Pistoning in continuous renal extracorporeal replacement therapy catheters: Longitudinal descriptive study

Pistoning is defined as the back-and-forth movement of the catheter at the insertion site.

To determine the frequency of pistoning in continuous renal replacement therapy catheters (CRRTC) and its relationship with intravascular thrombosis and catheter dysfunction.

A longitudinal descriptive study (March 2023-June 2024) was conducted in two intensive care units. Patients with CRRTC inserted in these units were included.Body mass index (BMI), insertion site, dwell time, and reason for removal were recorded. At each dressing change, pistoning, dysfunction, day of onset, suture fixation status (SFS), hematoma, and line traction were assessed. After catheter removal, ultrasound was performed to determine intravascular thrombosis. Descriptive statistics and bivariate analysis using chi-square or Fisher's exact test and t-Student test were applied, with significance set at p ≤ 0,05.

A total of 63 catheters were analysed. Pistoning occurred in 42.9% (n = 27;) and dysfunction in 31.8% (n = 20), at median 3 [P₂₅ = 2-P₇₅ = 9] and 3.5 [P₂₅ = 1.5-P₇₅ = 6.5] days respectively. Intravascular thrombosis was identified in 26.1% (n = 12). Incorrect SFS was observed in 59.3% of catheter with pistoning (CWP) compared with 11.1% of catheter without pistoning(CWoP) (p < 0.001). CWP remained in place for 11 days (8.5) and CWoP for 7.3 days (3.9) (p = 0.02). Patients with dysfunction had a BMI of 34.5 kg/m² (SD = 10.3) compared with 29.8 kg/m² (SD = 4.6) in those without dysfunction (p = 0.03). No significant differences were found between pistoning and thrombosis (p = 0.30) or between pistoning and dysfunction (p = 0.06).

Pistoning was frequent and was mainly associated with defective SFS and longer dwell time. Obesity was identified as a factor associated with catheter dysfunction.

Nearly half of CRRT catheters present pistoning, associated with inadequate fixation and longer dwell time. Catheter dysfunction is more frequent in patients with obesity.