A Comparative evaluation of the Proseal Laryngeal Mask Airway, the Laryngeal Mask Airway Supreme and the IGEL in Anaesthetized Unparalyzed Patients : A Study of 90 Cases

INTRODUCTION Supraglottic Airway Devices (SAD) have become a standard fixture in airway management. These devices sit outside the trachea but provide ahandsfree means of achieving a gas-tight airway. The first successful supraglottic airway device, the Laryngeal Mask Airway (LMA)-Classic, became available in 1989. Many varieties of supraglottic devices are developed after the overwhelming success of the laryngeal maskairway (LMA). Supraglottic devices use both inflatable and noninflatable cuff that fit into thepharynx and laryngopharynx and gives anoropharyngeal airway seal. The structuretheseairway gadgets provides an effective seal over the larynx of the patients. But one of the major limitations of these types of airways is the lack of airway protection from regurgitation especially in patients withoutfasting, pregnant patients, & and patients who have increased airway resistance.Supraglottic devices have reducedhemodynamic response during airway stimulation. In this study we tried to compare the performance of three supraglottic devices, the LMA Proseal, I gel and LMA Supreme. A quite number of studies have been done by using muscle relaxant for SAD insertion. Gasteiger et al, eschertzhuber et al, saraswat et al have used muscle relaxant for SAD insertion. In most of the studies only two SADs have been compared. Also mostly in anaesthetized paralyzed patients.In this study we used three devices in anaesthetizednon paralyzed patients during induction. AIM OF THE STUDY: To study the 1. Effective oropharyngeal leak pressure, 2. Time taken for insertion, 3. Number of attempts for insertion, 4. Hemodynamic responses, 5. Ease of gastric tube insertion, 6. Complications. MATERIALS AND METHODS: Study design: The study was a randomized, parallel group, prospective, comparative study. Sample size: 90 Patients (n=90). RANDOMIZATION: The study was done on 90 patients in the Department of Anaesthesiology, Tirunelveli Medical College, Tirunelveli from March 2011 to August 2012. After institutional ethical committee clearance and written informed consent, 90 female patients of ASA I and II, belonging to the age group 18 – 40 years and weight 40- 60 kg, were randomly chosen using computer generated random numbers. ALLOCATION: 90 Patients were randomly divided into 3 groups. 1. Group P 30 patients – will receive Proseal LMA, 2. Group S 30 patients – will receive LMA Supreme, 3. Group G 30 patients – will receive I-gel. MASKING: Observer blinded study. INCLUSION CRITERIA: 1. ASA I, II, 2. Female sex, 3. 18-40 yrs, 4. Weight- 40-60kgs, 5. Mallampatti class I and II, 6. Patients undergoing elective surgery under general anaesthesia. EXCLUSION CRITERIA: 1. ASA III and IV, 2. Mallampatti III and IV, 3. Anticipated difficult airway, 4. Obesity with BMI > 30, 5. Patients with lung diseases, 6. Patients atincreased risk of aspiration, 7. Patients with irregular dentition. Study Method: Pre-operative evaluation including age, weight, ASA status, base line vital parameters, blood routine investigations, ECG, Chest X-ray were recorded. History regarding previous anaesthesia, surgery/any significant illness, medications and allergy were recorded. Complete physical examination and airway examination was done. Patients were pre medicated with Inj. Midazolam 0.02 mg/Kg IM and Inj. Glycopyrrolate4mcg/Kg IM 45 minutes before induction. Routine monitoring including ECG, pulse oximetry, noninvasive blood pressure and end tidal carbon dioxide was established. A standard anaesthetic protocol was carried out. Preoxygenation was done with 100% oxygen via face mask for 3 minutes at tidal volume. Inj. Fentanyl Citrate 3μg/kg iv was administered followed by induction withInj. Propofol3mg/kg. After the loss of eye lash reflex patient’s head was positioned neutrally on a 7cm pillow. All the supraglottic airway devices were tested for leak before insertion, and the size chosen according to the patient’s weight. The devices were lubricated with 2% lignocaine jelly and inserted to the allotted group as per the standard insertion protocol.Anaesthesia was maintained with O2 and N2O at a ratio of 33% and 66% with Halothane 1% and incremental boluses of Inj. Atracurium. Insertion time- measured from the time between touching the prepared supra glottic airway device after the loss of eyelash reflex until the bilateral confirmed air entry or until the first expiratory tidal volume >200ml. CONCLUSION: We conclude that, 1. LMA proseal provides a betteroropharyngeal seal for controlled ventilation especially in patients where higher airway pressure are necessary for achieving a effective tidal volume . 2. The lesser time required for insertion of I gel may be due to the presence of non inflatable cuff. 3. Hemodynamic stability and postoperative morbidity were similar with all the three devices . 4. The insertion attempts for all the three devices was found to be similar and there was no failure in our study. 5. Gastric tube insertion was found to be easier with all the three devices and in none of the patients there was failure. Therefore I gel and LMA supreme can be an alternative to proseal LMA especially in patients with normal pulmonary function