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.
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The incidence of hypotension
Timeframe: From the start of anesthesia induction to 5 minutes after induction