Modified Mallampati Classification Research Articles

Derivation and Validation of a Simple Perioperative Sleep Apnea Prediction Score

Obstructive sleep apnea (OSA) is a largely underdiagnosed, common condition, which is important to diagnose preoperatively because it has implications for perioperative management. Our purpose in this study was to identify independent clinical predictors of a diagnosis of OSA in a general surgical population, develop a perioperative sleep apnea prediction (P-SAP) score based on these variables, and validate the P-SAP score against standard overnight polysomnography. A retrospective, observational study was designed to identify patients with a known diagnosis of OSA. Independent predictors of a diagnosis of OSA were derived by logistic regression, based on which prediction tool (P-SAP score) was developed. The P-SAP score was then validated in patients undergoing overnight polysomnography. The P-SAP score was derived from 43,576 adult cases undergoing anesthesia. Of these, 3884 patients (7.17%) had a documented diagnosis of OSA. Three demographic variables: age > 43 years, male gender, and obesity; 3 history variables: history of snoring, diabetes mellitus Type 2, and hypertension; and 3 airway measures: thick neck, modified Mallampati class 3 or 4, and reduced thyromental distance were identified as independent predictors of a diagnosis of OSA. A diagnostic threshold P-SAP score > or = 2 showed excellent sensitivity (0.939) but poor specificity (0.323), whereas for a P-SAP score > or = 6, sensitivity was poor (0.239) with excellent specificity (0.911). Validation of this P-SAP score was performed in 512 patients with similar accuracy. The P-SAP score predicts diagnosis of OSA with dependable accuracy across mild to severe disease. The elements of the P-SAP score are derived from a typical university hospital surgical population.

Effect of posture on mouth opening and modified Mallampati classification for airway assessment

Several bedside airway assessment methods have been proposed for preoperatively identifying patients who are difficult to intubate. To date, the Mallampati grading remains a time-tested technique for difficult airway assessment. Both Mallampati and the further modification by Samsoon and Young assessed patients in the seated position. During clinical practice, situations may arise where it may not be feasible for the patient to sit up for airway assessment. The aim of our prospective study was to determine whether there was any difference between the sitting and supine positions for the assessment of Mallampati grade. Eighty adult patients of American Society of Anesthesiologists (ASA) physical status I and II, aged 18-65 years, admitted to our neurosurgical ward were enrolled and assessed for airway. Our study revealed that change in posture produced a significant change in the mouth openings and Mallampati grades of the patients. This change was always toward a higher grade when the patient was turned supine from the sitting position.

An assessment of the predictors of difficult intubation in patients with acromegaly

Various clinical signs have been used for assessing difficult intubation in patients with acromegaly. These signs include the modified Mallampati classification, measurement of thyromental distance and head and neck movements. Some authors have also tried to establish a relationship between growth hormone levels and difficult intubation. We hypothesized that duration of symptoms in patients with acromegaly may have an association with difficult airway and difficult laryngoscopy. In this prospective study we evaluated tests of airway assessment such as: (i) the Mallampati grade; (ii) the thyromental distance; and (iii) the laryngoscopic grade (Cormack-Lehane). The growth hormone levels and the duration of disease symptoms were also examined. Significant correlation was observed between the Cormack-Lehane and Mallampati gradings (p = 0.05; ρ = 19.3%), and between the thyromental distance and the duration of the symptoms (p = 0.03; ρ = 26.9%). The incidence of Mallampati III and IV grades was higher in patients with acromegaly. Increased thyromental distance was noted in patients with a long duration of disease. However, increased thyromental distance was not associated with difficult laryngoscopy.

First step to safe anesthesia: Pre-operative prediction of difficult airway.

Corresponding author: Kye-Min Kim, M.D., Ph.D., Department of Anesthesia and Pain Medicine, Inje University College of Medicine, Sanggye Paik Hospital, 761-1, Sanggye 7-dong, Nowon-gu, Seoul 139-707, Korea. Tel: 82-2-950-1173, Fax: 82-2-950-1323, E-mail: kyemin@paik.ac.kr Copyright c Korean Society of Anesthesiologists, 2009 cc This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Difficult airway is a major factor threatening the safety of anesthesia. According to the database of the American society of Anesthesiologists Closed Claims Project [1], difficult tracheal intubation is the second most common cause of adverse events bringing about anesthesia-related malpractice claims. To avoid the unanticipated difficult intubation and the catastrophic outcomes, preoperative airway assessment and recognition of difficult intubation are necessary. Several factors such as Mallampati classification, thyromental distance, sternomental distance have been related to difficult intubation [2]. Predictive abilities for difficult intubation of these factors or composite indexes have been tested [2,3]. Postburn sternomental contractures with limited head and neck mobility are considered to increase the incidence of difficult airway. A recent case report on a child with an advanced neck contracture after burn shows us how serious it can be [4]. Therefore, very careful approach to the airway management is required in these patients. In this issue of Korean Journal of Anesthesiology, Jeong et al. [5] compared the predictive abilities for difficult intubation in those patients among three tests: modified Mallampati classification, modified Onah’s classification, El-Ganzouri and Colleagues Multivariate Risk Index (EGRI) [6]. In the study, Jeong et al. introduced Onah’s classification [7] which is originally for guiding surgical options. They modified it by removing elements of surgical consideration and used the simplified form for predicting difficult intubation. In their study, sensitivity and specificity of Mallampati classification for predicting difficult intubation were 97.7% and 19.7%, respectively. On the other hand, sensitivity and specificity of modified Onah’s classification were 86.0% and 84.9%, respectively, which are remarkably improved. Even though the diagnostic performance of EGRI were slightly lower than those of modified Onah’s, they seem to be acceptable also (sensitivity and specificity of EGRI were 83.7% and 75.8%, respectively). On the basis of these results, modified Onah’s classification was more accurate test for difficult intubation than the others in patients with sternomental contractures (Accuracy of modified Onah’s classification, EGRI and modified Mallampati classification were 85.3%, 78.9% and 50.5%, respectively). For safety issue, we must reduce the incidence of unanticipated difficult intubation as far as we can. To do so, we need to use more accurate test for the prediction of difficult intubation in case of postburn sternomental contractures. From this point of view, Jeong et al.’s study has clinical implication. However, we should also keep in mind that there is some probability of false negative prediction even with the most accurate test. So, it is recommended to be careful in the airway management regardless of the results of predictive tests. Furthermore, we should be fully aware of ‘practice Guidelines for Management of the Difficult Airway’ [8] and be familiar with several alternative techniques to laryngoscopic intubation.

Comparison of upper lip bite test with modified mallampati classification for prediction of difficult obstetric intubation

Failed obstetric intubation is a major contributory factor in anaesthesia related morbidity and mortality. Upper lip bite test (ULBT) is a relatively new test for prediction of difficult intubation, introduced in the year 2003. Here we have compared ULBT with Modified Mallampati classification (MMC) for prediction of difficult intubation in obstetric patients scheduled for caesarean section. Preoperative airway assessment for prediction of difficult laryngoscopy and intubation was done using the MMC and ULBT in hundred consecutive parturients undergoing elective as well as emergency Cesarean section under general anesthesia. Class III ULBT and a MMC of III or IV were considered to be predictive of difficult intubation (Cormack & Lehane class III or IV). Fourteen patients in the study had difficult intubation (14%). The sensitivity (92 Vs 85.7%), specificity (86 Vs 69.7%), positive predictive value (52.3 Vs 31.5%), negative predictive value (98.6 Vs 96.7%), and accuracy (87 Vs 72%) were as observed for ULBT and MMC respectively. Thus ULBT was found to be superior in every aspect studied.

Predictors of difficult intubation – a simple approach

Background: A common cause of anaesthesia related morbidity and mortality is difficult or failed intubation. A lot of studies have attempted to create a score or mathematical model to predict difficult intubation accurately without much success. Many of them consider all predictive parameters as equal. This study attempts to rank the predictors of difficult intubation without creating complicated mathematical models.Methods: Modified mallampati class, degree of head extension, mento-hyoid distance, thyromental distance, interincisor gap, forward movement of the mandible and indirect laryngoscopy were assessed in 498 patients scheduled for elective surgery. Grading of glottis exposure on direct laryngoscopy was done based on CormackLehane classification. Logistic regression analysis was done to identify factors that were significantly associated with difficult glottis exposure (Grades 3 & 4). The predictors were ranked according to the ‘odds’ derived from regression analysis.Results: Direct laryngoscopy was difficult in 40 patients (8%). Indirect laryngoscopy was excluded from the analysis in view of poor patient cooperation in a large number of patients (13%). Degree of head extension, Mento-hyoid distance of < 4 cm and modified Mallampati class 3&4 were found to have significant association with difficult glottic exposure . These predictors could be ranked in the same order based on ‘odds’ ratio (11, 3.4, and 2.5 respectively) calculated from logistic regression analysis.Conclusion: Patients with restricted head movement have much higher ‘odds’ of having a difficult glottic exposure at direct laryngoscopy, followed by those with decreased mentohyoid distance and higher modified mallampati class.

The Extended Mallampati Score and a Diagnosis of Diabetes Mellitus Are Predictors of Difficult Laryngoscopy in the Morbidly Obese

The modified Mallampati (MMP) classification is a standard method of oropharyngeal evaluation for predicting difficult laryngoscopy. Previous studies have demonstrated that the predictive value of the MMP is improved when the patient's craniocervical junction is extended rather than neutral (Extended Mallampati Score, EMS). In the present study, we compared the predictive value of the MMP and EMS in the morbidly obese. We performed a prospective study of adult patients with a Body Mass Index (BMI) > or = 40 over a 12-mo period comparing the MMP and EMS. The performance of the MMP, EMS, and other commonly used tests was compared for the ability to predict difficult laryngoscopy, defined as a Cormack-Lehane grade of 3 or 4. Positioning and direct laryngoscopic techniques were not standardized. The incidence of difficult laryngoscopy and difficult intubation was compared in patients with BMI > or = or < 40. Three-hundred-forty-six patients with a BMI > or = 40 were evaluated with both the MMP and EMS and received direct laryngoscopy. On average, craniocervical extension decreased the MMP class (P < 0.0001). Compared to the MMP, the EMS improved specificity and predictive value while maintaining sensitivity. Compared to the MMP and other tests, an EMS class of 3 or 4 and a diagnosis of diabetes mellitus were the only statistically significant predictors of difficult laryngoscopy in the morbidly obese. There was no difference in the incidence of difficult laryngoscopy or intubation in the morbidly obese compared to patients with a BMI < 40. The EMS was superior to the MMP in the prediction of difficult laryngoscopy in the morbidly obese population. A diagnosis of diabetes mellitus also warrants further investigation as a predictor of difficult laryngoscopy in this population. Finally, this study supports previous findings that morbid obesity is not itself a predictor of difficult laryngoscopy or intubation.

Improvement in laryngoscopy grade with dramatic weight loss

Obesity and obstructive sleep apnoea have both been described as risk factors for difficult laryngoscopy and mask ventilation [1, 2]. The role of weight loss in patients with difficult airway management has not previously been described. We present a case where weight reduction resulted in easier facemask ventilation and laryngoscopy. A late middle-aged ASA III male presented for an open, extended right hemicolectomy. Weight on admission was 124 kg (BMI 44 kg.m−2). Preoperative airway assessment revealed modified Mallampati Class 3 with partial dentition, limited neck movement and a thyromental distance of 5 cm. He was being treated for obstructive sleep apnoea with nocturnal nasal continuous positive airway pressure. Initial facemask ventilation with oropharyngeal airway required a two person technique (Han Grade 3 [3]). Laryngoscopy, by a consultant anaesthetist, with a size 4 Macintosh blade revealed a Cormack and Lehane grade IV view. The trachea was successfully intubated on the 4th attempt by blind passage of a Frova introducer followed by size 8.0 tracheal tube. Eight months later he was re-admitted to undergo reversal of ileostomy. In the intervening period he had lost 38 kg lowering his BMI to 30 kg.m−2. He also reported resolution of the symptoms of his obstructive sleep apnoea. Initial facemask ventilation was now possible by one person without adjuncts (Han Grade 1 [3]). Intubation was performed by an anaesthetic specialty registrar with seven months experience. Laryngoscopy with size 4 Macintosh blade and external laryngeal manipulation revealed a Cormack and Lehane Grade II view. The trachea was successfully intubated with a size 9.0 tracheal tube aided by a Frova introducer. This case, whilst reinforcing potential difficulties of obesity and obstructive sleep apnoea in airway management, suggests that weight loss may improve laryngoscopy grade and facilitate easier mask ventilation. This supports current recommendations of controlled weight loss as a risk reduction strategy in the morbidly obese patient [4].

The Effect of Head Position on Tracheal Intubation using a Lightwand

Background: Several methods have been attempted to enhance the success rate of tracheal intubation using a lightwand. Some studies have reported that changing the shape of a lightwand and the position of the head during intubation could influence the intubation time or success rate. However, there are no reports concerning the head position of a patient on influencing the success rate during tracheal intubation using a lightwand. Methods: We enrolled 109 ASA physical status 1 and 2 patients scheduled for elective surgery under general anesthesia. Patients were randomly allocated to the sniffing group (n=52) or neutral group (n=57), depending on the head position. A lightwand (Surch-LiteTM, Bovie/Aaron Medical, St. Petersburg, USA) was bent at 9.5 cm from the distal tip with a 0 cm extrusion for both groups of patients (J shape). The head was elevated by approximately 8 cm in the sniffing group of patients and by approximately 2 cm in the neutral group of patients, with the face straight up maintained by placement of a pillow. Results: The overall success rate at the first attempt was 98.1%. There were no differences in the mean intubation time between the two groups (sniffing group; 8.0±4.3 sec and neutral group; 9.3±4.1 sec). The mean intubation time tended to be longer in patients with modified Mallampati classification 3 than in patients with modified Mallampati classification 1 and 2. Conclusions: This study has demonstrated that the use of a J shaped lightwand did not affect the intubation time, regardless of the head position. The intubation time appears to be related to the airway condition when using a lightwand for tracheal intubation.

Craniocervical Extension Improves the Specificity and Predictive Value of the Mallampati Airway Evaluation

The modified Mallampati (MMP) classification is a standard airway examination that assesses mouth opening and structures within the oral cavity. Recent data suggest that maximal mouth opening (as measured by interdental distance) is possible only with extension of the craniocervical junction. Because the MMP examination is performed with the head in a neutral position, the airway may appear worse because of submaximal interdental distance. We hypothesized that adding craniocervical extension to the MMP would allow for greater mouth opening, lower scores, and less false positives than the traditional MMP examination. Multiple clinicians with at least 1 yr of airway experience evaluated adult airways (n = 60) with the MMP examination (with head in neutral position). The same examination was then repeated with the addition of craniocervical extension (Extended Mallampati Score, EMS). On average, craniocervical extension decreased the MMP class (P < 0.002). The EMS improved specificity from 70% to 80% and positive predictive value from 24% to 31% when compared with the traditional MMP. The sensitivity (83%) was the same for MMP and EMS. Craniocervical extension improves the specificity and positive predictive value of the MMP airway evaluation while retaining sensitivity of the traditional MMP examination. The introduction of the EMS into clinical practice should be considered.

Head and Neck Physical Examination: Comparison Between Nonapneic and Obstructive Sleep Apnea Patients

The purpose of this study was to apply a systematic physical examination, used to evaluate obstructive sleep apnea (OSA) patients, in nonapneic patients. Study was prospective. Patients were seen in the sleep laboratory and department of otorhinolaryngology. Nonapneic patients (n = 100) were involved in the study. Physical examination to evaluate facial skeleton, pharyngeal soft tissue, rhinoscopy, and body mass index. Data were compared with a previously published study (2003) on a group of OSA patients (n = 223). Skeletal examination detected retrognathism in 6%, class II occlusion in 12%, and high-arched hard palate in 11%. The modified Mallampati classification showed 54% in class I to II and 46% in class III to IV. Only 1% of nonapneic patients had tonsils of degree III to IV. Oropharynx evaluation showed web palate in 38%, posterior palate in 19%, thick palate in 10%, thick uvula in 10%, long uvula 15%, voluminous lateral wall in 11%, and tongue edge crenations in 28%. Anterior rhinoscopy detected significant septal deviation in 1% and turbinate hypertrophy in 31% of patients. The head and neck physical examination, considering both skeletal and soft tissue alterations, illustrated significant differences between nonapneic and OSA patients. Body mass index, modified Mallampati classification, tonsils hypertrophy, and high-arched hard palate previously related to the presence of sleep apnea in the literature showed different outcomes in nonapneic patients. Nonapneic patients had less alterations in nasal anatomy (severe septal deviation and enlarged turbinate). Skeletal parameters, such as retropositioned mandible and angle class II occlusion, were less frequent in nonapneic patients.

A Comparison of the Upper Lip Bite Test (a Simple New Technique) with Modified Mallampati Classification in Predicting Difficulty in Endotracheal Intubation

A Comparison of the Upper Lip Bite Test (a Simple New Technique) with Modified Mallampati Classification in Predicting Difficulty in Endotracheal Intubation

Association of systematic head and neck physical examination with severity of obstructive sleep apnea-hypopnea syndrome.

To identify upper airway and craniofacial abnormalities is the principal goal of clinical examination in patients with obstructive sleep apnea-hypopnea syndrome. The aim was to identify anatomical abnormalities that could be seen during a simple physical examination and determine their correlation with apnea-hypopnea index (AHI). Consecutive patients with obstructive sleep apnea-hypopnea syndrome who were evaluated in a public otorhinolaryngology center were studied. Adult patients evaluated previously with polysomnography met the inclusion criteria. All subjects underwent clinical history and otolaryngological examination and filled out a sleepiness scale. Physical examination included evaluation of pharyngeal soft tissue, facial skeletal development, and anterior rhinoscopy. Two hundred twenty-three patients (142 men and 81 women) were included (mean age, 48 +/- 12 y; body mass index, 29 +/- 5 kg/m2; AHI, 23.8 +/- 24.8 events per hour). Patients were distributed into two groups according to the AHI: snorers (18.4%) and patients with sleep apnea (81.7%). Sleepiness and nasal obstruction were reported by approximately half of patients, but the most common complaint was snoring. There was a statistically significant correlation between AHI and body mass index (P <.000), modified Mallampati classification (P =.002), and ogivale-palate (P <.001). The retrognathia was not correlated to AHI, but the presence of this anatomical alteration was much more frequent in patients with severe apnea when compared with the snorers (P =.05). Other correlations with AHI were performed considering multiple factors divided into two groups of anatomical abnormalities: pharyngeal (three or more) and craniofacial (two or more) abnormalities. There was a statistically significant correlation between pharyngeal landmarks and AHI (correlation coefficient [r] = 0.147, P =.027), but not between craniofacial landmarks and AHI. The combination of pharyngeal anatomical abnormalities, modified Mallampati classification, and body mass index were also predictive of apnea severity. Systematic physical examination that was used in the present study indicated that, in combination, body mass index, modified Mallampati classification, and pharyngeal anatomical abnormalities are related to both presence and severity of obstructive sleep apnea-hypopnea syndrome. Hypertrophied tonsils were observed in only a small portion of the patients. The frequency of symptoms of nasal obstruction was high in sleep apnea patients. Further studies are needed to find the best combination of anatomical and other clinical landmarks that are related to obstructive sleep apnea.

A Comparison of the Upper Lip Bite Test (a Simple New Technique) with Modified Mallampati Classification in Predicting Difficulty in Endotracheal Intubation: A Prospective Blinded Study

We explored the possibility that a simple and single test could replace the modified Mallampati score for either a difficult or an unaccomplished tracheal intubation in an impending hypoxic patient. Three hundred adult patients were enrolled in this study. They were subjected to the following assessments: 1) oropharyngeal class according to the modified Mallampati criteria; 2) the new, upper lip bite criteria—class I = lower incisors can bite the upper lip above the vermilion line, class II = lower incisors can bite the upper lip below the vermilion line, and class III = lower incisors cannot bite the upper lip; and 3) laryngeal view grading according to Cormack’s criteria. The incidence of difficult intubation was 5.7%. The upper lip bite test showed significantly higher specificity and accuracy than the modified Mallampati test (P < 0.001). Comparisons of sensitivity, positive and negative predictive values, between the two tests, however, did not reveal any significant differences (P > 0.05). In conclusion, the upper lip bite test is an acceptable option for predicting difficult intubation as a simple, single test.

The incidence of class "zero" airway and the impact of Mallampati score, age, sex, and body mass index on prediction of laryngoscopy grade.

In an earlier study we proposed the addition of a new airway class, zero (visualization of the epiglottis), to the four classes of the modified Mallampati classification. In this prospective study, 764 surgical patients were assessed with regard to their airway class (including class zero), laryngoscopy grade, and the effect of the airway class and other predictors on the laryngoscopy grade.

Assessment of the Modified Mallampati Classification on Supine Position

Background : The Modified Mallampati classification is a simple, easily reproducible, widely used test, which is performed with the patient in a sitting position with the tongue protruded and without phonation. It is more convenient when an assessment of modified Mallampati classification is performed while the patient is in a supine position on the operating table. The purposes of this study are to compare the correlation between the modified Mallampati classification in the supine and sitting positions, and the laryngoscopic grades of Cormack and Lehane. Methods : The data were collected from a total of 224 (98 male) patients older than 18 years of age undergoing elective surgery. The assessment of the modified Mallampati classification was performed two times to the same patient; once while the patient was in a sitting position, and the 2nd time in a supine pce ition on the operating table. Assessment of the modified Mallampati classification in a supine position was perfonned in the absence of tongue protrusion and the presence of performed phonation. Results : There were significant correlations between assessments of the modified Mallampati classi- fications (sitting position and supine position) and the laryngoscopic grades of Cormack and Lehane. Conclusions : Assessment of the Mallampati classification in the supine position had a significant correlation with laryngoscopic grades. We suggest that assessment of Mallampati classification in the supine position can be used as one of the predicting factors for difficult intubation, (Korean J Anesthesiol 2000; 38: 789~794)

Prevalence and prediction of difficult intubation in Chinese women.

We conducted a prospective, blind observational study to investigate the prevalence and prediction of difficult intubation in Chinese women. Two groups of Chinese women were studied (151 pregnant and 260 non-pregnant). The prevalence of difficult intubation was 1.99% in the pregnant and 1.54% in the non-pregnant group. The difference was not statistically significant. Predictive variables for difficult intubation, including modified Mallampati class, thyromental distance and atlanto-occipital extension, had high sensitivity but low positive predictive value when used alone. A shorter thyromental distance had to be used as the criterion for prediction in Chinese women. Combination of predictive variables could improve the positive predictive value.