Comparison of Different Approaches for Supraclavicular Block and Their Effects on Diaphragm Muscle Function

Overview

Brachial plexus blocks used for anesthesia in upper extremity operations can be performed with interscalene, axillary, supraclavicular and infraclavicular approaches. Plexus blockage can be performed under the guidance of needle nerve stimulation, artery palpation or ultrasonography (USG). Nowadays, the simultaneous use of USG during the block allows the protection of structures such as nerves, pleura and vessels, and allows practitioners to see the needle and the spread of local anesthetic during the injection. Although supraclavicular block seems to be advantageous because the brachial plexus is more compact and superficial in this region, it has a disadvantage of being close to the pleura. (Increased risk of pneumothorax) With the use of USG, this risk has decreased and the supraclavicular block has become an alternative to infraclavicular block, which is widely used in upper extremity surgery. Due to the compact structure of the brachial plexus trunk at the first rib level, the application of the block is easier and the block formation is faster due to the peripheral spread of the local anesthetic. With the spread of local anesthetic to C3-C5 nerve roots in the brachial plexus, paralysis can be seen in the ipsilateral phrenic nerve up to 67%. Patients who will be operated on, especially in patients with respiratory distress, may experience respiratory distress due to the dysfunction of that side diaphragm muscle. With the help of ultrasound, the inspiratory and end-expiratory thickness of the diaphragm is measured with the Diaphragm Thickness Index (DTI), which is a new and effective method used as a mechanical ventilator weaning index in intensive care units. With this method, we can examine the effect of phrenic nerve block on diaphragm muscle due to local anesthesia in the acute period. DTI is calculated as a percentage from the following formula: (Max thickness at the end of inspiration - Max thickness at the end of the expiration) / Max thickness at the end of the expiration. By comparing 3 different approaches used in supraclavicular block, we aimed to investigate the most appropriate block approach in terms of effectiveness, speed, complication rate, effects on diaphragm and 6 months effects.

In this prospective randomized double-blind study, patients will be divided into 3 groups using a computer program. Standard monitoring (ECG, pulse oximetry, noninvasive blood pressure) will be applied to the patients who will then be taken to the block application room . After the peripheral vascular access is established on the hand that will not be operated on, premedication will be provided with 2 mg iv midazolam. The blocks will be performed by an experienced anesthesiologist with the USG guidance. Block evaluation and measurements will be made by a different experienced anesthesiologist. After the antisepsis of the area to be blocked, a 22G 50 mm stimulator needle will be used for the block. Intermittent negative aspiration will be performed during all procedures to detect possible vascular puncture. The local anesthetic mixture we routinely use in our clinic will be used. 20 ml of bupivacaine(Buvicaine HCl %0.5) and prilocaine(Priloc HCl %2) 1:1 mixture will be prepared in a way that there will be 5mcg adrenaline per ml.(9ml bupivacaine, 9ml prilocaine and 2ml saline with 50 mcg adrenaline per ml) The ultrasound probe will be placed on the clavicle, the supraclavicular block will be applied in the coronal oblique plane using the in-plane technique. 3 different approaches of supraclavicular block will be compared. Approaches share the same probe position and needle entry point but differ in where the local anesthetic is given. Group 1: Local anesthetic mixture will be given to the corner pocket - where the artery and the first rib intersect in the sonoanatomical image. Group 2: 10 ml of the local anesthetic mixture will be given to the described corner pack and the remaining 10 ml into the largest nerve cluster (Intracluster injection). Group 3: Local anesthetic mixture will be administered by multi injection method between the nerve groups seen in the sonoanatomical image. The diaphragm thickening fraction and evaluations will be made by another experienced anesthesiologist, double-blindness will be achieved by being blind to the patient's group. Effects of phrenic nerve block on diaphraghma muscle will be evaluated by diaphraghma thickining fraction.All patients will be evaluated with USG in a head-up position facing the side to be operated before and 30 minutes after the block is performed.The probe will be placed perpendicular to the chest wall, in the eighth or ninth intercostal space, between the anterior axillary and midaxillary lines, 0.5 to 2 cm below the costophrenic sinus. The diaphragm will be viewed as a structure with three distinct layers, including two parallel echoic lines (Diaphragmatic pleura and peritoneum) and a hypoechoic line between them (Diaphragm muscle) . The patient will be instructed to breathe up to total lung capacity (TLC) and then exhale to residual volume (RV). Several diaphragm images will be taken, at least three at the point of maximum thickening in TLC and at least three at minimum thickness in RV. On each B-mode image, diaphragm thickness will be measured from the middle of the pleural line to the middle of the peritoneal line. Then DTI will be calculated as a percentage from the following formula: (Max thickness at the end of inspiration - Max thickness at the end of the expiration) / Max thickness at the end of the expiration. With this formula, we can determine the involvement of phrenic nerve by looking at the rate of diaphragm thickening before and after supraclavicular block in different groups. As a first line rescue anesthesia, patients will receive sedoanalgesia with remifentanil infusion. Laryngeal mask and general anesthesia will be commenced if needed. The postoperative analgesic regimen will routinely contain 1000 mg IV acetaminophen (3x1) and, if necessary, 1 mg opioid (Tramadol) per kg will be given.