Midline Catheters as an Alternative for Central Venous Catheters in Venous Pressure Monitoring: A Single Center Experience

Purpose: Midline catheters (ML) are long peripheral intravenous catheters placed in an upper extremity above the antecubital fossa via the basilic, cephalic, or brachial veins. These provide safe and comfortable long-term vascular access for critically ill patients. Central venous pressures (CVP) are obtained from central venous catheters (CVC) and are often used as resuscitation parameters. Given the proximity of ML to the axillary vein, we investigated if midline venous pressure (MVP) is comparable to CVP. Methods: This is an observational study conducted in adult critical care patients at a tertiary academic center. Inclusion criteria were patients with a CVC in the subclavian or internal jugular veins and a ML in place as part of standard ICU care. Pressure measurements were recorded from both catheters every 15 min over a 60-min period. Demographic, clinical, and physiological data points were collected. Continuous variables were analyzed using the t-test. Pearson correlation was used to evaluate the relationship between the paired variables. Results: We enrolled 50 patients with 5 pressure measurements taken per patient (n = 250). The mean MVP and CVP were 10.6 ± 6.4 mm Hg and 9.1 ± 6.3 mm Hg, respectively (P < .001). In Bland Altman analysis, the mean bias was −1.48 ± 3.99 mm Hg with limits of agreement of −9.3 mm Hg to 6.3 mm Hg. The Pearson correlation coefficient was 0.8 (P < .001). Conclusions: Our study investigated MVP as a correlate of CVP. Our results show a mean bias of −1.48 ± 3.99 mm Hg and a strong positive Pearson correlation coefficient of 0.8 between the MVP and the CVP. The large limits of agreement indicate MVP and CVP are not interchangeable. Despite this, clinically significant pressure values from CVCs and MLs trend similarly.