Air Versus Lignocaine for Endotracheal Tube Cuff Inflation and Effect on Postoperative Sore Throat and Intracuff Pressure

Overview

Endotracheal Tube (ETT) is frequently used for GA (general anesthesia) to deliver oxygen and volatile anesthetic agents to the patient and serves as a channel for anesthetic gases. The ETT cuff helps in positive pressure ventilation and maintains an adequate seal between the endotracheal tube and trachea. Prolonged inflation of ETT cuff can cause ischemic changes of tracheal mucosa and other complications like postoperative sore throat (POST), hoarseness of voice, difficulty in swallowing, tracheal wall ulcer, stricture etc. Among these, the occurrence of sore throat after GA ranges from 21 - 65% Hence it important to measure ETT cuff pressure in intubated patients. The reliable and convenient way for this is using an ETT manometer, which is not readily available in most of hospitals in Pakistan.Many studies have focused on incidence of POST. Most of these studies have been done in western population and differences in various ethnicities are well reported . In Pakistan, air is widely used for ETT cuff inflation. If the results depict minimal cuff pressure changes and postoperative side effects with Xylocaine as compared to air, then it can be inferred that cuff pressure does not increase due to N2O when Xylocaine is used, hence, it can be safely used for cuff inflation eliminating the requirement of ETT cuff pressure monitoring and also the ETT cuff manometer, serving as a cost-effective alternative.

Every patient will be evaluated in the preoperative clinic where detailed present and past history including any current illness, medication, previous surgeries and addiction will be taken and recorded. Also baseline investigations will be evaluated. Airway examination and Mallampati scoring will be done. The patients will be divided into 2 groups: Group A (Air) and Group X (Xylocaine plain 2%), using air and Xylocaine for alternate patients. In the OT, an anesthesia resident will record baseline vitals. An IV line with 18 or 20 G cannula will be secured and IV fluid Ringer Lactate will be infused according to the body weight. All patients will be preoxygenated for 3min. Patients will be premedicated Ondansetron 0.8mg/kg, Glycopyrrolate 0.2mg/kg, Dexamethasone 8mg, inducted with Propofol 2mg/kg, Atracurium 0.5mg/kg. Anesthesia will be maintained with Oxygen 50%, Nitrous oxide 50% and Isoflurane. Patient will be intubated with a cuffed ETT, size 7 or 7.5 mm for males and 6.5 or 7mm for females. For Group A the cuff of the ETT will be inflated with air and for Group X the ETT cuff will be inflated with Xylocaine plain 2% and the ETT cuff pressure will be measured by an anesthesia assistant using cuff manometer immediately after intubation and at 5, 15, 30min and then at every 30 min till the completion of surgery. On completion of surgery, anesthesia will be reversed by weaning of the anesthetic gases and neostigmine 0.05-0.07mg/kg with glycopyrrolate will be used to reverse the remaining muscle paralysis. When the patient is awake the ETT cuff will be deflated by removing the inflating agent. Then the patient will be oxygenated with a face mask until needed. Signs and symptoms like postoperative sore throat, cough and hoarseness of voice will be recorded immediately after extubation and at 30min, 6hr and 24 hr post operatively. The severity of POST will be scored on a scale of 0-3 (0: No POST; 1: Mild; 2: Moderate; 3: Severe).