Continuous positive airway pressure breathing increases cranial spread of sensory blockade after cervicothoracic epidural injection of lidocaine.

Abstract

BACKGROUND: Continuous positive airway pressure (CPAP) increases the caudad spread of sensory blockade after low-thoracic epidural injection of lidocaine. We hypothesized that CPAP would increase cephalad spread of blockade after cervicothoracic epidural injection. METHODS: Twenty patients with an epidural catheter at the C6-7 or C7-T1 interspace received an epidural dose of lidocaine while breathing at ambient pressure (control group), or while breathing with 7.5 cm H2O CPAP. After injection, we evaluated the spread of sensory blockade. Spirometry variables before and after epidural injection were also measured. RESULTS: Data are presented as median (interquartile range) values. Sensory block ranged from C7 (C4-7) to T4 (T4-6) in the control group and from C2 (C2-4) to T4 (T2-5) in the CPAP group (P = 0.003 for the cranial border). The total number of segments blocked was 7.5 (6.8-9.8) in the control group and 10 (8-12) in the CPAP group (P = 0.13). The number of segments blocked cranial to the injection site was one (0.8-3.5) in the control group and five (3.5-7) in the CPAP group (P = 0.006). The number of patients with a maximal cranial block (up to C2) was one in the control group and seven in the CPAP group (P = 0.02). In both groups, there was a small but significant decrease from baseline in spirometry values, with no differences between groups. CONCLUSION: Applying CPAP during cervicothoracic epidural injection of lidocaine resulted in a more cranial extension of sensory blockade when compared with breathing at ambient pressure.