Objective: To compare the percentage of nebulized albuterol delivered with conventional (intermittent mandatory ventilation) vs. synchronous (assist-control and assist-control with flow synchronization) ventilation in a neonatal lung model.
Design: Prospective in vitro laboratory study.
Setting: Research laboratory.
Subject: Neonatal lung model.
Interventions: The model simulated an intubated neonate with a spontaneous respiratory rate of 40, 60, or 80 breaths per minute and compliance and resistance values of bronchopulmonary dysplasia. A VIP Bird ventilator was used for all ventilator modes. Albuterol 2.5 mg was administered with a T Up-Draft II Neb-U-Mist nebulizer attached to a 12.75-cm (10-mL) reservoir of circuit tubing. Albuterol was collected onto a filter (particle retention <or=0.3 microm) placed proximal to the test lung. After nebulization, the filter was rinsed with water, and albuterol concentrations were determined by high-performance liquid chromatography. Ten random trials for each mode were completed.
Measurements and main results: No significant differences in percentage albuterol delivered were found among the three modes or the three spontaneous respiratory rates (mean +/- sd): intermittent mandatory ventilation, 0.11 +/- 0.04%; assist-control, 0.12 +/- 0.03%; assist-control with flow synchronization, 0.10 +/- 0.04%; 40 breaths per minute, 0.11 +/- 0.03%; 60 breaths per minute, 0.11 +/- 0.04%; and 80 breaths per minute, 0.11 +/- 0.05% (p >.05, two-factor analysis of variance).
Conclusions: The percentage of nebulized albuterol delivered to the end of the endotracheal tube in a mechanically ventilated neonatal model was not affected by mode of ventilation under the conditions studied. Further clinical studies are needed to determine whether lung deposition and distribution or clinical efficacy of albuterol is influenced by synchronous ventilation in this patient population.