The role of carotid FLOW time in predicting of hypotension after anesthetic induction in patients over 65 years of age

Objective: General anesthesia related hypotension is associated with postoperative complications, such as acute kidney injury and myocardial ischemia. The aim of our study is to determine the predictive value of preoperative FTc monitoring for the development of hypotension following general anesthesia induction in patients over 65 years of age. Material and Method: This prospective and cross-sectional study was conducted between June 1, 2022, and June 1, 2023, with approval from the Çukurova University Clinical Research Ethics Committee and informed consent from patients. Ninety-three patients 65 years and older undergoing elective surgery under general anesthesia were included in the study. The FTc value was calculating with ultrasonography 10 minutes before the patients were taken to the operating room. Before induction of general anesthesia, systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), and heart rate were measured. Anesthesia induction was achieved with intravenous (iv) 1-2 mg/kg propofol, and iv rocuronium 0.6 mg/kg was added for tracheal intubation. During mask ventilation, 1-2% sevoflurane and a mixture of 50% oxygen and 50% nitrous oxide were used. After induction, SBP, DBP, MAP, and heart rate were measured at 1-minute intervals for 3 minutes. Measurements were terminated prior to endotracheal intubation, because direct laryngoscopy and endotracheal intubation could cause sympathetic stimulation and blood pressure changes. Noradrenaline was the first-line treatment for hypotension, and crystalloid solution was used as the second option. Results: The mean age of the patients was 72.6±5.2 years, 66.7% male and 75.3% ASA II. Comorbidity was detected in 84.9% of the patients, and the most common comorbidity was hypertension (50.5%). Mean fasting time was 11.3±2.7 hours, and average preoperative corrected FTc value was 333.8±18.9. Post-induction hypotension developed in 25 patients. If the preoperative corrected FTc value was below 328.5, hypotension developed with 80% sensitivity and 79.4% specificity (p<0.001). It was observed that the preoperative FTc value of the patients who developed hypotension after induction (315.1±14.3 msec) was statistically lower than the patients who did not (340.7±15.5 msec) (p=0.001). It was found that hypotension developed at a higher rate in patients had hypertension (p=0.041). No correlation was found between preoperative corrected FTc value and administered doses of propofol, fentanyl, noradrenaline and crystalloid. Conclusion: Preoperative FTc values are a simple and noninvasive method for predicting hypotension that may develop after anesthesia induction in patients over the age of 65 who will undergo general anesthesia. Key Words: Hypotension, Carotid Doppler, Monitoring, Elderly Patients