Carotid Artery Corrected Flow Time Measured by Ultrasonography as a Predictor of Hypotension After Induction of General Anesthesia

Carotid Artery Corrected Flow Time Measured by Ultrasonography as a Predictor of Hypotension After Induction of General Anesthesia

Hypotension often happens immediately after anesthetic induction. Particularly in 5-10 minutes after anesthetic induction it is reported to happen more frequently. Patients may have preexisting hypovolemia resulting from dehydration and impaired compensatory responses, which increase the risk. However, it is still challenging to assess intravascular volume status in spontaneously breathing patients before anesthetic induction. Recently, the measurement of corrected flow time in carotid artery was introduced as quite useful, simple and noninvasive for the evaluation of circulating blood volume. The aim of this study is to evaluate whether corrected carotid artery flow time as determined by ultrasonography in spontaneously breathing patients before general anesthesia can predict hypotension after induction.

Inclusion Criteria:

• adult patients (19-80 years of age) who were scheduled to undergo elective surgery under general anesthesia

Exclusion Criteria:

• mean blood pressure < 70 mmHg before induction of general anesthesia
• Patients who have currently taken angiotensin-converting enzyme inhibitor
• Patients who have currently taken angiotensin receptor blocker
• the presence of carotid artery stenosis > 50%
• cardiac rhythm other than sinus
• unstable angina
• a left ventricular ejection fraction of < 40%
• severe vascular disease
• implanted pacemaker/cardioverter
• autonomic nervous system disorders
• anticipated difficult airway
• pregnancy