Midclavicle Block: a Clinical Observational Study

This prospective observational study aims to evaluate the effectiveness and safety of the ultrasound-guided Midclavicle Block (MCB) as an anesthetic and analgesic technique for midshaft clavicle fracture surgery. The primary objective is to assess intraoperative pain control using the Visual Analog Scale (VAS). Secondary outcomes include postoperative pain, sedation levels (Ramsay scale), motor and sensory block of the ipsilateral upper limb, hemidiaphragmatic paralysis, and hemodynamic stability. The requirement for rescue analgesia and the incidence of systemic complications will also be recorded. Intraoperative Qnox and Qcon monitoring will be used to explore potential correlations with pain and sedation levels. Data will be collected intraoperatively and postoperatively for up to 24 hours.

This prospective observational study aims to evaluate the effectiveness of the Midclavicle Block (MCB) as an anesthetic and analgesic technique in patients undergoing clavicle fracture surgery. The primary outcome is intraoperative pain control, assessed using the Visual Analog Scale (VAS) in awake patients, to determine the anesthetic effectiveness of the block.

The MCB will be performed under ultrasound guidance with a linear transducer placed in the sagittal plane immediately posterior to the midclavicle. Local anesthetic will be administered via three injections: two 15 mL injections on either side of the fracture site over the anterosuperior periosteum of the clavicle, and a third 10 mL injection crossing the subclavius muscle toward the posteroinferior region of the periosteum. The total volume of local anesthetic administered will be 40 mL.

Secondary outcomes include:

Postoperative pain, assessed using the VAS at immediate recovery and at 6, 12, and 24 hours postoperatively.

Sedation levels, measured with the Ramsay Sedation Scale at 30 minutes and 2 hours after block placement.

Incidence of hemidiaphragmatic paralysis, evaluated with M-mode ultrasound before and after the block, based on diaphragmatic excursion during deep breathing and sniff testing.

Motor block in the ipsilateral upper limb, scored in five nerve distributions (axillary, musculocutaneous, radial, median, ulnar) at baseline, 30 minutes, and 2 hours post-block.

Sensory block in the ipsilateral upper limb, assessed by pinprick in four dermatomes (C5-C8), scored at 30 minutes and 2 hours.

Sensory block in the clavicular region, evaluated over the sternoclavicular joint, midclavicle, and acromioclavicular joint at 30 minutes and 2 hours.

Requirement for postoperative rescue analgesia within the first 24 hours, including type and dosage.

Continuous intraoperative monitoring of Qnox and Qcon indices, to explore their correlation with nociceptive and sedation levels. Qnox estimates nociceptive response; Qcon estimates level of consciousness.

Incidence of systemic complications related to the block, such as hypotension, bradycardia, nausea, or vomiting.

Block onset time and duration, including the time to perform the MCB and onset of anesthetic effect.

Hemodynamic stability, assessed intraoperatively and up to 2 hours postoperatively, by monitoring non-invasive blood pressure, heart rate, and oxygen saturation. Episodes of hypotension (SBP \<90 mmHg or \>20% drop from baseline) or bradycardia (HR \<50 bpm) will be recorded.

The study will enroll 30 adult patients (ages 18-75) scheduled for clavicle fracture surgery at HM Nou Delfos Hospital. Data collection will span intraoperative and early postoperative periods, up to 24 hours after surgery.

Eligibility Criteria:
Inclusion Criteria:

* Adult patients with midshaft clavicle fractures scheduled for surgery.
* ASA I-III.
* Signed informed consent.

Exclusion Criteria:

* Allergy to local anesthetics.
* Coagulopathy or active anticoagulant therapy.
* Infection at the puncture site.
* Pregnant or breastfeeding patients.
* Pre-existing neuromuscular disorders.