The bubble study: ultrasound confirmation of central venous catheter placement

The objective was to determine if ultrasound (US) can more rapidly confirm central venous catheter (CVC) position in comparison to chest radiography (CXR) in the emergency department.

The study included a convenience sample of emergency department patients with supradiaphragmatic CVCs and a CXR for confirmation. Ultrasound was used for CVC confirmation by visualizing microbubble artifact in the right atrium after injection of saline through the distal port. To evaluate for pneumothorax (PTX), "sliding sign" of the pleura was noted on US of the anterior chest. Blinded chart review was performed to assess CXR timing, catheter position and CVC complications. Student's t test was used to compare US time to CXR performance time and radiologist reading time.

Fifty patients were enrolled; 4 were excluded because of inadequate views. Forty-six patients were included in the final analysis. Mean total US time was 5.0 minutes (95% confidence interval [CI], 4.2-5.9) compared to 28.2 minutes (95% CI, 16.8-39.4) for CXR performance with a mean difference of 23.1 minutes (95% CI, -34.5 to -11.8; P < .0002). When comparing only US CVC confirmation time to CXR time, US was an average of 24.0 minutes (95% CI, -35.4 to -12.7; P < .0001) faster. Comparing total US time to radiologist CXR reading time, US was an average of 294 minutes faster (95% CI, -384.5 to -203.5; P < .0000). There were a total of 3 misplaced lines and 2 patients with PTX, all of which were identified correctly on US.

Ultrasound can confirm CVC placement and rule out PTX significantly faster than CXR, expediting the use of CVCs in the critically ill.