TY - JOUR
T1 - Optimal volume of local anaesthetic for the adductor canal block
T2 - Using the continual reassessment method to estimate the ED95
AU - Jæger, P.
AU - Jenstrup, M. T.
AU - Lund, J.
AU - Siersma, Volkert Dirk
AU - Brøndum, V.
AU - Hilsted, K. L.
AU - Dahl, J. B.
PY - 2015/12/1
Y1 - 2015/12/1
N2 - Background: Theoretically, the ideal volume of local anaesthetic for adductor canal block (ACB) would ensure sufficient filling of the canal and avoid proximal spread to the femoral triangle. In this dose-finding study, we aimed to investigate the minimal effective volume for an ACB needed to fill the adductor canal distally in at least 95% of patients (ED95). Methods: We performed a blinded trial, enrolling 40 healthy men. All subjects received an ACB with lidocaine 1%. Volumes were assigned sequentially to the subjects using the continual reassessment method followed by Bayesian analysis to determine the ED95. Distal filling of the adductor canal was assessed by magnetic resonance imaging (primary outcome). Secondary outcomes were the effect of volume on proximal spread to the femoral triangle (also assessed by magnetic resonance imaging), quadriceps muscle weakness (decrease by ≥25% from baseline) and sensory block. Results: The ED95 was 20 ml, with an estimated probability of sufficiently filling the canal of 95.1% (95% credibility interval: 0.91-0.98). Proximal spread to the femoral triangle was seen in 0/4 (0%), 7/12 (58%), 4/8 (50%), and 8/16 (50%) subjects with the 5, 10, 15, and 20 ml doses, respectively (P=0.25). Seven subjects had a reduction in muscle strength, but there was no difference between groups (P=0.85). Conclusions: For an ACB, the dose closest to the ED95 needed to fill the adductor canal distally was 20 ml. There was no significant correlation between volume and proximal spread or muscle strength.
AB - Background: Theoretically, the ideal volume of local anaesthetic for adductor canal block (ACB) would ensure sufficient filling of the canal and avoid proximal spread to the femoral triangle. In this dose-finding study, we aimed to investigate the minimal effective volume for an ACB needed to fill the adductor canal distally in at least 95% of patients (ED95). Methods: We performed a blinded trial, enrolling 40 healthy men. All subjects received an ACB with lidocaine 1%. Volumes were assigned sequentially to the subjects using the continual reassessment method followed by Bayesian analysis to determine the ED95. Distal filling of the adductor canal was assessed by magnetic resonance imaging (primary outcome). Secondary outcomes were the effect of volume on proximal spread to the femoral triangle (also assessed by magnetic resonance imaging), quadriceps muscle weakness (decrease by ≥25% from baseline) and sensory block. Results: The ED95 was 20 ml, with an estimated probability of sufficiently filling the canal of 95.1% (95% credibility interval: 0.91-0.98). Proximal spread to the femoral triangle was seen in 0/4 (0%), 7/12 (58%), 4/8 (50%), and 8/16 (50%) subjects with the 5, 10, 15, and 20 ml doses, respectively (P=0.25). Seven subjects had a reduction in muscle strength, but there was no difference between groups (P=0.85). Conclusions: For an ACB, the dose closest to the ED95 needed to fill the adductor canal distally was 20 ml. There was no significant correlation between volume and proximal spread or muscle strength.
U2 - 10.1093/bja/aev362
DO - 10.1093/bja/aev362
M3 - Journal article
C2 - 26582853
SN - 0007-0912
VL - 115
SP - 920
EP - 926
JO - British Journal of Anaesthesia
JF - British Journal of Anaesthesia
IS - 6
ER -