Impact of intravascular thrombosis on failure of radial arterial catheters in critically ill patients: a nested case-control study

Purpose The patency of arterial catheters is essential for reliable invasive blood pressure monitoring. We sought to determine whether radial catheter failures were associated with intravascular thrombosis in critically ill adult patients. Methods This unmatched case-control study was conducted within a prospective cohort of patients admitted to an intensive care unit. The arterial catheter failure was the main outcome, which identified cases. Controls were patients with patent catheter until removal or 28 days of follow-up. The prevalence of intravascular thrombosis in cases and controls was determined by ultrasonography of the cannulated radial artery. Assessors were blinded to clinical findings. Failing catheters were removed and examined microscopically. Results Catheter failures occurred in 25.5% of 200 patients during 584 catheter-days (incidence rate, 87/1000 catheter-days). The median patency duration was 13.1 days. An intravascular thrombosis located in front of the catheter tip was diagnosed in 42 of 50 cases (84.0%) and 24 of 139 controls (17.3%). In multivariable logistic regression analysis, the probability of catheter failure was higher in patients with intravascular thrombosis [odds ratio (OR), 36.52; 95% confidence interval (CI), 12.86–103.74] and females (OR, 3.45; 95% CI 1.32–9.05), increased proportionally to arterial blood sampling frequency (OR, 1.20; 95% CI 1.04–1.38), and decreased in thrombocytopenia (OR, 0.28; 95% CI 0.10–0.78). After removal, 15.7% of failing catheters had some luminal fibrin deposits, but none were occluded. Conclusions Most failing radial arterial catheters had no luminal obstruction, but were associated with an intravascular thrombosis. Among predictive factors, arterial blood sampling frequency is the most susceptible to intervention.