Abstract
Extracorporeal membrane oxygenation (ECMO) has gained renewed interest in the treatment of respiratory failure since the advent of the modern polymethylpentene membranes. Limited information exists, however, on the performance of these membranes in terms of gas transfers during multiple organ failure (MOF). We investigated determinants of oxygen and carbon dioxide transfer as well as biochemical alterations after the circulation of blood through the circuit in a pig model under ECMO support before and after induction of MOF. A predefined sequence of blood and sweep flows was tested before and after the induction of MOF with fecal peritonitis and saline lavage lung injury. In the multivariate analysis, oxygen transfer had a positive association with blood flow (slope = 66, P<0.001) and a negative association with pre-membrane PaCO2 (slope = −0.96, P = 0.001) and SatO2 (slope = −1.7, P<0.001). Carbon dioxide transfer had a positive association with blood flow (slope = 17, P<0.001), gas flow (slope = 33, P<0.001), pre-membrane PaCO2 (slope = 1.2, P<0.001) and a negative association with the hemoglobin (slope = −3.478, P = 0.042). We found an increase in pH in the baseline from 7.50[7.46,7.54] to 7.60[7.55,7.65] (P<0.001), and during the MOF from 7.19[6.92,7.32] to 7.41[7.13,7.5] (P<0.001). Likewise, the PCO2 fell in the baseline from 35 [32,39] to 25 [22,27] mmHg (P<0.001), and during the MOF from 59 [47,91] to 34 [28,45] mmHg (P<0.001). In conclusion, both oxygen and carbon dioxide transfers were significantly determined by blood flow. Oxygen transfer was modulated by the pre-membrane SatO2 and CO2, while carbon dioxide transfer was affected by the gas flow, pre-membrane CO2 and hemoglobin.
Highlights
Extracorporeal membrane oxygenation (ECMO) has been successfully used to support patients with severe acute respiratory failure associated with refractory hypoxemia or uncompensated hypercapnia. [1,2,3,4] The choice of the ECMO settings depends on whether oxygenation or CO2 removal is the main indication of extracorporeal support
Data on the baseline hemodynamics, respiratory variables, and support measures collected at baseline and just before the second sequence of data collection are described in table 1
We found an increase in the pH in the post-membrane blood, a slight reduction in the ionized calcium value and a rise in the chloride concentration after the passage of blood through the membrane
Summary
Extracorporeal membrane oxygenation (ECMO) has been successfully used to support patients with severe acute respiratory failure associated with refractory hypoxemia or uncompensated hypercapnia. [1,2,3,4] The choice of the ECMO settings depends on whether oxygenation or CO2 removal is the main indication of extracorporeal support. The concept that blood flow affects the transfer of oxygen and CO2, and sweep (gas) flow, that of CO2 [5] is supported by evidence in healthy animals using a spiral coiled rubber silicone membrane. [6] There is, limited information about the main determinants of oxygen and carbon dioxide transfer during ECMO using the modern polymethylpentene membrane in subjects with multiple organ failure (MOF). [9] Some of the ECMO-associated electrolyte disturbances can be clinically significant. They can be associated with hemodynamic depression [11] and can affect the electrolyte clearance of renal replacement therapy when the blood is drained from the post-membrane ECMO circuit. They can be associated with hemodynamic depression [11] and can affect the electrolyte clearance of renal replacement therapy when the blood is drained from the post-membrane ECMO circuit. [12] An adequate characterization of these post membrane alterations is of potential clinical importance and has not been carried out so far
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