The Science Journal of the American Association for Respiratory Care

2004 OPEN FORUM Abstracts

COMPARISON OF DRUG DELIVERY BY VARIOUS MDI SPACERS IN A NEONATAL LUNG MODEL

Rick Amato, BS, RRT-NPS, James Johnson, BS, CRTT, Shelly Smith, RRT Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio

Introduction: MDI delivery during mechanical ventilation requires a spacer, involving opening of the circuit and added dead space. We created an in line MDI adapter for the inspiratory limb of the neonatal circuit. This adaptor eliminates opening of the circuit and dead space, and the circuit acts as the reservoir. We measured drug delivery using our new MDI adaptor and different spacers or adaptors in a neonatal lung model to see if our MDI adaptor provided comparable drug delivery.

Materials and Methods: Our lung model was a Siemens™ Servo 300® ventilator and Ingmar Medical™ Neonatal Demonstration Lung. Ventilator settings were: Pressure Control (PC) mode, Rate 40 bpm, Peak Inspiratory Pressure (PIP) 20 cm H2O, PEEP 5 cm H2O, Inspiratory Time (Ti) 0.4 seconds. Spacers tested were placed between the patient wye and a filter located proximal to a 4.5mm ETT connected to the lung model, while our MDI adaptor was placed in the inspiratory limb of the circuit proximal to the patient wye. Two puffs of Albuterol MDI (17grams/ 90mcg per actuation) 30 seconds apart were given using each spacer and filters were changed and identified to each spacer. Drug levels were measured with a Beckman 640 spectrophotometer at a wavelength of 276 nm. A sample of HCL solution was used as a placebo, and zeroed. (Disposable supplies used were: Pall™ Breathing Circuit Filters (cat# BB50T), Airlife™ isothermal breathing circuit (cat# 9048-4H2), Monaghan™ AeroChamber® MV, Airlife™ Dual Spray Minispacer (cat# 002090), Airlife™ Minispacer (cat# 002092), Airlife™ Minispacer (cat# 002063), Airlife™ T-Adaptor (cat# 5941-504), and an actuator from an Airlife™ Minispacer (cat# 002063), modified to place the actuator in the inspiratory stream.)

Results: Averages were obtained, Monaghan™ AeroChamber® MV was found to deliver 0.0276mg/ml. Airlife™ Dual Spray Minispacer (cat# 002090) delivered 0.0322mg/ml. Airlife™ Minispacer (cat# 002092) delivered 0.0277mg/ml. Airlife™ Minispacer (cat# 002063) delivered 0.0244mg/ml. The “home made” MDI adaptor delivered 0.0270mg/ml.

Conclusion: While our “home made” MDI adaptor did not deliver the highest concentration of medication, the patient safety factors played an important role in our decision to use it. There was no increase in dead space, and our patients tolerated treatments better than using the adaptor that delivered the most medication. The circuit only had to be broken into once, and the adaptor could be left in-line. This enabled us to deliver an MDI with out disturbing the patient, or removing them from the ventilator.

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