European Journal of Cardiovascular Medicine

Maintaining a patent airway is critical for preventing hypoxic brain injury and death in surgically treated patients. During the preoperative period, various bedside parameters are utilized to determine the ease or difficulty of intubation.¹Mallampati, an Indian American anesthesiologist, has developed a hypothesis based on the visualization of the uvula and faucial pillars cover-up by the base of the tongue and so many related structures.²Acomprehensiveassessment totheairwayiscrucial inensuringthesafetyofanaesthesiaadministration as well as prevention of risk to the patients life. Identifyingpotentialchallengesinairwaymanagement before initiating anaesthesia is essential for effective preparation and the implementation of  alternative strategies, thereby minimizing the risk of adverse events. Preoperative analysis or evaluation of the patients is must to dowith a specific focus on recognizing coming difficulties such as challengingMask ventilation and difficult tracheal intubation (DTI), holds significant importance in the preoperative assessmentconductedbyanaesthesiologists and observed by single observer.^3,4 This possible approachallowsfortheanticipationofdifficultiesand facilitates the application of appropriate measures to enhance airway maintenance, contributing to overall patient safety during the anaesthesia process.^5,6Pre-assessment of airway before anaesthesiais very vital. Assessment tools with repeatability and reliability are therefore important. Mallapati Classification is one such assessment tool which is extensively used by Anaesthesiologists. Developed by Mallampati,^7,8 it was successively modified by Samsoon3 in 1987. Cormack Lehane (CL) grading4 is another such assessment of airway at laryngoscopy. It is a gold standard for evaluation of difficulty of intubation as airway is assessed under direct vision. Over the years different airway assessments tools are evaluated against CL classification. The purpose of the present study was to assess the Mallampati classification with the help of CL classification in Indian population without obvious factors predicting difficult intubation, like decreased mouth opening, decreased range of motion of the neck, mass within oropharynx etc.

Aim & Objectives: Supine versus Sitting Position as a Predictor for Difficult Intubation comparison by Modified Mallampati Test.

A single‑centre prospective observational cross‑sectional study was conducted in The Department of Anesthesia and critical care, RajkiyaMedical College Jalaun. The study was done in 100 patients, aged >18 years, scheduled for surgery requiring general anaesthesia with orotracheal intubation.  After taken of consent from all enrolled patient for the study, convenience sampling was adapted as the method of selecting the patients for the study followed by the inclusion and exclusion criteria as mentioned below.

Inclusion criteria

All consenting adult patients of either gender or aged 18 years and above, scheduled for surgery requiring general anaesthesia with orotracheal intubation were included in the study.

Exclusion criteria

 Patients unwilling to participate in the study, scheduled for fibreoptic or awake/blind intubation those patients with upper airway pathology, restricted neck, cranio-vertebral junction anomalies, also excluded from this study.

Data collection technique

During preoperative evaluation, demographic data were collected and the MMT in a sitting position was recorded. On the operating table (OT), an independent observer who was blinded for preoperative results noted the MMT in a supine position. Induction of general anesthesia was as per standard institutional protocols. An operator performed direct laryngoscopy. Cormack– Lehane grade was noted.^9,10Patients with MMT I and II were considered easy laryngoscopy and those with MMT III, IV were considered as difficult laryngoscopy.. Similarly, patients having CL Grades I, IIA and IIB were considered easy tracheal intubation, whereas CL Grade IIIA, IIIB and IV were considered DTI.^11,12,13

Data analysis and interpretation

Data, were entered into Microsoft Excel and formation tabulating systemand underwent analysis  statistically.Descriptive statistics analysis, such as mean and standard deviation for continuous variables and frequencies or percentages for categorical ones. Variable associations were examined and performed Chi‑square tests for categorical variables and unpaired t‑ test. The significance level was considered at 0.05 for all analyses

Amongst 100 sample size, 56 (56%) were females, whereas 44 (44%) were males. The mean age of patients was 18± 48 years.

DTI: Difficult Tracheal Intubation, Easy: Easy Tracheal Intubation, MMT: Modified Mallampati Test

Table 1, shows the distribution of patients as per their MMT class. The most common MMT class observed in the sitting position was class 2 and class 1, whereas in the supine position, it was class 2 class 3. 

Table 3 shows a comparison of sensitivity, specificity and predictive accuracy of MMT in sitting and supine for DTI. Sensitivity was low (18%) in supine position compared to sitting (40%). Specificity was higher (72%) in the supine position than in sitting (82%). Positive predictive value for difficult intubation was 60%, with supine MMT, and 40% for sitting MMT.

The sensitivity and specificity in the supine position are comparable to those in the sitting position, and the area in the ROC curve analysis shows that both positions have good consistency in sensitivity and specificity, making them excellent diagnostic tools for predicting difficult laryngoscopy and intubation. After plotting the area under the curve for in our study, the area under the ROC curve (AUC) of MMT (sitting) was 0.60, while that of MMT (supine) was 0.78. This suggests that both are very good predictors of DTI. MMT (Sitting) is a slightly better predictor than MMT (supine).

As with all airway parameters, the major aim of Mallampati assessment is to predict difficult airways accurately because failure to predict both difficult face mask ventilation and difficult tracheal intubation could lead to disastrous clinical situations which may include hypoxia induced brain insult and death. In this study, the Mallampati test prediction for difficult intubation and laryngoscopy in sitting and supine was investigated and compared.An important purpose of preanaesthetic airway assessment is to predict the easy or difficult airway with regard to mask ventilation, laryngoscopy and/ or tracheal intubation. Anatomical factors and characteristics (e.g. mouth opening, tongue size relative to oropharyngeal structures, dentition, etc.) are of considerable importance in predicting difficulty in intubation but have limitations because of their variability from one person to another and in the same person at different periods of life.¹⁴

The original paper of Mallampatiet al.^15,16and the Samsoon and Young modification[9] did describe the Mallampati test which is performed with the patient seated, head in the sniffing or neutral positions, respectively, and without phonation. In most patients, MMT when performed as described, it successfully predicts difficult airway, when used along with other tests. However, it is important to note that conducting the MMT in a seated position may not always be practical, especially for patients with traumatic spine fractures, hip and limb fractures, or those unable to sit or remain upright. In addition, evaluating the airway in the supine position on the OT table is more convenient for the examiner. In this prospective observational study, we longitudinally compared airway assessments using MMT in both sitting and supine positions, examining their correlation in predicting a difficult airway.Out of total 100 adult patients (>18 years) enrolled in our study, 56.0% patients were females and 44.0% were males. The incidence of DTI, MMT supine and MMT sitting in our study was score 4(18%) and score 2(18%) respectively. This was comparable to the incidence reported by Bindraet al. [18] The probable explanation for higher incidence observed in our study is because our study was conducted in a teaching hospital where many  intubations are performed by anaesthesia residents and  trainees.

The effect of change of posture from sitting to supine has been well studied.^18,19,20We observed that the maximum discordance was seen for MMT Grade 1 followed by Grade 2 and least for Grade 0 and Grade 4. We observed changing the posture from sitting to supine significantly worsened Mallampati grade (i.e. Grade I/ II became Grade III/IV on supine) and our finding is consistent with most of other studies. Thamet al.¹⁹and Singhalet al.²⁰found that the MMT shifted towards a higher grade when the patient was turned to the supine position from the sitting position. This disparity in their results can be attributed to their technique of performing MMT which required patients to have head extension and phonation.Our study also evaluated the effect of posture on preoperative MMT for predicting difficult airway. Both supine and sitting MMT values were found to correlate well with DTI as shown in table 2. While analysing the diagnostic characteristics of MMT in two positions as shown in table 3, we found that the sitting MMT was substantially more sensitive than supine MMT in predicting DTI. This indicates a higher percentage of difficult intubations were correctly predicted by sitting MMT than by supine MMT. Similar observations were reported by Bindraet al.¹⁷. In our study, supine MMT demonstrated a higher positive predictive value compared to sitting MMT. This implies a greater accuracy in predicting difficult intubations as a proportion of all intubations judged by supine MMT. The negative predictive value (NPV) was 82% and 30% for sitting and supine MMT, respectively. Consequently, supine MMT has emerged as a better predictor of difficult intubation, supported by its higher PPV (60% compared to 40%), while sitting MMT was a superior predictor for easy intubation, evident from its higher NPV of 82% (compared to 30% for supine MMT). Similar findings were reported by Bindraet al andKhatiwadaet al.,observed a higher predictive value for MMT in the supine position compared to MMT in the sitting position . To assess the predictive value of MMT in sitting versus supine positions for difficult intubation, we generated a ROC curve. The AUC was 0.60 for sitting MMT and 0.78 for supine MMT, both indicating strong predictive capabilities for DTI. While sitting MMT slightly outperformed supine MMT (P = 0.05), both were considered very good predictors. Awasthiet al.²¹reported the area under ROC of 0.86 for sitting MMT and 0.74 for supine MMT in relation to difficult laryngoscopy, which is consistent or more similarly with our findings. However, the study by Awasthiet alwas conducted on children between 3 and 10 years age group. In a study by Hanouzet al.the AUC for supine MMT (0.82) was reported to be greater than that for sitting MMT (0.70).

Discrepancies amongst studies may result from the very fact that the test value is subjective related and it relies on individual observation, which has high inter‑individual variability and that there is a potential for involuntary phonation by the patient during the test, which can change the observer’s test result.^22,23

Our study concluded that the MMT assessment results notably worsen when the position is changed from sitting to supine. While MMT in the supine position exhibits lower sensitivity, it may be superior (with higher positive predictive value and comparable relative risk) to the sitting position in predicting difficult intubation in adults. Therefore, airway assessment using Supine MMT can be a valuable alternative in patients where, sitting position is not feasible.

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