Anaesthesia
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Randomized Controlled Trial
Volume of ropivacaine 0.2% and common peroneal nerve block duration: a randomised, double-blind cohort trial in healthy volunteers.
The volume-duration relationship using low concentrations of ropivacaine for peripheral nerve blocks is unknown, even though low concentrations of ropivacaine are increasingly used clinically. We investigated the effect of ropivacaine 0.2% on common peroneal nerve block duration. With ethical committee approval, 60 consenting, healthy volunteers were randomly allocated to receive one of five volumes of ropivacaine 0.2% (2.5, 5.0, 10, 15 or 20 ml) administered by ultrasound-guided, catheter-based injection (at 10 ml.min-1 ) near the common peroneal nerve. ⋯ Mean (SD) motor block durations were 3.3 (2.1), 7.2 (2.5), 9.2 (2.2), 12.7 (2.5) and 12.5 (2.5) h. Regression analysis showed that the effect of volume on block duration was progressively smaller with increasing volume, reaching a threshold volume above which there was no effect on nerve block duration (10 ml for sensory block and 15 ml for motor block). We conclude that there is a ceiling effect of increasing volume of ropivacaine 0.2% on both sensory and motor block duration of the common peroneal nerve.
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Randomized Controlled Trial
Effect of a single pre-operative 125 mg dose of methylprednisolone on postoperative delirium in hip fracture patients; a randomised, double-blind, placebo-controlled trial.
Postoperative delirium is common after hip fracture surgery, and may have a neuro-inflammatory cause. We conducted a single-centre, randomised, double-blind, placebo-controlled trial of 117 older hip fracture patients to see if a single, pre-operative intravenous dose of 125 mg methylprednisolone could reduce the severity and/or incidence of postoperative delirium, assessed using the Confusion Assessment Method delirium severity score. Modified intention-to-treat analysis found no significant difference in our primary outcome, median (IQR [range]) cumulative Confusion Assessment Method delirium severity score over the first three postoperative days between the methylprednisolone and placebo groups (1 (0-6 [0-39]) vs. 2 (0-10 [0-32]), p = 0.294). ⋯ There were no significant between-group differences in the rate of completing physiotherapy, postoperative pain, the administration of antipsychotic drugs, infection, length of inpatient stay or 30- and 90-day mortality. No major adverse reactions related to methylprednisolone were recorded. We conclude that a single, pre-operative dose of 125 mg methylprednisolone does not reduce the severity of postoperative delirium, but may reduce both the prevalence of delirium and the severity of fatigue after hip fracture surgery in older patients, enabling remobilisation and recovery.