Monitoring Central Venous Catheter Resistance to Predict Imminent Occlusion: A Prospective Pilot Study

Abstract

Background: Long-term central venous catheters are essential for the management of chronic medical conditions, including childhood cancer. Catheter occlusion is associated with an increased risk of subsequent complications, including bloodstream infection, venous thrombosis, and catheter fracture. Therefore, predicting and pre-emptively treating occlusions should prevent complications, but no method for predicting such occlusions has been developed.

Methods: We conducted a prospective trial to determine the feasibility, acceptability, and efficacy of catheter-resistance monitoring, a novel approach to predicting central venous catheter occlusion in pediatric patients. Participants who had tunneled catheters and were receiving treatment for cancer or undergoing hematopoietic stem cell transplantation underwent weekly catheter-resistance monitoring for up to 12 weeks. Resistance was assessed by measuring the inline pressure at multiple flow-rates via a syringe pump system fitted with a pressure-sensing transducer. When turbulent flow through the device was evident, resistance was not estimated, and the result was noted as "non-laminar."

Results: Ten patients attended 113 catheter-resistance monitoring visits. Elevated catheter resistance (>8.8% increase) was strongly associated with the subsequent development of acute catheter occlusion within 10 days (odds ratio = 6.2; 95% confidence interval, 1.8-21.5; p <0.01; sensitivity, 75%; specificity, 67%). A combined prediction model comprising either change in resistance greater than 8.8% or a non-laminar result predicted subsequent occlusion (odds ratio = 6.8; 95% confidence interval, 2.0-22.8; p = 0.002; sensitivity, 80%; specificity, 63%). Participants rated catheter-resistance monitoring as highly acceptable.

Conclusions: In this pediatric hematology and oncology population, catheter-resistance monitoring is feasible, acceptable, and predicts imminent catheter occlusion. Larger studies are required to validate these findings, assess the predictive value for other clinical outcomes, and determine the impact of pre-emptive therapy.

Trial registration: Clinicaltrials.gov NCT01737554.

Conflict of interest statement

Competing Interests: The intravenous pump used for this study was provided on loan from CareFusion Inc. The authors confirm that this does not alter their adherence to PLOS ONE policies on sharing data and materials.

Figures

Fig 1. Flow diagram of CRM results and clinical outcomes.

Per the STARD (STAndards for Reporting Diagnostic accuracy studies) initiative, the design of the study and flow of the patients are diagrammed [14]. The reasons for inconclusive CRM included first visit (n = 10), previous visit R2 was less than 85% (n = 7), TPA since previous visit (n = 10), and abnormal CVC function (n = 1). “CRM normal” indicates that the change in resistance was less than 8.8%. “CRM abnormal” indicates that either the change in resistance was at least 8.8% or the R2 was less than 85%. Clinical outcomes are also noted.

Fig 2. Patient positioning during CRM.

(A) Resistance measurements were performed with the participant lying at an angle of approximately 45°. The pressure sensor was placed below the estimated height of the participant’s right atrium. The relative heights and positions of the patient and pump were not altered between or during measurements. (B) Illustration of a tunneled external CVC. (C) Diagram of the catheter cross-section showing the different luminal diameters.

Fig 3. Estimation of catheter resistance.

Resistance was calculated as the gradient of a pressure-flow plot. Results that were a poor fit to a least squares regression line (R2 <85%) were termed non-laminar, and resistance was not estimated.

Fig 4. Metrics used to report change in resistance.

Change in resistance at each visit was described as the proportional change in estimated resistance within each lumen compared to that at Baseline (i.e., enrollment or first CRM visit), Reset (i.e., first CRM visit after TPA administration), or Last Visit (i.e., immediately previous CRM visit). Figure shows data from a single study participant and catheter lumen.

Fig 5. Scatter plot of catheter-resistance monitoring results.

Results are stratified by whether a clinical occlusion occurred within 10 days. The changes in resistance from Last Visit are shown. (A) Change in resistance in the smaller white lumen only, (B) the red lumen only, or (C) maximal change in either lumen. Occlusion was frequently preceded by a detectable rise in resistance that was not clinically apparent.

Fig 6. Receiver operating characteristic analysis for maximal change from Last Visit to predict catheter occlusion within 10 days.

(A) Any occlusion event and (B) an occlusion event requiring TPA therapy.