Modified Mallampati Classification Research Articles

Correlação entre os formatos da orofaringe e hipofaringe e posicionamento em intubação endotraqueal difícil

Background and objectivePrediction of intubation difficulty can save patients from major preoperative morbidity or mortality. The purpose of this paper is to assess the correlation between oro–hypo pharynx position, neck size, and length with endotracheal intubation difficulty. The study also explored the diagnostic value of Friedman Staging System in prediction cases with difficult intubation. MethodThe consecutive 500 ASA (I, II) adult patients undergoing elective surgery were evaluated for oro and hypopharynx shape and position by modified Mallampati, Cormack and Lehane score as well as Friedman obstructive sleep apnea classification systems. Neck circumference and length were also measured. All cases were intubated by a single anesthesiologist who was uninformed of the above evaluation and graded intubation difficulty in visual analog score. Correlation between these findings and difficulty of intubation was assessed. Sensitivity, Specificity, Positive and Negative Predictive Values were also reported. ResultsCormack–Lehane grade had the strongest correlation with difficulty of intubation followed by Friedman palate position. Friedman palate position was the most sensitive and had higher positive and negative predictive values than modified Mallampati classification. Cormack–Lehane grade was found to be the most specific with the highest negative predictive value among the four studied classifications. ConclusionFriedman palate position is a more useful, valuable and sensitive test compared to the modified Mallampati screening test for pre‐anesthetic prediction of difficult intubation where its involvement in Multivariate model may raise the accuracy and diagnostic value of preoperative assessment of difficult airway.

The role of drug-induced sleep endoscopy in surgical planning for obstructive sleep apnea syndrome.

This study investigated the role of drug-induced sleep endoscopy (DISE) in the surgical treatment planning of patients with obstructive sleep apnea syndrome (OSAS). This study was conducted using patients diagnosed with OSAS between January 2007 and March 2009, who were scheduled for surgical treatment. DISE was performed using propofol in patients considered to have upper respiratory tract obstruction as indicated by Muller's maneuver. After completing the sleep endoscopy, the patient was intubated and surgery was performed (tonsillectomy and uvulopalatopharyngoplasty). A successful operation was defined as a decrease in the respiratory disturbance index to below 5 or a decrease of ≥50 % following the operation. The study included 20 patients (4 female and 16 male) aged 19-57 years. No statistically significant correlation between modified Mallampati class and operation success or between the polysomnographic stage of disease and operation success was identified. A significantly high operation success rate was found in the group with obstruction of the upper airway according to DISE (p < 0.05), whereas a significantly low operation success rate was found in the group with obstruction of the lower airway according to DISE (p < 0.01). DISE may be used to identify the localization of obstruction for diagnostic purposes, and it can be helpful in selecting the treatment method.

Mallampati classification without tongue protrusion can predict difficult tracheal intubation more accurately than the traditional Mallampati classification

IntroductionThe modified Mallampati classification (m-MMT) is the most popular technique for predicting difficult tracheal intubation. However, tongue protrusion may sometimes hide the oropharynx when the distance of the mouth opening is short, and this may lead to false-positive (FP) estimations of difficulty. The purpose of this study is to determine whether the Mallampati classification with no tongue protrusion (NT-MMT) can predict difficult tracheal intubation more accurately than the traditional m-MMT method. MethodsA total of 748 patients requiring endotracheal intubation were enrolled in this study. They were evaluated by m-MMT and by NT-MMT prior to surgery. After induction of general anesthesia with muscle relaxation, all patients underwent direct laryngoscopy, and the best glottic view was recorded as defined by the grading system of Cormack and Lehane. The preoperative assessment data and the intubation findings were used to determine the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the aforementioned tests in predicting difficult intubation. ResultsNT-MMT classification scored higher in all parameters than m-MMT. Similarly, the coefficient of reliability of Spearman's ρ test was higher with NT-MMT than with m-MMT. ConclusionNT-MMT is easy to perform and was more accurate in predicting difficult tracheal intubation than m-MMT.

Sublingual ultrasound as an assessment method for predicting difficult intubation: a pilot study

Current methods to assess the airway before tracheal intubation are variable in their ability to predict a difficult airway accurately. We hypothesised that sublingual ultrasound could provide additional information to predict a difficult airway with greater success than current methods. We recruited 110 patients to perform sublingual ultrasound on themselves following brief instruction. Ability to view the hyoid bone on sublingual ultrasound, mouth opening distance, thyromental distance, neck mobility, size of mandible and modified Mallampati classification were recorded and assessed for ability to predict a difficult intubation based on the grade of laryngoscope. Visibility of the hyoid using ultrasound was associated with a laryngoscopic grade of 1-2 (p < 0.0001), and (p < 0.0001) had a positive likelihood ratio of 21.6 and a negative likelihood ratio of 0.28. Each of the other methods had considerably lower positive likelihood ratios and lower sensitivity. Our results suggest that sublingual ultrasound is a potential tool for predicting a difficult airway in addition to conventional methods.

Suction catheter guided insertion of ProSeal laryngeal mask airway: Experience by untrained physicians

Background:The use of suction catheter (SC) has been shown to improve success rate during ProSeal laryngeal mask airway (PLMA) insertion in expert users.Aims:The aim of this study was to compare insertion of PLMA performed by untrained physicians using a SC or the digital technique (DT) in anaesthetised non-paralysed patients.Methods:In this prospective randomised double-blind study, conducted in the operating setting, 254 patients (American Society of Anaesthesiologists I-II, aged 18-65 years), undergoing minor surgery were enrolled. Exclusion criteria were body mass index >35 kg/m2, laryngeal or oesophageal varices, risk of aspiration or difficult face mask ventilation either referred or suspected (Langeron's criteria ≥2) and modified Mallampati classification score >2. Participants were randomly allocated to one of the two groups in which PLMA was inserted using DT (DT-group) or SC (SC-group).Statistical Analysis:Chi-square test with Yates’ correction, Mann-Whitney U-test or Student's t-test were carried-out as appropriate.Results:The final insertion success rate was greater in SC-groupcompared with DT-group 90.1% (n = 109) versus 74.4% (n = 99) respectively (P = 0.002). Mean airway leak pressure was higher in SC-group compared to DT-group (23.7 ± 3.9 vs. 21.4 ± 3.2 respectively; (P = 0.001). There were no differences in insertion time, post-operative airway morbidity and complications.Conclusion:The findings of this study suggest that SC-technique improves the success rate of PLMA insertion by untrained physicians.

Risk Factors Assessment of the Difficult Intubation using Intubation Difficulty Scale (IDS).

The major responsibility of anaesthesiologist is to maintain adequate gas exchange in his patients in all circumstances and this require that patency of upper airway is constantly maintained. Problems with upper airway management are among the most frequent causes of anaesthetic mishaps. Using intubation difficulty scale (IDS) we made an attempt to objectively assess the predictors of difficult intubation. We assessed classical bedside tests such as modified Mallampati test, Thyromental distance test and also neck extension test. We prospectively observed 400 patients undergoing general anaesthesia with endotracheal intubation, for each patient intubation difficulty score was recorded during intubation. Risk factors assessment of difficult intubation done using IDS. Risk factor assessed includes modified mallampati class III and IV, thyromental distance ≤ 6cm and neck extension < 5cm. Patients were categorised as Easy intubation (IDS, 0 to 2), slightly difficult intubation (IDS, 3 to 4) and difficult intubation (IDS 5). Preoperative airway assessment was done by thyromental distance measurement, neck extension measurement and modified mallampati test. Data was analysed using Receiver operating characteristic curve (ROC) and area under curve (AUC) for each test computed. p<0.05 was considered significant. The incidence of difficult intubation was 8% and there were no failure to intubate the trachea. The AUC were as follows: modified Mallampati test 0.473 (p<0.005), Thyromental distance test 0.753 (p<0.005) and neck extension test 0.768 (p<0.005). The results indicate that neck extension test is strongest predictor of difficult intubation (IDS≥5) in comparison to Thyromental test and modified mallampati test.

Correlation between oro and hypopharynx shape and position with endotracheal intubation difficulty

Background and objectivePrediction of intubation difficulty can save patients from major preoperative morbidity or mortality. The purpose of this paper is to assess the correlation between oro–hypo pharynx position, neck size, and length with endotracheal intubation difficulty. The study also explored the diagnostic value of Friedman Staging System in prediction cases with difficult intubation. MethodThe consecutive 500 ASA (I, II) adult patients undergoing elective surgery were evaluated for oro and hypopharynx shape and position by modified Mallampati, Cormack and Lehane score as well as Friedman obstructive sleep apnea classification systems. Neck circumference and length were also measured. All cases were intubated by a single anesthesiologist who was uninformed of the above evaluation and graded intubation difficulty in visual analog score. Correlation between these findings and difficulty of intubation was assessed. Sensitivity, Specificity, Positive and Negative Predictive Values were also reported. ResultsCormack–Lehane grade had the strongest correlation with difficulty of intubation followed by Friedman palate position. Friedman palate position was the most sensitive and had higher positive and negative predictive values than modified Mallampati classification. Cormack–Lehane grade was found to be the most specific with the highest negative predictive value among the four studied classifications. ConclusionFriedman palate position is a more useful, valuable and sensitive test compared to the modified Mallampati screening test for pre-anesthetic prediction of difficult intubation where its involvement in Multivariate model may raise the accuracy and diagnostic value of preoperative assessment of difficult airway.

Predicting difficult laryngoscopy in acromegalic patients undergoing surgery for excision of pituitary tumors: A comparison of extended Mallampati score with modified Mallampati classification

Background:There are numerous reports of difficult laryngoscopy and intubation in patients with acromegaly. To date, no study has assessed the application of extended Mallampati score (EMS) for predicting difficult intubation in acromegalics. The primary aim of this study was to compare EMS with modified Mallampati classification (MMP) in predicting difficult laryngoscopy in acromegalic patients. We hypothesized that since EMS has been reported to be more specific and better predictor than MMP, it may be superior to the MMP to predict difficult laryngoscopy in acromegalic patients.Materials and Methods:For this prospective cohort study with matched controls, acromegalic patients scheduled to undergo pituitary surgery over a period of 3 years (January 2008-December 2010) were enrolled. Preoperative airway assessment was performed by experienced anesthesiologists and involved a MMP and the EMS. Under anesthesia, laryngoscopic view was assessed using Cormack-Lehane (CL) grading. MMP and CL grades of I and II were defined “easy” and III and IV as “difficult”. EMS grade of I and II were defined “easy” and III as “difficult”. Data were used to determine the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of MMP and EMS in predicting difficult laryngoscopy.Results:Seventy eight patients participated in the study (39 patients in each group). Both MMP and EMS failed to detect difficult laryngoscopy in seven patients. Only one laryngoscopy was predicted to be difficult by both tests which was in fact, difficult.Conclusion:We found that addition of neck extension did not improve the predictive value of MMP.

Difficult laryngoscopy and intubation in the Indian population: An assessment of anatomical and clinical risk factors.

Background and Aim:Differences in patient characteristics due to race or ethnicity may influence the incidence of difficult airway. Our purpose was to determine the incidence of difficult laryngoscopy and intubation, as well as the anatomical features and clinical risk factors that influence them, in the Indian population.Methods:In 330 adult patients receiving general anaesthesia with tracheal intubation, airway characteristics and clinical factors were determined and their association with difficult laryngoscopy (Cormack and Lehane grade 3 and 4) was analysed. Intubation Difficulty Scale score was used to identify degree of difficult laryngoscopy.Results:The incidence of difficult laryngoscopy and intubation was 9.7% and 4.5%, respectively. Univariate analysis showed that increasing age and weight, male gender, modified Mallampati class (MMC) 3 and 4 in sitting and supine positions, inter-incisor distance (IID) ≤3.5 cm, thyromental (TMD) and sternomental distance, ratio of height and TMD, short neck, limited mandibular protrusion, decreased range of neck movement, history of snoring, receding mandible and cervical spondylosis were associated with difficult laryngoscopy. Multivariate analysis identified four variables that were independently associated with difficult laryngoscopy: MMC class 3 and 4, range of neck movement <80°, IID ≤ 3.5 cm and snoring.Conclusions:We found an incidence of 9.7% and 4.5% for difficult laryngoscopy and difficult intubation, respectively, in Indian patients with apparently normal airways. MMC class 3 and 4, range of neck movement <80°, IID ≤ 3.5 cm and snoring were independently related to difficult laryngoscopy. There was a high incidence (48.5%) of minor difficulty in intubation.

Clinical Criteria for Airway Assessment: Correlations with Laryngoscopy and Endotracheal Intubation Conditions

Difficult intubation, inadequate ventilation and esophageal intubation are the principal causes of death or brain damage related to airway manipulation. The objective of this cross-sectional study was to correlate a preanesthetic evaluation that may be capable of predicting a difficult intubation with the conditions encountered at laryngoscopy and endotracheal intubation. Eighty-one patients submitted to general anesthesia were evaluated at a preanesthetic consultation according to the modified Mallampati classification, the Wilson score and the American Society of Anesthesiologists (ASA) difficult airway algorithm. Findings were then correlated with the Cormack-Lehane classification and with the number of attempts at endotracheal intubation. No statistically significant correlations were found between the patients’ Mallampati classification and their Cormack-Lehane grade or between the Mallampati classification and the number of attempts required to achieve endotracheal intubation. Laryngoscopy proved difficult in four patients and in all of these cases the Wilson score had been indicative of a possibly difficult airway, highlighting its good predicting sensitivity. However, the specificity of this test was low, since another 24 patients had the same Wilson score but were classified as Cormack-Lehane I/II. Moreover, two patients who had a Wilson score ≥ 4 were also classified as Cormack-Lehane grade I/II. The study concluded that the Wilson score, although seldom used in clinical practice, is a highly sensitive predictor of a difficult airway; its specificity, however, is low.

ACCURACY OF THE UPPER LIP BITE TEST;

Objective: To compare the accuracy of Upper lip bite test with modified Mallampati classification for predicting the difficultlaryngoscopic intubation. Study Design: Cross sectional Study. Place and duration of study: The study was carried out at Department ofAnaesthesiology, Intensive Care and Pain management, Combined Military hospital, Rawalpindi from September 2008 to August 2009.Patients and Methods: Four hundred patients undergoing elective surgery meeting the inclusion/exclusion criteria were enrolled afterwritten informed consent. The airways of the patients were evaluated by using the modified Mallampati classification (MMP) and theUpper lip bite test (ULBT). MMP class 3 or 4 and ULBT class 3 were considered as indicators of difficult intubation. The laryngeal view wasgraded by Cormack and Lehane classification (Gold standard). Grade 1 or 2 was considered to represent easy intubation and grade 3 or 4to represent difficult intubation. Sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy werecalculated for both the tests separately by using the 2×2 table. Results: ULBT had a higher accuracy of 94%, specificity of 99.2% andpositive predictive value 70% compared to MMP accuracy of 82.7%, specificity of 84.4% and positive predictive value of 22.7%.Conclusions: The diagnostic accuracy of the Upper lip bite test was more than the modified Mallampati classification. We suggest that itbe compared with the other prevailing tests as well which are often used to assess difficult intubations.

The Emergence of Central Sleep Apnea after Surgical Relief of Nasal Obstruction in Obstructive Sleep Apnea

By the current definition, complex sleep apnea (CompSA) refers to the emergence of central sleep apnea (CSA) during the treatment of obstructive sleep apnea (OSA) with continuous positive airway pressure (CPAP). However, new-onset CSA has been described with use of other treatments for OSA, including tracheostomy, maxillofacial surgery, and mandibular advancement device. We present a patient with CSA beginning after endoscopic sinus and nasal surgery for nasal obstruction in the setting of mild OSA. This case highlights the importance of non-PAP mechanisms in the pathogenesis of CompSA.

Evaluation of Difficult Airway Predictors in Pediatric Population as a Clinical Investigation

Background: Preoperative evaluation of anatomical landmarks and clinical factors help identify potentially difficult airway. Till date there are no criteria or absolute guidelines that can be helpful in detecting difficult airway in pediatric population. Aim: To find the predictors of difficult mask ventilation, difficult laryngoscopy and difficult intubation in pediatric population age 1-5 years. Setting and design a prospective study was conducted in 100 ASA grade I/II pediatric patients between 1-5 years, scheduled for surgery under general anesthesia. Patients with congenital upper airway malformations and those with neck or face swelling or scars were excluded from the study. Material and methods: We assessed the usefulness of interincisor gap (IIG), oropharyngeal view with mouth wide open (without tongue protrusion), modified mallampati Class (MMP) , relationship of maxillary and mandibular incisor during normal jaw closure, neck circumference(NC) , thyromental distance (TMD), sternomental distance (SMD), ratio of height to thyromental distance as preoperative predictors of difficult mask ventilation , laryngoscopy and intubation.

156 Utility of Bedside Ultrasound as Airway Assessment Tool in Patients Receiving Procedural Sedation

156 Utility of Bedside Ultrasound as Airway Assessment Tool in Patients Receiving Procedural Sedation

Comparison of modified Mallampati classification, upper lip bite test and neck circumference in prediction of difficult intubation

s and Programme: EUROANAESTHESIA 2011: The European Anaesthesiology Congress: Airway Management

Modified mallampati classification as a clinical predictor of peroral esophagogastroduodenoscopy tolerance

BackgroundUnsedated esophagogastroduodenoscopy (EGD) is simpler and safer than sedated EGD; however, approximately 40% of patients cannot tolerate it. Early identification of patients likely to poorly tolerate unsedated EGD is valuable for improving compliance. The modified Mallampati classification (MMC) has been used to evaluate difficult tracheal intubation and laryngoscope insertion. We tried to assess the efficacy of MMC to predict the tolerance of EGD in unsedated patients.MethodsTwo hundred patients who underwent an unsedated diagnostic EGD were recruited. They were stratified according to the view of the oropharynx as either MMC class I + II (good view) or class III + IV (poor view). EGD tolerance was assessed in three ways: gag reflex by endoscopist assessment, patient satisfaction by interview, and the degree of change in vital signs.ResultsMMC was significantly correlated to gag reflex (P < 0.001), patient satisfaction (P = 0.028), and a change of vital signs (P = 0.024). Patients in the poor view group had a 3.87-fold increased risk of gag reflex (P < 0.001), a 1.78-fold increased risk of unsatisfaction (P = 0.067), and a 1.96-fold increased risk of a change in vital signs (P = 0.025) compared to those in the good view group.ConclusionsMMC appears to be a clinically useful predictor of EGD tolerance. Patients with poor view of oropharynx by MMC criteria may be candidates for sedated or transnasal EGD.

Use of intubating laryngeal mask airway for intubation in patient with massive goitrous thyroid

Sir, Large thyroid masses are a nightmare for the anaesthesiologist not only because of thyroid endocrinal abnormality but also because of difficult airway.[1] Fiberoptic bronchoscopy for tracheal intubation is considered the gold standard in such scenarios but may not be available sometimes.[23] We report a successful airway management in a patient with a large thyroid mass with distorted laryngeal anatomy using an intubating laryngeal mask airway (ILMA). A 65-year-old male was scheduled for total thyroidectomy for multinodular goitre. Patient complained of progressively increasing swelling over neck and difficulty in speaking, swallowing and breathing since last six months. The swelling extended superiorly up to the chin, laterally up to the posterior border of sternocleidomastoid and below up to the suprasternal notch (size, 30 × 20 cm) [Figure 1a and b]. There was prominence of veins over the mass and also over the anterior chest. Airway assessment revealed adequate mouth opening, modified mallampati class MMC II and neck movements were restricted. Investigations revealed normal haemogram, biochemical and thyroid profile. Indirect laryngoscopy revealed fixed left vocal cord and left pyriform fossa was not opening up. Soft tissue neck X-ray revealed compression and right deviation of trachea [Figure 2]. Contrast-enhanced computed tomography scan of neck and chest showed compression and right anterior displacement of the trachea. After overnight fasting, pantoprazole (40 mg) and glycopyrrolate (0.2 mg) was administered in the morning of surgery. In the operation room, routine monitors were attached. Lignocaine (4%) gargles were done. Left radial artery was cannulated. Anaesthesia was induced with sevoflurane (6%) in 100% oxygen. After lignocaine spray (10%), laryngoscopy revealed Cormack lehane CL Grade III. Even after manipulating the thyroid mass externally, the glottic chink could not be visualised. We could only appreciate a small hole in the left lateral aspect of the oral cavity and glottis was oedematous. We tried to negotiate the tube with a stylet but could not achieve tracheal intubation. Even bougie could not be negotiated. We attempted intubation using ILMA and optimal ventilation was achieved after adjusting the ILMA handle in different directions. This was achieved only when ILMA was rotated laterally and anteriorly. Stabilising the ILMA at this position of best ventilation and optimal capnograph, endotracheal tube was gently inserted and successful intubation was achieved. Thereafter the anaesthetic procedure was uneventful.Figure 1: (a, b). Patient with a larger thyroid massFigure 2: X-ray soft tissue neckWe predicted difficulty in tracheal intubation in our patient. Fiberoptic bronchoscope was not available with us for this patient. Tracheostomy as a definitive airway was not possible in our patient because of the large thyroid mass extending till the suprasternal notch and also due to airway distortion. So we planned to topicalize the airway and to secure the airway under sevoflurane induction. Since the endotracheal tube could not be negotiated in multiple attempts even after using bougie and stylet and manipulating the thyroid mass, ILMA was used as a rescue attempt. By manoeuvring the ILMA based on the predicted location of the glottic chink to achieve optimal ventilation helped us to adjust the ILMA cuff in line with the glottis and thereafter tracheal intubation was achieved in the first attempt. ILMA has been attempted earlier for tracheal intubation in patients with larger goitre but intubation was not successful though ventilation was easy.[4] They presumed that it could be because of distorted laryngeal anatomy and they performed standard manoeuvres for achieving the tracheal intubation. But we suggest that the manoeuvres need to be done on the basis of the predicted location of the glottic opening. We suggest that achieving optimal ventilation by ILMA could help in aligning the glottic chink and thus successful tracheal intubation could be done in a patient with a large goitrous thyroid with distorted laryngeal anatomy.

Mallampati Class Is Not Useful in the Clinical Assessment of Sleep Clinic Patients

To assess the utility of Mallampati class, a simple grade of oropharyngeal appearance used to assess difficulty of intubation, to predict severe obstructive sleep apnea and absence of OSA (rule in severe OSA and rule out OSA). Retrospective review of consecutive patients undergoing diagnostic polysomnography in a tertiary referral sleep disorders center. Modified Mallampati class and other simple patient characteristics (age, gender, body mass index) were compared to apnea-hypopnea index (AHI). The sensitivity, specificity, and the positive and negative likelihood ratios (LR+ and LR-) were calculated for Mallampati class IV to detect an AHI > 30 (rule in severe OSA) and Mallampati class I to detect an AHI < 5 (rule out OSA). A total of 953 consecutive patients (619 male) undergoing diagnostic polysomnography were included. The age of the cohort was 50.0 ± 6.4 years, with a BMI of 33.8 ± 8.6 kg/m² and AHI of 26.1 ± 25.1 /h (95% CI 1.4-78.8). Mallampati class was significantly associated with AHI (r = 0.13, p < 0.001), but there were no differences in AHI between Mallampati classes. A Mallampati class IV had a sensitivity of 40%, specificity of 67%, LR+ of 1.21, and LR- of 0.90 for an AHI > 30. A Mallampati class I was only 13% sensitive but 92% specific for an AHI < 5, with LR+ of 1.63 and LR- 0.90. Mallampati class is associated with AHI but does not significantly modify likelihood of severe OSA or absence of OSA. As such, it is of limited use to "rule in" severe OSA or "rule out OSA" in the sleep clinic population.

A comparison of upper lip bite test and the modified mallampati classification in airway assessment

Objective To compare preoperative anesthetic airway evaluation methods of the modified Mallamapti test and Upper lip bite test (ULBT),and to discuss the feasibility of Upper lip bite test on airway assessment. Methods 820 patients admitted for elective surgical procedure requiring endotracheal intubation were prospectively studied to predict difficultly level of intubation. All the patients were assessed preoperatively using the Modified Mallampati Classification and Upper Lip Bite Test. The sensitivity, specificity,positive predictive value, negative predictive value and accuracy were calculated. Results The accuracy, sensitivity, specificity,positive predictive value and negative predictive value of ULBT and the modified Mallamapti test are 86.1%, 63.46%, 89.39%, 46.48%,94.4% and 73.66%, 51.92%, 76.82%, 24.55%, 91.67% repectively. Conclusion Compared to the Modified Mallampati Classification,ULBT has higher accuracy, sensitivity, specificity, positive predictive value and negative predictive value, and should be served as a complementary to other methods. It is also worthy of promotion and application. Key words: Upper lip bite test; Modified Mallampati test; Airway assessment

Predicting Difficult Laryngoscopy in Acromegaly: A Comparison of Upper Lip Bite Test With Modified Mallampati Classification

Upper lip bite test (ULBT) is a simple test for predicting difficult intubation. However, it has not been evaluated in acromegalic patients. The primary aim of this study was to compare ULBT with modified Mallampati classification (MMPC) to predict difficult laryngoscopy in acromegalic patients. Over a 5-year period, 64 acromegalic and 63 nonacromegalic patients presenting for excision of pituitary tumor were enrolled. Preoperative airway assessment was done using MMPC and the ULBT. Under anesthesia, laryngoscopic view was assessed using Cormack-Lehane (CL) grading. MMPC III/IV and ULBT grade III were considered predictive of difficult laryngoscopy that was defined as Cormack-Lehane grades III or IV. Difficult intubation was defined as more than 2 direct laryngoscopy attempts involving change of blade or use of bougie/fiberoptic bronchoscope/intubating laryngeal mask airway. Sensitivity, specificity, positive and negative predictive values, and accuracy of both tests in predicting difficult laryngoscopy were calculated. Incidence of difficult laryngoscopy and intubation in acromegalics were 24% and 11%, respectively. MMPC and ULBT predicted difficulty in 61% and 14% acromegalics, respectively. However, only 26% and 44% of the laryngoscopies predicted to be difficult by MMMC and ULBT, respectively, were actually difficult. MMPC failed to predict 33% of difficult laryngoscopies whereas ULBT failed to predict 73%. Neither test predicted difficulty in 33% laryngoscopies that turned out to be difficult. Twenty-seven percent of the difficult laryngoscopies were correctly predicted by both tests. In acromegalic group, MMPC was more sensitive, whereas ULBT was more specific. Sensitivity and accuracy of both tests were less in acromegalic patients compared with nonacromegalic controls.