PURPOSE:The NAEPP Guidelines for the Diagnosis and Management of Asthma were revised in 2007 to include the use of Heliox (21%v/v oxygen/79%v/v helium) for treatment of severe exacerbations that are unresponsive to initial treatments. We report data for delivery of a beta-2 adrenergic agonist by Breath-Actuated Nebulizer (BAN) as guidance to clinicians.
METHODS:AeroEclipse-II® BANs (n=5 devices, Monaghan Medical Corp., Plattsburgh, NY) were operated simulating adult tidal breathing (tidal volume = 600-ml, 10 bpm, 33% duty cycle) and delivering 3-ml albuterol (0.83 mg/ml). Each nebulizer was powered at 50 psig by compressed air at 8 L/min (condition A, maximum achievable); Heliox at 8 L/min (condition B); Heliox at 16 L/min (condition C, maximum achievable). Emitted droplets were collected on separate filters at the mouthpiece of the BAN at 1-min intervals and recovered albuterol assayed by HPLC-UV spectrophotometry. The nebulizers were operated until onset of sputtering to determine total emitted mass (TEM). In a parallel study the emitted fine droplet fraction < 4.7 μm diameter obtained at each condition (FDF<4.7μm) was determined by laser diffractometry (n=3 replicates with 1 device). Total fine droplet delivery (FDM<4.7μm) was calculated as the product of TEM and FDF<4.7μm.
RESULTS:FDF<4.7 μm (mean ± SD) was 78.4 ± 1.8% (condition A); 68.7 ± 2.9% (condition B) and 84.8 ± 3.2% (condition C). The BANs operated for 10-min, 19-min and 11-min with corresponding values of FDM<4.7 μm (mean ± SD) of 90.2 ± 3.3, 28.8 ± 2.0 and 80.3 ± 4.5 μg/min at conditions A, B and C respectively.
CONCLUSION:Fine droplet delivery from the BAN can be maintained at a near equivalent delivery rate with Heliox if the flow rate is set to maximum. The reduction in aerosol output if flow rate is unchanged between air and Heliox reflects the lower density of the latter driving gas.
CLINICAL IMPLICATIONS:Clinicians should be mindful of the need to set the flow rate of Heliox to the BAN at maximum to maintain aerosol delivery characteristics established for air.
DISCLOSURE:Dominic Coppolo, Employee The authors are employees of Monaghan Medical Corp. or Trudell Medical International, manufacturers of the nebulizer described in this abstract.; No Product/Research Disclosure Information