Objective: Hyperlactatemia and lactic acidosis are common in adults with acute severe asthma however only a few cases have been reported in children. Type A lactic acidosis is associated with impaired oxygen delivery; type B occurs in the presence of normal oxygen delivery and has been described to occur with excessive adrenergic stimulation. Type A and B lactic acidosis can be distinguished by the blood lactate/pyruvate ratio. Our objectives are to 1) investigate the incidence of hyperlactatemia and lactic acidosis in children with acute severe asthma, and 2) determine whether lactate elevation is type A or B.
Design: Prospective observational study.
Setting: University-affiliated tertiary care children's hospital.
Patients: All children (n = 105) with acute severe asthma admitted to the pediatric intensive care unit between May 1, 2008 and November 30, 2009 were included.
Interventions: Blood lactate concentration was measured on a blood gas analyzer for all blood gas assessments obtained for clinical care. Hyperlactatemia was defined as lactate >2.2 mmol/L and lactic acidosis as lactate >5 mmol/L and pH <7.35. If lactate concentration was >5 mmol/L, consent was requested for measuring blood lactate and pyruvate using enzymatic laboratory methods. Lactate/pyruvate ratio >25:1 indicated type A lactic acidosis.
Measurements and Main Results: Eighty-seven (83%) children had lactate >2.2 mmol/L and 47 (45%) had lactate >5 mmol/L. Of those with lactate >5 mmol/L, 33 (70%) had corresponding blood pH <7.35. Lactate/pyruvate ratios were obtained for 16 patients. Of these, lactate/pyruvate ratio was <10 in three patients; 10–25 in 11; >25 in one; and indeterminate in one.
Conclusions: Lactic acidosis is common in children with acute severe asthma and is primarily type B occurring in the presence of normal oxygen delivery.
From the Department of Pediatrics, Children's Hospital of Michigan, Wayne State University, Detroit, MI.
Supported, in part, by institutional department funds.
The authors have not disclosed any potential conflicts of interest.
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