The Science Journal of the American Association for Respiratory Care

1997 OPEN FORUM Abstracts

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

David Blakeman AS SRCP, Scott Fedrizzi MPA RRT, Andrea Easley, SRCP, Butte Community College, Oroville, CA.

Introduction: After an extensive literature review, we found no documented evidence regarding the delivery of aerosolized bronchodilator treatments to spontaneously breathing tracheostomy patients on continuous high flow blowby systems. Therefore, we developed a bench model to evaluate 3 methods for delivering aerosolized bronchodilator via Small Volume Nebulizer (SVN) treatment to a spontaneous breathing tracheostomy model attached to a continuous high flow blowby system calibrated to 70 liters per minute. Study Question: Does method of delivery affect medication deposition and FIO_{2} delivered? Methods: Work of Breathing (WOB) studies conducted were acceptable for all 3 methods. Carbon Dioxide (CO_{2}) rebreathing study proved negative. Five SVN's from the same lot were protested for comparability. The 3 methods used for delivery of the SVN treatments are as follows; Method 1) SVN placed inline of large bore tubing 18" upstream from trach T-piece with 6" reservoir tubing, Method 2) "Mask on Trach Mask Technique". This consists of a SVN attached to large bore tubing connector of trach collar with aerosol mask connected to high flow held over the trach collar, Method 3) "T Reservoir Technique". This consists of a delivery system of 6" high flow tubing connected on one end to the trach tube and on the other end to SVN T-piece, followed by 12" high flow tubing connected to the high flow blowby tubing T-piece. 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 the Hamilton Veolar (Vt 700, rate 12/min, sine wave, flow 60 L/min) and the other side was attached to Tygon tubing, (10 1/2 cm long, with 2 cm diameter), which was intended to simulate the trachea of a spontaneously breathing patient. An 8 mm ID trach tube was inserted into the tubing and cuff was then inflated. 100% cotton wadding was place in a collection chamber approximately 5 1/2 cm from end of trach tube. The tracheal model was maintained at approx. 85 degree angle to prevent drops from contacting the cotton. SVN's in all methods were run until sputter, tapped 6 times and run until sputter again. Albuterol drug was extracted from the cotton using a previously described method (Resp. 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 and 3 consistently delivered the set (50%) FIO_{2} while method 2's FIO_{2} was variable. Method 1 delivered 0.86% of the total dose. Method 2 increased drug delivery to 1.98% of the total dose. Method 3 increased drug delivery still further to 2.49%. ANOVA for repeated measures revealed significant differences between the 3 methods (p < .01).

(See original for figure)

Conclusion: Method 3, "T Reservoir Technique", delivered reliable FIO_{2} and consistently demonstrated greater deposition as compared to the alternate methods evaluated. Although Method 2 had better deposition than Method 1, FIO_{2} was variable. Our results show that our T Reservoir Technique is a superior method for delivering aerosolized medication under these particular conditions.

The authors wish to thank Jerry Hunt, MS, RRT, RPFT for technical assistance and support.

OF-97-035

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