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High frequency oscillation in acute lung injury and ARDS

2010; BMJ; Volume: 340; Issue: may19 2 Linguagem: Inglês

10.1136/bmj.c2315

0959-8138

Eddy Fan, Gordon D. Rubenfeld,

Cardiac Arrest and Resuscitation

Background: Albuterol and budesonide are commonly prescribed for aerosol therapy during mechanical ventilation. Aerosolized drug delivery is affected by numerous factors, yet the delivery efficiency of budesonide is not well studied. The objective of this study was to evaluate the effect of drug dilution and chemical properties on aerosol delivery of solution and suspension during mechanical ventilation. Methods: The surface tension of each formulation was measured by Du Nouy ring method, and the viscosity of formulations measured by a viscometer. A Servo-i ventilator (Maquet, Sweden) operated in volume control (500 mL, 16 breaths/min, PEEP 5 cm H 2 O) with heated humidification at 37 degrees C was connected to an endotracheal tube, with an absolute filter connected to a lung model (Michigan Instruments). A vibrating mesh nebulizer (VMN, Aerogen, Ireland) and a pneumatic jet nebulizer (JN, Galemed, Taiwan) powered by oxygen at 8 L/min were operated with salbutamol and budesonide standard unit dose (2.5 mg/2.5 mL and 0.5 mg/2.0 mL, respectively), and with dose diluted to 4 mL with normal saline. Both nebulizers were placed at the inlet of the heated humidifier, and nebulization was terminated when no aerosol was visually seen. Drug collected on filter distal to endotracheal tube, and eluted and assayed by a spectrophotometery (salbutamol) and by HPLC (budesonide; n = 5). Results: Inhaled drug dose in Table below. The surface tension of salbutamol and budesonide were 69.0 ± 0.1 dyn/cm and 44.0 ± 0.2 dyn/cm, respectively, with viscosity of 1.073 ± 0.01 mPa/s and 1.032 ± 0.01 mPa/s. The budesonide suspension unit-dose delivered lower inhaled dose than salbutamol solution with both nebulizers, but increased significantly with dilution. The VMN delivered greater inhaled drug dose than JN. The Pearson9s test demonstrated a moderate correlation between surface tension and inhaled mass ( P <0.03). Conclusions: Dilution of budesonide suspension increased aerosol delivery during mechanical ventilation with both JN and VMN. The efficiency of drug delivery is associated with surface tension of the formulation.