Effects of In-Line Nebulization on Preset Ventilatory Variables

Abstract

Background

The effects of nebulization on preset ventilator variables have not been fully studied. The objectives of this study were to determine the effect of in-line nebulization on exhaled volume (VE), peak inspiratory pressure (PIP), and positive end-expiratory pressure (PEEP) during ventilation, and to compare these effects among three ventilators (Bear Cub, Sechrist Infant, and Siemens 900C).

Methods & Materials

In an in-vitro experiment, we used ventilator circuits attached to a model-test lung and five groups of ventilator variables to simulate clinical situations. The ventilator circuits were connected to an infant test lung; a pressure probe and respirometer were connected at the expiratory limb; and a small-volume nebulizer was attached in the inspiratory limb of the circuit. Baseline measurements and changes in PIP, VE, and PEEP obtained during nebulization were repeated in triplicate in the pressure-controlled mode of the Bear Cub and Sechrist Infant and in the pressure- and volume-controlled modes of the Siemens 900C. Results were analyzed using repeated measures of variance with p < 0.05 considered statistically significant. Newman-Keuls multiple range test was used for post-hoc comparison procedures.

Results

Statistically significant changes were observed in mean Ve and PIP during nebulization in all ventilators studied (p < 0.01). PEEP increased by 1-2 cm H2O in the Sechrist Infant ventilator during nebulization. Changes from baseline were consistent across all five ventilator settings tested.

Conclusions

In-line nebulization results in changes in VE and PIP. The least possibly adverse changes were seen with the Bear Cub and Sechrist Infant ventilators. To avoid potential complications, preset ventilator variables may need to be adjusted when in-line nebulization is performed.