Carbon dioxide overload: the neglected caveat of renal replacement therapy.
Marco Marano, Maria Rosaria Clinc
3 June 2015
If renal replacement therapy are offered as support to AKI as well as to multiple organ failure, I am quite surprised to find no notice of dialysis bath, because it could be a source of carbon dioxide (CO2), not a negligible issue [1].
In such fluid a buffer has the obvious role to support metabolic derangement, but an acid inevitably exists - and this is not so intuitive - to avoid salts precipitation. The chemical reaction between the acid and the buffer generates CO2 which ultimately acidifies dialysis fluid and keeps salts in their soluble form. As largely expected by physical properties, CO2 easy crosses the filtering membrane and flows in patient’s bloodstream [2,3,4].
Severely ill patients and those with cardio-pulmonary marginal status should withstand the CO2 overload from dialysate. This is not an academic caveat because extracorporeal CO2 removal can be offered in series with RRT, as underlined by the authors. Also, and above all, acetate-free biofiltration - a buffer-free technique with sodium bicarbonate reinfusion - does not return to the patient unphysiological amount of carbon dioxide as other dialysis techniques possibly do [4]. Evidences to support this technique as treatment of choice to prevent CO2 overload in critically ill patients are lacking, and in my opinion this conjecture deserves further researches, however this neglected and unwanted effect must kept in mind in the choice of kind and dose of RRT.
References
Golper TA, Fissel R, Fissel WH, Hartle M, Sanders ML, Schulman G: Hemodialysis: core curriculum 2014. Am J Kidney Dis 2014;63(1):153-163
Sombolos KI, Bamichas GI, Christidou FN Gionanlis LD, Karagianni AC, Anagnostopoulos TC, Natse TA: pO2 and pCO2 increment in post-dialyzer blood: the role of dialysate. Artif Organs 2005;29:892-8
Symreng T, Flanigan MJ, Lim VS: Ventilatory and metabolic changes during high efficiency hemodialysis. Kidney Int 1992;41:1064-9
Marano M, D'Amato A, Patriarca A, Di Nuzzi LM, Giordano G, Iulianiello G. Carbon Dioxide and Acetate-Free Biofiltration: A Relationship to be Investigated. Artif Organs. 2015 May 1. doi: 10.1111/aor.12477
Critical Care
Carbon dioxide overload: the neglected caveat of renal replacement therapy.
3 June 2015
If renal replacement therapy are offered as support to AKI as well as to multiple organ failure, I am quite surprised to find no notice of dialysis bath, because it could be a source of carbon dioxide (CO2), not a negligible issue [1].
In such fluid a buffer has the obvious role to support metabolic derangement, but an acid inevitably exists - and this is not so intuitive - to avoid salts precipitation. The chemical reaction between the acid and the buffer generates CO2 which ultimately acidifies dialysis fluid and keeps salts in their soluble form. As largely expected by physical properties, CO2 easy crosses the filtering membrane and flows in patient’s bloodstream [2,3,4].
Severely ill patients and those with cardio-pulmonary marginal status should withstand the CO2 overload from dialysate. This is not an academic caveat because extracorporeal CO2 removal can be offered in series with RRT, as underlined by the authors. Also, and above all, acetate-free biofiltration - a buffer-free technique with sodium bicarbonate reinfusion - does not return to the patient unphysiological amount of carbon dioxide as other dialysis techniques possibly do [4]. Evidences to support this technique as treatment of choice to prevent CO2 overload in critically ill patients are lacking, and in my opinion this conjecture deserves further researches, however this neglected and unwanted effect must kept in mind in the choice of kind and dose of RRT.
References
Competing interests
The Author declares no conflict of interest