Midclavicle Block: A Clinical Observational Study

Intraoperative pain will be assessed using the Visual Analog Scale (VAS), where 0 indicates no pain and 10 represents the worst imaginable pain. Pain scores will be recorded during the procedure whenever feasible, in awake patients, to evaluate the anesthetic effectiveness of the midclavicle block.

Postoperative pain will be assessed using the Visual Analog Scale (VAS), which ranges from 0 (no pain) to 10 (worst imaginable pain). Pain scores will be recorded in the immediate postoperative period, as well as at 6, 12, and 24 hours after surgery to evaluate the analgesic efficacy of the midclavicle block throughout the early recovery phase.

Sedation will be assessed at 30 minutes and 2 hours after block performance using the Ramsay Sedation Scale, a widely used clinical tool ranging from 1 (anxious or agitated) to 6 (no response to stimuli). This outcome aims to determine whether patients remain adequately awake and cooperative under regional anesthesia.

Hemidiaphragmatic function will be evaluated using M-mode ultrasonography before the block and at 30 minutes and 2 hours post-block. The measurement will be performed at the right anterior axillary line in the subcostal area, using the liver as an acoustic window. Diaphragmatic excursion will be measured during deep breathing. Hemidiaphragmatic paralysis is defined as a reduction of more than 50% in diaphragmatic excursion compared to baseline, and/or paradoxical movement during sniff testing.

Motor block will be assessed before the block, and at 30 minutes and 2 hours after block performance. The evaluation will include motor function in the distribution of the axillary (shoulder abduction), musculocutaneous (elbow flexion), radial (wrist extension), median (wrist flexion), and ulnar (thumb/finger adduction) nerves. Each nerve will be scored using a 3-point scale:

0 = normal strength

• = paresis
• = paralysis

The total motor block score will range from 0 to 10.

Sensory function will be assessed by testing response to pinprick in four dermatomes of the ipsilateral upper limb: C5 (deltoid area), C6 (lateral forearm), C7 (dorsum of the hand), and C8 (medial forearm). A 3-point scale will be used in each area:

0 = normal sensation

• = decreased sensation to pinprick
• = no sensation to pinprick Sensory block will be considered effective if a score of 1 or 2 is present in at least two dermatomes.

Sensory block will be assessed at 30 minutes and 2 hours after block performance in three anatomical areas: the sternoclavicular joint, midclavicle, and acromioclavicular joint. A 4-point scale will be used:

0 = no reduction in sensation

• = decreased sensitivity to pinprick
• = no sensitivity to pinprick
• = no tactile sensation

Sensory block will be considered effective if the score is 2 or 3 in the assessed area.

Assess the need for rescue analgesia within the first 24 postoperative hours, including the type of analgesic administered and the doses required.

During the surgical procedure, continuous monitoring of the Qnox and Qcon indices will be performed using a neurological state monitor with frontal sensors. The Qnox index provides an objective estimate of the patient's nociceptive response, while the Qcon index estimates the level of consciousness.

The incidence of intraoperative and postoperative systemic complications potentially related to the Midclavicle Block (MCB) will be recorded. These include hypotension, bradycardia, nausea, and vomiting.

Measure the onset time of the midclavicular block after local anesthetic injection, as well as the total time required to perform the technique.

Hemodynamic stability will be assessed intraoperatively and during the immediate postoperative period by monitoring non-invasive blood pressure (NIBP), heart rate (HR), and peripheral oxygen saturation (SpO₂). Any episode of hypotension (defined as a systolic blood pressure <90 mmHg or a decrease of >20% from baseline) or bradycardia (heart rate <50 bpm) will be recorded and treated as per standard protocol.