Objective: The Fencl-Stewart approach to acid-base physiology allows detailed, quantitative insights into acid-base disorders. We tested the hypothesis that this type of analysis would reveal complex acid-base changes in patients after liver transplantation that differed from those in a general intensive care unit population.
Methods: Data were collected retrospectively on patients on admission to the ICU after liver transplantation between 2001 and 2003 and prospectively on a convenience group of general ICU patients in 2001.
Results: Data were collected from 100 ICU patients and 83 liver transplant patients. Values for most clinical chemistry variables differed between the two groups, with considerable variation within the groups. All acid- base variables differed between the control and transplant groups (P < 0.005). Overall, the transplant group had metabolic acidosis (mean base excess +/-SD, -4.5 +/-3.1mmol/L) due to both a sodium chloride effect on base excess (-4.0 +/-4.1 mmol/L) and an other ion effect on base excess (-6.3 +/-4.2 mmol/L). The sodium chloride effect was mainly due to increased chloride concentration. All estimates of other anions (anion gap, corrected anion gap, strong ion gap, and the other ion effect on base excess) suggested that other anions play an important role in the acid-base status of patients after liver transplantation. These effects on base excess were partly offset by a greater metabolic alkalosis in the transplant group caused by a marked effect of decreased albumin on base excess (5.8 +/-1.5 mmol/L).
Conclusions: The Fencl-Stewart approach allowed us to quantitatively assess the factors contributing to patients' acid-base status. We found complex acid-base changes in patients immediately after liver transplantation.