Evaluation of Second Esmarch Application on Intravenous Regional Anesthesia Effectiveness

Intravenous regional anesthesia (IVRA), also known as Bier block, is a technically simple and reliable technique for achieving anesthesia for short surgical procedures. It is performed by injecting a local anesthetic (usually lidocaine) intravenously in the setting of a double tourniquet on the upper arm which limits the anesthetic effect to that portion of the body to avoid systemic effects. This technique is suitable for short procedures on the forearm and the hand with minimal complications. Variations of the technique alter the location of the tourniquet, the volume of local anesthetic, or the addition of additional anesthetic agents in an effort to provide the best anesthesia. Despite these variations, the block may still fail. Some studies show a success rate of 94-98% while others show a success rate of 78.1% depending on the definition of success (usually defined by whether or not additional anesthesia was necessary during the surgery). In general, however, IVRA has a high success rate. This study aims to improve the success rate (defined by no additional anesthetic needs during surgery) of IVRA by slightly modifying the IVRA protocol. This modification is described in greater detail below (in the research procedures section), but in essence one of the steps involved in the IVRA procedure is to apply an elastic bandage (Esmarch bandage) to the upper extremity to achieve exsanguination before inflating the double tourniquet. The only modification the investigators are making in this study is to reapply the Esmarch bandage in the exact same fashion after the anesthetic has been injected intravenously. This reapplication of the bandage is not for exsanguination but instead for promoting anesthetic extravasation into the interstitial space. Studies show that the main site of action for IVRA is in the interstitial space where small nerve endings and nerve trunks are located. The modification proposed in this study hopes to improve extravasation of the local anesthetic from the venous system into the interstitial space where it will be better able to function. In this study the investigators hope to compare success rates of the standard technique of IVRA to our method in which the investigators reapply the Esmarch bandage soon after injecting local anesthetic intravenously for short hand and upper extremity cases.

Two groups of human subjects with similar demographics will be used for this research: 40 patients randomly assigned to the control group and 40 patients randomly assigned to the study group. The REDCap randomization module will be used for the randomization process, and this process will take place in clinic on the day the patient is recruited and consented. For patients willing to be part of the study, it will be made absolutely clear to them during the consent process that there is a chance they will be assigned to the control group.

In the pre-operative area on the day of the procedure, patients will be reminded of their voluntary participation in the study (and their ability to withdraw at any time before or after the surgery). At this time the individual who initially recruited/consented the patient (e.g. Dr. Turker or Dr. Morin, henceforth "surgeon") will have the patient fill out the demographic information portion of the Bier Block Research Data Collection Form which includes the following: date of birth, sex, BMI, forearm circumference measured at greatest circumference, and comorbidities. Next, the surgeon will fill out the procedure information section of the data collection form which includes the following: date of the procedure, name of the surgeon, name of the anesthesiologist, name of the procedure, and the side of the procedure. At this point the patient may proceed to surgery.

Intravenous anesthesia will be performed using a tourniquet, Esmarch bandage, an intravenous line, and lidocaine diluted with normal saline. First, intravenous access will be obtained on the surgical side, preferably on the dorsum of the hand (however it is standard procedure to try the wrist or forearm if adequate intravenous access cannot be achieved on the dorsum of the hand). Then, a double tourniquet will be applied to the upper arm. An Esmarch bandage will be applied from the fingertips to the tourniquet with protection of the intravenous line. The distal cuff of the tourniquet will then be inflated to 250-300 mmHg. The proximal cuff will be immediately inflated to the same pressure and the Esmarch bandage will be removed. The patient's radial pulse will be checked and the surgeon will then assess the arm for adequate exsanguination prior to injection of 0.5-1% lidocaine, 25-50 milliliters, depending on patient size and anesthesiologist choice. At this point, if the patient was randomized to the study group, the Esmarch bandage will then be applied again in the exact same fashion as above and then immediately removed (this is the ONLY research portion of the study). If the patient was randomized to the control group, the reapplication of the Esmarch bandage will be skipped. Next, the distal cuff will be deflated and the intravenous line on the surgical side will be removed. Standard surgical preparation will commence while the Bier block sets up. If the patient experiences tourniquet pain, the distal cuff will be inflated and the proximal cuff will be deflated. The time to adequate block will be recorded on the data collection form once the patient is no longer able to feel sharp sensation (typically tested by gently poking skin with a sharp surgical instrument). If at any point during the surgery the patient requires additional anesthesia to control pain, the Bier block will be considered a failure. Once adequate pain control is achieved, the surgery proceeds in the usual fashion. Only cases lasting less than 45 minutes will be included in the study. The remainder of the data collection form will be filled out by the surgeon at the end of the procedure and includes the following information: tourniquet time/pressure, block success/failure, blood pressure at time of tourniquet, whether the Esmarch was applied twice, anesthesia type/dose, anatomical IV placement, complications, and additional anesthesia requirements. These completed data collection forms will then be immediately stored in a locked cabinet in the Human Movement Biomechanics Lab (B103). Every week these forms will be transferred to REDCap, and the hard copies will be destroyed securely.

To reiterate and emphasize, the reapplication of the Esmarch bandage is the only research procedure. All other procedures are standard of care. This step may improve the time to adequate block and quality of anesthesia.

After the data from each of the 80 patients' collection forms have been transferred to REDCap, the research team will review and statistically analyze the data. The duration of participation for patients is the length of surgery (in operating room time).