Nebulization associated with Bi-level noninvasive ventilation: Analysis of pulmonary radioaerosol deposition

Summary Nebulization associated with noninvasive ventilation is used in emergency services and intensive care units. Purposes To compare pulmonary radioaerosol deposition during jet nebulization associated to noninvasive ventilation versus spontaneous breathing nebulization; to measure the rate of lung depuration and the correlation between lung deposition, inspiratory flow and tidal volume (Vt) using scintigraphy. Subjects Thirteen healthy volunteers (with normal spirometry), mean age (23.3±1.49) years, body mass index 21.2±2.3 kg/m2. Methods Nebulization was performed in spontaneous breathing and associated with bi-level noninvasive ventilation (inspiratory pressure=12 cm H2O, expiratory pressure=5 cm H2O). The radioaerosol used in the nebulization was technetium (Tc99m) with diethylene triamine penta acetic acid, generated over a period of 9 min in a jet nebulizer. Analysis was performed through scintigraphy. Statistical analysis was performed by analysis of variance (for repeated measures), Bonferroni method, Student's t-test and Person's correlation. Results There was a decrease in radioaerosol lung deposition with nebulization associated to noninvasive ventilation (mean counts in spontaneous breathing 200,510+11,012 and mean counts in noninvasive ventilation 106,093+2811 ( P 0.001 ). During spontaneous breathing nebulization there was a significant correlation between Vt and radioaerosol deposition ( r = 0.565 , P 0.05 ), also between inspiratory flow and radioaerosol deposition in the lungs ( r = 0.141 , P 0.05 ). However, there was no correlation between Vt and pulmonary deposition of radioaerosol in bi-level noninvasive ventilation nebulization ( r = 0.082 ). Conclusion During nebulization with noninvasive ventilation in healthy volunteers, there was an increase in Vt associated to a higher inspiratory flow rate, without resulting in a significant increase in pulmonary radioaerosol deposition.