[Prospective research on the prognosis of septic shock based on the change of lactate concentration in arterial blood].

Objective: To evaluate the correlation between the lactate in artery blood and lactate clearance rate and prognosis in patients with septic shock in intensive care unit (ICU).

Methods: Prospectively studied 221 consecutive patients with septic shock from December 2005 to December 2007, the diagnosis of septic shock was made based on the criteria of 2001 ACCP/SCCM. For inclusion in the study, we required admission of the patients within 24 h of septic shock diagnosed. The criteria for exclusion from the study were an age of less than 18 years, pregnancy, serious inadequacy of liver and renal, needing blood purification, or acidosis result of biguanides drugs, or do-not-resuscitate. The eligible patients assigned to early goal-directed therapy. The 6-, 24- and 72-hour lactate clearance rate were calculated, the relationship between the level of lactate, lactate clearance rate, the APACHE II score, the number of failed organ and the 28-day mortality were evaluated.

Results: One hundred and five patients with septic shock were admitted, 74 male and 31 female, the mean age was 70 +/- 12 years. The 28-day mortality was 54.3%. The average APACHE II score at baseline was 20 +/- 8, the number of failed organs was 3.0 +/- 1.1 and the average concentration of lactate in artery blood at baseline was (3.8 +/- 3.6) mmol/L. Significant differences of the lactate at 0-, 6-, 24- and 72-hour were found between death group and survival group. There were 69 patients whose lactate in artery blood at baseline was > 2 mmol/L, 24 survived. The lactate clearance rate of 6- and 24-hour in survival group were significantly higher than death group (P < 0.01, P < 0.05, respectively), but the lactate clearance rate of 72-hour was not (P > 0.05). By using a multivariate logistic regression analysis, it showed that the lactate clearance rate of 6-hour was the independent predictive factor of survival. The area under the receiver operating characteristic curve (ROC) was 0.564, 0.649, 0.754, 0.784, respectively according to the level of the lactate at 0-, 6-, 24-hour and the 6-hour lactate clearance rate. The cutoff of 6-hour lactate clearance rate was >or= 30.0%, resulting in a sensitivity of 60.0% and a specificity of 77.3%.

Conclusions: Dynamic observation of lactate level is very important for the survival in the patients with septic shock. Patients with elevated lactate and not decreased rapidly have a worse outcome. The 6-hour lactate clearance rate might be the indicator for predicting the prognosis of patients with septic shock.