Sensory block duration after spinal anaesthesia supplemented with intravenous dexamethasone: a randomised controlled double-blinded trial.

BACKGROUND: Intravenous dexamethasone prolongs duration of analgesia or sensory block after injection of local anaesthetics close to peripheral nerves by an average of 8 h. Uncertainty remains on the potential increase in the duration of sensory block after spinal anaesthesia. The objective of this randomised controlled double-blinded trial was to investigate whether dexamethasone i.v. prolongs the sensory block of spinal anaesthesia with bupivacaine when compared with a control group. METHODS: Of 50 patients undergoing lower limb osteoarticular surgery under spinal anaesthesia with isobaric bupivacaine 15 mg i.t. with morphine 100 µg i.t. were randomised to receive either dexamethasone 0.15 mg kg-1 i.v. or normal saline 3 ml i.v. The primary outcome was duration of sensory block defined as the time elapsed between injection of the local anaesthetic in the intrathecal space and the regression of sensory block by two dermatomes compared with the highest dermatome blocked. Secondary outcomes included intravenous morphine consumption, pain scores at rest and on movement, postoperative nausea and vomiting, and blood glucose at 2, 24, and 48 h. RESULTS: Median duration of sensory block was 135 (105-225) min in the dexamethasone group and 158 (135-240 min) in the control group (P=0.19). Patients in the dexamethasone group received less morphine at 24 h, had significantly less postoperative nausea and vomiting at 2 h and 24 h, and had increased blood glucose at 24 h. Other secondary outcomes were similar between groups. CONCLUSION: Intravenous dexamethasone did not prolong the sensory block of spinal anaesthesia with isobaric bupivacaine. However, it reduced morphine consumption and rate of postoperative nausea and vomiting at 24 h, at the expense of an increased blood glucose. CLINICAL TRIAL REGISTRATION: NCT03527576 (Clinicaltrials.gov).

Impact of an extrafascial versus intrafascial injection for supraclavicular brachial plexus block on respiratory function: a randomized, controlled, double-blind trial.

INTRODUCTION: Hemidiaphragmatic paresis after ultrasound-guided supraclavicular brachial plexus block is reported to occur in up to 67% of patients. We tested the hypothesis that an injection outside the brachial plexus sheath reduces the incidence of hemidiaphragmatic paresis compared with an intrafascial injection while providing similar analgesia. METHODS: Fifty American Society of Anesthesiologists I-III patients scheduled for elective upper limb surgery received a supraclavicular brachial plexus block using 30 mL of 1:1 mixture of mepivacaine 1% and ropivacaine 0.5%. The block procedures were randomized to position the needle tip either within the brachial plexus after piercing the sheath (intrafascial injection) or outside the brachial plexus sheath (extrafascial injection). The primary outcome was the incidence of hemidiaphragmatic paresis 30 min after the injection, measured by M-mode ultrasonography. Additional outcomes included time to surgery readiness, and resting and dynamic pain scores at 24 hours postoperatively (Numeric Rating Scale, 0-10). RESULTS: The incidence of hemidiaphragmatic paresis 30 min after the injection was 9% (95% CI 1% to 29%) and 0% (95% CI 0% to 15%) in the intrafascial and extrafascial groups respectively (p=0.14). Extrafascial injection was associated with a longer time to surgery readiness (intrafascial: 18 min (95% CI: 16 to 21 min); extrafascial: 37 min (95% CI: 31 to 42 min); p<0.001). At 24 hours, resting and dynamic pain scores were similar between groups. DISCUSSION: Ultrasound-guided supraclavicular brachial plexus block with an extrafascial injection does not reduce the incidence of hemidiaphragmatic paresis although it provides similar analgesia, when compared with an intrafascial injection. The longer time to surgery readiness is less compatible with contemporary operating theater efficiency requirements. TRIAL REGISTRATION NUMBER: NCT03957772.