Acute ventilatory restriction in children after weaning off inhaled nitricoxide: relation to rebound pulmonary hypertension

Objective: To assess the interaction between pulmonary hemodynamics and res piratory mechanics during acute pulmonary hypertension. Patients: Ventilated and paralysed children treated with inhaled nitric oxi de because of post-operative pulmonary hypertension. Interventions: Weaning of inhaled nitric oxide. Measurements: Air now and airway pressure, calculation of dynamic respirato ry system compliance and respiratory system resistance for each breath by m ultiple linear regression. Results: In four patients, increases in pulmonary arterial pressure from 26 .1 to 56.7 mmg (p < 0.001) during weaning off nitric oxide were associated with decreases in tidal volume (from 9.7 --> 8.2 ml/kg, p < 0.01) and reduc tions in dynamic respiratory system compliance (from 0.52 --> 0.34 cmH(2)0/ ml/kg, p < 0.001). while respiratory system resistance was unchanged. Conclusions: Impaired ventilation during acute pulmonary hypertension is pr edominantly related to a reduction in respiratory system compliance.