Effect of half-molar sodium lactate infusion on biochemical parameters in critically ill patients

To evaluate the impact of the infusion of sodium lactate 500ml upon different biochemical variables and intracranial pressure in patients admitted to the intensive care unit.

A prospective experimental single cohort study was carried out.

Polyvalent intensive care unit of a university hospital.

Critical patients with shock and intracranial hypertension.

A 500ml sodium lactate bolus was infused in 15min. Plasma levels of sodium, potassium, magnesium, calcium, chloride, lactate, bicarbonate, PaCO₂, pH, phosphate and albumin were recorded at 3 timepoints: T0 pre-infusion; T1 at 30min, and T2 at 60min post-infusion. Mean arterial pressure and intracranial pressure were measured at T0 and T2.

Forty-one patients received sodium lactate: 19 as an osmotically active agent and 22 as a volume expander. Metabolic alkalosis was observed: T0 vs. T1 (p=0.007); T1 vs. T2 (p=0.003). Sodium increased at the 3 timepoints (T0 vs. T1, p<0.0001; T1 vs. T2, p=0.0001). In addition, sodium lactate decreased intracranial pressure (T0: 24.83±5.4 vs. T2: 15.06±5.8; p<0.001). Likewise, plasma lactate showed a biphasic effect, with a rapid decrease at T2 (p<0.0001), including in those with previous hyperlactatemia (p=0.002).

The infusion of sodium lactate is associated to metabolic alkalosis, hypernatremia, reduced chloremia, and a biphasic change in plasma lactate levels. Moreover, a decrease in intracranial pressure was observed in patients with acute brain injury.