Poster presentation | Open | Published:
Lactate clearance: the earlier the better?
Critical Carevolume 12, Article number: P451 (2008)
In cardiorespiratory failure there is an oxygen-metabolism imbalance mirrored in a timely fashion by a rise in blood lactate associated with a lowering of blood pH. If the therapeutic approach were able to repay this oxygen debt and to restore an adequate blood flow to the lactate-remover organs, effective lactate clearance (LC) should be observed. The study aim was to evaluate whether a short-term (2 hour) LC could be used as a prognostic marker to tailor the therapy in cardiorespiratory insufficiencies.
Ninety-seven consecutive admissions to our emergency department for acute cardiorespiratory insufficiency were included. Exclusion criteria were sepsis, GCS < 8 and need for immediate intubation. Arterial blood gas analysis (BGA) and lactatemia were assessed at emergency department arrival and 2, 6, and 24 hours later. LC was calculated as: [lactate start - lactate 2 hours] × 100/lactate start. The 7-day mortality or orotracheal intubation (negative outcome) versus discharge or downward transfer (positive outcome) was evaluated. A logistic regression model was performed taking into account different risk factors.
Of the 97 patients enrolled (54 females, 43 males; age 76.5 ± 9.6 years; APACHE II score 19.3 ± 4.5), 70.1% had a positive outcome and 29.9% had a negative outcome (7-day mortality 15.5%), 86.2% of patients with negative outcome had LC < 25% versus 17.6% in those with positive outcome. The mean LC in the positive outcome group was 43.6 ± 30.1 versus -12.2 ± 46.9 in that with negative outcome (P < 0.0001). Arterial lactate at 2 hours also correlated with outcome (2.2 ± 0.9 vs 4.7 ± 2.8 mmol/l in positive vs negative outcomes, respectively; P < 0.0001), but when a cutoff value of 25% was used, LC showed a stronger significance (Table 1). LC < 25% had a better specificity than lactate at 2 hours > 2 mmol/l (83.3 vs 73.0%), with higher negative predictive value (93.3 vs 53.3%).
The systematic monitoring of 2-hour LC could be used in cases of acute cardiorespiratory insufficiencies to identify high-risk patients who require more aggressive therapy/monitoring. On the other hand, 2-hour LC > 25% is highly predictive of positive outcome and may confirm the therapeutic approach.