Carotid Artery Corrected Flow Time and Respiratory Variation of Blood Flow Peak Velocity for Prediction of Hypotension After Induction of General Anaesthesia in Adult Patients With Chronic Liver Disease

Baseline Measurements

For the ultrasound parameters, it is the average of three readings In supine position .

The investigators will continuously monitoring during induction and 10 minutes after.

Hemodynamic Monitoring:

• Heart rate from ECG
• SpO2
• Etco2
• Blood pressure . invasive Blood pressure
• The radial artery level is the site of continuous arterial pressure monitoring with an arterial catheter.
• Ultrasound Measurements:

The patient will be positioned in a supine position, with the right side of the neck completely exposed. The transverse part Of the main carotid artery beneath the thyroid cartilage will be precisely identified using ultrasound device (sonosite edge portablp.fojy usa)via a linear array probe (4-15 MHz), with the marker directed toward the patient's head. Thus, the sampling line will be positioned at the center of the carotid lumen, around 2 cm from the carotid bifurcation, and the electronic angle correction cursor will be pointed in the direction of blood flow. Insonation angles between the ultrasound beam and blood flow will be maintained at or < 60°. Next, the carotid blood flow waveform will be acquired, and the consecutive stable carotid pulse Doppler flow spectrum will be determined with an optimal level of image quality.

The Correction: To get the corrected carotid flow time (ccFT), the measured FT will be adjusted for the patient's heart rate (HR). A commonly used formula is Wodey's formula.

A single, experienced sonographer will perform all measurements, and a subset of measurements will be reviewed by a second blinded observer to assess inter-rater reliability."

Peak Velocity: Measure the peak systolic blood flow velocity at the same location.

Respiratory Variation (ΔVpeak): Calculate the difference between the maximum and minimum peak velocities during a single respiratory cycle: \Delta V_{peak} = (V_{peak(max)} - V_{peak(min)}) / ((V_{peak(max)} + V_{peak(min)})/2) \times 100\%. The patient should be asked to breathe normally during this measurement.

Flow time (FT), which is known as the time period between the systolic increase phase and dicrotic notch, was calculated and then adjusted for heart rate (HR) via equations outlined below.

Wodey's (W) equation∶ FTc(W) = FT + 1.29 ∗ (HR - 60)

Anasthesia:

Patients will have routine fasting for at least 6 to 8 h and will not allowed to drink any solution or fluid 2 to 4 h prior to surgery.

No premedication will be given A standardized induction protocol will be used. At the operating theatre, a three-lead electrocardiogram (ECG), pulse oximetry (SpO2), and noninvasive arterial pressure monitoring will be applied.

After pre-oxygenation for 5 min anesthesia induction of propofol 1_2mg , fentanyl 1 ug/kg, and 0.15 mg/kg cisatracurium . After 3 min of mask ventilation, direct laryngoscopy will be employed for tracheal intubation. . Respiratory setting of anesthesia machine (Aestiva, GE/Datex-Ohmeda) will be set as follows: volume-controlled ventilation (VCV), inspiratory-expiratory (I:E) ratio of 1:2, respiratory rate of 8-10 bpm, tidal volume of 8 mL/kg of ideal weight [45.5 + 0.91x (height in cm-152.4)], and PEEP of 5 cm H2O in 50% oxygen with air. Respiratory settings will be adjusted to maintain the PETCO2 at less than 50 mmHg. Anesthesia will be maintained with sevoflurane (1.5-2.5%) and intermittent injection of cisatracurium 0.02mg/kg as needed to keep the entropy scale between 40 and 60 and for muscle relaxation. The mean arterial pressure was kept between 60 and 80 mmHg.

Hemodynamic Data Collection: Invasive mean arterial pressure (MAP) will be continuously recorded for 5-10 minutes post-induction.

Hypotension Definition: Hypotension will be defined as a decrease in MAP by >20% from the baseline value or an absolute MAP of <65 mmHg for more than one minute.This definition is clinically relevant and widely used in the anesthesia literature.

Postinduction hypotension will be treated with 250 ml saline iv boluse repeated if successfully restore blood pressure.

If refractory to fluid we will inject intravenous ephedrine in 3 mg bolus doses and repeated when necessary.

Significant bradycardia (heart rate < 40 beats/min) will be treated with intravenous boluses of atropine (0.5 mg).

Study duration 3 months or end of recruitment of sample