Randomized comparative study between classic laryngeal mask airway and I gel Airway in obese patients having BMI 35-40 during elective non-abdominal surgery

Background: In this study, we compare between classic laryngeal mask airway versus I gel airway as a conduit for ventilation in obese patients having BMI 35 -40 during elective non-abdominal surgery. Methods: 50 Adult obesepatients having BMI 35-40 who are arranged for elective non-abdominal surgery under general anesthesia are randomly divided into 2 equal groups: 1-Group A(n = 25), in which classic laryngeal mask is used for ventilation. 2- GroupB (n = 25), in which I gel mask is used for ventilation. This study compared between cLMA and I gel regarding insertion success rate, the time of insertion, leaking pressure, assessment of position by fiber optic, hemodynamic, Spo2 for each device during insertion and maintenance of general anaesthesia and postoperative complications in obese patients. Results: The present study showed that the classic laryngeal mask airway and I gel mask airway are effective in ventilation in obese patients with shorter insertion time and higher leaking pressure in I gel mask than cLMA,these finding was statistically significant.there was hemodynamic stability and no episodes of hypoxia. There was statistical insignificance regarding all hemodynamic variables and oxygen saturation between both groups.There is no statistical significance difference two groups concerning position assessment by fiber optic,Regarding postoperative complicationsafter removal of the device, postoperative blood stain was found in 1 case in laryngeal mask and no cases for I gel, also 1 case of laryngospasm in laryngeal mask with no statistical significant differences between groups. Clinically no case of hoarseness of voice or sore throat in the study. Conclusion: Both supraglottic airway devices; the classic LMA and the I GEL mask are satisfactory devices providing high airway leaking pressures. Although both devices provide high airway leaking pressures, our study revealed that the I gel mask provides a better seal with the glottic aperture and shorter time of insertion than cLMA. Both devices showed also effective ventilation, more hemodynamic stability and no

There are a lot of supraglottic airway devices available which are used in general anesthesia to avoid hemodynamic changes during endotracheal intubation (1).and may be used in difficult airway (Obese patients) or may be a simple alternative to intubation in short term elective surgery in the supine position (2).
The introduction of LMA-Classic™ laryngeal mask airway (Classic™ LMA) by Dr. Archie Brain into clinical practice in 1988 brought about a revolution in anesthesia. (3). Many different variants of this device have been designed and marketed, trying to offer a simple and effective alternative to the endotracheal intubation. (4) New generations come out with devices designed to increase safety and some have features which might reduce the risk of aspiration. (5,6) I gel is a new type of laryngeal mask and doesn't have an inflatable cuff. Because of its thermoplastic elastomeric structure, it exactly adapts to the supraglottic tissue by binding with body temperature, thus minimizing air leakage (7).

Methods:
This randomized controlled study was conducted in Kasr Al-Ainy Hospital, Faculty of medicine, Cairo University from September 2017 till March 2018, after approval of the Ethical committee and written patients consent. Study was registered in ClinicalTrials.gov There was a total number of 50 obese adult patients were included in this study. They were scheduled for elective non-abdominal surgery under general anesthesia. Those patients are allowed to fast for 6-8 h before surgery. They were randomly divided by computer designed lists then concealed in closed envelopes into two equal groups: Fig 1   1-Group A (n = 25), in which LMA was used for ventilation.
2-Group B (n 25), in which I gel was used for ventilation.  difficult mask ventilation , obstructive sleep apnea ,any position rather than supine , any form of sore throat ,patients allergic to any drugs used in the study and in PCV mode if measured tidal volume was lesser than 6 ml/kg it will be excluded.

Peri-operative Management:
Pre-operative assessment through: After taking history, clinical examination, routine investigation and Mallampati airway assessment. An adequate intravenous line was inserted and secured then all patients received an intravenous anti-emetic, Ondansetron 4 mg and an antacid, Ranitidine 50 mg, 1 hour before the operation.
The patients are premeditated with intravenous atropine 0.01 mg/kg.

Intra-operative Management:
Basic monitoring was established; pulse oximeter, ECG, non-invasive blood pressure and co2 analyzer.
After preoxygenation using a facemask for 5 min, induction of anaesthesia is done with Fentanyl 2 ug/kg, Propofol 1.5-2.5 mg/kg and Atracurium 0.5mg/kg and Lidocaine 1 mg/kg before device insertion. The ventilatory strategy is pressure-controlled ventilation (PCV) to achieve tidal volume of 6-8 ml/kg and the peak inspiratory airway pressure is not more than15 cmH2o. Maintenance of anaesthesia will be achieved by isoflurane and Atracurium.
The randomly assigned supraglottic device for each group is inserted. Insertion time and trials of the study device are recorded for each device which started from removal of the ventilation mask until appearance of capnography waves. Proper positioning is confirmed by inspection of chest inflation bilaterally, auscultation of the chest bilaterally, absence of any leak sounds from the device, capnography readings of six successive waves and by fiber optic. The success rate is recorded. If placement is inadequate, manipulations are done in the following sequence, gentle pulling and pushing of the device, head flexion and extension, jaws thrust and chin lift. If after 3 attempts, the device is not properly inserted, endotracheal intubation is done, and those patients are excluded from the study.
Hemodynamic data and episode of hypoxia are recorded just before device insertion, after device insertion, during removal, 1min after removal to monitor the occurrence of any hemodynamic changes due to device insertion. Leaking pressure will be performed as follows: set fresh gas flow at 3L/min, close the pressure limiting valve completely and then minimal airway pressure is measured at which an audible gas leak occurred using a stethoscope placed just lateral to the thyroid cartilage.(8)(9)(10)After recovery, patients will be asked about sore throat and hoarseness of voice in the form of yes or no.
Measurement tools 1-The ease of each device insertion and rate of success (three attempts at insertion were allowed before the device was considered inappropriate, difficulty of insertion was graded as easy=1, moderate=2, difficult=3). 5-Hemodynamic data (blood pressure and heart rate) are recorded just before device insertion, after device insertion, during removal and 1 min after removal.
6-The Presence of complications as laryngospasm, or post-operative blood stains, sore throat or hoarseness of voice is assessed after surgery.
Post-Operative Assessment: At the end of surgery, the anesthetic gas was replaced with 100 % oxygen to facilitate patient recovery was assessed with the following removal criteria: return of consciousness, ability to protect the airway, Spontaneous breathing, regular respiratory rate and < 30 breaths/min, adequate tidal volume > 5 ml/Kg. Stable hemodynamic and metabolic status and adequate reversal of residual neuromuscular block by clinical tests.
The device was removed and checked for blood streaked mucous on it as a sign of airway trauma. After recovery and complete return of conscious level, Patients administered a simple questionnaire that assess the presence of sore throat and hoarseness postoperatively in the form of (Yes /No).
I. Sample size: G-power software was used to calculate sample size. Sample size was calculated considering a power of 0.9 and a p-value of 0.05 to be statistically significant. The mean and standard deviation of the time to insertion was derived from a similar study (11)

Results
This study was conducted on 50 adult's patients who were scheduled for elective nonabdominal surgery lasting less than 2 hours under general anesthesia. Patients were randomly divided by computer designed lists and then concealed in closed envelopes into 2 equal groups: 1. GA (n=25) in which classic laryngeal mask was used for ventilation.
1. GB (n=25) in which I gel was used for ventilation.
There was no statistical significance difference between the two groups regarding the demographic data shown in table (1).  Data were presented as number (%). p<0.05 is consideredstatistically significant.
Concerning hemodynamic monitoring, we recorded a baseline reading of heart rate, systolic blood pressure, diastolic blood pressure and oxygen saturation before insertion of both devices. A second reading was taken after insertion of both devices, just before removal.
The fourth reading was recorded 1 min after removal of both devices. There was statistical insignificance regarding all hemodynamic variables and oxygen saturation between both groups as shown in Figures (2, 3,4and 5).   Data were presented as number (%). p<0.05 is considered statistically significant.
Finally, there was no significant difference in the mean number of postoperative complication rates concerning sore throat, hoarseness of voice, laryngospasm and postoperative blood stain between both devices. Only two cases was reported to have postoperative blood stain and the other case have laryngospasm,  Regarding all hemodynamic variables including heart rate, systolic blood pressure, diastolic blood pressure and oxygen saturation, they were compared in both groups and there was statistical insignificance between them.
Regarding assessment of position by fiber optic there was no statistical significance difference between 2 groups, in group (A) there was 18 patients showed grade 1and 7 patients showed grade 2, in group (B) there was 18 patients showed grade 1, 6 patients showed grade 2 and one patient showed grade 4.
Cattano D., et al (20) found that there was no hoarseness of voice or sore throat complains in both groups.
In contrast to our study Francksen, H., et al (21)showed that fiberoptic position was excellent in I gel airway in lean patient than LMA unique may be due to large sample size rather than us.  Heart rate (beat/min) difference between both groups Systolic blood pressure (mmHg) difference between both groups. Diastolic blood pressure (mmHg) difference between both groups.

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