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

Objective: To assess the interaction between pulmonary hemodynamics and respiratory mechanics during acute pulmonary hypertension. Patients: Ventilated and paralysed children treated with inhaled nitric oxide because of post-operative pulmonary hypertension. Interventions: Weaning of inhaled nitric oxide. Measurements: Air flow and airway pressure, calculation of dynamic respiratory system compliance and respiratory system resistance for each breath by multiple 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 reductions in dynamic respiratory system compliance (from 0.52 → 0.34 cmH₂0/ml/kg, p < 0.001), while respiratory system resistance was unchanged. Conclusions: Impaired ventilation during acute pulmonary hypertension is predominantly related to a reduction in respiratory system compliance. Received: 26 March 1998 Final revision received: 9 June 1998 Accepted: 30 July 1998