Saline flush test for bedside detection of misplaced subclavian vein catheter into ipsilateral internal jugular vein

The most common misplacement during subclavian vein (SCV) catheterization is into the ipsilateral internal jugular vein (IJV). Chest radiography is the gold standard for the confirmation of correct placement. However, it is time-consuming and has the disadvantage of radiation exposure. We assessed the sensitivity and specificity of our previously reported 'flush test' for confirming correct central line placement.

All neurosurgical patients who underwent successful SCV catheterization on the right side by an infraclavicular approach were enrolled in this study. The flush test was performed by injecting 10 ml of normal saline in the distal port of catheter, while anterior angle of ipsilateral neck was palpated by an independent observer. A thrill of fluid elicited on the palm of hand (positive test) was suggestive of misplaced catheter into ipsilateral IJV. This was confirmed with chest fluoroscopy.

SCV catheterization was performed in 570 patients. The flush test was positive in 19 patients (3.3%) and negative in 551 patients (96.7%). There were 26 (4.6%) misplacements as detected by chest radiography; 19 entered the IJV (3.3%) and seven the contralateral SCV (1.2%). In all patients who had a misplaced catheter into the ipsilateral IJV, the flush test results were positive, whereas the results were negative in patients who had normally placed catheter or misplaced catheter elsewhere. It was found that the test had 100% sensitivity and specificity to detect misplacement of SCV catheter into the ipsilateral IJV.

Saline flush test is a simple and sensitive bedside test that successfully detects misplaced SCV catheters into ipsilateral IJV.