Inhaled β2-Agonist therapy increases functional residual capacity in mechanically ventilated children with respiratory failure. (Emrath)

Ramsi MA, Henry M, Milla CE, Cornfield DN. Inhaled β2-Agonist therapy increases functional residual capacity in mechanically ventilated children with respiratory failure. Pediatr Crit Care Med. 2015 Apr 21. [Epub ahead of print]

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OBJECTIVES: To test the hypothesis that in mechanically ventilated children with respiratory failure, aerosolized albuterol modifies functional residual capacity, lung mechanics, oxygen consumption, and hemodynamics.

DESIGN: Prospective, self-control clinical trial.

SETTING: A 24-bed PICU in a quaternary care, academic children’s hospital.

PATIENTS: 25 children (age range, 1-18 yr) undergoing mechanical ventilation to treat respiratory failure. Entry criteria included previously prescribed inhaled β2 agonists. Physiologic measurements were performed prior to and 20 minutes after administration of aerosolized albuterol solution. Functional residual capacity was determined via nitrogen washout.

INTERVENTIONS: Functional residual capacity, oxygen consumption, respiratory mechanics, and vital signs were measured were measured prior to and 20 minutes after administration of aerosolized albuterol solution. Functional residual capacity was determined via nitrogen washout.

MEASUREMENT AND MAIN RESULTS: At baseline, functional residual capacity is only 53% of predicted. After aerosolized albuterol, functional residual capacity increased by 18.3% (p = 0.008). Overall, aerosolized albuterol had no effect on airway resistance. However, in patients with an endotracheal tube size of more than or equal to 4.0 mm, resistance decreased from 33 ± 3 to 25 ± 3 (p < 0.02). Inhaled albuterol administration had no effect on oxygen consumption despite an increase in heart rate from 116 ± 2 to 128 ± 2 beats/min (p < 0.0001).

CONCLUSIONS: In pediatric patients with respiratory failure, aerosolized albuterol increases functional residual capacity without a decrease in resistance. In infants and children, aerosolized albuterol might favorably enhance pulmonary mechanics and thereby represent a novel strategy for lung recruitment in children with respiratory failure.

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Albuterol administration is commonly associated with increases in serum lactate in asthmatics treated for acute exacerbation of asthma. (Fortenberry)

Lewis LM, Ferguson I, House SL, Aubuchon K, Schneider J, Johnson K, Matsuda K. Albuterol administration is commonly associated with increases in serum lactate in asthmatics treated for acute exacerbation of asthma. Chest. 2014 Jan; 145(1): 53–59.

BACKGROUND: Controversy exists surrounding the incidence and cause of hyperlactatemia during asthma exacerbations. We evaluate incidence, potential causes, and adverse events of hyperlactatemia in patients with acute asthma exacerbation.

METHODS: Sub-analysis of placebo subjects from a prospective, randomized trial evaluating an intravenous beta-adrenergic agonist in acute asthma exacerbation (clinicaltrials.gov identifier NCT00683449).Subjects had plasma albuterol, serum lactate and bicarbonate concentrations measured at baseline and 1.25 hours as well as dyspnea score and spirometry measured at baseline and hourly for 3 hours. All subjects had a therapeutic trial consisting of 5-15 mg of nebulized albuterol, 0.5-1 mg of nebulized ipratropium, and at least 50 mg of oral prednisone, or its equivalent prior to initiation of the study. Following randomization, subjects were treated with continued albuterol and intravenous magnesium at the discretion of their treating physician. Subjects were followed to admission or discharge with follow up at 24 hours and 1 week.

Results: 175 subjects were enrolled in the parent trial, 84 in the placebo group. 65 had complete data. Mean albuterol administration prior to baseline was 12.3mg (SD±5.3).Mean baseline lactate was 18.5mg/dL (SD±8.4) vs. 26.5mg/dL (SD±11.8) at 1.25 hours; p>0.001. 45 subjects (69.2%) had hyperlactatemia. Mean baseline bicarbonate was 22.6mEq/L (SD±2.9) vs. 21.9mEq/L (SD±4.0) at 1.25 hours; p=0.11.Plasma albuterol concentration correlated to lactate concentration (β coefficient=0.45; p<0.001), and maintained significant association after adjusting for asthma severity (β=0.41; p=0.001). Hyperlactatemia did not increase the risk of hospitalization/relapse (p=0.26), nor was it associated with lower %FEV1 at 3 hours (p=0.54).

CONCLUSION: Plasma albuterol was significantly correlated with serum lactate concentration, after adjusting for asthma severity. Hyperlactatemia was not associated with poorer pulmonary function as measured by 3-hour %FEV1, or increased hospitalization/relapse at one week.

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