The Science Journal of the American Association for Respiratory Care

1999 OPEN FORUM Abstracts

PERFORMANCE COMPARISON OF 4 SPACERS IN A PEDIATRIC MECHANICAL VENTILATOR-LUNG MODEL.

Ralph A. Lugo, PharmD, Jim Keenan, BS, RRT, Keith Elkins, BS. University of Utah College of Pharmacy and Primary Children's Medical Center, Salt Lake City, Utah.

Background: Aerosolized albuterol is commonly administered to mechanically ventilated children in the PICU. Many institutions have favored switching from nebulized albuterol to MDIs since the latter is more cost-effective. To administer albuterol to intubated children via MDI, several spacers are commercially available. This study compared the efficiency of albuterol delivery among four spacers. A secondary objective was to quantify albuterol rainout within the spacer.

Methods: The model consisted of a Bird VIP ventilator in a volume mode to simulate a 15-kg child with moderate lung disease: VT 150 mL (10 mL/kg), PIP 45 cm H2O, rate 12, Ti 0.75 sec, PEEP 4 cm H2O, FiO2 0.4, ventilator flow 11 L/min, and gas conditioned to 34° C. The circuit was attached to a 5-mm endotracheal tube (ETT) and a pediatric test lung (Vent AidÒ TTLÒ): compliance = 7.1 mL/cm H2O and resistance = 95 cm H2O/L/s. Spacers were new and unwashed and were placed in the inspiratory limb immediately proximal to the wye according to the package insert. A Sims filter (SIMS Portex) was placed between the ETT and test lung to collect aerosolized albuterol. A minimum of 5 replicate experiments were performed for each spacer. Filters were rinsed with 50 mL of 50% methanol solution and albuterol concentration was analyzed chromatographically by HPLC (99.1% accuracy and CV < 3.3%, n=9).

Results: Mean (SD) albuterol delivery is presented below.

Spacer Brand Albuterol Delivery (%) Rainout in Spacer (%)
ACEÒ (DHD Healthcare) 19.9 (6.4)* 57.9 (6.1)
AerochamberÒ MV (Monaghan Medical Corp.) 26.8 (2.6)? 37.0 (9.1)
AeroventÒ (Monaghan Medical Corp.) 6.6 (0.9) 71.3 (10.0)
MinispacerÒ (Thayer / Allegiance Medical Corp.) 8.5 (0.2) 35.1 (9.5)
* p<0.05 compared to AeroventÒ; ?p<0.05 compared to AeroventÒ and MinispacerÒ (ANOVA on Ranks with Dunn's all pairwise comparison)

CONCLUSION: There are clinically important differences in albuterol delivery between four commonly used spacers. The AerochamberÒ MV and ACEÒ spacer performed similarly when tested with this model.

OF-99-207

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