The Science Journal of the American Association for Respiratory Care

1998 OPEN FORUM Abstracts

COMPARISON OF FOUR NEBULIZER-PATIENT INTERFACES IN A PEDIATRIC LUNG MODEL.

Bob Dickerson, MS HCA, RRT. Children's Hospitals and Clinics, Minneapolis, Minnesota. Nick Delich, SRT, Gary Sakomoto, SRT, St. Paul Technical College, St. Paul, Minnesota.

Background: The recommended patient nebulizer interface for infants is a face mask. Many infants do not tolerate the use of face masks and cry throughout nebulizer treatments. Lung deposition of aerosolized drugs is known to decrease significantly with crying. Current literature does not recommend alternative interfaces when a face mask is not tolerated. The purpose of this study was to compare two alternative interfaces, currently used in clinical practice, with an aerosol face mask. The alternatives are blow-by, aerosol is directed into the patient's face using an elbow adapter, and a head-box, aerosol is directed into a head box placed over the infant's head. Methods: An infant lung model was constructed using an infant CPR mannequin and a double sided test lung with a lift bar, driven by an LP-6 ventilator (Aequitron Medical Inc.) at a rate of 30 and inspiratory time of 0.6 seconds. Aerosol concentration was measured using an APS (Aerodynamic Particle Sizer) Model 3320 (TSI Inc.). The mannequin head was connected to a "T" adapter with a 10 cm section of 5 mm tubing. One branch of the "T" was connected to the open side of the test lung. The other branch of the "T" was connected to the sampling port of the APS 3320. Tidal volume was adjusted to achieve 50 ml. measured with a Wright's respirometer at the "T". Six nebulizers of the same brand were filled with 0.5 ml of albuterol and 3 ml of normal saline and powered by 8 Lpm of oxygen. Four interface configurations were tested: aerosol face mask, blow-by 2 cm from the face, blow-by 4 cm from the face and a 10 inch collapsible head box. All nebulizers were tested in each configuration. The face mask and blow-by trials ran for 30 seconds and the head box ran for 2 minutes prior to sampling. Results: The graph shows the mean concentration of aerosol particles in the 1 to 5 micron range, for each interface. The aerosol mask yielded the highest concentration. Concentration for blow by at 2 cm was not significantly lower than the aerosol mask. Blow-by at 4 cm delivered significantly less than the mask (p < 0.05). The head-box delivered a significantly lower concentration than both the mask and blow by at 2 cm (p < 0.01) (Mann Whitney Rank Sum Test). Conclusions: The results support the use of aerosol face masks as the recommended interface for infants. Blow-by held close to the face (2 cm) should be considered for infants who do not tolerate the use of a face mask, if it will prevent crying and the distance from the face can be maintained. Differences in clinical effect remain to be determined.

(See Original for Figure)

The 44th International Respiratory Congress Abstracts-On-DiskĀ®, November 7 - 10, 1998, Atlanta, Georgia.

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