Abstract
We assessed the effectiveness of inhaled nitric oxide (NO) in two patients, of six and two months of age, who developed severe pulmonary hypertension after corrective cardiac surgery for a complete atrioventricular canal. In the post-op period, attempts to wean the patients from ventilatory support resulted in marked increase of pulmonary arterial pressure (PAP) to suprasystemic levels, with severe desaturation and metabolic acidosis. Two life-threatening episodes did need cardiac resuscitation in the second patient. Short administrations of inhaled NO, at 30 parts per million (ppm), dramatically reduced the PAP to about half the systemic values in the first patient (systemic arterial pressure (SAP)=35/24 and PAP=44/33 before NO, and SAP=58/38 with PAP=31/19 after five minutes of NO treatment), while in the second patient NO showed a slower effect on PAP, but an immediate improvement of hemodynamics. Thus, continuous inhaled NO, at 10-50 ppm, was administered through the ventilator, with good clinical response. Electrochemical analysis provided on line monitoring of NO and nitrogen dioxide (NO2) concentrations. NO2 did not exceed 1.6 ppm. Inhaled NO was tapered to the minimal effective concentration able to maintain low pulmonary pressures and normal oxygenation. Treatment with NO was stopped after 55 and 62 hours, respectively. No complications were noted. Met hemoglobin levels ranged between 0.7-1.2% in case 1, and 0.1-5.1% in case 2. In the latter case, methemoglobin was directly correlated with NO concentration levels. Weaning was successful in both cases, with extubation performed on day 29 and day 17 post-op, respectively.
CONCLUSIONS: Inhaled nitric oxide at concentrations of 10-50 ppm exerts a potent dilatory effect on pulmonary vascular bed in children with congenital heart disease who present pulmonary hypertension after surgical correction. Although toxicity by NO and NO2 seems to be negligible at these dosages, continuous on-line gas monitoring is recommended.
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Biban, P., Milanesi, O., Stellin, G. et al. 360 EFFECTIVENESS OF INHALED NITRIC OXIDE ON LIFE-THREATENING PULMONARY HYPERTENSION AFTER CARDIAC SURGERY. Pediatr Res 36, 62 (1994). https://doi.org/10.1203/00006450-199407000-00360
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DOI: https://doi.org/10.1203/00006450-199407000-00360
