Epidural pressure changes following caudal blockade: a prospective, observational study.

Purpose: Recent case reports raise the question as to whether anesthetic agents injected into the epidural space could lead to a 'compartment syndrome' and neurovascular sequelae. Single-shot caudal epidural anesthesia has been established as a safe technique, but changes in pressure in the caudal epidural space have not been described. Our aim was to study pressure changes to provide preliminary information for future studies design.

Methods: We prospectively measured the pressure changes in the caudal epidural space in 31 pediatric patients. The pressures were measured at loss of resistance, immediately after the bolus dose of local anesthetic (1 ml/kg), and at 15-s intervals up to 3 min.

Results: The pressure at loss of resistance was 35.6 ± 27.8 mmHg. A pulsatile waveform was observed once the epidural space was accessed. The pressure after administration of the local anesthetic bolus (1 ml/kg 0.2 % ropivacaine/bupivacaine with 1:200,000 epinephrine) was 192.5 ± 93.3 mmHg. The pressure decreased to 51.5 ± 39.0 mmHg at 15 s, 26.9 ± 9.9 mmHg after 2 min, and 24.7 ± 11.7 after 3 min. The return to baseline occurred at approximately 45-60 s.

Conclusions: Following the administration of the local anesthetic into the caudal epidural space, there was a marked, but transient, increase in the pressure within the epidural space. It appears unlikely that a slow epidural catheter infusion could lead to a sustained increase in epidural pressure.