Data concerning the long-term outcomes of NSI before endotracheal
suctioning are also needed. An in vitro study reported that NSI might
cause bacteria to proceed to the base of the lung and, therefore, cause
lower respiratory system contamination and VAP [11]. In opposition
to this report, the study performed by Caruso et al [21] demonstrated
that the incidence of VAP decreased significantly in the group in
which NSI was applied. The proposed mechanism of this impact was
that NSI increases the amount of secretions by stimulating coughing
and, therefore, decreasing the biofilm layer in the endotracheal tube.
In Reeve's [34] commentary on this study, it was stated that these
mechanisms, which were reported to cause a decrease in VAP, were
not measured in the study performed by Caruso et al [21]; therefore,
this impact could not be determined completely. It was proposed that
the effect of this mechanism should be investigated in future studies
[34]. This criticism and recommendation were also stated in the study
performed by Caruso et al[21]. In our study, nearly half of the nurses believed
that NSI might be harmful. With similar studies [30,35] in our
study, nurses believe that NSI might have negative impact, such as
lung infection, decreased oxygen saturation, and disturbances in the patient.
It is remarkable that although nurses believe that normal saline
may have adverse effects, they use it widely. This situation suggests
that nurses have difficulties when dealing with endotracheal secretions
and that they focus primarily on removing the secretions without considering
the negative effects of NSI.