Optimization of Albuterol Delivery via Anesthesia Bag in Pediatric Critical Care

Abstract

Background/Objectives: Aerosolized medications are common practice for mechanically ventilated pediatric patients. Infants often receive nebulized medications via hand ventilation using an anesthesia bag, but evidence on optimal aerosol delivery with this method is limited. For this study, various configurations of the Mapleson breathing circuit were tested to optimize albuterol delivery to a simulated pediatric model. Methods: Using a simulated pediatric lung model (ASL 5000) with the semi-open Mapleson anesthesia circuit, 2.5 mg/3 mL of albuterol sulfate solution was nebulized to a viral/bacterial filter (Respiguard 202). Four models were compared with varying fresh gas flows (FGFs), small-volume nebulizer (SVN) placements, and adjusting dead space. Five Registered Respiratory Therapists (RRTs) bagged the aerosol into a collection filter following defined ventilation parameters. Each model was tested in random order to avoid fatigue bias. Albuterol concentrations eluted from in-line filters were measured by spectrophotometry (absorbance at 276 nm). Results: No inter-user variability was observed among the RRTs. Significant differences in albuterol recovered were noted between models (One Way ANOVA, Tukey's post hoc, n = 5). Model 4, with the nebulizer closest to the collecting filter, recovered 21.77 ± 1.89% of albuterol. The standard clinical model was the least effective, with only 0.10 ± 0.17% albuterol recovery. Conclusions: Modifying the anesthesia breathing circuit significantly improved aerosol drug delivery efficiency. Our findings suggest that current clinical practices for nebulized drug delivery are inefficient and can be markedly improved with simple adjustments in nebulizer positioning and gas flow within the circuit.

Keywords: manual ventilation; mechanical ventilation; nebulization; pediatric aerosol.

Figure 1

Model 1: FGF 8 LPM with nebulizer distal to FGF; Model 2: FGF 2 LPM with nebulizer distal to FGF; Model 3: FGF 2 LPM with nebulizer proximal to FGF; Model 4: FGF 2L PM with nebulizer between FGF and filter.

Figure 2

Comparison of albuterol recovered from each delivery model. Each data point represents results from individual participant (n = 5, each user assigned a unique symbol). Data were analyzed by one-way ANOVA with Tukey’s multiple-comparison test using GraphPad Prism version 10.1.1 (San Diego, CA, USA). Normality of residuals passed Shapiro-Wilk test. Data represent mean ± SE, p < 0.05 was considered significant, * p < 0.05, *** p < 0.001.