Post-induction Hypotension

This single-center prospective cohort study is designed to evaluate whether preoperative physical activity measured by a wearable accelerometer is associated with cardiovascular autonomic function and whether it can help predict post-induction hypotension in elderly patients undergoing elective non-cardiac surgery. Patients aged 65 years or older scheduled for general anesthesia with tracheal intubation will undergo preoperative physical activity monitoring using an ActiGraph wearable accelerometer. Activity-related parameters, including sedentary time, light-, moderate-, and vigorous-intensity activity, daily step count, and sleep duration, will be recorded. Cardiovascular autonomic function will be assessed perioperatively using noninvasive continuous hemodynamic monitoring, with baroreflex sensitivity-related indices derived from continuous blood pressure and beat-to-beat timing data. The primary outcome is post-induction hypotension. Secondary outcomes include early intraoperative hypotension, postoperative complications, and 30-day mortality. This study aims to clarify the relationship between habitual physical activity and autonomic regulation in older surgical patients and to provide evidence supporting future prehabilitation strategies.

The purpose of this study is to develop a high-performance machine learning model combining dynamic baroreflex sensitivity (BRS) metrics and multi-dimensional static clinical features to predict the risk of post-induction hypotension (PIH) in elderly patients undergoing elective non-cardiac surgery under general anesthesia.

This study tests whether giving a low-dose norepinephrine infusion just before induction of anesthesia can reduce low blood pressure during emergency surgery for peritonitis. Adults with secondary peritonitis who are scheduled for emergency surgery and have stable blood pressure after initial resuscitation will be randomly assigned to receive either norepinephrine or placebo (normal saline) during induction of anesthesia. The main outcome is the cumulative time spent with mean arterial pressure (MAP) below 65 mmHg from the start of propofol administration to 10 minutes after endotracheal intubation. The study will also evaluate rescue vasopressor use, heart rate changes, drug-related adverse events, and selected early postoperative outcomes.

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.

This prospective observational study aims to evaluate whether non-invasive hemodynamic parameters, including the plethysmographic variability index (PVI) and perfusion index (PI), can predict post-induction hypotension in patients undergoing diagnostic direct laryngoscopy under general anesthesia. Patients aged 18-75 years with ASA physical status I-III scheduled for elective direct laryngoscopy will be included. PVI and PI values will be recorded before anesthesia induction and in the early post-induction period. The relationship between these indices and the decrease in mean arterial pressure after induction will be analyzed to determine their predictive value for hypotension.

Video-assisted thoracoscopic surgery (VATS) is widely used in thoracic surgery due to small incisions, low stress response, and high patient tolerance. Compared with open thoracotomy, VATS has fewer complications, shorter hospital stays, and better postoperative quality of life. Despite being minimally invasive, VATS can cause severe postoperative pain via pleural/lung parenchyma damage, intercostal nerve traction, and chest tube stimulation. This pain impairs patient mobility (e.g., turning over, getting out of bed), increasing risks of atelectasis and pulmonary infections. Approximately 78% of patients experience moderate-to-severe postoperative pain, and 50% receive inadequate analgesia \[3\]. Effective postoperative pain management is critical for recovery and reducing pulmonary infections. In recent years, combined general anesthesia with regional nerve blocks has been recommended to enhance postoperative comfort and accelerate recovery, as regional blocks alleviate pain and reduce general anesthetic dosage. Thoracic paravertebral block (TPVB), an effective regional anesthesia technique, is commonly used for postoperative analgesia in VATS. TPVB involves injecting local anesthetics near thoracic spinal nerves exiting the intervertebral foramen, blocking ipsilateral somatic and sympathetic nerves. It is mainly used for analgesia after rib fractures, breast surgery, and thoracic surgeries (open or VATS). However, preoperative TPVB blocks both thoracic nerves and sympathetic nerves. Sympathetic inhibition reduces myocardial contractility, heart rate, and peripheral vascular resistance. Additionally, rapid administration of multiple drugs during general anesthesia induction further increases hypotension risk. Esketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist, has stronger sedative/analgesic effects and fewer adverse events than ketamine. Studies show sub-anesthetic doses (0.15-0.3 mg/kg) reduce induction hypotension, opioid-induced cough, and other adverse events via sympathetic stimulation, analgesia, and NMDA receptor antagonism. The passive leg raising (PLR) test assesses fluid responsiveness in acute circulatory failure by shifting \~300 mL of venous blood from lower limbs to the right heart. Its hemodynamic effects are reversible, avoiding fluid overload. Based on this, lower limb elevation during anesthesia induction rapidly and transiently increases venous return, reducing hypotension. Bilateral elevation enhances venous return, increases cardiac preload, improves cardiac output, and stabilizes blood pressure. General anesthesia induction is a period of frequent hemodynamic fluctuations. Elderly patients, often with comorbidities and reduced physiological reserve, are more susceptible to induction-related hemodynamic disturbances (40% incidence). Sustained/severe hypotension causes inadequate organ perfusion/ischemia, increasing postoperative complications (myocardial injury, ischemic stroke, acute kidney injury). Preventing post-induction hypotension in the elderly is clinically valuable. Opioids, propofol, and muscle relaxants induce hypotension via arterial dilation and reduced peripheral resistance. TPVB-induced sympathetic block further increases hypotension risk. This study hypothesizes that esketamine administration or lower limb elevation during induction reduces hypotension incidence in elderly VATS patients with TPVB.

Postprandial hypotension (PPH) and post-induction hypotension (PIH) are very common in the elderly population and are associated with a variety of poor outcomes.The purpose of this study is to investigate the correlation between PPH and perioperative adverse events such as PIH in the elderly.