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: V_T 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.

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