Stage 1 palliation of hypoplastic left heart syndrome: implications of blood gases.

OBJECTIVE

To estimate ratios of pulmonary-to-systemic blood flows (Qp/Qs) after stage I palliation (Norwood operation) for hypoplastic left heart syndrome and to determine whether early postoperative death can be associated with abnormalities of Qp/Qs ratios.

DESIGN

Retrospective.

SETTING

University hospital.

PARTICIPANTS

Patients who underwent stage I palliation (Norwood operation) for hypoplastic left heart syndrome (n = 76).

INTERVENTIONS: None.

MEASUREMENTS AND MAIN

RESULTS

The results of the last intraoperative blood gas analysis were compared between patients who survived the day of operation (58 of 76) and the patients who died intraoperatively or within 4 hours after operation (18 of 76). Qp/Qs ratios were calculated using the Fick principle from arterial and venous oxygen saturations at estimated pulmonary venous oxygen saturation of 95%. A lower arterial oxygen saturation (SaO(2), 69.0 +/- 20.5% v 77.3 +/- 8.5%; p < 0.05) and more marked metabolic acidosis (pH, 7.244 +/- 0.115 v 7.298 +/- 0.095; p < 0.05; base excess, -6.8 +/- 4.4 v -3.0 +/- 4.2; p < 0.05) were observed in nonsurvivors. Calculated Qp/Qs ratios ranged between 0.2 and 6.5 in survivors and between 0.6 and 1.9 in nonsurvivors.

CONCLUSIONS

Postoperative excessive pulmonary blood flow was not implicated as a cause of death based on blood gas data and Qp/Qs ratios. In nonsurvivors, low cardiac output and hypoxemia were assumed to be major problems.