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Intravenous sildenafil and inhaled nitric oxide: a randomised trial in infants after cardiac surgery

  • Neonatal and Pediatric Intensive Care
  • Published:
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To investigate the acute effects of intravenous sildenafil on haemodynamics and oxygenation, and its interaction with inhaled nitric oxide (iNO) in infants at risk of pulmonary hypertension early after cardiac surgery.


Prospective, randomised trial.


Paediatric intensive care unit of a children’s hospital.

Patients and participants

Sixteen ventilated infants early after closure of ventricular or atrioventricular septal defects, were randomly assigned to one of two groups. The study was completed in 15 infants.


Studies were commenced within 7 h of separation from bypass. Seven infants received iNO (20 ppm) first, with the addition of intravenous sildenafil (0.35 mg/kg over 20 min) after 20 min. Eight infants received sildenafil first, iNO was added after 20 min. Vascular pressures, cardiac output and a blood gas were recorded at 0, 20 and 40 min.

Measurements and results

In infants receiving iNO first, iNO lowered the pulmonary vascular resistance index (PVRI) from 3.45 to 2.95 units (p=0.01); sildenafil further reduced PVRI to 2.45 units (p<0.05). In those receiving sildenafil first, PVRI was reduced from 2.84 to 2.35 units (p<0.05) with sildenafil, and fell to 2.15 units (p=0.01) with the addition of iNO. In both groups, sildenafil reduced the systemic blood pressure and systemic vascular resistance (p<0.01) and worsened arterial oxygenation and the alveolar-arterial gradient (p<0.05).


Intravenous sildenafil augmented the pulmonary vasodilator effects of iNO in infants early after cardiac surgery. However, sildenafil produced systemic hypotension and impaired oxygenation, which was not improved by iNO.

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We would like to thank Dr Robert Henning, Consultant in Intensive Care, and the ICU technologists Brad Carter, Mark Hochmann and Tony Osborne for their technical support with this project. We are also indebted to Kay Hines, Pharmacy, for her help with the randomisation process and preparation of sildenafil. We are also grateful to Pfizer Pharmaceuticals (Sydney) for supplying the intravenous sildenafil and for providing financial support which made this study possible.

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Correspondence to Daniel J. Penny.

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Stocker, C., Penny, D.J., Brizard, C.P. et al. Intravenous sildenafil and inhaled nitric oxide: a randomised trial in infants after cardiac surgery. Intensive Care Med 29, 1996–2003 (2003).

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