Effect of Topical Lidocaine Spraying on the Vocal Cords Before Intubation During Robotic Surgery: a Randomized Controlled Trial

Endotracheal intubation is a respiratory management technique used during general anesthesia. It is essential for certain surgical procedures as it ensures a secure airway for the patient. However, during the placement of the endotracheal tube, the passage of the tube through the vocal cords can cause pain stimulation, leading to an increase in heart rate and blood pressure. Lidocaine reversibly blocks the conduction of nerve impulses along nerve fibers by preventing the movement of sodium ions across the nerve membrane. Topical application of lidocaine near the vocal cords before endotracheal tube placement may be a way to reduce the surgical pleth index and changes in vital signs (heart rate, blood pressure) caused by excessive endotracheal tube stimulation. This study aims to investigate the benefit of topical spraying of lidocaine on the vocal cords before endotracheal tube placement during routine da Vinci surgery. The primary outcomes were the pharmacological effects of spraying either lidocaine or normal saline (control group) on the vocal cords. These included: post-intubation hypertension (defined as an increase in systolic blood pressure of more than 20% from baseline), changes in mean arterial pressure before and after intubation, and objective pain indices such as the Surgical Pleth Index. Secondary outcomes included post-intubation hypotension (defined as mean arterial pressure less than 70 mmHg), as well as postoperative complaints and severity of sore throat, pain on swallowing, and hoarseness.