Intra- and inter-Individual variability in nerve block duration: A randomized cross-over trial in the common peroneal nerve of healthy volunteers

TY - JOUR

T1 - Intra- and inter-Individual variability in nerve block duration

T2 - A randomized cross-over trial in the common peroneal nerve of healthy volunteers

AU - Madsen, Mikkel H.

AU - Christiansen, Claus B.

AU - Mølleskov, Elise

AU - Rothe, Christian

AU - Jensen, Andreas E. K.

AU - Lundstrøm, Lars H.

AU - Lange, Kai H. W.

PY - 2020/3/1

Y1 - 2020/3/1

N2 - Background: The reported variation in nerve block duration is considerable. To individualize nerve block therapy, knowledge of the intra- vs inter-individual variability is essential. We investigated the relative contribution of these 2 parameters to the overall nerve block duration variability. Methods: With ethics committee approval, we conducted a randomized cross-over trial where 20 healthy volunteers received 8 common peroneal nerve blockades with lidocaine 0.5% on 4 consecutive days. Allocations were 5 mL to either the right or left side and 10 mL to the opposite side on day 1 and 2 and vice versa on day 3 and 4. With fixed needle entry and nerve target, we repeated local anaesthetic deposition for each blockade. The primary outcome was variation in duration of sensory nerve block defined as insensitivity to a cold stimulus. Data were analysed using linear mixed model regression. Results: The mean sensory block duration of 380 (95% CI = [342; 418]) minutes on day one was 55 [33; 77] minutes longer than on day two (P <.001), but there were no differences in mean duration between days 2, 3 and 4. The ratios with 2.5; 97.5 percentiles between inter- and intra-individual variation were 2.4 [0.8; 5.2] for the 5 mL blockades and 3.0 [0.9; 6.7] for the 10 mL blockades. The probabilities of inter- to intra-individual variation-ratios >1 were 96% and 97%. Conclusion: The intra-individual variability is a substantially minor contributor to the overall variability in sensory nerve block duration compared with the inter-individual variability.

AB - Background: The reported variation in nerve block duration is considerable. To individualize nerve block therapy, knowledge of the intra- vs inter-individual variability is essential. We investigated the relative contribution of these 2 parameters to the overall nerve block duration variability. Methods: With ethics committee approval, we conducted a randomized cross-over trial where 20 healthy volunteers received 8 common peroneal nerve blockades with lidocaine 0.5% on 4 consecutive days. Allocations were 5 mL to either the right or left side and 10 mL to the opposite side on day 1 and 2 and vice versa on day 3 and 4. With fixed needle entry and nerve target, we repeated local anaesthetic deposition for each blockade. The primary outcome was variation in duration of sensory nerve block defined as insensitivity to a cold stimulus. Data were analysed using linear mixed model regression. Results: The mean sensory block duration of 380 (95% CI = [342; 418]) minutes on day one was 55 [33; 77] minutes longer than on day two (P <.001), but there were no differences in mean duration between days 2, 3 and 4. The ratios with 2.5; 97.5 percentiles between inter- and intra-individual variation were 2.4 [0.8; 5.2] for the 5 mL blockades and 3.0 [0.9; 6.7] for the 10 mL blockades. The probabilities of inter- to intra-individual variation-ratios >1 were 96% and 97%. Conclusion: The intra-individual variability is a substantially minor contributor to the overall variability in sensory nerve block duration compared with the inter-individual variability.

U2 - 10.1111/aas.13512

DO - 10.1111/aas.13512

M3 - Journal article

C2 - 31738448

SN - 0001-5172

JO - Acta Anaesthesiologica Scandinavica

JF - Acta Anaesthesiologica Scandinavica

ER -