2081840 Perioperative Ultrasound Monitoring of Radial Artery Catheter Failure

To investigated possible mechanisms of radial artery catheter (RAC) failure using ultrasound (US) pre and post RAC insertion in surgical patients. Twenty-five patients requiring RAC (Arrow International; outer diameter 0.8 mm) were enrolled in this prospective study. Gray-scale and Doppler US with a 12-5 MHz probe (S-9, SonoScape, Shenzhen, China) was used to assess diameters and flow dynamics through radial (RA) and ulnar (UA) arteries. Perioperative US was conducted before and after RAC insertion, and intermittently every 2-6 hrs. A composite vessel trauma score (CVTS) was created to assess RAC insertion factors. RAC failure was defined as inability to aspirate blood from RAC or loss of pressure waveform. A total of 211 US scans were obtained in 25 patients. Of those, 21 (84%) had initial failure event and four patients (18%) had final failure. For RACs that did not exhibit final failure, the median No. of cannulation attempts was 9 and median CVTS was 8.5 compared to 3 and 8.3 respectively for failed RACs. The mean No. of blood draws from failed RACs was 5±3.3. The median time to initial dampening of RA waveform was 5.9 hrs in 22 cases. RA peak velocity was significantly decreased (p=0.021) after RAC (56.2±18.7 to 36.6±24.5 cm/s). UA peak velocity increased from 53.7±19.3 to 63.4±20.5 cm/s after RAC (p=0.114). When comparing RA and UA changes in peak velocity pre and post RAC, peak velocity was significantly reduced (p<0.01) in RA. RA and UA diameters were significantly increased (p=0.002, p=0.007) after RAC. When comparing RA and UA changes in diameters post RAC, there was not significantly different (p=0.97). The failed RACs (n=4) did not show differing patterns in velocity or diameter compared to RACs that did not fail. In failed RAC cases, US revealed that reasons of RAC failure included the RAC out of vessel and located in subcutaneous tissue (n=1), the tip against vessel wall with a small thrombus at RAC tip (n=1), a thrombus in front of RAC (n=1), and the RAC resting against superior wall of tortuous RA with intima thickening (n=1). US revealed that failed RACs were primarily due to flow reduction, vascular anatomy, RAC position and movement, and thrombus formation on the tip of RAC.