After the loss of consciousness during general anesthesia, the Supine Horizontal Position is adopted.

The vasoactive drugs are selected from the following according to the protocol: phenylephrine, ephedrine, norepinephrine, and epinephrine.

The complications are assessed using the Claviene-Dindo score.

The postoperative recovery is assessed using the quality of recovery-15 questionnaire (QoR-15) .The QoR-15 has 15 questions. Each question is rated on a 10-point scale, ranging from 0 (none of the time or poor) to 10 (all of the time or excellent). The maximum score (best recovery) is 150.

If either of the following two definitions is met, it is considered refractory hypotension:

1. During the anesthesia induction period, the total administered dosage exceeds the maximum dose, and the patient's hypotension does not recover. The maximum usage dose of ephedrine is 0.5 mg/kg (ideal body weight), and the maximum usage dose of phenylephrine is 8 μg/kg (ideal body weight).
2. When two or more vasoactive drugs are used, the systolic blood pressure is less than 80 mmHg or the mean blood pressure is less than 65 mmHg continuously for more than 5 minutes.

The VIDIAC score is comprised of: E, the interaction between the blade tip and epiglottis; V, the best view of the vocal cords from the blade camera; and A, enlargement of the arytenoids. The score range of the VIDIAC score is from -1 to 5 points. The VIDIAC score classification is as follows: Easy, with a score of -1 or 0; Moderate, with a score of 1; Difficult, with a score of 2; Severe, with a score of ≥3.

The usage of medications other than propofol, remifentanil, phenylephrine, ephedrine, norepinephrine, and epinephrine.

The monitor records continuous arterial blood pressure data at intervals of 1 second.

The monitor records continuous arterial blood pressure data at intervals of 1 second.

The monitor records continuous arterial blood pressure data at intervals of 1 second.