosis and Acute Kidney Injury

Each year > 200 000 adult patients are admitted to intensive-care units (ICUs) in Germany of which around half develop acute kidney injury (AKI). AKI markedly increases morbidity, mortality, ICU/hospital length of stay, and the risk of progression to chronic kidney disease.2-4 Metabolic acidosis significantly raises hospital mortality, the need for kidney-replacement therapy (KRT), and the incidence of major adverse kidney events within 30 days (MAKE30).5,6 When AKI and metabolic acidosis coexist, 90-day mortality ranges from 53 % to 59 % (vs 26 % for AKI alone).

Acidaemia depresses cardiovascular function through reduced myocardial contractility, impaired catecholamine responsiveness, hyperkalaemia, pulmonary vasoconstriction and arrhythmogenesis.7,8 Restoring extracellular pH is therefore biologically plausible as a strategy to improve organ perfusion and outcomes.

Sodium bicarbonate is the most widely used buffer in clinical practice, yet high-quality evidence for its benefit in AKI with metabolic acidosis is lacking. To date, despite numerous calls for appropriately designed studies, there have only been two RCTs primarily addressing the effects of sodium bicarbonate in critically ill patients with severe acidosis.1,9 Due to methodological limitations (open-label study design, selection bias, risk of confounding) and lack in generalizability, the question on using sodium bicarbonate in critically ill patients with AKI and metabolic acidosis cannot be answered with certainty.

The "Evaluating the clinical effectiveness of sodium bicarbonate for critically ill patients with metabolic acidosis and acute kidney injury" trial is a multicenter, double-blinded, randomized controlled trial. It is designed to determine whether treatment with intravenous 8.4% weight/volume (w/v) sodium bicarbonate is superior to placebo in terms of the composite endpoint major adverse kidney events (MAKE) at day 90 (composite of death from any cause, receipt of any KRT within the 90-day period, or persistent renal dysfunction (defined as a creatinine value ≥200% of the baseline value) at day 90) in critically ill patients with AKI (KDIGO stage 2 or 3) and metabolic acidosis. The findings of the ESCALATE trial are expected to have significant implications for clinical practice and patient outcomes, both in Germany and internationally, by providing high-quality evidence to guide the management of a critically ill population with high risk of mortality.

Inclusion criteria

• Adult ≥ 18 years
• Critically ill patients (requiring treatment on an ICU or IMC)
• Metabolic acidosis, defined as all of the following:

• Arterial pH ≤7.25
• PaCO2 < 6.5kPa (<49 mmHg)
• Standard bicarbonate ≤20 mmol/L
• Standard Base Excess <-2
• AKI stage 2 or 3 of the KDIGO classification
• Written informed consent of the patient or legal representative or authorized representative or emergency inclusion (according to Article 35 EU-Regulation 536/2014)

Exclusion criteria

• Pregnant or breastfeeding patients
• Respiratory acidosis (acute or chronic) [dynamic, and if corrected, patient may be reconsidered for the trial]
• Patients on KRT, or KRT immediately indicated and treating clinician(s) unwilling to defer
• Deemed unsuitable for KRT
• High output stoma/ileostomy
• Percutaneous biliary drainage
• End stage kidney failure defined as documented eGFR <15ml/min/1.73m 2 prior to onset of this acute illness or end stage kidney disease (ESKD) on dialysis
• Known renal tubular acidosis
• Diabetic ketoacidosis
• High anion gap acid poisoning (e.g. polyethylene glycol (PEG), aspirin, methanol)
• Symptomatic hypocalcaemia (Ionized calcium <1.05 mmol/L)[dynamic, and if corrected, patient may be reconsidered for the trial]
• Hypernatremia (plasma sodium >150 mmol/L)[dynamic, and if corrected, patient may be reconsidered for the trial]
• Severe hypokalemia (potassium <3.0 mmol/L)[dynamic, and if corrected, patient may be reconsidered for the trial]
• Death perceived as imminent
• Known hypersensitivity to sodium bicarbonate or EDTA (Disodiumedetate)
• Previously randomized into ESCALATE