The instillation of normal saline (NS) for the purpose of thinning or loosening secretions in the airway has been an accepted procedure in the critical care setting for some time. To date there have been only two reported studies on the effect of NS instillation in artificial airways.

The first purpose of this study was to further test the effect of using saline lavage prior to tracheal or endotracheal suctioning on oxygen saturation. The second purpose was to explore the effect of using saline lavage prior to suctioning on physiologic stress variables. The third purpose was to investigate whether or not the patient's systemic hydration status had any effect on suctioning. The final purpose was to describe any patient characteristics that would indicate or contraindicate the use of saline lavage prior to suctioning.

There were 40 male subjects enrolled in this study who were either endotracheally or tracheal intubated and on a ventilator.

The instillation of saline prior to suctioning was found to have, on the average, a negative effect on oxygen saturation. Statistically significant results were found at 2, 3, 4, and 5 minutes following suctioning utilizing 2 tailed t-tests. Saline lavage prior to suctioning had marginal effects on the physiologic stress variables of heart rate and systolic blood pressure. There were no relationships between the antecedent variables (diagnosis, hydration status, or nurse's assessment of need for saline lavage) and oxygen saturation treatment effects, utilizing the Spearman correlation coefficient. There was a positive correlation between age and the effect of the saline bolus on oxygenation. This relationship implies that patients who were older did better than patients who were young using saline lavage. Deviant case analysis was done for cases that had treatment effect values that were outside 2 standard deviations of the mean. It appears that patients with marginal oxygenation status may be at greatest risk when utilizing saline lavage. These results suggest that use of a saline bolus should be discontinued as standard practice, and more research should be done to establish what types of patients this practice actually helps, if any. (Abstract shortened with permission of author.).