Abstract
Rationale: Aerosolized medications are crucial for resolving
respiratory issues in mechanically ventilated patients. Infants often
receive nebulized medications via hand ventilation using an anesthesia
bag, but evidence on optimal aerosol delivery with this method is
limited. We tested various configurations of the Mapleson breathing
circuit to optimize albuterol delivery to simulated intubated pediatric
patients. Methods: Using a simulated pediatric lung model (ASL
5000) with the semi-open Mapleson anesthesia circuit, we delivered 2.5
mg albuterol sulfate to a viral/bacterial filter (Respiguard 202). Four
models were compared, varying fresh gas flows (FGF), nebulizer
placements, and the use of dead space. Five Registered Respiratory
Therapists (RRTs) administered the aerosol into the 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 delivery efficacy were noted
between models (One Way ANOVA, Tukey’s post hoc, N=5). Model 4, with the
nebulizer closest to the collecting filter, recovered 21.7±3.87% of
albuterol. The standard clinical model was least effective, with only
0.1±0.47% albuterol recovery. Conclusion: 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.