Patients at risk for low systemic oxygen delivery after the Norwood procedure

Background. Identification of patients at risk for inadequate systemic oxyg en delivery following the Norwood procedure could allow for application of more intensive monitoring, provide for earlier intervention of decreased ca rdiac output, and result in improved outcome. Methods and Results. Superior vena cava saturation (SvO(2)) and arterioveno us oxygen content difference were prospectively monitored as indicators of systemic oxygen delivery and recorded hourly for the first 48 hours in 29 o f 33 consecutive patients following the Norwood procedure. Risk factors wer e evaluated using multiple linear regression to determine their impact on S vO(2) and arteriovenous oxygen content difference. Age less than 8 days, we ight less than 2.5 kg, aortic atresia, and prolonged cardiopulmonary bypass time were risk factors for low SvO(2) and wide arteriovenous oxygen conten t difference (p < 0.05). Phenoxybenzamine and increasing time after operati on were associated with higher SvO(2) and narrower arteriovenous oxygen con tent difference (p < 0.05). Thirty-day survival was 97% and hospital surviv al was 94%. The earliest death occurred on postoperative day 20. Survival t o bidirectional cavopulmonary shunt was 77%. Preoperative mechanical ventil ation was the only risk factor identified for late death. Conclusions. Aortic atresia, low weight, younger age, and prolonged cardiop ulmonary bypass, previously identified risk factors for mortality, were ass ociated with decreased SvO(2) and narrower arteriovenous oxygen content dif ference in the early postoperative period. The impact of this hemodynamic v ulnerability on mortality was minimized by continuous SvO(2) monitoring. (C ) 2000 by The Society of Thoracic Surgeons.