**5. Predictive factors for hyperlactatemia**

Hyperlactatemia appears in association with peripheral circulatory failure (reduced arterial blood pressure, tachycardia, sweating and mental confusion), with low arterial blood 02 saturation, and with acid base disturbance. Significant hyperlactatemia and dangerous hypoperfusion can exist despite the lack of acidosis. Patients with hyperlactatemia may have variable blood pyruvate concentrations because renal dysfunction, electrolyte abnormalities serum lactate and base deficits may not always be linked due to alterations in the body's buffer base. Also relevant is whether the patients did or did not undergo treatment.

While they may present clinically with normal vital signs and are hemodynamically stable, many surgical patients have increased blood lactate levels ('occult hypoperfusion' or 'compensated shock') (Jansen et al., 2008; Meregalli et al., 2004).
