Practice patterns in neonatal cardiopulmonary bypass

Single-Shot Cold Histidine-Tryptophan-Ketoglutarate Cardioplegia for Long Aortic Cross-Clamping Durations in Neonates

OBJECTIVE

More than 30% of European pediatric cardiac surgery centers use single-dose cold histidine-tryptophan-ketoglutarate cardioplegia (Custodiol; Dr Franz Köhler Chemie GmbH, Bensheim, Germany). In neonates with transposition of the great arteries, arterial switch surgery (ASO) implies aortic division, and it is unknown whether repeated ostial cannulation causes intimal insult and affects long-term results, and therefore, single-dose Custodiol is appealing. The present study investigated the association among myocardial no-flow duration, postoperative troponins, and postoperative outcomes in neonates undergoing ASO with Custodiol cardioplegia.

DESIGN

Retrospective analysis of the association among myocardial no-flow duration, postoperative troponin release (concentration magnitude × measurement duration within 48 h), and outcomes using stratification according to coronary anatomy and attending surgeon.

SETTING

Single-institutional, tertiary pediatric cardiac surgery unit of a university hospital.

PARTICIPANTS

The study comprised 101 neonates undergoing ASO.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The mean age of patients was 6.1 ± 5.4 days, the cardiopulmonary bypass duration was 108.7 ± 54.1 minutes, the temperature during cross-clamping was 31.1°C ± 1.7°C, the duration of mechanical ventilation was 4 (3-6) days, the length of intensive care unit stay was 7 (5-8) days, delayed sternal closure occurred in 32 (31.7%) patients, and no patients died. The myocardial no-flow duration averaged 62.3 ± 14.6 minutes and was linked with both troponin release (p = 0.04) and low cardiac output syndrome, as assessed by the requirement for delayed sternal closure (p = 0.03), regardless of cardiopulmonary bypass duration and temperature. Eighty-two percent of the patients with myocardial no-flow duration >74 minutes necessitated delayed sternal closure.

CONCLUSIONS

Single-dose Custodiol may be inadequate for prolonged cross-clamping durations without myocardial perfusion in neonates.

Comparison of hollow-fiber membrane oxygenators in terms of pressure drop of the membranes during normothermic and hypothermic cardiopulmonary bypass in neonates

The objective of this study was to investigate the effects of two hollow-fiber membrane oxygenators, the Capiox SX10 and the Lilliput 901, on pressure drop of the membranes during normothermic and hypothermic cardiopulmonary bypass (CPB) in neonates.

Methods: Twenty-six congenital heart surgery patients (n=13 in each group) with a mean weight of 3 kg were included in this study. Pressure drops of the membranes, pre- and post-oxygenator extracorporeal circuit pressures (ECC) were recorded during normothermic CPB, hypothermic CPB (208C) and after rewarming. There were no differences between the groups in mean arterial pressure, pump flow rate, temperature, duration of CPB, cross- clamp time or the severity of the surgical repairs.

Results: Pressure drop of the Capiox SX10 oxygenator was significantly lower during normothermic (329/10 versus 559/16 mmHg, p B/0.001), hypothermic (389/15 versus 729/18 mmHg, p B/0.001) and post-rewarming (429/13 versus 729/21 mmHg, p B/0.001) periods compared to the Lilliput oxygenator. In the Capiox group, the pre-oxygenator ECC pressure was also significantly lower during normothermic CPB (1429/27 versus 1849/43 mmHg, p B/0.01), hypothermic CPB (1629/30 versus 1999/38 mmHg, p B/0.01) and after rewarming periods (1729/32 versus 2129/42 mmHg, p B/0.01). Post-oxygenator pressures in the Capiox group were also lower than in the Lilliput group, but results were not statistically significant.

Conclusions: These results suggest that the Capiox SX10 hollow-fiber membrane oxygenator produced significantly lower membrane pressure drops and pre- and post-oxygenator ECC during normothermic and hypothermic CPB. Thus, blood trauma with the Capiox during extracorporeal circulation may be significantly lower compared to the Lilliput. Further studies, including the level of complements, platelets, neutrophils and cytokines, with these oxygenators are warranted.

Comparison of parameters for detection of splanchnic hypoxia in children undergoing cardiopulmonary bypass with pulsatile versus nonpulsatile normothermia or hypothermia during congenital heart surgeries

The aim of this study is to evaluate gastric mucosal oxygenation together with whole-body oxygen changes in infants undergoing congenital heart surgery with cardiopulmonary bypass (CPB) procedure and the use of either pulsatile or nonpulsatile mode of perfusion with normothermia and pulsatile or nonpulsatile moderate hypothermia. Sixty infants undergoing congenital cardiac surgery were randomized into four groups as: nonpulsatile normothermia CPB (NNCPB, n = 15), pulsatile normothermia CPB (PNCPB, n = 15), nonpulsatile moderate hypothermia CPB (NHCPB, n = 15), and pulsatile moderate hypothermia CPB (PHCPB, n = 15) groups. In NNCPB and PNCPB groups, mild hypothermia was used (35°C), whereas in NHCPB and PHCPB groups, moderate hypothermia (28°C) was used. Gastric intramucosal pH (pHi), whole-body oxygen delivery (DO(2)) and consumption (VO(2)), and whole-body oxygen extraction fraction were measured at sequential time points intraoperatively and up to 2 h postoperatively. The measurement of continuous tonometry data was collected at desired intervals. The values of DO(2), VO(2), and whole-body oxygen extraction fraction were not different between groups before CPB and during CPB, whereas the PNCPB group showed higher values of DO(2), VO(2), and whole-body oxygen extraction fraction compared to the other groups at the measurement levels of 20 and 60 min after aortic cross clamp, end of CPB, and 2 h after CPB (P < 0.0001). Between groups, no difference was observed for pHi, lactate, and cardiac index values (P > 0.05). This study shows that the use of normothermic pulsatile perfusion (35°C) provides better gastric mucosal oxygenation as compared to other perfusion strategies in neonates and infants undergoing congenital heart surgery with CPB procedures.

Randomized comparison between mild and moderate hypothermic cardiopulmonary bypass for neonatal arterial switch operation

OBJECTIVES

To compare neonates receiving arterial switch operation (ASO) either with mild or moderate hypothermic cardiopulmonary bypass.

METHODS

Forty neonates undergoing ASO were randomized to receive either mild (Mi > 32 °C, n = 20) or moderate (Mo > 26 °C, n = 20) hypothermic cardiopulmonary bypass (CPB) between April 2007 and June 2010. All patients were diagnosed with simple transposition of the great arteries. Mean age (Mi: 8.32 ± 4.5 days, Mo: 7.54 ± 5.0 days, P = 0.21) and body weight were similar in both groups (Mi: 3.64 ± 0.91 kg, Mo: 3.73 ± 0.84 kg, P = 0.14). Follow-up was 3.1 ± 2.5 years for all patients.

RESULTS

Lowest perioperative rectal temperature was 33.5 ± 1.4 °C (Mi) versus 28.2 ± 2.1 °C (Mo) (P < 0.001). All patients safely weaned from CPB required lower doses of dopamine (Mi: 5.1 ± 2.4 µg/kg min, Mo: 6.5 ± 2.1 µ/kg min, P = 0.04), dobutamine (Mi: 7.2 ± 2.5 µg/kg min, Mo: 8.6 ± 2.4 µ/kg min, P = 0.04) and adrenalin (Mi: 0.02 ± 0.02 µg/kg min, Mo: 0.05 ± 0.03 µ/kg min, P = 0.03) in mild hypothermia group. Intraoperative blood transfusion (Mi: 190 ± 58 ml, Mo: 230 ± 24 ml, P = 0.03) and postoperative lactate levels (Mi: 2.7 ± 0.9 mmol/l, Mo: 3.1 ± 2.2 mmol/l, P = 0.02) were lower under mild hypothermia. Secondary chest closure was performed in 30% (Mi) versus 35% (Mo) (P = 0.65). Duration of inotropic support (Mi: 7 (4-11) days, Mo: 11 (7-15) days, P = 0.03), time to extubation (Mi: 108 (88-128) h, Mo: 128 (102-210) h, P = 0.04), lengths of intensive care unit (ICU) stay (Mi: 9 (5-14) days, Mo: 12 (10-18) days, P = 0.04) and hospital stay (Mi: 19 (10-29) days, Mo: 23 (15-37) days, P = 0.04) were significantly shorter under mild hypothermia. Two-year freedom from reoperation was 100% for both the groups.

CONCLUSIONS

The ASO under mild hypothermia seemed to be beneficial for pulmonary recovery, need for inotropic support and length of ICU and hospital stay. No worse early- or intermediate-term effects of mild hypothermia were found.

Perioperative hypothermia: use and therapeutic implications

Perioperative cerebral ischemic insults are common in some surgical procedures. The notion that induced hypothermia can be employed to improve outcome in surgical patients has persisted for six decades. Its principal application has been in the context of cardiothoracic and neurosurgery. Mild (32-35 degrees C) and moderate (26-31 degrees C) hypothermia have been utilized for numerous procedures involving the heart, but intensive research has found little or no benefit to outcome. This may, in part, be attributable to confounding effects associated with rewarming and lack of understanding of the mechanisms of injury. Evidence of efficacy of mild hypothermia is absent for cerebral aneurysm clipping and carotid endarterectomy. Deep hypothermia (18-25 degrees C) during circulatory arrest has been practiced in the repair of congenital heart disease, adult thoracic aortas, and giant intracranial aneurysms. There is little doubt of the protective efficacy of deep hypothermia, but continued efforts to refine its application may serve to enhance its utility. Recent evidence that mild hypothermia is efficacious in out-of-hospital cardiac arrest has implications for patients incurring anoxic or global ischemic brain insults during anesthesia and surgery, or perioperatively. Advances in preclinical models of ischemic/anoxic injury and cardiopulmonary bypass that allow definition of optimal cooling strategies and study of cellular and subcellular events during perioperative ischemia can add to our understanding of mechanisms of hypothermia efficacy and provide a rationale basis for its implementation in humans.

Central cannulation in pediatric cardiac surgery

The present paper describes the cannulation techniques which are used routinely in our institution. They are established on two basic principles: most operations are performed under full-flow normothermic cardiopulmonary bypass (CPB); deep hypothermic circulatory arrest is avoided. When full-flow conventional CPB is used, cannulation of the ascending aorta and both venae cavae is usually required and should be performed with great caution (with institution of partial bypass as soon as possible) to provide hemodynamic stability during the cannulation process. Additional cannulations and/or technical modifications may be necessary to accommodate frequent associated anomalies (left superior vena cava, systemic or pulmonary venous return anomalies, multiple reoperations). In children requiring aortic arch repair, moderate hypothermia, circulatory arrest and selective cerebral perfusion are used and require specific techniques for arterial cannulation.