Preoperative and postoperative response to inhaled nitric oxide

The preoperative dose response to inhaled nitric oxide (NO) was compared wi th the need for and response to NO after cardiac surgery in patients with c ongenital heart defect and secondary pulmonary hypertension. In a preoperat ive vasodilator test with inhaled NO 20, 40 and 80 ppm and oxygen, mean pul monary artery pressure (BAP) was at least 40 mmHg and/or the pulmonary vasc ular resistance index (PVRI) 4 Wood units. Preoperatively, NO 40 ppm and Fi 0(2) 0.9 reduced systolic pulmonary/systemic arterial pressure (PAPs/SAP(s) ) from 0.89 (SD 0.10) to 0.80 (0.18) and pulmonary/systemic vascular resist ance (PVR/SVR) from 0.26 (0.13) to 0.13 (0.08). Haemodynamic assessment was repeated in 11 patients post operatively, NO treatment was starred if PAP( s)/SAP(s) rose to 0.8 or the pulmonary oximetry fell below 40%. Postoperati vely, eight of II patients, including 6 patients with Down's syndrome, need ed NO. PAP(s)/SAP(s) decreased more than preoperatively: 48.5% vs 11.2, p = 0.0045. Pulmonary oximetry increased by 15.7%, p = 0.02. The degree of pre operative response to NO did not differ between the patients with postopera tive pulmonary hypertension and the other children. Patients with early pul monary hypertensive crisis (first 24 h; n = 6) had a higher PVRI (7.6 vs 4. 4 Um(2); p = 0.003) and PVR/SVR (0.34 VS 0.17; p = 0.02) preoperatively. Tw o patients died in pulmonary hypertensive crisis.