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 mm Hg (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 cm H20/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.