Figure 2. Dose-related increases in duration of tolerance (A) to transcutaneous electrical stimulation (TES) at the knee (L3 dermatome) equivalent to surgical stimulation (bupivacaine, R2= 0.90; P < 0.0001; ropivacaine, R2= 0.63; P < 0.0001) and (B) to pneumatic thigh tourniquet at 300 psi (bupivacaine, R2= 0.89; P < 0.0001; ropivacaine, R2= 0.77; P < 0.0001). Mean and 95% confidence intervals of the slope of linear regression are plotted for bupivacaine and ropivacaine. For all doses, n = 6.