Effects on membrane lung gas exchange of an intermittent high gas flow recruitment maneuver: preliminary data in veno-venous ECMO patients

Castagna, Luigi; Zanella, Alberto; Scaravilli, Vittorio; Magni, Federico; Deab, Salua Abd El Aziz El Sayed; Introna, Michele; Mojoli, Francesco; Grasselli, Giacomo; Pesenti, Antonio; Patroniti, Nicolò

doi:10.1007/s10047-015-0831-3

Cited by 14 publications

(14 citation statements)

References 19 publications

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“…The assumption of predominantly perfusion limited gas exchange is unlikely to result in major inaccuracy during vv-ECMO, providing a suitable oxygenator is used. Oxygenator performance deteriorates with time, due to deposition of protein and clot formation on the surface exposed to blood, and water accumulation on the surface exposed to gas [ 22 ]. With long-term use, the findings of the model may become less applicable as the oxygenator performance deteriorates.…”

Section: Discussionmentioning

confidence: 99%

“…The model does not include a dead space compartment in the oxygenator. Castagna et al studied oxygenators after several days of vv-ECMO (4.0 days, IQR 2.0–8) and found of 47.8 ± 15.3 (mean ± sd) [ 22 ]. This finding fits the clinical observation that the sweep gas flow rate required to maintain normocapnia often gradually increases during an ECMO run.…”

Section: Discussionmentioning

confidence: 99%

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A mathematical model of CO2, O2 and N2 exchange during venovenous extracorporeal membrane oxygenation

Joyce

Shekar

Cook

2018

ICMx

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BackgroundVenovenous extracorporeal membrane oxygenation (vv-ECMO) is an effective treatment for severe respiratory failure. The interaction between the cardiorespiratory system and the oxygenator can be explored with mathematical models. Understanding the physiology will help the clinician optimise therapy. As others have examined O2 exchange, the main focus of this study was on CO2 exchange.MethodsA model of the cardiorespiratory system during vv-ECMO was developed, incorporating O2, CO2 and N2 exchange in both the lung and the oxygenator. We modelled lungs with shunt fractions varying from 0 to 1, covering the plausible range from normal lung to severe acute respiratory distress syndrome. The effects on PaCO2 of varying the input parameters for the cardiorespiratory system and for the oxygenator were examined.ResultsPaCO2 increased as the shunt fraction in the lung and metabolic CO2 production rose. Changes in haemoglobin and FIO2 had minimal effect on PaCO2. The effect of cardiac output on PaCO2 was variable, depending on the shunt fraction in the lung.PaCO2 decreased as extracorporeal circuit blood flow was increased, but the changes were relatively small in the range used clinically for vv-ECMO of > 2 l/min. PaCO2 decreased as gas flow to the oxygenator rose and increased with recirculation. The oxygen fraction of gas flow to the oxygenator had minimal effect on PaCO2.ConclusionsThis mathematical model of gas exchange during vv-ECMO found that the main determinants of PaCO2 during vv-ECMO were pulmonary shunt fraction, metabolic CO2 production, gas flow to the oxygenator and extracorporeal circuit recirculation.Electronic supplementary materialThe online version of this article (10.1186/s40635-018-0183-4) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

A mathematical model of CO2, O2 and N2 exchange during venovenous extracorporeal membrane oxygenation

Joyce

Shekar

Cook

2018

ICMx

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“…. 14 Our results suggest the effect of F CO sweep 2 on P a CO 2 can be simply predicted, with reasonable accuracy. Addition of CO 2 to the sweep gas reduces the in P a CO 2 that occurs as V sweep is increased.…”

Section: Discussionmentioning

confidence: 99%

What Determines the Arterial Partial Pressure of Carbon Dioxide on Venovenous Extracorporeal Membrane Oxygenation?

et al. 2021

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Rapid reductions in P a CO 2 during extracorporeal membrane oxygenation (ECMO) are associated with poor neurologic outcomes. Understanding what factors determine P a CO 2 may allow a gradual reduction, potentially improving neurologic outcome. A simple and intuitive arithmetic expression was developed, to describe the interactions between the major factors determining P a CO 2 during venovenous ECMO.This expression was tested using a wide range of input parameters from clinically feasible scenarios. The difference between P a CO 2 predicted by the arithmetic equation and P a CO 2 predicted by a more robust and complex in-silico mathematical model, was <10 mm Hg for more than 95% of the scenarios tested. With no CO 2 in the sweep gas, P a CO 2 is proportional to metabolic CO 2 production and inversely proportional to the "total effective expired ventilation" (sum of alveolar ventilation and oxygenator ventilation). Extracorporeal blood flow has a small effect on P a CO 2 , which becomes more important at low blood flows and high recirculation fractions. With CO 2 in the sweep gas, the increase in P a CO 2 is proportional to the concentration of CO 2 administered. P a CO 2 also depends on the fraction of the total effective expired ventilation provided via the oxygenator. This relationship offers a simple intervention to control P a CO 2 using titration of CO 2 in the sweep gas.

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“…The infrared capnometer sampler must not impose great resistance in order to avoid pressure increase in the ML. A correct measurement can be obtained after at least 30 seconds of purge with high GF (10 L/min) in order to get rid of excessive moisture, as condensation and water vapour when trapped into hollow-fibers reduce ML decarboxylation capacity (20). V'CO 2 ML power is directly proportional to GF, as in the NL CO 2 elimination (V'CO 2 NL), which is proportional to alveolar ventilation.…”

Section: Carbon Dioxide Removalmentioning

confidence: 99%

Oxygenator performance and artificial-native lung interaction

Epis

Belliato

2018

J. Thorac. Dis.

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During extracorporeal membrane oxygenation (ECMO), oxygen (O) transfer (V'O) and carbon dioxide (CO) removal (V'CO) are partitioned between the native lung (NL) and the membrane lung (ML), related to the patient's metabolic-hemodynamic pattern. The ML could be assimilated to a NL both in a physiological and a pathological way. ML O transfer (V'OML) is proportional to extracorporeal blood flow and the difference in O content between each ML side, while ML CO removal (V'COML) can be calculated from ML gas flow and CO concentration at sweep gas outlet. Therefore, it is possible to calculate the ML gas exchange efficiency. Due to the ML aging process, pseudomembranous deposits on the ML fibers may completely impede gas exchange, causing a "shunt effect", significantly correlated to V'OML decay. Clot formation around fibers determines a ventilated but not perfused compartment, with a "dead space effect", negatively influencing V'COML. Monitoring both shunt and dead space effects might be helpful to recognise ML function decline. Since ML failure is a common mechanical complication, its monitoring is critical for right ML replacement timing and it also important to understand the ECMO system performance level and for guiding the weaning procedure. ML and NL gas exchange data are usually obtained by non-continuous measurements that may fail to be timely detected in critical situations. A real-time ECMO circuit monitoring system therefore might have a significant clinical impact to improve safety, adding relevant clinical information. In our clinical practise, the integration of a real-time monitoring system with a set of standard measurements and samplings contributes to improve the safety of the procedure with a more timely and precise analysis of ECMO functioning. Moreover, an accurate analysis of NL status is fundamental in clinical setting, in order to understand the complex ECMO-patient interaction, with a multi-dimensional approach.

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Effects on membrane lung gas exchange of an intermittent high gas flow recruitment maneuver: preliminary data in veno-venous ECMO patients

Cited by 14 publications

References 19 publications

A mathematical model of CO2, O2 and N2 exchange during venovenous extracorporeal membrane oxygenation

A mathematical model of CO2, O2 and N2 exchange during venovenous extracorporeal membrane oxygenation

What Determines the Arterial Partial Pressure of Carbon Dioxide on Venovenous Extracorporeal Membrane Oxygenation?

Oxygenator performance and artificial-native lung interaction

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