The Science Journal of the American Association for Respiratory Care

2003 OPEN FORUM Abstracts


Matthew P. Branconnier, RRT; Dean R. Hess, PhD, RRT, FAARC. Massachusetts General Hospital and Harvard Medical School, Boston MA.

Background: Inhaled albuterol is an effective treatment for bronchospasm. Although it is commonly used with noninvasive ventilation, only a few published papers have addressed issues related to albuterol delivery during NPPV.

Albuterol delivered by oronasal mask with BiPAP is effected by type of aerosol delivery (nebulizer vs inhaler) and site of fixed leak (hose vs mask).

Methods: A Puritan-Bennett 840 ventilator was attached to one chamber of a dual-chambered test lung. A lift bar was placed between the chambers such that the ventilator triggered simulated spontaneous breathing of the second chamber at a rate of 20/min. A Respironics BiPAP S/T30 was set for an IPAP of 15 cm H2O and EPAP of 5 cm H2O. Tidal volume to the lung model was measured (Novametrix NICO) at 0.4 L. A single limb circuit was placed between the BiPAP and oronasal mask. The mask was glued to a Plexiglas plate, from which a 15 mm hole led to a Puritan-Bennett D/Flex filter and the test lung. Two mask types were used; the Respironics Spectrum in which the leak port is incorporated into the circuit and the ResMed Mirage in which the leak port is incorporated into the mask. For the nebulizer experiments, a Hudson Micro Mist nebulizer was connected via T-piece directly to the mask; for the Spectrum, the nebulizer was placed between the mask and leak port. The nebulizer was filled with 4 mL containing 5 mg of albuterol and operated at 8 L/min for 15 min. For the inhaler studies, a Monaghan AeroVent spacer was placed between the mask and the BiPAP circuit. A pressurized metered-dose inhaler was actuated into the spacer either synchronized with the initiation of inhalation or during the exhalation phase (4 actuations separated by =15 s in each case). Albuterol was washed from the filter and measured by UV spectrophometry.

Results: For the nebulizer, significantly more albuterol was delivered to the filter with the Spectrum mask (P=0.001). Significantly more albuterol was delivered by nebulizer than by inhaler (P<0.001) (Figure 1). The efficiency of albuterol delivery (percent delivered) was similar for nebulizer and inhaler with the Spectrum mask (P=0.57), but better for the inhaler with the Mirage mask (P=0.001) (Figure 2). Albuterol delivery was 50% less when the inhaler was actuated during exhalation (P=0.001).

Conclusions: Albuterol delivery with BiPAP is affected by the method of aerosol delivery (nebulizer vs inhaler), by the location of the leak port (mask vs. circuit), and by actuation of the inhaler at the proper time in the respiratory cycle. Figure 1 Figure 2 12 Nebulizer Inhaler Nebulizer Inhaler albuterol amount (mcg) 10 percent delivered 8 6 4 100 2 0 0 Spectrum Mirage Spectrum Mirage