Background:
Children requiring cardiac surgery with cardiopulmonary bypass (CPB) frequently develop Low Cardiac Output Syndrome (LCOS), particularly when very young, A pilot study of 16 children by Checchia et al. (2013) showed that the delivery of nitric oxide (NO) to the CPB circuit shortened duration of mechanical ventilation and ICU stay. We hypothesized that administering NO to oxygenator gas flow during CPB would decrease the incidence of LCOS and effect subsequent clinical outcomes.
Methods:
We conducted a prospective, blinded, randomized controlled trial in children with congenital heart disease having surgery with CPB. Randomization was stratified by age and ‘blocked’ at six in each group. Children received oxygen alone or 20 ppm gaseous NO and oxygen to the CPB gas administration line. Only the study perfusionist was aware of the allocation and all equipment and devices were otherwise identical in each group; in particular the cardiac surgeon and anesthetist remained blinded to patient allocation.
Results:
198 children were enrolled following written consent. There were no differences in patient characteristics, diagnoses or surgeries between groups. 101 children received NO and had a significant reduction in LCOS (14% vs 31%, p=0.004), use of ECMO (1% vs 8%, p=0.014) and a non-significant reduction in ICU length of stay (48hrs vs 72hrs, p=0.111), compared to the 97 children who did not receive NO. The reduction in LCOS was most pronounced in children less than 6 weeks of age (20% vs 52%, p=0.012) and in those aged 6 weeks to 2 years (6% vs 24%, p=0.026), who also had significantly reduced ICU length of stay (43hrs vs 84hrs, p=0.031). LCOS occurred equally between groups in children greater than 2 years of age (17% vs 21%, p=0.678). There was no difference in the amount of post-operative bleeding in any age group. Children greater than 2 years of age who received NO required fewer blood transfusions (8.3% vs 24.1%, p=0.096).
Conclusions:
Delivery of NO to the CPB circuit for children undergoing cardiac surgery significantly reduces the incidence of LCOS, use of ECMO and ICU length of stay by varying degrees, according to age group.