This is a prospective observational study investigating the correlation between Perfusion Index (PI) ratio and End Diastolic Velocity (EDV) ratio as early predictors of successful supraclavicular brachial plexus block (SCBPB) in patients undergoing superficialization surgery of the upper limb.

Regional anesthesia is fundamental for upper limb surgeries, with SCBPB providing dense anesthesia. However, early confirmation of successful block performance remains challenging. Traditional clinical methods (sensory/motor testing) are subjective and delayed. This study proposes using objective, noninvasive indices - PI (evaluated via pulse oximetry) and EDV (measured by Doppler ultrasound) - to determine their accuracy in detecting sympathetic blockade shortly after SCBPB. Early and reliable detection of block success is particularly important in superficialization surgeries such as arteriovenous fistula (AVF) superficialization in patients with compromised vascular status. The results are expected to enhance anesthesia practice by providing quantitative, reproducible, and rapid assessment tools.

Inclusion Criteria:

• Adults aged 18-65 years

Both genders

ASA II-VI classification

Undergoing elective upper limb superficialization surgery (e.g., AVF superficialization)

Provided written informed consent

Exclusion Criteria:

• Patient refusal

Coagulopathy or bleeding disorders

Local infection at injection site

Allergy to local anesthetics

Use of vasopressors or beta-blockers

Severe peripheral vascular disease

Morbid obesity (BMI > 35)

Severe neurological or psychiatric disorders

Participants are adult patients aged 18-65 years, both male and female, classified as ASA II-VI, and scheduled for elective superficialization procedures (mainly AV fistula superficialization). Patients must be capable of understanding and signing informed consent. Excluded are patients with contraindications to nerve block such as coagulopathy, local infection, allergy to local anesthetics, severe vascular disease, morbid obesity (BMI >35), severe neurological or psychiatric impairment, or those taking vasopressors or beta-blockers that could alter vascular reactivity.