Effect of Interscalene Block on Heart Rate Variability (HRV)

Effect of Interscalene Block on Heart's Autonomic Nervous System With Heart Rate Variability Measurement

The Left interscalene block has a different effect on heart's autonomic nervous system, as measured with Heart Rate Variability, compared to Right interscalene block

Inclusion Criteria:

• elective shoulder surgery
• Age 20- 45 years old
• ASA I - II

Exclusion Criteria:

• Coagulopathy disorders
• Infection at the puncture site for the interscalene block
• Neurologic deficit in the arm that is going to be operated
• Allergy to local anesthetics
• BMI > 35
• Psychiatric disorders
• Patient's refusal
• Problems with patient communication
• Arrythmia
• Ischaemic heart disease
• Diabetes mellitus
• Thyroid function disorders
• Patients with conduction disorders on the ECG
• Electrolyte disorders (K+, Na+, Ca++)
• Patients on medication that affect the ECG