Purpose: Partial pressure of carbon dioxide (P-CO2), strong ion difference (SID), and total amount of weak acids independently regulate pH. When blood passes through an extracorporeal membrane lung, P-CO2 decreases. Furthermore, changes in electrolytes, potentially affecting SID, were reported. We analyzed these phenomena according to Stewart's approach. Methods: Couples of measurements of blood entering (venous) and leaving (arterial) the extracorporeal membrane lung were analyzed in 20 patients. Changes in SID, P-CO2, and pH were computed and pH variations in the absence of measured SID variations calculated. Results: Passing from venous to arterial blood, PCO2 was reduced (46.5 +/- 7.7 vs 34.8 +/- 7.4 mm Hg, P < .001), and hemoglobin saturation increased (78 +/- 8 vs 100% +/- 2%, P < .001). Chloride increased, and sodium decreased causing a reduction in SID (38.7 +/- 5.0 vs 36.4 +/- 5.1 mEq/L, P < .001). Analysis of quartiles of Delta P-CO2 revealed progressive increases in chloride (P < .001), reductions in sodium (P < .001), and decreases in SID (P < .001), at constant hemoglobin saturation variation (P = .12). Actual pH variation was lower than pH variations in the absence of measured SID variations (0.09 +/- 0.03 vs 0.12 +/- 0.04, P < .001). Conclusions: When P-CO2 is reduced and oxygen added, several changes in electrolytes occur. These changes cause a P-CO2-dependent SID reduction that, by acidifying plasma, limits pH correction caused by carbon dioxide removal. In this particular setting, P-CO2 and SID are interdependent.

Electrolyte shifts across the artificial lung in patients on extracorporeal membrane oxygenation : interdependence between partial pressure of carbon dioxide and strong ion difference / T. Langer, E. Scotti, E. Carlesso, A. Protti, L. Zani, M. Chierichetti, P. Caironi, L. Gattinoni. - In: JOURNAL OF CRITICAL CARE. - ISSN 0883-9441. - 30:1(2015 Feb), pp. 2-6. [10.1016/j.jcrc.2014.09.013]

Electrolyte shifts across the artificial lung in patients on extracorporeal membrane oxygenation : interdependence between partial pressure of carbon dioxide and strong ion difference

T. Langer;E. Carlesso;A. Protti;L. Zani;M. Chierichetti;P. Caironi;L. Gattinoni
2015-02

Abstract

Purpose: Partial pressure of carbon dioxide (P-CO2), strong ion difference (SID), and total amount of weak acids independently regulate pH. When blood passes through an extracorporeal membrane lung, P-CO2 decreases. Furthermore, changes in electrolytes, potentially affecting SID, were reported. We analyzed these phenomena according to Stewart's approach. Methods: Couples of measurements of blood entering (venous) and leaving (arterial) the extracorporeal membrane lung were analyzed in 20 patients. Changes in SID, P-CO2, and pH were computed and pH variations in the absence of measured SID variations calculated. Results: Passing from venous to arterial blood, PCO2 was reduced (46.5 +/- 7.7 vs 34.8 +/- 7.4 mm Hg, P < .001), and hemoglobin saturation increased (78 +/- 8 vs 100% +/- 2%, P < .001). Chloride increased, and sodium decreased causing a reduction in SID (38.7 +/- 5.0 vs 36.4 +/- 5.1 mEq/L, P < .001). Analysis of quartiles of Delta P-CO2 revealed progressive increases in chloride (P < .001), reductions in sodium (P < .001), and decreases in SID (P < .001), at constant hemoglobin saturation variation (P = .12). Actual pH variation was lower than pH variations in the absence of measured SID variations (0.09 +/- 0.03 vs 0.12 +/- 0.04, P < .001). Conclusions: When P-CO2 is reduced and oxygen added, several changes in electrolytes occur. These changes cause a P-CO2-dependent SID reduction that, by acidifying plasma, limits pH correction caused by carbon dioxide removal. In this particular setting, P-CO2 and SID are interdependent.
Extracorporeal membrane oxygenation; Respiratory failure; Gas exchange; Acid-base equilibrium; Stewart approach; Electrolyte shift
Settore MED/41 - Anestesiologia
22-set-2014
JOURNAL OF CRITICAL CARE
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/243762
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