Anaesthesia
-
We have developed an ultrasound probe through the centre of which an epidural needle can pass, intended to reduce the rate of contact between bone and needle during epidural insertion. We tested the ability of this probe to identify the lumbar interspace, using A-mode ultrasound, in a submerged plastic model, a porcine phantom and five human volunteers. ⋯ The human study also showed that the maximum bone echo was at least three times stronger than the interspace echo. Axial ultrasound guidance, with the needle passing through the probe, offers a method for reducing bone contact during epidural insertion.
-
Hip fracture is the most common orthopaedic emergency. We investigated the concentration of 30 ml levobupivacaine that provided analgesia to 50% and 95% of patients with a hip fracture when injected around the femoral nerve under ultrasound guidance. ⋯ We increased the concentration of levobupivacaine if the preceding dose had been ineffective and decreased it if the preceding dose had been effective. Probit regression modelling estimated the effective (95% CI) concentration of 30 ml levobupivacaine in 50% and 95% of patients with a fractured hip to be 0.026 (0.023-0.028)% w/v and 0.036 (0.027-0.047)% w/v, respectively.