Perfusion Index for Predicting Brachial Plexus Block Success Under General Anesthesia

Usefulness of Pulse Oximeter Perfusion Index for Predicting the Success of Interscalene Brachial Plexus Blockade Under General Anesthesia

This study was designed to determine whether the success or failure of interscalene brachial plexus block under general anesthesia can be predicted using perfusion index (PI).

The success of peripheral nerve blocks is usually evaluated by assessment of sensory and motor function; however, this method cannot be applied in the patient who has uncheckable mental status, e.g. general anesthesia, or who is uncommunicable, e.g. different language user.

The perfusion index (PI) is a numerical value for the ratio between pulsatile and non-pulsatile blood flow measured by a special pulse oximeter, and PI had been proved as a useful tool for evaluation of successful supraclavicular nerve block in awake patients as an objective method.

With the use of ultrasound guidance in skilled hands, it is a reasonable option to perform neuraxial and peripheral regional blocks in sedated or anesthetized patients. However, there has been no evidence of applying PI for predicting the success of nerve block in general anesthetized patients.

Inclusion Criteria:

• 20-70 years old,
• BMI 20-35 kg.m-2,
• elective shoulder surgery,
• ASA physical status I-III

Exclusion Criteria:

• refusal of the patient,
• comorbid with serious vascular disease,
• diabetes,
• allergy to local anesthetics,
• patients on regular opioids,
• peripheral neuropathy.