The Science Journal of the American Association for Respiratory Care

1996 OPEN FORUM Abstracts

EVALUATION OF THREE METHODS FOR DELIVERING AEROSOLIZED ALBUTEROL TO A SPONTANEOUSLY BREATHING MODEL ON A CONTINUOUS HIGH FLOW MASK SYSTEM

Scott Fedrizzi BVE, RRT, Earl Davis, Paul Navarro. Butte Community College, Oroville, CA.

Introduction: There is very little in the literature regarding the delivery of aerosolized bronchodilator treatments to patients on continuous high flow mask systems. As such, we developed a bench model to evaluate 3 methods for delivering aerosolized bronchodilator via Small Volume Nebulizer (SVN) treatments to a spontaneous breathing model attached to a continuous high flow mask system.

Study Question: Does method of delivery affect medication disposition?

Methods: Five SVN's from the same lot were pretested for comparability. The 3 methods used for delivery of the SVN treatments are as follows; Method 1) SVN placed inline 18" from high flow mask, Method 2) SVN attached to large bore hose connector on high flow mask with high flow tubing placed thru mask entrainment port and Method 3) a new method, mask on mask therapy. Mask on mask technique consists of using two standard aerosol masks. Mask one is placed directly on the patient's face with SVN connected to the large bore hose connector. The second mask is attached to a high flow gas source placed directly on top of the first mask. Five trials for each of the three delivery methods were performed. A double-sided test lung with lift bar was used to simulate spontaneous breathing. One side of the test lung was attached to a Hamilton Veolar (rate 12/min, V_{T} 700 ml, sine wave, flow 60 L/min) and other side was attached to an intubation mannequin intended to simulate the airway of a spontaneously breathing patient. Cotton wadding was placed in a collection chamber distal to the mainstern bronchi. SVN's used in each of the 3 methods were run until dry. Albuterol drug was extracted from the cotton using a previously described method (Respir Care 1992 37:1233). The extracted solution was filtered through a slow-flow paper filter to remove any cotton fibers or impurities. Absorbance was measured at 278 nm (Perkin Elmer low beam spectrophotometer). The amount of albuterol extracted from the cotton was calculated based on the known standard solution (0.05 mg/ml) using a modification of Beer's Law.

Results: Method 1 delivered 0.55% of the total dose. Method 2 increased drug delivery to 1.22% of the total dose. Method 3 increased drug delivery further to 2.10%. ANOVA for repeated measures revealed significant differences between the 3 methods (p < .001).

(See original for figure).

Conclusion: Method 3, mask on mask therapy, consistently demonstrated greater deposition as compared to the alternate methods evaluated. Based on our findings, the choice of delivery method may be an important consideration in the delivery of aerosolized bronchodilator in the spontaneously breathing patient on a high flow oxygen system. It is our contention that mask on mask therapy represents a superior method for delivering aerosolized medication under these particular conditions.

Reference: OF-96-029

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