Prospective Randomised Comparison of LMA - Supreme and Endotracheal Tube in Elective Laparoscopic Gynaecological Surgeries

INTRODUCTION: Supraglottic airway devices have become a standard fixture in airway management filling a niche between the face mask and tracheal tube in terms of both anatomical position and degree of invasiveness. These devices sit outside the trachea but provide a hands free means of achieving a gas tight airway. Originally created as hands free replacement for the face mask, the LMA has gone on to replace endotracheal tubes as the preferred airway in millions of cases each year. This remarkable shift has occurred for number of reasons including ease of placement, lower drug requirement, reduced hemodynamic response, smoother emergence and lower incidence of sore throat. Though LMA provided all the above advantages, the risk of gastric distension, pulmonary aspiration of gastric contents and fear of inadequate ventilation acted as a deterrent to the widespread use of LMA. To overcome the above complications Dr. Archie Brain designed the new airway device, LMA – Supreme in 2007, with the modifications to separate the respiratory and gastro intestinal tract. It represents the most advanced laryngeal airway yet developed by Archie Brain, the inventor of original LMA airway, the LMA Classic. Laparoscopic surgery or more appropriately minimal access surgery is well established since last two decades. General anaesthesia with controlled ventilation remains the gold standard technique for laparoscopic surgeries. The ETT has been proved to be a reliable method of securing the airway and is considered the standard of care for protecting the airway from aspiration. They carry an inherent risk of patient trauma, from vocal cord injury to pharyngeal soft tissue injury and also produces hemodynamic responses to rigid laryngoscopy. Because of ease on insertion and reduced trauma, LMA airways have replaced ETT in many procedures. With its integrated gastric tube and verifiable placement, the LMA Supreme is an even more effective alternative. LMA Supreme is a new airway device that combines the different features of its predecessors. It is curved like the LMA-Fastrach, it offers gastric access like LMA- Proseal and it is of single use like LMA- Unique. The LMA-Supreme forms two seals: an effective first seal with the oropharynx (oropharyngeal seal) and an innovative second seal with the upper oesophageal sphincter (the oesophageal seal). The optimised distal tip with gastric access functionally separates the digestive and respiratory tracts thus effectively protecting against regurgitation and gastric distension. With this background this study was conceptualized to compare the performance of LMA- Supreme and Endotracheal tube in elective laparoscopic gynaecological surgeries. AIM OF THE STUDY: To evaluate the advantages and disadvantages of LMA- Supreme (LMA-S) over Endotracheal tube (ETT) for general anaesthesia in women coming for laparoscopic gynaecological surgeries in terms of the following parameters. 1. Ease of insertion of airway device. 2. No. of attempts for insertion of airway device. 3. Time taken for insertion of airway device. 4. Ease of insertion of gastric tube. 5. No. of attempts for insertion of gastric tube. 6. Gastric distension. 7. Haemodynamic responses. 8. Capnography. 9. Blood staining of devices. 10. Incidence of complications. MATERIALS AND METHODS: It was a prospective, randomised, single - blinded, case - controlled study conducted in the Department of Anaesthesiology, Kasturba Gandhi Hospital, Chennai. 60 adult patients satisfying the inclusion criteria were enrolled in the study. INCLUSION CRITERIA: 1. Age : 18 years and above. 2. Weight : BMI < 30 kg/m2. 3. ASA : I & II. 4. Surgery : Elective. 5. Mallampatti scores : I & II. 6. Who have given valid informed consent. EXCLUSION CRITERIA: 1. Not satisfying inclusion criteria. 2. Patients posted for emergency surgery. 3. Patients with difficult airway. 4. Lack of written informed consent. 5. Pregnant female. MATERIALS: 1. LMA Supreme size 3 & 4. 2. Endotracheal tubes- 7 & 7.5 mm CETT. 3. Macintosh laryngoscope with blade size 3. 4. 20 ml syringe. 5. Lubricant jelly, 14 Fr orogastric tube. 6. Drugs: glycopyrolate, fentanyl, midazolam, ondansetron, propofol, atracurium, sevoflurane, neostigmine. 7. Monitors: ECG, Pulse oximetry, Capnography, NIBP. 8. Weighing machine calibrated to 1 kg. OBSERVATION AND RESULTS: This prospective, randomized, comparative, single blinded case control study compares LMA-Supreme insertion with Endotracheal tube in 60 adult females undergoing elective laparoscopic gynaecological surgery. Results are expressed as mean and standard deviation. All statistical analyses were carried out using SPSS for Windows version 15.0. The t-test was used for comparison of quantitative variants. Qualitative variants were compared using the chi-squared test. A P value of less than 0.05 was considered statistically significant. SUMMARY: From this Prospective, Randomised, Comparative single blinded case control study which evaluated the effectiveness of LMA-S and ETT, it is found that, 1. Both LMA-S and ETT were intubated with similar ease (P = 0.314). 2. Number of attempts required for successful insertion of LMA-S was more than that of ETT but not statistically significant. 3. Time taken for insertion of LMA-S was lesser than ETT, which is statistically significant (P <0.001). 4. Ease of insertion of Gastric tube with LMA-S was better than that of ETT, which is statistically significant (P = 0.005). 5. Number of attempts required for successful insertion of gastric tube was lesser with LMA-S than with ETT but not statistically significant. 6. No significant gastric distension occurred intra operatively with both LMA-S and ETT. So, LMA-S provides good oropharyngeal seal and pulmonary ventilation. 7. Both the techniques had no significant differences in SpO2 and EtCO2 before inflation, after inflation and after deflation. Thus LMA-S is also a good airway device for laparoscopic surgeries. 8. Haemodynamically there was a significant difference between two groups with regard to heart rate, systolic blood pressure, diastolic blood pressure and mean arterial pressure after insertion. LMA-S was found to be a better device in this aspect. 9. Blood staining on LMA-S and ETT were comparable and was not statistically significant. 10. Incidence of post operative sore throat and hoarseness of voice was less with LMA-S than with ETT and was statistically significant. CONCLUSION: LMA-Supreme is an equally effective airway device to ETT in laparoscopic gynaecological surgeries. It has potential advantages like rapid placement, less haemodynamic response, less airway trauma, less pharyngolaryngeal morbidity and better oesophageal seal resulting in reduced risk of gastric distension and aspiration.