Peripheral cannulae selection for veno-arterial extracorporeal life support: a paradox

Abstract

Explosive penetration of veno-arterial extracorporeal life support in everyday practice has drawn awareness to complications of peripheral cannulation, resulting in recommendations to use smaller size cannulae. However, using smaller cannulae may limit the effectiveness of extracorporeal support and thereby the specific needs of the patient. Selection of proper size cannulae may therefore pose a dilemma, especially since pressure-flow characteristics at different hematocrits are lacking. This study evaluates the precision of cannula pressure drop prediction with increase of fluid viscosity from water flow-pressure charts by M-number, dynamic similarity law, and via fitted parabolic equation. Thirteen commercially available peripheral cannulae were used in this in vitro study. Pressure drop and flow were recorded using water and a water-glycerol solution as a surrogate for blood, at ambient temperature. Subsequently, pressure-flow curves were modeled with increased fluid viscosity (0.0031 N s m−2), and then compared by M-number, dynamic similarity law, and fitted parabolic equation. The agreement of predicted and measured values were significantly higher when the M-number (concordance correlation = 0.948), and the dynamic similarity law method (concordance correlation = 0.947) was used in comparison to the fitted parabolic equation (concordance correlation = 0.898, p < 0.01). The M-number and dynamic similarity based model allow for reliable prediction of peripheral cannula pressure drop with changes of fluid viscosity and could therefore aid in well-thought-out selection of cannulae for extracorporeal life support.

An Inexpensive Cardiovascular Flow Simulator for Cardiac Catheterization Procedure Using a Pulmonary Artery Catheter

“…We expect that its effect might be negligible for catheterization simulation at the testing stage of the system. However, if blood-like fluid was desired, it is possible to use a mixture of glycerol and water at a ratio aligned with the viscosity of blood which would more precisely mimic physiological hemodynamics and may reveal some valuable information about catheter behavior ( 49 , 50 ).…”

Oxygen debt repayment in the early phase of veno-arterial extracorporeal membrane oxygenation: a cluster analysis

“…One might speculate that if the patients with higher initial total oxygen debt were supported by higher pump flows, oxygen debt repayment would commence at a higher pace. However, there is a paradox during cannula size selection due to cannula restrictions where anatomical considerations and the desired targeted flow rate need to be taken into account, which in turn determines the maximum pump flow rate [34]. Moreover, using larger cannulas in patients with a higher oxygen debt might introduce an increased risk of vascular complications as well as lower limb ischemia [35,36].…”

Understanding lactate and its clearance during extracorporeal membrane oxygenation for supporting refractory cardiogenic shock patients

“…To do so, cardio-respiratory support using ECMO should be initiated timely by using a larger cannula. Often, this is unattainable due to vascular restrictions [ 6 ]. Hence, further studies focusing on the dynamics of oxygen debt repayment rather than solely lactate levels and its clearance will be valuable to understand this complex topic during temporary mechanical circulatory support.…”