The Science Journal of the American Association for Respiratory Care

2007 OPEN FORUM Abstracts

EVALUATION OF POSITION OF AEROSOL DEVICE IN TWO DIFFERENT VENTILATOR CIRCUITS DURING MECHANICAL VENTILATION

A. Ari1, H. Aerabi1, J. Sampson1


Background: The position of nebulizers in the ventilator circuit affects drug delivery during mechanical ventilation. These effects have not been evaluated with all types of nebulizers.

Methods: Representative jet (Misty-neb; Cardinal Health), vibrating mesh (AeronebPro; Aerogen Inc), and ultrasonic (Easyneb; PB) nebulizers were compared in both heated and unheated ventilator circuit during mechanical ventilation. Nebulizers were operated continuously with albuterol (2.5 mg / 3 mL) in 3 positions: 1) between the endotracheal tube (ETT) and “Y”; 2) 6 in from “Y” on the inspiratory limb ; 3) 6 inches from the ventilator (n=3). A ventilator (Vt 500 mL, ramp flow pattern, 15 breaths/min) with circuit (heated or unheated) was attached to an intubated lung model. Drug deposited on an absolute filter distal to an 8.0 mmID ETT (n=3) was eluted and analyzed by spectrophotometry (276 nm). A 2 x 3 x 3 repeated measures ANOVA test was used for the statistical analysis of the study. Multiple follow-up comparisons were performed using the Bonferronni method (p<0.05).

Results: Table 1 shows mean (standard deviation) percent of dose delivered in a heated (wet) and unheated (dry) circuit, respectively. There were significant differences between nebulizers and for each nebulizer across the positions tested.

Conclusion: During CMV, the optimal aerosol efficiency is nebulizer and position dependent.

Table 1. Means (Standard Deviations) of Total Inhaled Drug Mass Percent for Each Type of Nebulizer and Position in Two Different Ventilator Circuits.
 Position 1 Position 2 Position 3
 Wet Dry Wet Dry Wet Dry
Jet Neb 7.62 (0.9) 4.66 (0.5) 3.61 (0.2) 9.66 (1.5) 5.98 (0.1) 14.66 (1.5)
Vibrating Mesh 12.82 (0.5) 14.54 (1.0) 16.79 (2.6) 30.24 (1.0) 8.39 (2.1) 24.20 (1.2)
Ultrasonic 10.07 (3.9) 10.70 (1.5) 16.53 (4.3) 24.68 (4.4) 4.59 (2.0) 10.51 (0.3)



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