Hyperlacticaemia in children with status asthmaticus. The Stewart approach.

BACKGROUND: Patients with status asthmaticus (SA) frequently present with lactic acidosis (LA). Our goal is to identify the nature of this LA using the Stewart physicochemical model and to identify the independent factors associated with LA in children with SA.

METHODS: Analytical study of a retrospective cohort using a nested case-control design. Twenty-eight episodes of SA in 24 children were included. Patients admitted to a paediatric intensive care unit (PICU) for SA over a 9-year period were recruited consecutively. Data were analysed using the Stewart model and the Strong Ion Calculator. Data were analysed using descriptive statistics and regression models were fitted within the general linear model.

RESULTS: Hyperlacticaemia (Lact[mM/L] = 3.905 [95% CI = 3.018-4.792]) and acidosis (pH = 7.294 [95% CI = 7.241-7.339]) were observed in 18 episodes (15 patients; 62.5%). According to the Stewart model, acidosis was caused by a decrease in strong ion difference. Initially, pCO2 was high (pCO2[mmHg] = 45.806 [95% CI = 37.314-54.298]) but the net unmeasured ion (NUI) component was normal (NUI=-4,461 [95% CI=-3.51 - -5.412]), and neither changed significantly over the clinical course. There was no need to determine pyruvate, as the NUI was normal and the LA was type B (non-hypoxic, lactate / pyruvate < 25). We observed a correlation (p = 0.023) between LA and intramuscular epinephrine administered on arrival at hospital, but not between LA and the cumulative dose of nebulized salbutamol.

CONCLUSIONS: Most patients with SA presented LA. The Stewart model confirmed that LA is not hypoxic, probably due to sympathomimetic-related glycolysis.