Its use is likely to improve the speed and accuracy of selection of appropriate patients for transplantation.
King's College Hospital (KCH) selection criteria for emergency liver transplantation in paracetamol-induced acute liver failure are widely used. They include a combination of renal failure, encephalopathy, coagulopathy (blood clotting), or severe acidosis.
However, strategies to improve sensitivity and to facilitate earlier transplantation are required. This is because many patients identified by KCH criteria are too ill for transplantation by the time a suitable graft becomes available.
Julia Wendon and colleagues from Kings College Hospital, London, England, investigated the use of the measurement of arterial blood lactate (a derivative of lactic acid) for the identification of transplantation patients.
The investigators measured blood lactate concentrations early (at 4 hours) and after fluid resuscitation (at 12 hours) in patients admitted to an intensive-care unit.
Threshold values, that best identified individuals likely to die without transplantation, were derived in a retrospective initial sample of 103 patients with paracetamol-induced acute liver failure. These were then applied to a prospective validation sample of 107 patients.
Predictive value and speed of identification were compared with those of the KCH criteria.
In the initial sample, average lactate concentrations were significantly higher in non-surviving patients than in survivors. This was true both in the early samples (8.5 mmol/l compared with 1.4 mmol/l, respectively) and after fluid resuscitation (5.5 mmol/l compared with 1.3 mmol/l).
Blood lactate measurement identified non-surviving transplant patients earlier than KCH criteria.
| Julia Wendon |
When applied to the validation sample, a threshold value of 3.5 mmol/l early after admission had a sensitivity of 67%, and a specificity of 95%.
The combination of early and postresuscitation lactate concentrations had predictive ability similar to the KCH criteria. However, it identified non-surviving patients earlier (4 hours compared with 10 hours).
Dr Wendon comments, "On the basis of this analysis, we propose modification of the KCH criteria to include blood lactate concentrations measured early in the course of and after completion of volume resuscitation.
"We expect that this approach will further improve the speed and accuracy of selection of appropriate candidates for transplantation."