Comparative Study on Extubation Stress Response with Endotracheal Tube, Laryngeal Mask Airway and Replacement of Endotracheal Tube with Laryngeal Mask Airway
INTRODUCTION: General anaesthesia with endotracheal intubation and intermittent positive pressure ventilation is frequently performed in the practice of anaesthesia. Endotracheal intubation (insertion of ETT into the trachea) and extubation (trans laryngeal removal of ETT) are a part of general anaesthesia and both are associated with hemodynamic responses. Endotracheal extubation is associated with haemodynamic changes due to reflex sympathetic discharge and cough caused by epipharyngeal and laryngopharyngeal stimulation. Increase in sympathoadrenal activity results in tachycardia, hypertension and arrhythmias. This increase in heart rate and blood pressure are usually for a short period of time, variable and unpredictable. This response is more harmful to patients with systemic hypertension, coronary artery disease or cerebrovascular diseases. Therefore haemodynamic response to tracheal extubation has always been a challenge to anaesthesiologist. Many pharmacological methods like administration of lignocaine, verapamil, diltiazem before extubation have been studied, but none of them proved to completely abolish extubation stress response. Non pharmacological methods like extubation of the patient in deep plane with spontaneous respiration have been studied to reduce the hemodynamic stress response and cough during extubation. Major disadvantage of these methods is that they produce cardiovascular depression and inadequate upper airway reflexes. The laryngeal mask airway is a supraglottic airway device. It is a good alternative to endotracheal tube and face mask for spontaneous or positive pressure ventilation. LMA makes intubation and extubation less stimulating than endotracheal tube. So we replaced ETT with LMA at the end of the procedure and studied extubation stress responses. Hence the present study was undertaken to compare the extubation stress response with endotracheal tube, laryngeal mask airway and replacement of endotracheal tube with laryngeal mask airway AIM OF THE STUDY: The aim of the study was to compare the extubation stress response with endotracheal tube, laryngeal mask airway and replacement of endotracheal tube with laryngeal mask airway, in terms of hemodynamic stress responses and respiratory complications during extubation. MATERIALS: The materials needed for the study includes, 1. Drugs for general anesthesia: a. Injection Glycopyrollate, b. Injection Midazolam, c. Injection Fentanyl, d. Injection Propofol, e. Injection Suxamethonium, f. Injection Atracurium, g. Injection Neostigmine. 2. Appropriate size face masks, 3. Appropriate size laryngoscopes, 4. Appropriate size Endotracheal tubes, 5. Laryngeal mask airway size 3 4, 6. Working suction apparatus, 7. Monitors Pulse oximeter, ECG, NIBP, 8. Intravenous fluids and intravenous cannula, 9. Circle system, 10. All emergency drugs. STUDY METHODS: This study was a randomized comparative study conducted in Government Stanley hospital, Chennai during the period of March 2012 to August 2012. After obtaining clearance from the Institutional Ethical Committee of the Stanley Medical College, Chennai, a pilot study was done to define study population and to decide on inclusion and exclusion criteria. A target population of 90 patients was decided. After proper screening of patients for the inclusion and exclusion criteria, they were informed about the purpose of the study and the procedure on the day before surgery. A written informed consent was obtained from the patient. CRITERIA FOR SELECTION: Inclusion Criteria: 1. Age Group 20 60 years, 2. ASA I or ASA II, 3. Elective surgeries done under general anaesthesia. Exclusion Criteria: 1. Obesity, 2. Craniofacial anomalies, 3. Hyperreactive airway. The study population were randomly assigned to three Groups labeled as A, B and C. Each Group was allotted 30 patients. Randomization was achieved by allotting lots with alphabets A, B and C. Patients with lot A assigned to Group A. Those with lot Bassigned to Group B. Those patients with lot C assigned to Group C. Statistical Analysis: The data were analysed using SPSS (Statistical Package for Social Science) Version 16.01. The data collected were scored and analyzed, Continues variables were presented as mean with Standard deviation (Sd) and categorical variables were presented as frequency and percentages. Student t test and Analysis of Variance (Anova) were used for testing the significance of all the variables (Mean &Sd) Chi square test was used to compare proportions. All the Statistical results were considered significant at P value 0.05. SUMMARY: The study " Comparative Study on Extubation Stress Response with Endotracheal Tube, Laryngeal Mask Airway and Replacement of Endotracheal Tube with Laryngeal Mask Airway" was carried out at Stanley Medical College and Hospital Chennai from March 2012 To August 2012. The Groups were comparable for Age, Sex, Weight. Our observations were: 1. There was a marked rise in Heart rate at 1 3 5 and 10 minutes after ETT extubation (Group A) when compared to removal of LMA (Group B) and replacing ETT with LMA before extubation (Group C) 2. There was a marked rise in Mean arterial blood pressure at 1, 3, 5 and 10 minutes after ETT extubation (Group A) when compared to removal of LMA (Group B) and replacing ETT with LMA before extubation (Group C) 3. Increased incidence of cough ,sorethroat and hoarseness of voice after ETT extubation (Group A) when compared to removal of LMA (Group B) and replacing ETT with LMA before extubation (Group C) 4. There was no significant difference in HR and MAP values at baseline, 5 minutes before reversal and at 1 3, 5 and 10 minutes after removal of LMA between LMA (Group B) and ETT replacing LMA (Group C) CONCLUSION: Many pharmacological and non pharmacological methods have been used to attenuate hemodynamic stress response and cough during extubation,but none are satisfactory. Replacement of Endotracheal tube with Laryngeal Mask Airway 20 minutes before the end of procedure is a simple and effective method to attenuate extubation stress response with endotracheal tube. It is ideal to have an Endotracheal tube to maintain the airway for prolonged surgical procedures requiring general anaesthesiawith positive pressure ventilationand by replacing Endotracheal tube with Laryngeal Mask Airway at the end of prolonged surgeries we can have the combined advantage of both Endotracheal tube and smoother emergence due to Laryngeal Mask Airway.