Changes in Pulse Wave Transit Time and Its Variability After Placement of Interscalene Brachial Plexus Block

Changes in Pulse Wave Transit Time and Its Variability Measured From the Ipsilateral First Finger After Placement of Interscalene Brachial Plexus Block

Pulse wave transit time (PWTT) increases due to decreased arterial vascular tone resulting from sympathetic blockade caused by regional anesthesia. Its oscillation (PWTT variability) also contains information on the interaction between autonomic nervous system and the cardiovascular system. The changes in PWTT and its variability have not been investigated in patients receiving interscalene brachial plexus block (ISBPB). It was hypothesized that ISBPB increases PWTT and reduces low frequency power of PWTT variability.

Inclusion Criteria:

• American Society of Anesthesiologists status of 1
• Scheduled to receive interscalene brachial plexus block for arthroscopic shoulder surgery

Exclusion Criteria:

• Coagulopathy
• Infection of the skin area for interscalene brachial plexus block
• Peripheral neuropathy or neurologic sequelae in the upper limb ipsilateral to the surgery
• Allergy to local anesthetics or a history of allergic shock
• Contralateral vocal cord palsy, hemidiaphragmatic paresis/paralysis or pneumo/hemo thorax
• Arrhythmias
• Cardiac conduction abnormalities
• A history of medication affecting cardiac conduction
• Ischemic heart disease
• Hypertension
• Diabetes mellitus
• Thyroid disfunction
• Other medical conditions affecting autonomic nervous activity