Stefano Elli

Background: Peripherally Inserted Central Catheters play an increasingly important role in Central Venous Access Devices. However, the use of these devices should be carefully considered in specific situations such as central catheterisation in patients with chronic kidney disease. When evaluating the feasibility of placement for a patient undergoing dialysis, the relationship between changes in circulating volume before and after dialysis treatment, and potential variations in the size of deep veins in the upper limbs, should be considered. Materials: Upper limb veins, specifically the basilic or brachial veins, were identified and measured before and after dialysis treatment. Patient data and weight loss data during dialysis treatment were also collected. Linear regression analysis was performed to assess the correlation between the variables. Results: The average variation in vein size for the entire sample was +0.17 ± 0.43 mm. The mean volume removed was 2.2 ± 0.8 l. In subgroup 1 (fluid volume loss <2000 ml), the population experienced a decrease in the measured vein size after dialysis. In subgroup 2 (fluid volume loss ⩾2000 ml), the population experienced an increase in the measured vein size after dialysis. Conclusions: Upper arm vascular access placement in dialysed patients with fluid removal of less than 2000 ml should be performed after the dialysis session. Conversely, in dialysed patients with fluid removal of more than 2000 ml, where a significant increase in vein size was observed, vascular access placement should be performed before the dialysis session when the veins are smaller. Additionally, it should be noted that in patients with chronic kidney disease, the venous system of the upper limbs should be preserved as much as possible to prevent thrombosis and stenosis in potential arteriovenous fistula creation.

Introduction: Correct tip positioning is a critical aspect in central vascular access devices insertion. The verification of positioning at the cavo-atrial junction is usually performed by intracavitary electrocardiography. Recently, echocardiographic techniques were proposed, including the direct visualization of the catheter or the visualization of a saline/air bolus (i.e. “bubble test”). As for the latter, a push-to-bubbles delay time below 2 s was proposed to indicate a correct positioning of the catheter tip. The aim of this study was to measure the variations of the push-to-bubbles time at increasing distance from the cavo-atrial junction, to verify if a cut-off of 1–2 s correspond to a well-positioned catheter. Methods: We performed a prospective study including patients with clinical indication of positioning a peripherally inserted central catheter. The catheter tip was positioned at the cavo-atrial junction (P0) via intracavitary electrocardiography, and the push-to-bubbles delay time was measured. The catheter was then retracted 5 cm (P1) and 10 cm (P2), and the test was repeated at this positioning. Push-to-bubbles time measurements were performed off-line by analyzing an audio/video recording which included the echography screen and the voice signal of the operator. Results: Forty-nine patients were included. The average push-to-bubble time when the catheter tip was in the reference position was 0.41 ± 0.21 s. Retraction of the PICC catheter of 5 and 10 cm determined a significant increase of the push-to-bubbles time: mean time difference was +0.34 (95% IC 0.25–0.43, p < 0.001) s between P0 and P1 (5 cm distance), and +0.77 (95% IC 0.62–0.92, p < 0.001) s between P0 and P2 (10 cm distance). When the catheter was at the reference position (i.e. cavo-atrial junction) only 2.1% of bubbles delay times were above 1 s. Conclusion: The push-to-bubbles time is very low when the catheter tip is at the cavo-atrial junction. This delay increases progressively with increasing distance from the target. Push-to-bubbles delay time above 1 s might indicate a catheter not close to the cavo-atrial junction.