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.
Study Type
OBSERVATIONAL
Enrollment
30
Hospital HM Nou Delfos
Barcelona, Barcelona, Spain
Intraoperative Pain Assessment Using the Visual Analog Scale
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.
Time frame: Intraoperative period
Postoperative Pain Assessment Using Visual Analog Scale
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.
Time frame: Immediate postoperative period, and at 6, 12, and 24 hours postoperatively
Sedation Level Assessed by the Ramsay Sedation Scale
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.
Time frame: 30 minutes and 2 hours post-block
Incidence of Hemidiaphragmatic Paralysis Assessed by M-mode Ultrasound
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.
Time frame: Baseline (pre-block), 30 minutes and 2 hours after the block
Assessment of Motor Block in the Ipsilateral Upper Limb
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 1. = paresis 2. = paralysis The total motor block score will range from 0 to 10.
Time frame: Pre-block (baseline), 30 minutes and 2 hours post-block
Assessment of Sensory Block in the Ipsilateral Upper Limb
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 1. = decreased sensation to pinprick 2. = no sensation to pinprick Sensory block will be considered effective if a score of 1 or 2 is present in at least two dermatomes.
Time frame: 30 minutes and 2 hours post-block
Assessment of Sensory Block in the Clavicle Region
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 1. = decreased sensitivity to pinprick 2. = no sensitivity to pinprick 3. = no tactile sensation Sensory block will be considered effective if the score is 2 or 3 in the assessed area.
Time frame: 30 minutes and 2 hours post-block
Requirement for Postoperative Rescue Analgesia.
Assess the need for rescue analgesia within the first 24 postoperative hours, including the type of analgesic administered and the doses required.
Time frame: 24 hours postoperative.
Continuous Monitoring of Nociception and Sedation Using Qnox and Qcon
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.
Time frame: Intraoperative period
Incidence of Intraoperative and Postoperative Systemic Complications Related to the Midclavicle Block
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.
Time frame: During surgery and up to 24 hours postoperatively.
Onset Time and Duration of the Midclavicular Block Procedure.
Measure the onset time of the midclavicular block after local anesthetic injection, as well as the total time required to perform the technique.
Time frame: Intraoperative
Evaluation of Hemodynamic Stability.
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.
Time frame: Intraoperative period and up to 2 hours post-block.
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