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Kidney Week

Abstract: PO1172

Effect of Continuous Dialysis on Blood pH in Acidaemic Hypercapnic Animals with Severe AKI: A Randomized Experimental Study Comparing High vs. Low Bicarbonate Affluent

Session Information

Category: Fluid, Electrolyte, and Acid-Base Disorders

  • 902 Fluid, Electrolyte, and Acid-Base Disorders: Clinical

Author

  • Romano, Thiago Gomes Romano Gomes, Sirio Libanes, research and teach institute, Sao Paulo, SP, Brazil
Background

Controlling blood pH during acute ventilatory failure and hypercapnia in individuals suffering from severe acute kidney injury (AKI) and undergoing continuous renal replacement therapy (CRRT) is of paramount importance in critical care settings. In this situation, the concentration of sodium bicarbonate in dialysate is still an unsolved question in critical care since high concentrations may worsen carbon dioxide levels and low concentrations may not be as effective in controlling pH.

Methods

We performed a randomized, non-blinded, experimental study. AKI was induced in twelve female pigs via renal hilum ligation and hypoventilation by reducing the tidal volume during mechanical ventilation with the goal of achieving a pH between 7.10 - 7.15. After achieving the target pH, animals were randomized to undergo isovolemic haemodialysis with one of two concentrations of bicarbonate dialysate (40 mEq/L [group 40] vs. 20 mEq/L [group 20]).

Results

The haemodynamic, respiratory, and laboratory data were collected. The median pH value at CRRT initiation was 7.14 [7.12, 7.15] in group 20 and 7.13 [7.09, 7.14] in group 40 (P=ns). The median baseline PaCO2 was 74 [72, 81] mmHg in group 20 vs. 79 [63, 85] mmHg in group 40 (P=ns). During the last hour of CRRT, the pH value was 7.05 [6.95, 7.09] in group 20 and 7.12 [7.1, 7.14] in group 40 (P<0.05), with corresponding values of PaCO2 of 85 [79, 88] mmHg vs. 81 [63, 100] mmHg (P=ns). The difference in pH after three hours was due to a metabolic component [standard base excess: -10.4 [-12.5, -9.5] mEq/L in group 20 vs. -7.6 [-9.2, -5.1] mEq/L in group 40) (P<0.05)]. Despite the increased infusion of bicarbonate in group 40, the blood CO2 content did not change during the experiment. The 12-hour survival rate was higher in group 40 (67% vs. 0, p=0.032).

Conclusion

A higher bicarbonate concentration in the dialysate of animals undergoing hypercapnic respiratory failure was associated with improved blood pH control increasing the PaCO2 levels.