Regional ventilation and perfusion in patients with status asthmaticus. Chapter 15

The 81Krsup(m) ventilation technique has been used for assessing regional ventilation of six patients in status asthmaticus, and after the administration of bronchodilators. A 99Tcsup(m) perfusion scan was also performed on two of the patients. Standard chest radiographs taken during status asthmaticus showed large volume lungs and generalized oligaemia, without detecting regional alteration in the lung fields. 81Krsup(m) scans, on the contrary, showed not only an increase in lung volume (compared with scans obtained during the remission phase), but also the presence of multiple areas of reduced ventilation in both lungs. These areas had a characteristic segmental, sub-segmental or lobar appearance, as best demonstrated on the lateral views. In the two patients studied with both 81Krsup(m) and 99Tcsup(m) microspheres, regional perfusion was also found to be grossly abnormal. Following bronchodilators, an immediate reduction in lung volume and a more homogeneous distribution of regional ventilation were observed. A progressively more uniform distribution of both ventilation and perfusion was noticed during follow-up: after three weeks of treatment both ventilation and perfusion scans were either normal or showed minor abnormalities. (author)