Maintaining patency in totally implantable venous access devices (TIVAD): a time-to-event analysis of different lock irrigation intervals.

Purpose: To evaluate the effectiveness of irrigating totally implantable venous access devices (TIVADs) every eight weeks instead of every four in maintaining the patency of the device.

Methods: An explorative, pragmatic, prospective study design was conducted in two day hospital centres located in the northeast of Italy, from January 2011 to September 2012. Twenty patients who had skipped an appointment and were thus washing their TIVAD every eight weeks (exposed) were included, as were 17 patients following the typical wash regimen of every four weeks (controls). TIVAD occlusion-defined as the inability of the device to aspirate blood and/or the inability to properly irrigate the device-was the principal study end-point.

Results: A total of six occlusions were documented in six patients. Four cases were observed among the exposed group (4/20; 20.0%), while two were observed among the control group (2/17; 11.7%). No statistically significant differences were observed in the occurrence of occlusion between the groups (RR: 1.29, 95%CI: 0.67-2.50, p = 0.49). No statistically significant differences emerged between groups in the time that elapsed from study inclusion to occlusion occurrence according to the time-to-event analysis performed using the Kaplan-Meier estimation model (Log Rank [Mantel-Cox] = χ(2) 0.284, df 1, p = 0.594).

Conclusions: Within the limitations of the study which should be addressed with further research based on double-blinded randomised clinical trials, postponing the irrigation regimen of TIVADs to eight weeks seems to be sufficient to maintain device patency.