This prospective observational study aims to evaluate the predictive value of preoperative carotid Doppler ultrasound parameters, including carotid velocity-time integral (carotid VTI) and corrected carotid flow time (ccFT), for post-induction hypotension in adult patients undergoing elective non-cardiac surgery under general anesthesia. Hemodynamic instability during anesthesia induction is a common and clinically important problem associated with adverse perioperative outcomes. Carotid Doppler ultrasonography provides a rapid and non-invasive method for assessing hemodynamic status at the bedside. In this study, carotid Doppler measurements will be performed in the preoperative period and their association with post-induction hypotension will be analyzed. The results of this study may help identify patients at risk for hypotension and improve perioperative hemodynamic management.

Post-induction hypotension (PIH) is a common hemodynamic complication during the induction of general anesthesia and is associated with increased risk of perioperative morbidity and mortality. Identifying patients at risk of developing hypotension before anesthesia induction may allow anesthesiologists to implement preventive strategies and optimize perioperative hemodynamic management.

Traditional static hemodynamic parameters are often insufficient to accurately assess intravascular volume status and cardiovascular reserve. Doppler ultrasound-based measurements have emerged as useful non-invasive tools for evaluating cardiovascular dynamics. Carotid Doppler ultrasonography, in particular, allows rapid bedside assessment of hemodynamic parameters such as carotid velocity-time integral (carotid VTI) and corrected carotid flow time (ccFT), which may reflect changes in stroke volume and preload responsiveness.

This prospective observational study aims to evaluate the ability of preoperative carotid Doppler parameters, including carotid VTI and corrected carotid flow time (ccFT), to predict the development of post-induction hypotension in adult patients undergoing elective non-cardiac surgery under general anesthesia. Carotid Doppler measurements will be performed during the preoperative period, and anesthetic induction will be conducted in accordance with the study protocol under standard monitoring conditions. Hemodynamic parameters will be recorded during the induction period, and the occurrence of post-induction hypotension will be documented.

The primary objective of this study is to determine the predictive performance of carotid VTI and corrected carotid flow time for post-induction hypotension. Secondary analyses will explore the relationship between Doppler-derived hemodynamic parameters and perioperative hemodynamic changes. The findings of this study may contribute to improving perioperative risk stratification and guiding individualized hemodynamic management strategies.

Inclusion Criteria:

• Adult patients aged 18-65 years

American Society of Anesthesiologists (ASA) physical status I-II

Scheduled for elective non-cardiac surgery under general anesthesia

Planned endotracheal intubation

Ability to provide written informed consent

Exclusion Criteria:

Refusal to participate in the study

Planned emergency surgery

Planned cardiac surgery

Presence of carotid artery stenosis greater than 50%

Moderate to severe valvular heart disease

Presence of atrial fibrillation or significant arrhythmia

Advanced heart failure

Preoperative hypotension or hemodynamic instability

Inability to obtain reliable ultrasonographic measurements

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Adult patients aged 18-65 years with American Society of Anesthesiologists (ASA) physical status I-II who are scheduled for elective non-cardiac surgery under general anesthesia will be included in this study.