Twelve right-handed patients drove 18 miles under baseline conditions and completed various parking tasks during the first 45- to 55-minute test. The instrumented vehicle they drove obtained kinematic data automatically, and behavioral responses were recorded on video cameras. Then the same subjects completed the same driving exercise in the same vehicle—but this time after having their right hand injected with 10 mL of 1% lidocaine over the volar wrist, and another 10 mL into the carpal tunnel. To further simulate WALANT conditions, researchers applied a bulky hand dressing to each participant’s right hand. The WALANT-modeled driving test included a simulated “surprise event” that required avoidance maneuvers. Researchers analyzed before-and-after data on a variety of kinematics, including braking, acceleration, right and left turning, and proportion of time spent driving with each or both hands.
Overall, Orfield et al. found no evidence of a negative impact on driving fitness in the simulated WALANT state. In fact, the subjects braked harder and steered more smoothly in the WALANT-modeled state, an indication that they perceived they might be impaired. Not surprisingly, participants in the WALANT-modeled state spent decreased time using both hands (from 72% to 62%), while left-hand-only driving increased from 2% to 16% of the time. All participants reported that they felt safe to drive with a numb, bandaged right hand.
These noninferiority findings suggests that WALANT patients are no worse off with immediate driving after the surgical procedure than they were beforehand. The authors are quick to point out that these findings should not be generalized beyond right-handed people driving a passenger car with an automatic transmission in the United States. Still, this study gives us some evidence-based data to better inform patients undergoing common hand procedures now frequently performed under WALANT conditions, such as trigger-finger and carpal-tunnel release. However, we can’t guarantee they will save on their auto insurance.
Click here to view a 3-minute “Author Insight” video with study co-author Peter J. Apel, MD, PhD.
Matthew R. Schmitz, MD
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