BackgroundEndotracheal suctioning is a necessary procedure practiced by nurses in intensive care units to remove lung secretions. This procedure leads to higher oxygenation levels and reduced breathing difficulties. It also prevents atelectasis, pulmonary infections, and the accumulation of secretions.ObjectivesThe present study aims to compare the effectiveness of open and closed endotracheal suction tube systems on pain and agitation in patients under mechanical ventilation.MethodsA randomized controlled clinical trial was conducted in the general intensive care units of Khatam-ol-Anbia hospital and Sina hospital, Tehran, Iran, in 2015. In total, 60 patients who were qualified to be included in the study were randomly assigned to either the intervention group or the control group. When necessary, suction was carried out for each patient using the standard technique. The patients’ level of pain and agitation was measured in both groups at five stages (before, during, immediately after, 5 minutes after, and 15 minutes after the intervention) using the behavioral pain scale and the Richmond agitation sedation scale.ResultsSignificant statistical differences in the pain and agitation at different times within each of the two groups were observed for both open and closed suction (P > 0.001). However, these changes at different times between the two groups was not significant (P < 0.05).ConclusionsAlthough statistical differences were observed in the levels of pain and agitation in the two groups, the type of suction system did not have any effect on the level of pain and agitation of patients under mechanical ventilation. The researchers recommend that other studies with larger sample sizes should be carried out.