The effect of inhaled bronchoconstrictors on transcutaneous gas tensions in normal adult subjects.

The administration of histamine and leukotriene D4 (LTD4) by nebulised aerosol in logarithmically increasing doses to normal subjects resulted in significant bronchoconstriction. Transcutaneous oxygen tension (tcPO2) was monitored during and after the bronchial challenge tests. Following histamine challenge there was significant hypoxaemia in all subjects (mean fall in tcPO2, 20 mmHg). However, following LTD4 administration, there was a small and insignificant fall in tcPO2. Transcutaneous carbon dioxide tension (tcPCO2) was also monitored throughout bronchial challenge, but showed no significant change. We suggest that the hypoxaemia following histamine challenge was due to increased ventilation/perfusion (V/Q) mismatching in the lung induced by histamine deposition.