Brachial non-invasive blood pressure (NIBP) monitoring is recommended as part of the American Society of Anesthesiology (ASA) basic monitoring package. Although brachial NIBP is often practical, some surgeries and patients may require NIBP measurement elsewhere (e.g. the ankle).

Several studies have shown that ankle NIBP overestimates brachial NIBP measurements. Algorithms have been proposed, based on correlation studies, to estimate brachial NIBP from ankle NIBP during general anesthesia and mechanical ventilation. These algorithms, however, are based on both heterogeneous populations and surgeries.

Our aim was to determine if ankle brachial NIBP difference occurs in in young ASA physical status 1 patients undergoing general anesthesia in the supine position. We also aim to determine if this difference is constant during anesthesia or if it varies according to different predefined time points.

Inclusion Criteria:

• American Society of Anesthesiology (ASA) pysical status score 1
• Patient undergoing elective surgery requiring general anesthesia in supine position

Exclusion Criteria:

• Patient refusal
• systemic pathology
• Body mass index (BMI) superior to 30
• Surgeon requiring a position other than supine

Patient undergoing elective surgery requiring general anesthesia in supine position. American Society of Anesthesiology (ASA) pysical status score 1.