Hemi-diaphragmatic paresis following extrafascial versus conventional intrafascial approach for interscalene brachial plexus block: A double-blind randomised, controlled trial

BACKGROUND AND AIMS: Hemidiaphragmatic paresis occurs in almost all patients undergoing interscalene block for proximal upper limb surgeries. This study tested hypothesis that ultrasound-guided extrafascial approach of interscalene block under nerve stimulator guidance reduces incidence of hemidiaphragmatic paresis in comparison to intrafascial approach by achieving same degree of anaesthesia and analgesia. METHODS: Sixty patients undergoing proximal upper limb surgeries were randomised to receive an ultrasound-guided interscalene brachial plexus block (ISB) with the aid of nerve stimulator for surgical anaesthesia and analgesia using 20 mL 0.5% ropivacaine by extrafascial (Group E) or intrafascial (Group I) approach. The incidence of hemidiaphragmatic paresis was measured by M-mode ultrasound before and 30 min after the procedure. Secondary outcomes such as respiratory functions (forced vital capacity, forced expiratory volume in 1 s and peak expiratory flow rate) were measured, and complications were recorded and compared. The statistics was obtained using SPSS Version 19. Levene's test and paired and unpaired t-test were used. P value <0.05 was considered significant. RESULTS: The incidence of hemidiaphragmatic paresis was 17% and 46% in Group E and Group I, respectively (P < 0.0001). All other respiratory outcomes were preserved in Group E compared with Group I. CONCLUSION: Ultrasound-guided ISB with the aid of nerve stimulator through extrafascial approach reduces the incidence of hemidiaphragmatic paresis and also reduces respiratory function impairment when compared with intrafascial approach.