Measuring the Efficiency of an Artificial Lung: 1. Carbon Dioxide Transfer

While hypercapnia is typically well treated with modern membrane oxygenators, there are cases where respiratory acidosis persists despite maximal extracorporeal membrane oxygenation support. To better understand the physiology of gas exchange within the membrane oxygenator, CO2 clearance within an adult Maquet Quadrox-iD oxygenator was evaluated at varying blood CO2 tensions and V/Q ratios in an ex vivo extracorporeal membrane oxygenation circuit. A closed blood-primed circuit incorporating two Maquet Quadrox-iD oxygenators in series was attached to a Maquet PLS Rotaflow pump. A varying blend of CO2 and air was connected to the first oxygenator to provide different levels of pre-oxygenator blood CO2 levels (PvCO2) to the second oxygenator. Varying sweep gas flows of 100% O2 were connected to the second oxygenator to provide different V/Q ratios. Exhaust CO2 was directly measured, and then VCO2 and oxygenator dead space fraction (VD/VT) were calculated. VCO2 increased with increasing gas flow rates with plateauing at V/Q ratios greater than 4.0. Exhaust CO2 increased with PvCO2 in a linear fashion with the slope of the line decreasing at high V/Q ratios. Oxygenator dead space fraction varied with V/Q ratio—at lower ratios, dead space fraction was 0.3-0.4 and rose to 0.8-0.9 at ratios greater than 4.0. Within the Maquet Quadrox-iD oxygenator, CO2 clearance is limited at high V/Q ratios and correlated with elevated oxygenator dead space fraction. These findings have important implications for patients requiring high levels of extracorporeal membrane oxygenation support.

show abstract

“…Oxygenator dead space fraction (V D /V T ) was calculated using the formula 16,18 V / V P CO mmHg ExCO mmHg P CO mmHg…”

Section: Discussionmentioning

confidence: 99%

Extracorporeal membrane oxygenation and V/Q ratios: an ex vivo analysis of CO₂ clearance within the Maquet Quadrox-iD oxygenator

2020

View full text Add to dashboard Cite

show abstract

“…Conversely, artificial lungs have a much higher efficiency in clearing venous blood from the CO 2 , with an optimal ventilation/perfusion ratio of around 0.4-0.5. 17 As a consequence, the sweep gas mixture to the artificial lung rarely exceeds 50% of the Qc in the daily clinical practice in order to avoid an excessive CO 2 removal.…”

Section: Vco 2 Assessment In Artificial Lung Ventilating Patients (Cpb)mentioning

confidence: 99%

Carbon dioxide production during cardiopulmonary bypass: pathophysiology, measure and clinical relevance

et al. 2016

View full text Add to dashboard Cite

Carbon dioxide production during cardiopulmonary bypass derives from both the aerobic metabolism and the buffering of lactic acid produced by tissues under anaerobic conditions. Therefore, carbon dioxide removal monitoring is an important measure of the adequacy of perfusion and oxygen delivery. However, routine monitoring of carbon dioxide removal is not widely applied. The present article reviews the main physiological and pathophysiological sources of carbon dioxide, the available techniques to assess carbon dioxide production and removal and the clinically relevant applications of carbon dioxide-related variables as markers of the adequacy of perfusion during cardiopulmonary bypass.

show abstract

“…The appropriate oxygen gas flow rate is reliably given by the blood flow rate. 1,2 This study focused on the control of blood flow and oxygen gas flow at the beginning of CPB, aiming to develop a novel, safe mechanism to prevent the cessation of oxygen insufflation during CPB by synchronizing blood flow to the oxygen gas flow meter. A new system was developed to accomplish this synchronization, 3 and the efficacy of this device was examined using in vitro and animal model experiments.…”

Section: Introductionmentioning

confidence: 99%

A novel measurement and delivery system for synchronizing oxygen gas flow with blood flow during cardiopulmonary bypass

et al. 2013

View full text Add to dashboard Cite

Monitoring the blood pump and the oxygen gas flow meter are important maneuvers at the initiation of cardiopulmonary bypass (CPB). We present a novel system, designed to improve safety in the heart-lung machine by linking the control of blood flow and the oxygen gas flow meter. This system uses a mass flow controller to provide and control oxygen flow based on the ventilation-perfusion (V/Q) ratio, using the electronic signal of the blood flow. We tested the system, in vitro and in vivo, and examined the resulting level of blood oxygenation. When extracorporeal circulation was initiated, the oxygen flow was instantly linked to the circulating blood flow, providing an adequate V/Q ratio; the partial pressure of oxygen in the blood was maintained at a normal level. Although we have yet to confirm the safety of this system in clinical trials, the new safety assist device can automatically supply oxygen to the oxygenator at the beginning of CPB.

show abstract

Measuring the Efficiency of an Artificial Lung: 1. Carbon Dioxide Transfer

Cited by 8 publications

References 9 publications

Extracorporeal membrane oxygenation and V/Q ratios: an ex vivo analysis of CO₂ clearance within the Maquet Quadrox-iD oxygenator

Extracorporeal membrane oxygenation and V/Q ratios: an ex vivo analysis of CO₂ clearance within the Maquet Quadrox-iD oxygenator

Carbon dioxide production during cardiopulmonary bypass: pathophysiology, measure and clinical relevance

A novel measurement and delivery system for synchronizing oxygen gas flow with blood flow during cardiopulmonary bypass

Contact Info

Product

Resources

About

Measuring the Efficiency of an Artificial Lung: 1. Carbon Dioxide Transfer

Cited by 8 publications

References 9 publications

Extracorporeal membrane oxygenation and V/Q ratios: an ex vivo analysis of CO2 clearance within the Maquet Quadrox-iD oxygenator

Extracorporeal membrane oxygenation and V/Q ratios: an ex vivo analysis of CO2 clearance within the Maquet Quadrox-iD oxygenator

Carbon dioxide production during cardiopulmonary bypass: pathophysiology, measure and clinical relevance

A novel measurement and delivery system for synchronizing oxygen gas flow with blood flow during cardiopulmonary bypass

Contact Info

Product

Resources

About

Extracorporeal membrane oxygenation and V/Q ratios: an ex vivo analysis of CO₂ clearance within the Maquet Quadrox-iD oxygenator

Extracorporeal membrane oxygenation and V/Q ratios: an ex vivo analysis of CO₂ clearance within the Maquet Quadrox-iD oxygenator