Preoperative lung function in newborn infants with univentricular hearts compared with healthy controls

Aim: To measure the difference in lung function between newborns with univentricular hearts and healthy controls and study associations between lung function and pulmonary blood flow and pulmonary vasculature markings. Method: Tidal flow‐volume measurements and single occlusion tests were performed before surgery on 25 unsedated spontaneously breathing newborns with univentricular hearts recruited over a 3‐year period. Seventy‐five healthy control infants were measured. Pulmonary blood flow was graded according to the haemodynamic effect of the echocardiographically defined anatomy of the heart defect. Pulmonary vasculature was graded according to radiological markings. Results: The infants with univentricular hearts had a lower mean tidal volume of 4.7 ml (CI 2.3, 7.2, p < 0.001) (n = 24) and a lower mean compliance of the respiratory system of 12.7 ml/kPa (CI 4.6, 20.8, p = 0.004) (n = 14). Pulmonary blood flow grading was associated with respiratory rate (r = 0.53, p < 0.001), tidal volume (r =–0.48, p < 0.001), compliance (r =–0.55, p < 0.001) and resistance (r =–0.31, p = 0.043). Pulmonary vasculature grading was associated with compliance (r =–0.68, p = 0.006), resistance (r =–0.69, p = 0.007) and the time constant (r =–0.62, p = 0.042). Conclusion: Newborns with univentricular hearts have reduced tidal volumes and reduced compliance of the respiratory system. The lung function abnormalities are associated with the degree of pulmonary blood flow and pulmonary vasculature markings.