Measurement of intercostal and pleural pressures by epidural catheter

The pressures in the intercostal and interpleural spaces were measured in 20 patients using an 18 gauge epidural catheter to confirm accurate catheter positioning for continuous intercostal and interpleural local anaesthetic blockade. In the intercostal space the mean (SD) pressure was negative (-1.8 (0.3)) mmHg and positive (+2.1 (0.3)) mmHg at the end of inspiration and expiration respectively. In contrast, in the interpleural space although the pressure varied with the respiratory cycle it remained negative both at the end of inspiration (-8.3 (1.0)) mmHg and expiration (-2.1 (0.8)) mmHg. We conclude that measurement of intercostal and interpleural pressures with an epidural catheter is a straightforward procedure which may be helpful in confirming accurate catheter placement for continuous intercostal or interpleural local anaesthetic blockade.