Objective Bronchopulmonary dysplasia (BPD) is the most common chronic lung disease in infancy causing substantial morbidity. It is currently graded at 36 weeks according to the need for extra oxygen and/or positive pressure support. We investigated whether the oxygen need was related to ventilation/perfusion abnormalities and if these abnormalities increased relative to an increasing severity score.

Methods We used a quantative single photon emission computed tomography (SPECT) technique to study the regional ventilation/perfusion relationship. Perfusion was mapped with a human albumin-99m tecnetium injection and ventilation by inhalation of a gas containing 99m tecnetium. Previously we have found a good correlation between measured gas exchange and the gas exchange calculated from SPECT.

Results 20 infants were examined with SPECT, chest x ray, echocardiography and lung mechanics at approximately 36 weeks gestational age. Clinical data on respiratory management, sepsis, patent ductus arteriosus, intraventricular haemorrhage were collected (see table).

Conclusion The V/Q ratio correlates well with both the severity score and clinical data. Some patients had a substantionally lower V/Q ratio than expected from the clinical grading, possibly indicating a less favourable outcome and the need for more intensive follow-up. SPECT could therefore be a valuable addition in the grading of BPD.