**8. Recommendations - The function of lactate as a warning signal**

Serial lactate monitoring can be used to assess the severity of illness and response to therapy. Although conventional monitoring with blood gases during CPB may detect inadequate tissue oxygenation, blood lactate concentration monitoring during CPB might be more sensitive for detecting an imbalance between oxygen supply and demand. Monitoring alone, however, cannot improve outcome, and the therapeutic plan shares equal importance.

When high blood lactate levels are identified, consideration must be given to the ratio of lactate production to lactate metabolism, oxygen status and blood pH before those levels can be meaningfully interpreted. Normal levels do not exclude and high levels do not confirm the presence of critical illness.

We recommend the administration of additional fluids and the increased use of vasodilators in patients considered as having higher lactate levels. Another recommendation is the perioperative increase of oxygen delivery with dopexamine hydrochloride, in agreement with Boyd et al. (Boyd et al., 1993).

In summary, the combination of serial measurements of postoperative lactate levels after surgical repair for CHD in children assigned to a preoperative risk subgroup was predictive of prognosis after surgery. Lactate levels differed significantly between survivors and nonsurvivors in the same subgroup. This combination should serve as a useful marker for the child's postoperative course, allowing the targeting of appropriately intensive interventions and therapies for the sickest patients. It should be borne in mind, however, that although the measurement of blood lactate level is relatively a low invasive procedure, it is carried out intermittently, whereupon an acute deterioration may be missed. Finally, frequent blood sampling leads to increased blood loss and an increased risk of infection (Chakravarti, Mittnacht, Katz, Nguyen, Joashi and Srivastava 2009).
