Shivani Gajpal, Sandeep Sharma, Santosh, Lalit K Raiger
Background: Difficulty in visualizing the glottis may cause difficulty, even failure in endotracheal intubation leading to catastrophes. Difficult laryngoscopy is frequently overcome by using molar approach for laryngoscopy combined with optimal external laryngeal manipulation (OELM). The present study was planned to compare conventional midline approach of laryngoscopy to left molar and right molar approach of laryngoccopy (using Macintosh blade) for endotracheal intubation Material and Methods: This prospective randomized double blind controlled study was conducted on 120 patients of 18-60 years age, belonging to ASA grade I and II of either sex, posted for elective surgery under general endotracheal anaesthesia. Depending on the approach of laryngoscopy used, the patients were randomly divided into three groups of 40 each into Group M (midline approach), Group L (left molar approach) and Group R (right molar approach). Predictors of difficult intubation (Modified Mallampati grading, Thyromental distance, abnormal Dentition) and their association with unsuccessful intubation, Cormack Lehane grading, attempts of intubation, duration of intubation, success rate of intubation, adjuvant measures needed (stylet, retraction of mouth) for intubation were noted. Results: Patients having predictors of difficult intubation had significant risk of unsuccessful intubation with midline approach (p=0.01 for MPG III/IV, p=0.04 for TMD <6.5 cm) whereas occurrence of MPG III/IV and TMD <6.5 cm did not increase risk of unsuccessful intubation when molar approaches were used (p>0.05). Presence of tooth lesion significantly increased risk of unsuccessful intubation in all the three groups (p<0.05). OELM improved difficult laryngoscopic view (CL III/IV) to easy laryngoscopic view (CL I/II) in all patients in group L(4/4) and R(6/6)as compared to 50% patients (3/6) in group M. Also, after application of OELM, the Cormark Lehane grading improved from grade II to Grade I significantly in all groups (p<0.0001). Most of the patients were successfully intubated within 20 seconds in group M (87.50%, n=35) as compared to group L (20%, n=8) and group R (42.5%, n=17). Mean time taken for laryngoscopy and intubation was significantly longer in both molar approaches (right > left) as compared to midline group. Retraction of angle of mouth was used an adjuvant measure during laryngoscopy by significantly higher number of patients in group R (n=38, 95%) as compared to group L (n=2, 5%) and group M (0%) (p <0.0001). Stylet was required as an adjuvant in significantly higher number of patients in group L (n=37, 92.5%) to facilitate successful intubation as compared to group M (n=5, 12.5%) and group R (n=1, 2.5%) (p<0.0001). Conclusion: We concluded that the success rate of laryngoscopy and intubation via midline, left molar and right molar approach is high and comparable. Molar approaches provide a better laryngeal view as compared to midline laryngoscopy especially in cases predicted to have difficult intubation( MPG II/IV, TMD<6.5). Molar intubations were associated with prolonged intubation time and increased use of stylet and retraction of angle of mouth.
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