You’re treating an asthmatic 22-year-old. You give 5 back-to-back nebs, steroids and mag. When you reassess, she’s moving air better with minimal wheezing, but more tachypneic. Additionally, her lactate has climbed from 2 to 6.8 in 2 hours. She’s not hypoxic and there are no signs of hypoperfusion. What gives?
This patient has albuterol-induced hyperlactatemia. As opposed to Type A lactic acidoses, this is not caused by hypoxia or hypoperfusion. As a type B lactic acidosis, the exact etiology is not entirely understood. However, studies point to an increase in both endogenous and exogenous catecholamines. Enhanced beta 2 receptor activation leads to increased glycogenolysis, gluconeogenesis, lipolysis and conversion of pyruvate to lactic acid. Corticosteroid use may potentiate these affects. The idea that increased respiratory muscle usage leads to increased lactate production has been shown to be less likely, given that even paralyzed and ventilated patients can have similarly elevated lactate levels in the setting of albuterol usage.
This phenomenon is still undergoing study. Not all patients receiving high dose albuterol develop lactic acidosis and the reasons behind this are not well understood. The dose-response curve is also being elucidated. Most reports are case studies showing elevated lactate after back-to-back dosing and/or IV dosing within a few hours. One prospective, randomized trial looked at the relationship between serum albuterol levels and lactate levels, determining that there was a 3.1 mg/dL increase in the 1.25h serum lactate concentration for each 5ng x h/mL increase in total plasma albuterol level. How this relates to dosing is not defined, but it appears that higher doses cause larger effects.
Finally, albuterol-induced lactic acidosis may cause tachypnea as a compensation for metabolic acidosis. It is important to consider this when determining whether an asthmatic is improving on current therapy. Serial peak flow measurements and physical examination is the best way to differentiate between tachypnea caused by compensation versus asthma. Additionally, decrease and/or removal of beta agonist dosing leads to reduction of the serum lactate.
1) Lewis L et al., Albuterol administration is commonly associated with increases in serum lactate in patients with asthma treated for acute exacerbation of asthma. Chest 2014 Jan; 145(1): 53-9.
2) Rodrigo, GJ and Rodrigo C. Elevated plasma lactate level associated with high dose inhaled albuterol therapy in acute severe asthma. Emerg Med J, 2005. 22(6): p. 404-8.
3) Dodda V, Spiro P. Albuterol, an Uncommonly Recognized Culprit in Lactic Acidosis. Chest 2011; 140(4_MeetingAbstracts):183A.
4) Phillips PJ et al., Metabolic and cardiovascular side effects of the beta 2-adrenoceptor agonists salbutamol and rimiterol. Br J Clin Pharmacol, 1980. 9(5): 483-91.
Pearl inspired by Dr. Nemes.