engleski

Comparison of minimum effective volume of local anesthetic for ultrasound guided supraclavicular block (MEAV95) in elderly and middle aged patients

The aim of this study was to determine the minimum effective volume of local anesthetic (LA) required to produce an efficient supraclavicular block in 95% of patients (MEAV95) using an ultrasound (US)- guided technique in an elderly (>65 y) and a middle aged group (<45 y) of patients. Furthermore, we aimed to calculate potency ratio of LA between the groups. We assumed a reduced MEAV95 in elderly group. Fourty-four patients (N=22 per group) undergoing upper limb surgery received a US- guided supraclavicular block. The study method is a previously validated step-up/step-down sequential model where the volume of LA for each following patient is determined according to the outcome of the previous block. The starting volume was 30 mL ; in the case of block failure, the volume was increased by 5 ml. After successful block, the volume was reduced by 5 mL. MEAV95 was calculated using probit transformation and logistic regression. Potency ratio of LA is calculated using Fieller’s method. The calculated minimum effective anesthetic volume in 95% of patients was 16.49 mL (95% CI, 12.23–20.75 mL) in elderly and 44.52 mL (95% CI, 19.05– 69.99 mL) in middle aged group (95% CI, 0.7–55.3 mL, P=0.044). A potency ratio of LA between middle aged and elderly is 2.69 (95% CI 2.13 to 3.44). The minimum volume requirement for effective US-guided supraclavicular block in 95% of elderly patients was significantly reduced. A potency ratio of 2.69 indicates almost three times stronger LA potency in the elderly.

Supraclavicular brachial plexus block ; Local anaesthetic

nije evidentirano