Contrast enhanced ultrasound as a new tool to estimate the performance of midline catheters in the single patient

Background: Contrast enhanced ultrasound (CEUS) through MicroBubbles Time (MBT) (time from infusion of saline with addition of micro-bubbles of air to visualization of first bubbles in right atrium (RA), visualized by subxiphoid or apical echocardiography) is an alternative to Intracavitary ECG and chest X-ray in evaluation of tip location in central venous catheters. Objective: To evaluate feasibility and variability of CEUS in peripheral catheters (Midline-MC) in a cohort of patients and in a subgroup where tip location was also performed through chest X-ray. Secondary outcomes were verifying the correlation between MBT and distance between tip of MC and RA (anthropometric and radiological measures), body mass index (BMI), vein diameter at point of insertion. Methods: Patients with insertion of MC were enrolled in this prospective cohort. After catheter insertion, CEUS was performed recording MBT. Results: One hundred thirty-two MCs were inserted, 45 performed Chest X-ray. MBT wasn’t feasible in 7 (5%) because of low quality echocardiographic images. Subcostal view was available in 114 patients (91.2%), while 11 patients (8.8%) were examined through apical four-chamber view. Mean MBT in the whole population was 2.3 ± 0.8 s. Significant correlation between anthropometric and radiological measures, BMI and MBT was found. 32.8% of MC had a MBT ⩽2 s. Conclusions: CEUS could be useful to estimate tip position. Our study showed how 2 s is not a suitable cutoff to confirm central catheter’s tip.