An alternative approach for blocking the superior trunk of the brachial plexus evaluated by a single arm clinical trial
Thiago Nouer Frederico, Rioko Kimiko Sakata, Luiz Fernando dos Reis Falcão, Paulo César Castello Branco de Sousa, Fernanda Melhmann, Cesar Augusto Simões, Leonardo Henrique Cunha Ferraro
Interscalene brachial plexus block is associated with phrenic nerve paralysis. The objective of this study was to evaluate an alternative approach to interscalene brachial plexus blocks in terms of efficacy, grade of motor and sensory blockade and phrenic nerve blockade.
The study was prospective and interventional. The ten living patients studied were 18 to 65 years old, ASA physical status I or II, and submitted to correction of rotator cuff injury. A superior trunk blockade was performed at the superior trunk below the omohyoid muscle, without blocking the phrenic nerve. The needle was advanced below the prevertebral layer until contacting the superior trunk. In order to guarantee the correct positioning of the needle tip, an intracluster pattern of the spread was visualized. The block was performed with 5 mL of 0.5% bupivacaine in ten patients. In the six cadavers, 5 mL of methylene blue was injected. Diaphragmatic excursion was assessed by ultrasonography of the ipsilateral hemidiaphragm. In three patients, pulmonary ventilation was evaluated with impedance tomography. Pain scores and analgesic consumption were assessed in the recovery room for 6 h after the blockade.
In the six cadavers, methylene blue didn’t reach the phrenic nerve. Ten patients underwent arthroscopic surgery, and no clinically phrenic nerve paralysis was observed. No patient reported pain during the first 6 h.
This study suggests that this new superior trunk approach to block the superior trunk may be an alternative technique to promote analgesia for shoulder surgery in patients with impaired respiratory function.