Pressure drop across common LV vent catheters

Abstract

Purpose

This study examined the pressure drop across several LV vent catheters commonly used in adult and pediatric cardiac surgery to identify optimal vent catheters for different flows that may be required based on patient and surgical specific factors.

Methods

In an experimental set up, 5 sizes of Medtronic DLP Left Heart vent catheters (10Fr, 13Fr, 15Fr, 18Fr, and 20Fr) were tested using a blood analogous solution. Flow was increased incrementally by either 5 or 10 RPMs on a roller pump and measured using a non-invasive flow sensor. Pressures were measured before and after the vent catheters and pressure drop across the catheter (ΔP) was recorded for each. Trials were done with and without a Quest Medical VRV-II safe vacuum relief valve in the circuit. This was all performed under temperature regulation at normothermia (37°C) and moderate hypothermia (28°C).

Results

All vent catheters tested demonstrated a steady decline in pressure with increased flow. For all catheters, with and without vent vacuum relief valves (VRVs), a less negative pressure gradient was achieved at 37°C compared to 28°C at a given flow. Graphs were created for each vent catheter to aid in selection for a variety of patients.

Conclusion

Larger Medtronic DLP Left Heart vent catheters provide a lesser pressure drop for a given flow compared to a smaller catheter. Additionally, a greater flow may be achieved with a larger catheter before the VRV opens. VRVs should be used with left heart vent catheters as inclusion does not typically affect vent catheter performance.