**7. Treatment of postoperative hyperlactatemia after pediatric cardiac surgery**

Poor outcome was associated with multi-organ involvement, as reflected by high blood lactate values, and the need for ventilatory or inotropic support. The therapy for type A hyperlactatemia is optimal hemodynamic resuscitation combined with supportive treatment, such as alkalinization, thiamine, dialysis, and dichloroacetate (Mizock 1989).

Serum lactate best predicted major adverse events for values greater than 8 mmol/L (>72 mg/dL) with a low sensitivity (73.7%), a high specificity (96.3%) and a low positive predictive value (63.6%) in high risk cases (Seear et al., 2008). The ratio of central venous oxygen sampling (Scv02, measured in %) per lactate (measured in mmol/L) had a better predictive value for major adverse events than each individual value measured alone (if the value of the ratio fell below 5 at any time after surgery, the positive predictive value for

The length of time it took for serum lactate levels to reach normal values was a useful predictor of mortality in children undergoing repair or palliation of CHD under CPB, while initial and peak lactate levels had a poor positive predictive value for mortality in that retrospective study (Kalyanaraman et al., 2008). Hyperlactatemia was described as the only predictor of persistent renal impairment at 48 hours at the time of admission to the intensive care unit was the admission blood lactate level (p = 0.018) (Duke et al., 1997). The odds ratio for renal impairment was 3.2 (with a confidence interval of 1.1 to 9.5) for patients whose admission lactate level was greater than 4 mmol/L (36 mg/dL) (Duke et al., 1997). According to the results of a retrospective review of children aged 0-21 years who had been admitted to a cardiac ICU, the length of time during which the lactate level remained greater than 2 mmol/L (18 mg/dL) was associated with the number of ventilator days and hospital days for the survivors. They all had surgery for CHD and required CPB (DeCampli &

The lactate level was also considered as being a risk factor for cerebral damage, which was defined as the development of seizures, movement disorders, developmental disorders, cerebral hemorrhage, infarction, hydrocephalus, or marked cerebral atrophy in children

Measurements of blood lactate reflect oxygen delivery to tissues and, therefore, are useful in guiding clinical management. Levels of serum lactate are indirect markers of tissue hypoxia secondary to insufficient peripheral oxygen delivery. They have been used to monitor progress after pediatric heart surgery and to report positive predictive values (Duke et al.,

Lactate levels differed significantly between survivors and non-survivors even within the same preoperative prognosis subgroup. As such, a combination of preoperative scores and postoperative serial lactate measurements is needed in order to serve as a useful marker for the postoperative course of cardiac patients, allowing the targeting of appropriately intensive interventions and therapies for the sickest among them, especially for the apparently low risk groups whose poorer perioperative course and worse outcome may not have been predictable from the preoperative scores alone. A cutoff threshold of 3 mmol/L (27 mg/dL) at ICU admission will identify a subpopulation of patients at higher

**7. Treatment of postoperative hyperlactatemia after pediatric cardiac surgery**  Poor outcome was associated with multi-organ involvement, as reflected by high blood lactate values, and the need for ventilatory or inotropic support. The therapy for type A hyperlactatemia is optimal hemodynamic resuscitation combined with supportive treatment, such as alkalinization, thiamine, dialysis, and dichloroacetate (Mizock 1989).

major adverse events was above 90%).

Burke, 2009; Kalyanaraman et al., 2008).

1997; Hatherill et al., 2000; Munoz et al., 2000).

**6.3 Summary** 

postoperative risk.

after they had undergone cardiac surgery (Trittenwein et al., 2003).

Resuscitation of surgical patients has traditionally been guided by the normalization of vital signs, e.g., blood pressure, urine output, and heart rate. A goal-oriented protocol targeting a normal blood lactate level can shorten the length of hospitalization among cardiac surgical patients (Polonen et al., 2000). Polonen et al. showed that therapy aimed at achieving an Sv02 level greater than 70% and a lactate concentration less than 2 mmol/L (18 mg/dL) immediately after cardiac surgery improves outcome. Specifically, early monitoring of lactate levels with the added target to reduce levels by 20%/2 hours on top of currently recommended resuscitation guidelines significantly reduced the length of ICU stay of patients with a lactate level at or above 3.0 mmol/L on admission (Jansen et al., 2010). The deliberate increasing of peri- and postoperative oxygen delivery (D02I) for the guided postoperative therapy which decreased mortality by 75%, was monitored by lactate levels, and that maneuver was maintained in the protocol group until blood lactate levels had fallen below 1.5 mmol/L (13.5 mg/dL) for 2 consecutive measurements (Boyd et al., 1993).

Early postoperative supply of oxygen improved the outcome during the early stages of surgery-related sepsis in cases of late postoperative hyperlactatemia. This was accomplished by the administration of D02I and by the use of intravenous dopexamine, a novel dopamine analogue with action at b2-adrenoceptors and DA1 receptors.

Dichloroacetate enhanced the activity of pyruvate dehydrogenase and lowered blood lactate concentrations in these septic patients but had no effect on hemodynamics or survival (Stacpoole et al., 1994).
