Extracorporeal carbon dioxide removal through ventilation of acidified dialysate: an experimental study.
BACKGROUND
Extracorporeal (EC) carbon dioxide (CO(2)) removal (ECCO(2)R) may be a powerful alternative to ventilation, possibly avoiding the need for mechanical ventilation and endotracheal intubation. We previously reported how an infusion of lactic acid before a membrane lung (ML) effectively enhances ECCO(2)R. We evaluated an innovative ECCO(2)R technique based on ventilation of acidified dialysate.


METHODS
Four swine were sedated, mechanically ventilated, and connected to a venovenous dialysis circuit (blood flow, 250 ml/min). The dialysate was recirculated in a closed loop circuit including a ML (gas flow, 10 liters/min) and then returned to the dialyzer. In each animal, 4 different dialysis flows (DF) of 200, 400, 600, and 800 ml/min were evaluated with and without lactic acid infusion (2.5 mEq/min); the sequence was completed 3 times. At the end of each step, we measured the volume of CO(2)R by the ML (V(co2)ML) and collected blood and dialysate samples for gas analyses.


RESULTS
Acid infusion substantially increased V(co2)ML, from 33 ± 6 ml/min to 86 ± 7 ml/min. Different DFs had little effect on V(co2)ML, which was only slightly reduced at DF 200 ml/min. The partial pressure of CO(2) of blood passing through the dialysis filter changed from 60.9 ± 3.6 to 37.1 ± 4.8 mm Hg without acidification and to 32.5 ± 5.3 mm Hg with acidification, corresponding to a pH increase of 0.18 ± 0.03 and 0.03 ± 0.04 units, respectively.


CONCLUSIONS
Ventilation of acidified dialysate efficiently increased ECCO(2)R of an amount corresponding to 35% to 45% of the total CO(2) production of an adult man from a blood flow as low as 250 ml/min.
Dipartimento di Scienze della Salute, Università di Milano-Bicocca, Ospedale San Gerardo Nuovo dei Tintori, Monza, Milan.
Alberto
A
Zanella
Dipartimento di Scienze della Salute, Università di Milano-Bicocca, Ospedale San Gerardo Nuovo dei Tintori, Monza, Milan.
Paolo
P
Mangili
Dipartimento di Scienze della Salute, Università di Milano-Bicocca, Ospedale San Gerardo Nuovo dei Tintori, Monza, Milan.
Marco
M
Giani
Dipartimento di Scienze della Salute, Università di Milano-Bicocca, Ospedale San Gerardo Nuovo dei Tintori, Monza, Milan.
Sara
S
Redaelli
Dipartimento di Scienze della Salute, Università di Milano-Bicocca, Ospedale San Gerardo Nuovo dei Tintori, Monza, Milan.
Vittorio
V
Scaravilli
Dipartimento di Scienze della Salute, Università di Milano-Bicocca, Ospedale San Gerardo Nuovo dei Tintori, Monza, Milan.
Luigi
L
Castagna
Dipartimento di Scienze della Salute, Università di Milano-Bicocca, Ospedale San Gerardo Nuovo dei Tintori, Monza, Milan.
Simone
S
Sosio
Dipartimento di Patologia animale, Igiene e Sanità Pubblica Veterinaria, sez. di Biochimica e Fisiologia, Università degli studi di Milano, Milan, Italy.
Federica
F
Pirrone
Dipartimento di Patologia animale, Igiene e Sanità Pubblica Veterinaria, sez. di Biochimica e Fisiologia, Università degli studi di Milano, Milan, Italy.
Mariangela
M
Albertini
Dipartimento di Scienze della Salute, Università di Milano-Bicocca, Ospedale San Gerardo Nuovo dei Tintori, Monza, Milan.
Nicolò
N
Patroniti
Dipartimento di Scienze della Salute, Università di Milano-Bicocca, Ospedale San Gerardo Nuovo dei Tintori, Monza, Milan. Electronic address: antonio.pesenti@unimib.it.
Antonio
A
Pesenti
D000818:Animals; D002245:Carbon Dioxide / Q000097:blood*; D015314:Dialysis Solutions / Q000737:chemistry / Q000494:pharmacology*; D004195:Disease Models, Animal; D015199:Extracorporeal Membrane Oxygenation / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D006435:Renal Dialysis / Q000009:adverse effects*; D012121:Respiration, Artificial / Q000379:methods*; D013552:Swine; D055397:Ventilator-Induced Lung Injury / Q000097:blood / Q000628:therapy*
D015314:Dialysis Solutions; D002245:Carbon Dioxide
Extracorporeal circulation; carbon dioxide; extracorporeal membrane oxygenation; ventilator-induced lung injury