Perfusion Index and End Diastolic Velocity Ratios as Predictors of Supraclavicular Block Success in Vascular Access Surgery

Correlation Between Perfusion Index Ratio and End Diastolic Velocity Ratio After Supraclavicular Brachial Plexus Block as an Early Predictor of Successful Block in Superficialization Surgery of the Upper Limb

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