**4. The prevalence and incidence of postoperative hyperlactatemia**

#### **The prevalence and incidence of postoperative hyperlactatemia after pediatric cardiac surgery**

An increase in serum lactate reflects anaerobic metabolism, and this yardstick has been used in many studies of postoperative management in congenital heart defects (CHD) as a predictor of adverse outcome, given that an elevated serum lactate is common at the time of ICU admission after surgical correction of CHD.

Postoperative hyperlactatemia was seen in 38% of a cohort of 68 patients who underwent isolated atrial septal defect repair at Arkansas Children's Hospital between January 2001 and March 2006 (Abraham et al., 2010).

Our previous studies and validated data of a clinical database encompassing all the consecutive children who underwent surgery for CHD between 1999 and 2001 at the Sheba Medical Center, revealed a prevalence of 41% (89 out of 215 patients) of hyperlactatemia on pediatric cardiac critical-care unit (PCCU) admission, and of 49% in the last blood lactate level taken at the operating room post-CHD repair (our unpublished data). The prevalence declined to 27% and 17% at 6 and 12 hours, respectively, post-PCCU admission after CHD repair. Moreover the mean initial postoperative lactate level was significantly lower for survivors (42.2 ±32.0 mg/dL) than for nonsurvivors (85.4 ± 54.1 mg/dL) (p<0.01) (Molina Hazan et al., 2010).

In another study in which 23 pediatric non-cyanotic patients were included, lactate was measured at 0, 2, 4, 6, and 24 hours after admission to the pediatric intensive care unit (PICU), and more often if clinically indicated (Chakravarti et al., 2009). A total of 163 lactate measurements were recorded, of which 18% had a value greater than 3 mmol/L (27 mg/dL).

#### **The prevalence and incidence of postoperative hyperlactatemia in adults**

Maillet et al. (2003) found immediate postoperative hyperlactatemia in 20.6% patients, and early postoperative hyperlactatemia in 17.2% patients among 325 patients following coronary heart disease repair. Hyperlactatemia was observed in a substantial proportion of patients who had been operated on under extracorporeal circulation in a Russian study which included 270 patients after cardiac surgery (Bakanov et al., 2009).

Ranucci et al. (2006) reported the rate of patients with hyperlactatemia during cardiopulmonary bypass (CPB) as being relatively low (5.7%) when they measured

is a relationship between rS02 measured at various body locations by near-infrared spectroscopy and blood lactate level in children after cardiac surgery (Chakravarti et al.,

Hyperlactatemia may be physiologic or pathologic. It can be caused by increased lactate production (i.e., an increase in the rate of glycolysis or unregulated substrate entry into

Common causes for type A hyperlactatemia include intense exercise or hypoxemia, anemia, systemic or regional hypoperfusion, shock, CO poisoning and impaired liver blood flow

glycolysis) as well as a decrease in its clearance (i.e., liver or renal insufficiency).

**4. The prevalence and incidence of postoperative hyperlactatemia** 

**The prevalence and incidence of postoperative hyperlactatemia after pediatric cardiac** 

An increase in serum lactate reflects anaerobic metabolism, and this yardstick has been used in many studies of postoperative management in congenital heart defects (CHD) as a predictor of adverse outcome, given that an elevated serum lactate is common at the time of

Postoperative hyperlactatemia was seen in 38% of a cohort of 68 patients who underwent isolated atrial septal defect repair at Arkansas Children's Hospital between January 2001

Our previous studies and validated data of a clinical database encompassing all the consecutive children who underwent surgery for CHD between 1999 and 2001 at the Sheba Medical Center, revealed a prevalence of 41% (89 out of 215 patients) of hyperlactatemia on pediatric cardiac critical-care unit (PCCU) admission, and of 49% in the last blood lactate level taken at the operating room post-CHD repair (our unpublished data). The prevalence declined to 27% and 17% at 6 and 12 hours, respectively, post-PCCU admission after CHD repair. Moreover the mean initial postoperative lactate level was significantly lower for survivors (42.2 ±32.0 mg/dL) than for nonsurvivors (85.4 ± 54.1 mg/dL) (p<0.01) (Molina

In another study in which 23 pediatric non-cyanotic patients were included, lactate was measured at 0, 2, 4, 6, and 24 hours after admission to the pediatric intensive care unit (PICU), and more often if clinically indicated (Chakravarti et al., 2009). A total of 163 lactate measurements were recorded, of which 18% had a value greater than 3 mmol/L (27

Maillet et al. (2003) found immediate postoperative hyperlactatemia in 20.6% patients, and early postoperative hyperlactatemia in 17.2% patients among 325 patients following coronary heart disease repair. Hyperlactatemia was observed in a substantial proportion of patients who had been operated on under extracorporeal circulation in a Russian study

Ranucci et al. (2006) reported the rate of patients with hyperlactatemia during cardiopulmonary bypass (CPB) as being relatively low (5.7%) when they measured

**The prevalence and incidence of postoperative hyperlactatemia in adults** 

which included 270 patients after cardiac surgery (Bakanov et al., 2009).

below 25%. This type is more common in postoperative patients.

ICU admission after surgical correction of CHD.

and March 2006 (Abraham et al., 2010).

2009).

**surgery** 

Hazan et al., 2010).

mg/dL).

**3.3 Summary** 

progressive hyperlactatemia during the procedure (excluding 30 patients who had preexisting hyperlactatemia). The overall incidence of hyperlactatemia was 11.4%. Non-preexisting hyperlactatemia during CPB for cardiac operations in adults occurred in approximately 6% of the patients.

O'Connor and Fraser's (2010) single-center review of prospectively collated data from 529 post-cardiac surgical patients in a tertiary Australian cardiac surgical ICU showed 25% late hyperlactatemia (above 2.5 mmol/L [23 mg / dL]).

Demers et al. (2000) reported higher rates: they recorded peak blood lactate levels of 4.0 mmol/L (36 mg/dL) or higher during CPB in 18.0% of their patients
