Risk factors for occurrence of failed interscalene brachial plexus blocks for shoulder arthroscopy using 20 mL 0.5% ropivacaine: a randomised trial.

Abstract

Adequate pain management after arthroscopic procedures improves patients' satisfaction with the performed procedure, as well as facilitating early rehabilitation. The aim of the current randomised, prospective clinical study was to assess the influence of anthropometric parameters and the interscalene brachial plexus block (IBPB) technique on the quality of post-operational analgesia. 109 randomly selected patients of ASA I-III status were scheduled for elective shoulder arthroscopy. Reasons for non-inclusion were as follows: neurological deficit in the upper arm; allergies to amide Las; coagulopathy; and pregnancy. The patients received 20 mL of 0.5% ropivacaine for an ultrasound (US)-guided IBPB (group U), peripheral nerve stimulation (PNS)-confirmation IBPB (group N), or US-guided, PNS-confirmed IBPB (dual guidance; group NU). We observed that the studied groups did not differ in mean time of sensory and motor block terminations and, surprisingly, in each group in individual cases the sensory block lasted up to 890-990 minutes providing satisfactory long-lasting post-operational analgesia in patients receiving IBPB. We observed a negative correlation between BMI and termination of the motor block and a positive correlation between age and termination of the sensory block in patients receiving US-guided IBPB (group U) in comparison with the two other groups. We found a positive correlation between the male gender and termination of the motor block in patients receiving PNS-guided IBPB (group N) in comparison with two other groups. In our study, patients received satisfactory analgesia in the post-operational period no matter what technique was used regardless of their age, gender or potentially uncommon anthropometry.