Traditional Dorsal Digital Block Vs Volar Subcutaneous Digital Block

This is a prospective, randomized, double-blinded controlled trial comparing two different techniques for digital blocks. Participants will be physicians who perform digital blocks as part of their everyday duty. Each participant will undergo two digital blocks and will have the opportunity to perform a digital block on another participant.

This study follows a two-period cross-over design with four groups that are defined by the sequence of treatments within each group. Participants will receive two digital blocks, one using the traditional dorsal technique and one using the volar technique. Of the two injections, one of the syringes will contain 1% lidocaine without epinephrine and the other will contain sterile normal saline. The injections will be to the index finger on each hand. The hand injected first will be up to the participant. The order in which the dorsal technique versus the volar technique is performed will be randomized. Participants will not be told one of the syringes contains normal saline. Injection pain will be measured by visual analog score and recorded after each injection. Sensation in each of the 12 zones of the finger described by Cummings et al will be recorded at each minute mark until loss of sensation in all 12 zones is achieved or 15 minutes has passed, whichever comes first.

Set Up Prior to Study Performance Four-digit codes will be created for all participants. The 4-digit codes will be randomly assigned to a treatment group, A, B, C and D. Group A will undergo the volar technique first with lidocaine (V1) and then the dorsal technique second with sterile saline (D2). Group B will undergo the volar technique first with sterile saline and then undergo the second injection with the dorsal technique with lidocaine. Group C will undergo the dorsal technique first with lidocaine (D1) and then the volar technique second with sterile saline (V2). Group D will undergo the dorsal technique first with sterile saline followed by the volar technique second with lidocaine. Two syringes will be prepared for each 4-digit code, one with 4 mL of 1% lidocaine and 4 mL of sterile normal saline. They will be labelled with the four-digit code and a separate letter-digit code. The letter-digit code will contain one letter, either V or D, and one number, 1 or 2. The letter corresponds to the technique used to perform the injection (V for volar technique, D for traditional dorsal technique). The number corresponds to the order to which the syringe is to be used, first or second. Figure 1 shows a typical example of how a syringe will be labelled. In this example, participant 4883 in Group A would receive a syringe of lidocaine labelled 4883 V1 and a syringe of saline labelled 4883 D2. Each syringe will also be marked with an * indicating lidocaine and a # indicating sterile saline. This is added to the syringes to immediately determine the syringe contents in case of adverse reaction. The meaning of the * and # will not be shared with participants but will be known to all members of the study team.

Date of Study

An anonymous survey will be given to all participants with three questions: