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

A Systematic Review and Meta-Analysis of Randomized Controlled Trials on Supine vs. Nonsupine Endotracheal Intubation

Background

This systematic review and meta-analysis of randomized controlled trials (RCTs) was performed to compare the safety and efficacy of supine vs. nonsupine positions during intubation.

Methods

Based on the literature from inception to October 2020, 13 studies with nonemergent intubation in supine and nonsupine positions were chosen using PRISMA and MOOSE protocols. Pooled estimates were calculated using random-effects models with 95% confidence interval (CI). The primary outcome was a successful intubation, attempt, and duration of intubation. The secondary outcome was adverse events (trauma and hypoxia). Bias was evaluated qualitatively, by visual analysis, and quantitatively through the Egger test.

Results

The final analysis included 13 clinical trials with 1,916 patients. The pooled success rates in the supine vs. lateral positions were 99.21% and 98.82%. The supine vs. semierect positions were 99.21% and 98.82%. The 1st attempt success rate in the supine vs. lateral position was 85.35% and 88.56% compared to 91.38% and 90.76% for the supine vs. semierect position. The rate of total adverse events in the supine position was 3.73% vs. 6.74% in the lateral position, and the rate of total adverse events in the supine position was 0.44% vs. 0.93% in semierect position. Low to substantial heterogeneity was noted in our analysis. Discussion. There is no significant difference between total successful intubations and success from 1st intubation attempt between supine and nonsupine positions. However, there are slightly higher rates of adverse events in nonsupine position. Addition of more recent studies on supine vs. nonsupine intubations would improve this study. Given these findings, it is important to develop more studies regarding different intubation positions and techniques with the aim of improving efficacy and decreasing adverse outcomes. Other. This review is not registered in a public database. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

A Randomized Study of Rigid Video Stylet versus Macintosh Laryngoscope for Double-Lumen Endobronchial Tube Intubation Assistance in Thoracoscopic Pulmonary Surgery

Double-lumen endobronchial tube (DLT) intubation is more challenging than single-lumen tube intubation is, and the rigid video stylet (RVS) is one of the tools that has emerged to deal with this demanding intubation procedure. We evaluated whether the UE® RVS can shorten the DLT intubation time and improve the first-attempt intubation success rate compared with that of Macintosh laryngoscope (ML). A total of 130 participants scheduled to undergo thoracoscopic pulmonary surgeries were enrolled. They were randomized to receive either ML- or RVS-assisted DLT intubation. The primary outcomes were the intubation time and first-attempt intubation success rate. The secondary outcomes were the overall intubation success rate, mean arterial pressure, postoperative sore throat (POST), and postoperative hoarseness at 1 h and 24 h. Compared with the ML group, the intubation time was significantly shorter in the RVS group (p < 0.001; 30.82 ± 10.61 vs. 39.62 ± 6.54 s), however, the first-attempt success rate was significantly lower (p = 0.048; 83.08% vs. 95.16%). The POST at 1 h was less severe in the RVS group (p = 0.021). No significant differences were found for the other indicators. Among the patients with normal airways, the UE® RVS can achieve faster DLT intubation and decrease the severity of a POST at 1 h, although it was associated with a lower first-attempt intubation success rate.

Predictive values of the modified Mallampati test, upper lip bite test, thyromental distance and ratio of height to thyromental distance to predict difficult laryngoscopy in pediatric elective surgical patients 5-12 years old at selected Addis Ababa governmental hospitals, Ethiopia: a multicenter cross-sectional study

BACKGROUND

Maintaining patent airways is vital in pediatric anesthetic management. Failure to manage and anticipate difficult laryngoscopy (DL) preoperatively is the leading cause of morbidity and mortality. Data on the predictive values of screening parameters in predicting DL are limited in children. Therefore, this study aimed to assess the predictive value of the modified Mallampati test (MMT), upper lip bite test (ULBT), thyromental distance (TMD), and ratio of height to thyromental distance (RHTMD) in predicting DL in children aged 5-12 years at selected Addis Ababa governmental hospitals in Ethiopia.

METHODS

A multicenter cross-sectional study was conducted on 141 elective pediatric surgical patients aged 5 to 12 years selected using a systematic random sampling technique at three governmental hospitals from December 1, 2021, to April 30, 2022. The collected data were entered and analysed by SPSS version 26. Chi-square and Fisher's exact tests were used to compare categorical variables. The receiver operating characteristic curve analysis was used to compare the accuracy of MMT, ULBT, TMD, and RHTMD against DL. A P value < 0.05 was considered statistically significant.

RESULTS

The magnitude of DL was 15.6%. MMT has the highest sensitivity (86.4%), specificity (91.6%), and negative predictive value (NPV) (97.3%) compared to other tests. The ULBT also has a high sensitivity (72.7%) and specificity (84%) with comparable diagnostic accuracy (90.8%) with the MMT (P < 0.05). The sensitivity, specificity, positive predictive value (PPV), NPV, and accuracy of TMD were 63.6%, 95.8%, 73.7%, 93.4%, and 82.2%, respectively. The RHTMD has the lowest specificity (63.6%), PPV (22.5%), NPV (91.4%), and accuracy (56.7%) in predicting DL.

CONCLUSION

The MMT and ULBT are good screening tests, followed by the TMD in predicting DL, while the RHTMD was the least accurate predictor. Because no single test has 100% predictive value, a combination of screening tests is advised in pediatrics for predicting DL.

Comparison of modified mallampati classification with Cormack and Lehane grading in predicting difficult laryngoscopy among elective surgical patients who took general anesthesia in Werabie comprehensive specialized hospital - Cross sectional study. Ethiopia, 2021

Background

Difficult laryngoscopy/intubation can cause a multitude of issues, including hypoxia, brain damage, and even death if not addressed swiftly. The Modified Mallampati test (MMT) is frequently used to predict difficult airway in patients with no clear difficult airway signal, despite its limited predictive power, in patients with no obvious difficult airway signal. Cormack and Lehane grading (CLG) is the gold standard, however it is not utilized before anesthesia.

Objective

To compare modified Mallampati classification (MMC) with Cormack and Lehane grading in predicting difficult laryngoscopy among patients who took general anesthesia.

Method

An institutionally based cross sectional survey study of 141 elective surgical patients with no obvious difficult airway sign was conducted from February to April 2021. The correlation between MMC and CLG was computed using spearman's correlation coefficient, and the area under the curve (AUC) for MMT was assessed using receiver operating characteristics (ROC) curve analysis.

Result

The incidence of difficult laryngoscopy and intubation, respectively, was 14.9% and 9.2%. The Spearman correlation coefficient (ρ) was 0.330, with a significance level of 0.001. The AUCs for difficult laryngoscopy and intubation, respectively, were 0.705 and 0.726. MMT had 47.6% sensitivity and 93.3% specificity for difficult laryngoscopy and 53.8% and 91.4% specificity for difficult intubation, respectively.

Conclusion

and Recommendation: There was little correlation between MMC and CLG. MMT sensitivity was similarly low. As a result, as part of the screening test for difficult airway, extra clinical tests are required.

•

Effective preoperative airway assessment reduces the difficulties of laryngoscopy and airway-related problems.

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The modified Mallampati air way assessment is routinely used.

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Cormack and Lehane grading is the gold standard for assessing airways.

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This study compares the Mallampati and Lehan's grading techniques for predicting difficult laryngoscopy.

The Association of Laryngeal Position on Videolaryngoscopy and Time Taken to Intubate Using Spatial Point Pattern Analysis of Prospectively Collected Quality Assurance Data

BACKGROUND

During videolaryngoscopy (VL), the larynx appears within the defined area of the video screen, and its location can be measured as a point within this space. Spatial statistics offer methods to explore the relationship between location data and associated variables of interest. The aims of this study were to use spatial point pattern analysis to explore if the position of the larynx on VL is associated with longer times to intubate, increased risk of a needing >1 intubation attempt, or percentage of glottic opening.

METHODS

Quality assurance data and clinical notes from all prehospital intubations using C-MAC Pocket Monitor with CMAC-4 blade (Karl Storz) from January 1, 2018, to July 31, 2020, were reviewed. We extracted 6 measurements corresponding to the time taken to obtain the initial and then best laryngeal view, time to manipulate a bougie, and time to place the endotracheal tube, as well a percentage of glottic opening and a number of intubation attempts. Larynx location was the middle of the base of glottis, in cm from the left and bottom on the C-MAC screen. Two plots were produced to summarize the base of glottis location and time to perform each time component of intubation. Next, a cross mark function and a maximum absolute deviation hypothesis test were performed to assess the null hypotheses that the spatial distributions were random. The association between glottis location and >1 intubation attempt was assessed by a spatial relative risk plot.

RESULTS

Of 619 eligible intubations, 385 had a video for analysis. The following time variables had a nonrandom spatial distribution with a tendency for longer times when the larynx was off-center to the top or right of the screen: laryngoscope passing from teeth to glottis, glottis first view to best view of the larynx, time from bougie appearing to being placed in the cords, and overall time from teeth to endotracheal tube passing through cords. There was no increased relative risk for >1 intubation attempt.

CONCLUSIONS

Spatial point pattern analysis identified a relationship between the position of the larynx during VL and prolonged intubation times. We did not find a relationship between larynx location and >1 attempt. Whether the location of the larynx on the screen is a marker for difficult VL or if optimizing the larynx position to the center of the screen improves intubation times would require further prospective studies.

2022 American Society of Anesthesiologists Practice Guidelines for Management of the Difficult Airway

The American Society of Anesthesiologists; All India Difficult Airway Association; European Airway Management Society; European Society of Anaesthesiology and Intensive Care; Italian Society of Anesthesiology, Analgesia, Resuscitation and Intensive Care; Learning, Teaching and Investigation Difficult Airway Group; Society for Airway Management; Society for Ambulatory Anesthesia; Society for Head and Neck Anesthesia; Society for Pediatric Anesthesia; Society of Critical Care Anesthesiologists; and the Trauma Anesthesiology Society present an updated report of the Practice Guidelines for Management of the Difficult Airway.

Mallampati class zero airway. A narrative review

We aim to summarize the current knowledge about Mallampati class zero airway and its implication on airway management. Mallampati class zero airway describes a visible epiglottis on pharyngoscopic view. We reviewed the reported studies about visible epiglottis on pharyngoscopy and 35 publications were selected. Mallampati class zero airway has a low prevalence in the general population and it is more frequent in children and female. The cause for this phenomenon is not well understood but in clinical practice it is associated with an easy airway. Its inclusion as a new class in modified Mallampati classification would facilitate its diffusion and promote further investigation.

Study comparing different airway assessment tests in predicting difficult laryngoscopy: A prospective study in geriatric patients

Background and Aims

Limited studies are available comparing diagnostic accuracy of various airway predictors in geriatric patients. We conducted this study with primary aim to evaluate and validate the predictive value of 'standard airway predictors' like modified Mallampati test, thyromental distance (TMD), sternomental distance, neck movement (NM), mouth opening (MO), dentition and 'new airway predictors' like upper lip bite test (ULBT), ratio of height to thyromental distance and thyromental height test (TMHT) for predicting difficult laryngoscopy in geriatric patients.

Methods

This prospective, observational study was conducted on 140 patients above 65 years of age of either sex, scheduled for elective surgery under general anaesthesia requiring endotracheal intubation. The age, weight, height, body mass index (BMI) and airway parameters were recorded. The laryngoscopic view was assessed by modified Cormack-Lehane scale. Standard formulae were used to calculate validity indexes.

Results

The incidence of difficult larygoscopy found in our study was 25%. The mean age of our study population was 69.37 ± 4.23 years. TMD exhibited the highest sensitivity (80%) and negative predictive value (NPV) (91.86%) as compared to other studied airway predictors. The positive predictive value (PPV) of ULBT was 100%. Moreover, ULBT exhibited highest accuracy (82.14%) and odds ratio (86.88) and high specificity (91.30%) for predicting difficult laryngoscopy in geriatric patients. NM and TMHT also exhibited high accuracy (77.85%, 77.14%) and PPV (59.09%, 52.94%).

Conclusions

TMD and ULBT both showed good predictive value in diagnosing difficult laryngoscopy in geriatric patients. Furthermore, NM and TMHT also exhibited higher diagnostic accuracy in predicting difficult airway in these patients.

Unscheduled Procedural Sedation: A Multidisciplinary Consensus Practice Guideline

The American College of Emergency Physicians (ACEP) organized a multidisciplinary effort to create a clinical practice guideline specific to unscheduled, time-sensitive procedural sedation, which differs in important ways from scheduled, elective procedural sedation. The purpose of this guideline is to serve as a resource for practitioners who perform unscheduled procedural sedation regardless of location or patient age. This document outlines the underlying background and rationale, and issues relating to staffing, practice, and quality improvement.

A feasibility study of jaw thrust as an indicator assessing adequate depth of anesthesia for insertion of supraglottic airway device in morbidly obese patients

Background:

Jaw thrust has been proven as a useful test determining adequate depth of anesthesia for successful insertion of supraglottic airway device (SAD) in normal adults and children receiving intra-venous or inhalational anesthesia induction. This prospective observational study aimed to determine the feasibility and validity of this test when using as an indicator assessing adequate depth of anesthesia for successful insertion of SAD in spontaneously breathing morbidly obese patients receiving sevoflurane inhalational induction.

Methods:

Thirty morbidly obese patients with a body mass index 40 to 73 kg/m² undergoing bariatric surgery in Beijing Friendship Hospital from October 2018 to January 2019 were included in this study. After adequate pre-oxygenation, 5% sevoflurane was inhaled and inhalational concentration of sevoflurane was increased by 1% every 2 min. After motor responses to jaw thrust disappeared, a SAD was inserted and insertion conditions were graded. The anatomic position of SAD was assessed using a fiberoptic bronchoscope.

Results:

The SAD was successfully inserted at the first attempt in all patients. Insertion conditions of SAD were excellent in nine patients (30%) and good in 21 patients (70%), respectively. The fiberoptic views of SAD position were adequate in 28 patients (93%).

Conclusions:

Jaw thrust test is a reliable indicator determining adequate anesthesia depth of sevoflurane inhalational induction for successful insertion of SAD in spontaneously breathing morbidly obese patients.

Clinical trial registration:

ChiCTR1800016868; http://www.chictr.org.cn/showproj.aspx?proj=28646.

Comparison of King Vision video laryngoscope and Macintosh laryngoscope: a prospective randomized controlled clinical trial

Background and objectives

We compared the efficiency of the King Vision video laryngoscope and the Macintosh laryngoscope, when used by experienced anesthesiologists on adult patients with varying intubating conditions, in a prospective randomized controlled clinical trial.

Methods

A total of 388 patients with an American Society of Anesthesiologists physical status of I or II, scheduled for general anesthesia with endotracheal intubation. Each patient was intubated with both laryngoscopes successively, in a randomized order. Intubation success rate, time to best glottic view, time to intubation, time to ventilation, Cormack–Lehane laryngoscopy grades, and complications related to the laryngoscopy and intubation were analyzed.

Results and conclusions

First pass intubation success rates were similar for the King Vision and the Macintosh (96.6% vs. 94.3%, respectively, p > 0.05). King Vision resulted in a longer average time to glottic view (95% CI 0.5–1.4 s, p < 0.001), and time to intubation (95% CI 3–4.6 s, p < 0.001). The difference in time to intubation was similar when unsuccessful intubation attempts were excluded (95% CI 2.8–4.4 s, p < 0.001). Based on the modified Mallampati class at the preoperative visit, the King Vision improved the glottic view in significantly more patients (220 patients, 56.7%) compared with the Macintosh (180 patients, 46.4%) (p < 0.001). None of the patients had peripheral oxygen desaturation below 94%. Experienced anesthesiologists may obtain similar rates of first pass intubation success and airway trauma with both laryngoscopes. King Vision requires longer times to visualize the glottis and to intubate the trachea, but does not cause additional desaturation.

[Comparison of King Vision video laryngoscope and Macintosh laryngoscope: a prospective randomized controlled clinical trial]

BACKGROUND AND OBJECTIVES

We compared the efficiency of the King Vision video laryngoscope and the Macintosh laryngoscope, when used by experienced anesthesiologists on adult patients with varying intubating conditions, in a prospective randomized controlled clinical trial.

METHODS

A total of 388 patients with an American Society of Anesthesiologists physical status of I or II, scheduled for general anesthesia with endotracheal intubation. Each patient was intubated with both laryngoscopes successively, in a randomized order. Intubation success rate, time to best glottic view, time to intubation, time to ventilation, Cormack-Lehane laryngoscopy grades, and complications related to the laryngoscopy and intubation were analyzed.

RESULTS AND CONCLUSIONS

First pass intubation success rates were similar for the King Vision and the Macintosh (96.6% vs. 94.3%, respectively, p>0.05). King Vision resulted in a longer average time to glottic view (95% CI 0.5-1.4s, p<0.001), and time to intubation (95% CI 3-4.6s, p<0.001). The difference in time to intubation was similar when unsuccessful intubation attempts were excluded (95% CI 2.8-4.4s, p<0.001). Based on the modified Mallampati class at the preoperative visit, the King Vision improved the glottic view in significantly more patients (220 patients, 56.7%) compared with the Macintosh (180 patients, 46.4%) (p<0.001). None of the patients had peripheral oxygen desaturation below 94%. Experienced anesthesiologists may obtain similar rates of first pass intubation success and airway trauma with both laryngoscopes. King Vision requires longer times to visualize the glottis and to intubate the trachea, but does not cause additional desaturation.

Effect of Manual Caudal and Downward Displacement of Lower Cervical Adipose Tissue on Laryngoscopic Grade of Patients with Morbid Obesity

Background

The prevalence of obesity has substantially increased all over the world in the past decades and anesthesiologists more commonly encounter these patients. Excess cervical adipose tissues can result in the narrowing of the pharyngeal opening and affect laryngoscopic grade.

Objectives

To evaluate the effect of manual caudal and cervical displacement of cervical adipose tissue on laryngoscopic view of morbid obese patients.

Methods

A total of 70 patients with a BMI ≥ 35 were enrolled in this study. All patients were placed in the ramp position. Manual caudal and downward displacement of cervical adipose tissue was performed by an anesthesiologist. Laryngoscopy was performed by an anesthesiologist before and after manual displacement. The anesthesiologist was blinded as we had drawn a curtain, therefore, he could not recognize if the maneuver was being performed or not. Thyromental distance, upper lip bite test, hyomental distance, and BMI were recorded for all patients.

Results

Age, weight, and BMI didn't have any significant relation with difficult intubation. There was a significant relationship between difficult intubation and thyromental distance, upper lip bite test, Mallampati score, and hyomentaldistance (P: 0.01, 0.04, 0.001, and 0.005, respectively). Cormack-Lehane grade significantly improved after the maneuver (P: 0.001).

Conclusions

Preparation and appropriate management of airway is very important for morbid obese patients. Manual caudal and downward displacement of adipose tissue has a significant effect on the improvement of laryngoscopic view in morbid obese patients. Therefore, ramped position or manual and caudal displacement of chest wall fat tissue can be added to "standard" preoperative airway assessment.

Pre-selection of primary intubation technique is associated with a low incidence of difficult intubation in patients with a BMI of 35 kg/m2 or higher

Background

The incidence of difficult intubation (DI) in obese patients may reach a two-digit figure. No studies have assessed the effect of primary use of special intubation devices on lowering the incidence of DI. We assessed the effect of primary selection of special intubation techniques on the incidence of DI in patients with a BMI of 35 kg/m² or higher.

Patients and methods

Data from 546 patients with a BMI of 35 kg/m² or higher who underwent bariatric surgery at Wolfson Medical Center from 2010 through 2014 was retrospectively extracted and analyzed for demographics, predictors of DI and intubation techniques employed. Difficult intubation was defined as the presence of at least one of the followings: laryngoscopy grade 3 or 4, need for >1 laryngoscopy or intubation attempt, need for changing the blade size, failed direct laryngoscopy (DL), difficult or failed videolaryngoscopy (VL-Glidescope), difficult or failed awake fiberoptic intubation (AFOI) and using VL or awake AFOI as rescue airway techniques. Primary intubation techniques were direct DL, VL and AFOI. We correlated the predictors of DI with the actual incidence of DI and with the choice of intubation technique employed.

Results

The overall incidence of DI was 1.6% (1.5% with DL vs. 2.2 with VL + AFOI, p = 0.61). With logistic regression analysis, age was the only significant predictor of DI. Predictors of DI that affected the selection of VL or AFOI as primary intubation tools were Mallampati class 3 or 4, limited neck movement, age, male gender, body mass index and obstructive sleep apnea syndrome.

Conclusion

The lower incidence of DI in our study group may stem from the primary use of special intubation devices, based on the presence of predictors of DI.

Airway physical examination tests for detection of difficult airway management in apparently normal adult patients

BACKGROUND

The unanticipated difficult airway is a potentially life-threatening event during anaesthesia or acute conditions. An unsuccessfully managed upper airway is associated with serious morbidity and mortality. Several bedside screening tests are used in clinical practice to identify those at high risk of difficult airway. Their accuracy and benefit however, remains unclear.

OBJECTIVES

The objective of this review was to characterize and compare the diagnostic accuracy of the Mallampati classification and other commonly used airway examination tests for assessing the physical status of the airway in adult patients with no apparent anatomical airway abnormalities. We performed this individually for each of the four descriptors of the difficult airway: difficult face mask ventilation, difficult laryngoscopy, difficult tracheal intubation, and failed intubation.

SEARCH METHODS

We searched major electronic databases including CENTRAL, MEDLINE, Embase, ISI Web of Science, CINAHL, as well as regional, subject specific, and dissertation and theses databases from inception to 16 December 2016, without language restrictions. In addition, we searched the Science Citation Index and checked the references of all the relevant studies. We also handsearched selected journals, conference proceedings, and relevant guidelines. We updated this search in March 2018, but we have not yet incorporated these results.

SELECTION CRITERIA

We considered full-text diagnostic test accuracy studies of any individual index test, or a combination of tests, against a reference standard. Participants were adults without obvious airway abnormalities, who were having laryngoscopy performed with a standard laryngoscope and the trachea intubated with a standard tracheal tube. Index tests included the Mallampati test, modified Mallampati test, Wilson risk score, thyromental distance, sternomental distance, mouth opening test, upper lip bite test, or any combination of these. The target condition was difficult airway, with one of the following reference standards: difficult face mask ventilation, difficult laryngoscopy, difficult tracheal intubation, and failed intubation.

DATA COLLECTION AND ANALYSIS

We performed screening and selection of the studies, data extraction and assessment of methodological quality (using QUADAS-2) independently and in duplicate. We designed a Microsoft Access database for data collection and used Review Manager 5 and R for data analysis. For each index test and each reference standard, we assessed sensitivity and specificity. We produced forest plots and summary receiver operating characteristic (ROC) plots to summarize the data. Where possible, we performed meta-analyses to calculate pooled estimates and compare test accuracy indirectly using bivariate models. We investigated heterogeneity and performed sensitivity analyses.

MAIN RESULTS

We included 133 (127 cohort type and 6 case-control) studies involving 844,206 participants. We evaluated a total of seven different prespecified index tests in the 133 studies, as well as 69 non-prespecified, and 32 combinations. For the prespecified index tests, we found six studies for the Mallampati test, 105 for the modified Mallampati test, six for the Wilson risk score, 52 for thyromental distance, 18 for sternomental distance, 34 for the mouth opening test, and 30 for the upper lip bite test. Difficult face mask ventilation was the reference standard in seven studies, difficult laryngoscopy in 92 studies, difficult tracheal intubation in 50 studies, and failed intubation in two studies. Across all studies, we judged the risk of bias to be variable for the different domains; we mostly observed low risk of bias for patient selection, flow and timing, and unclear risk of bias for reference standard and index test. Applicability concerns were generally low for all domains. For difficult laryngoscopy, the summary sensitivity ranged from 0.22 (95% confidence interval (CI) 0.13 to 0.33; mouth opening test) to 0.67 (95% CI 0.45 to 0.83; upper lip bite test) and the summary specificity ranged from 0.80 (95% CI 0.74 to 0.85; modified Mallampati test) to 0.95 (95% CI 0.88 to 0.98; Wilson risk score). The upper lip bite test for diagnosing difficult laryngoscopy provided the highest sensitivity compared to the other tests (P < 0.001). For difficult tracheal intubation, summary sensitivity ranged from 0.24 (95% CI 0.12 to 0.43; thyromental distance) to 0.51 (95% CI 0.40 to 0.61; modified Mallampati test) and the summary specificity ranged from 0.87 (95% CI 0.82 to 0.91; modified Mallampati test) to 0.93 (0.87 to 0.96; mouth opening test). The modified Mallampati test had the highest sensitivity for diagnosing difficult tracheal intubation compared to the other tests (P < 0.001). For difficult face mask ventilation, we could only estimate summary sensitivity (0.17, 95% CI 0.06 to 0.39) and specificity (0.90, 95% CI 0.81 to 0.95) for the modified Mallampati test.

AUTHORS' CONCLUSIONS

Bedside airway examination tests, for assessing the physical status of the airway in adults with no apparent anatomical airway abnormalities, are designed as screening tests. Screening tests are expected to have high sensitivities. We found that all investigated index tests had relatively low sensitivities with high variability. In contrast, specificities were consistently and markedly higher than sensitivities across all tests. The standard bedside airway examination tests should be interpreted with caution, as they do not appear to be good screening tests. Among the tests we examined, the upper lip bite test showed the most favourable diagnostic test accuracy properties. Given the paucity of available data, future research is needed to develop tests with high sensitivities to make them useful, and to consider their use for screening difficult face mask ventilation and failed intubation. The 27 studies in 'Studies awaiting classification' may alter the conclusions of the review, once we have assessed them.

Airway Management for the Oral Surgery Patient

This article discusses anesthesia assessment concepts related to airway evaluation and airway maintenance for safe and reliable selection of either open system (entrainment of room air) or closed system (no entrainment of room air) airway devices, which can be used during office-based oral surgical procedures, depending on the needs of a patient. Dental facial and oral structures are integral to an anesthetist's preoperative patient evaluation prior to surgery. The preoperative medical history and physical examination as well as the nature of the oral surgical procedure affect the selection of a proper and safe airway device.

Cross Sectional Observational Study Performed to See for Relation of Mallampati Score and Extended Mallampati Score with Body Mass Index

INTRODUCTION

There is increasing incidence of obesity worldwide. Since obese patients have an increased fatty tissue distributed in a truncal fashion, they may have an important and negative impact on the airway patency and respiratory function. Various scoring systems have been used to predict difficult airway, the most commonly used universal bedside tool is the Modified Mallampati Scoring (MMS). It was shown that the Extended Mallampati Score (EMS) predicted difficult laryngoscopy better than the MMS in the obese populations.

AIM

To evaluate the association of Mallampati score and EMS in adults.

MATERIALS AND METHODS

This cross-sectional prospective observational study was performed on 323 subjects. The selection method included convenience sampling technique. Patient data which included name, age, sex, weight, height, Body Mass Index (BMI) and Neck Circumference (NC), Mallampati Score, and EMS were collected by two observers, anaesthesiologists. The observers noted their findings of MMS and EMS on the same patient independently. Their findings were entered independently and disclosed only during analysis.

RESULTS

There was good agreement between the observers (kappa value 0.635) for MMS and EMS. The intraobserver correlation coefficient was 0.8 for MMS (p<0.001) and 0.7 (p=0.004) for EMS which was significant. A positive correlation between sex and NC with BMI, MMS and EMS was seen.

CONCLUSION

From this study we concluded that there was no difference between the MMS and EMS. There was interobserver agreement between MMS and EMS and a positive correlation of body mass index with MMS and EMS was seen.

Regional anesthesia in difficult airway: The quest for a solution continues

Difficult airway, a scenario with potentially life threatening outcome, is routinely encountered by an anesthesiologist leaving him with the dilemma of whether to use regional anesthesia (RA) or general anesthesia. Our study aims to look into this problem. The literature search was performed in the Google, PubMed, and Medscape using key words "regional anesthesia, difficult airway, pregnancy, ventilation, intubation, epidural anesthesia, nerve blocks." More than 38 free full articles and books published from the year 1987 to 2014 were retrieved and studied. At first sight, RA may appear to offer an ideal solution as it helps to avoid the problem of difficult airway. However, the possibility of a total spinal block, failed or incomplete RA, local anesthetic toxicity or unforeseen surgical complication may make it imperative that the airway is secured. The correct decision can only be made by the anesthetist when all the relevant clinical information is taken into account. It is also important to ensure that before considering RA in a patient of difficult airway, an anesthesiologist must have a preformulated strategy for intubation.

Comparison of clinical validation of acceleromyography and electromyography in children who were administered rocuronium during general anesthesia: a prospective double-blinded randomized study

Background

Electromyography and acceleromyography are common neuromuscular monitoring devices. However, questions still remain regarding the use of acceleromyography in children. This study compared the calibration success rates and intubation conditions in children after obtaining the maximal blockade depending on each of the devices

Methods

Children, 3 to 6 years old, were randomly allocated to the TOF-Watch SX acceleromyography group or the NMT electromyography group. The induction was performed with propofol, fentanyl, and rocuronium. The bispectral index and 1 Hz single twitch were monitored during observation. The calibration of the each device was begun when the BIS dropped to 60. After successful calibration, rocuronium 0.6 mg/kg was injected. A tracheal intubation was performed when the twitch height suppressed to 0. The rocuronium onset time (time from administration to the maximal depression of twitch height) and intubating conditions were rated in a blinded manner.

Results

There was no difference in the calibration success rates between the two groups; and the calibration time in the electromyography group (16.7 ± 11.0 seconds) was shorter than the acceleromyography group (28.1 ± 13.4 seconds, P = 0.012). The rocuronium onset time of the electromyography group (73.6 ± 18.9 seconds) was longer than the acceleromyography group (63.9 ± 18.8 seconds, P = 0.042) and the intubation condition of the electromyography group (2.27 ± 0.65) was better than the acceleromyography group (1.86 ± 0.50, P = 0.007).

Conclusions

Electromyography offers a better compromise than acceleromyography with respect to the duration of calibration process and surrogate for the optimal time of tracheal intubation in children.

Comparing ease of intubation in obese and lean patients using intubation difficulty scale

Background:

Difficult tracheal intubation contributes to significant morbidity and mortality during induction of anesthesia. There are divided opinions regarding ease of intubation in obese patients. Moreover, the definition of difficult intubation is not uniform; hence we have use the Intubation Difficulty Scale (IDS) to find the incidence of difficult intubation in obese patients.

Aims:

The primary aim of the following study is to find out the incidence of difficult intubation in obese and lean patients using IDS and secondary aim is to assess the performance of bedside screening tests to predict difficult intubation, mask ventilation and laryngoscopy in obese and lean patients.

Materials and Methods:

A prospective, observational cohort study of 200 patients requiring general anesthesia were categorized into 100 each based on body mass index (BMI) into lean (BMI <25 kg/m²) and obese (BMI ≥25 kg/m²) groups. IDS score ≥5 was termed as difficult intubation. Pre-operative airway assessment included Mallampati score, mouth opening, neck circumference (NC), upper lip bite test, thyromental distance, sternomental distance (SMD) and head neck mobility. Patients having difficulty in mask ventilation and laryngoscopy was recorded.

Results:

Over all in 200 patients the incidence of difficult intubation was 9%. Obese patients were slightly more difficult to intubate than lean (11% vs. 7%, P = 0.049). Age >40 years, NC >35 cm, SMD <12.5 cm and restricted head neck mobility were factors which were associated with IDS ≥5. Multivariate analysis revealed SMD <12.5 cm to predict difficult intubation in obese patients. Obese patients were difficult to mask ventilate (6% vs. 1%, P = 0.043). There was no difference regarding grading of laryngoscopy between the two groups.

Conclusion:

Obese patients are difficult to mask ventilate and intubate. During intubation of obese patients who is more than 40 years age and SMD <12.5 cm, it is preferable to have a second skilled anesthesiologist.

Visible epiglottis in children

Visible epiglottis is a rare anatomical variant which is usually asymptomatic without the need of any medical or surgical intervention. It is most commonly seen in children but there are some reports of its prevalence in adults too. Cases of visible epiglottis seem to be unfamiliar among dental professionals. In this report, we have attempted to present this anatomical variant of epiglottis in the feld of dentistry by describing a case of an 8-year-old girl who presented to the department of pediatric dentistry for normal dental check-up unaware of the existence of the visible epiglottis.

How to cite this article: Ahmed FJ, Shinohara AL, da Silva SMB, Andreo JC, de Castro Rodrigues A. Visible Epiglottis in Children. Int J Clin Pediatr Dent 2014;7(3):223-224.

Adult airway evaluation in oral surgery

Patients with a history of difficult intubation or with conditions associated with difficult airway should be approached with organized primary and secondary plans for airway management. When these potential problems are detected, patient safety may be improved with use of advanced airway management techniques and equipment. Additionally, patient referral for consultation and/or management at facilities where advanced airway management practitioners and equipment are available may be beneficial in some cases.

The causes of difficult tracheal intubation and preoperative assessments in different age groups

Background

We studied the differences in airway assessment factors among old, middle, and young age groups, and evaluated the frequency and causes of difficult intubation among these groups.

Methods

Patients were divided into young (< 40 yr, n = 75 ), middle (40-59 yr, n = 83), and old (≥ 60 yr, n = 89) group. Airway assessment factors such as head and neck movement, thyromental distance, interincisor gap, dentition, Mallampati score, and Arné score were assessed. After muscle relaxation, cervical joint rigidity and Cormack-Lehane (C-L) grade were assessed. The differences in airway assessment factors between difficult (C-L grade 3, 4) and easy (C-L grade 1, 2) intubation were then examined. Logistic regression analysis was also carried out to identify the extent to which airway assessment factors reflected difficult intubation.

Results

As aging, head and neck movement, thyromental distance, and interincisor gap decreased, the grade of dentition, Mallampati score, cervical joint rigidity and the ratio of Arné score > 11 increased. In the old and middle group, the incidence of difficult intubation was increased compared with the young group. Dentition in the young group, Mallampati score and interinsisor gap in the middle group and Mallampati score, cervical joint rigidity in the old group respectively predicted difficult intubation.

Conclusions

Compared to young individuals, middle-aged or elderly adults are likely to experience more difficulty in endotracheal intubation and its predictive factors could vary by age group.

The effect of body mass index on intubation success rates and complications during emergency airway management

We evaluated the effect of body mass index (BMI) on intubation success rates and complications during emergency airway management. We retrospectively analyzed an airway registry at an academic medical center. The primary outcomes were the incidence of difficult intubation and complication rates, stratified by BMI. We captured 1,075 (98 %, 1,075/1,102; 95 % CI 97-99) intubations. Four hundred twenty-six patients (40 %) had a normal BMI, 289 (27 %) were overweight, 261 (25 %) were obese, and 77 (7 %) were morbidly obese. In a multivariate analysis, obesity (OR 1.90; 95 % CI 1.04-3.45; p = 0.04), but not morbid obesity (OR 2.18; 95 % CI 0.95-4.99; p = 0.07), predicted difficult intubation. BMI was not predictive of post-intubation complications. Airway management in the morbidly obese differed when compared with lean patients, with less use of rapid sequence intubation and increased use of fiberoptic bronchoscopy in the former. During emergency airway management, difficult intubation is more common in obese patients, and morbidly obese patients are more commonly treated as potentially difficult airways.

Airway difficulty in Mallampati 'class zero' patients: a prospective double-blind observational study

CONTEXT

Assessment of Mallampati class is an integral part of preoperative airway evaluation. Increasing Mallampati class is known to be associated with greater difficulty with intubation, but some cases of airway difficulty in Mallampati 'class zero' patients have been reported.

OBJECTIVE(S)

We undertook this study to evaluate intubation difficulty and to correlate this with indirect laryngoscopy findings in Mallampati class zero patients. The incidence of Mallampati class zero airway in Indian patients and the difficulty in mask ventilation were also evaluated.

DESIGN

Prospective double-blind observational study.

SETTING

A tertiary care medical college hospital in Karnataka, India.

STUDY PERIOD

September 2010 to April 2011.

PATIENTS

Patients of either sex, 18 years and older, presenting for preanaesthetic examination for elective surgery were evaluated. All patients with Mallampati class zero airway undergoing general anaesthesia with tracheal intubation were included. Exclusion criteria were upper airway disorder, unstable cervical spine, increased risk for aspiration, ischaemic heart disease, increased intracranial pressure, respiratory distress, those unable to sit upright, or infected with hepatitis B, hepatitis C, HIV or pulmonary tuberculosis, or requiring emergency surgery. All underwent indirect laryngoscopy performed by the otorhinolaryngologist and subsequently, direct laryngoscopy performed by the anaesthesiologist. Intubation difficulty was assessed by the Cormack & Lehane grades.

MAIN OUTCOME MEASURES

Evaluation of intubation difficulty and correlation with indirect laryngoscopy findings in Mallampati class zero patients. Estimation of the incidence of Mallampati class zero airway in Indian patients and the difficulty in mask ventilation.

RESULTS

Twenty women and thirteen men, aged 18-65 years, of Mallampati class zero were identified out of 1937 (incidence, 1.7%). The data of 27 patients were analysed. Two patients had 'difficult' mask ventilation. All had a 'predicted easy' airway on indirect laryngoscopy and 'easy' (Cormack & Lehane grade 1 or 2) tracheal intubation. Upon direct laryngoscopy, the epiglottis was described as 'large' in 10 (37%) patients.

CONCLUSION

A Mallampati class zero per se is not associated with difficult airway unless other airway characteristics contribute to the difficulty. Even though the epiglottis may be large and overhanging, it rarely causes airway difficulty in Mallampati class zero airway.

Tracheal intubation in morbidly obese patients: a comparison of the Intubating Laryngeal Mask Airway™ and Laryngeal Mask Airway CTrach™

The aim of this study was to evaluate the efficacy of the Intubating Laryngeal Mask Airway™ (ILMA) and Laryngeal Mask Airway CTrach™ (LMA CTrach) in facilitating tracheal intubation in morbidly obese patients. Eighty patients (body mass index >40 kg x m(-2)) were randomly allocated to the ILMA or the LMA CTrach. The median (IQR [range]) total time taken for tracheal intubation was shorter with the ILMA than with the LMA CTrach (78 (63-105 [40-265]) s vs 128 (98-221 [60-423]) s, respectively; p<0.001). Significantly more manoeuvres were applied for the satisfactory ventilation and viewing of the glottis with the LMA CTrach (25% vs 55% with the ILMA; p=0.006). During the postoperative period, there was more sore throat with the LMA CTrach (p<0.02). We conclude that the ILMA results in shorter intubation times with fewer manoeuvres and sore throat compared with the LMA CTrach in the morbidly obese.

Predictors of a difficult intubation in the bariatric patient: does preoperative body mass index matter?

BACKGROUND

The incidence of difficult intubations in morbidly obese patients has been reported to be 12-20%; however, no well-established predictors of a difficult intubation exist for this patient population. Our objective was to evaluate the factors associated with a difficult intubation in morbidly obese patients undergoing laparoscopic Roux-en-Y gastric bypass at an integrated multispecialty health system with a 325-bed community teaching hospital serving 19 counties.

METHODS

The anesthetic records of patients undergoing LRYGB from 2001 to 2010 were reviewed. Difficult intubations were defined as direct laryngoscopy graded ≥1 on a 0-2 difficulty scale and unplanned fiberoptic intubations. Statistical analysis included chi-square, univariate, and multivariate logistic regression.

RESULTS

A total of 915 consecutive patients underwent LRYGB during the study period. Of these, 3 patients were excluded because of incomplete data. Of the 912 included patients, 25 (2.7%) underwent planned fiberoptic intubation, 830 (91%) had an uneventful intubation, and 57 (6.3%) had a difficult intubation. Difficult intubations were more common in men than in women (11% versus 6%, P = .027). Difficult intubations were not associated with an increasing preoperative body mass index (P = .073), the presence of obstructive sleep apnea (P = .784), or the presence of gastroesophageal reflux disease (P = .335). Multivariate predictors of a difficult intubation were Mallampati class 4 (odds ratio [OR] 2.76, P = .035), abnormal thyromental distance (OR 4.39, P = .001), restricted jaw mobility (OR 3.26, P = .018), and a history of a difficult intubation (OR 4.17, P = .002).

CONCLUSIONS

An increased Mallampati class, abnormal thyromental distance, restricted jaw mobility, and a history of difficult intubations were independent predictors of a difficult intubation. An increasing body mass index did not predict for a difficult intubation.

Poor prognostic value of the modified Mallampati score: a meta-analysis involving 177 088 patients

The modified Mallampati score is used to predict difficult tracheal intubation. We have conducted a meta-analysis of published studies to evaluate the Mallampati score as a prognostic test. A total of 55 studies involving 177 088 patients were included after comprehensive electronic and manual searches. The pooled estimates from the meta-analyses were calculated based on a random-effects model and a summary receiver operating curve. Meta-regression analyses were performed to explore sources of possible heterogeneity between the studies. The summary receiver operating curve demonstrated an area under the curve of 0.75. The pooled odds ratio for a difficult intubation with a modified Mallampati score of III or IV was 5.89 [95% confidence interval (CI), 4.74-7.32]. The pooled estimates of the specificity and sensitivity were 0.91 (CI, 0.91-0.91) and 0.35 (CI, 0.34-0.36), respectively. The pooled positive and negative likelihood ratios were 4.13 (CI, 3.60-4.66) and 0.70 (CI, 0.65-0.75), respectively. The meta-analyses had statistical and clinical heterogeneity ranging from 87.2% to 99.4%. Meta-regression analyses did not identify any significant explanation of the heterogeneity. We conclude that the prognostic value of the modified Mallampati score was worse than that estimated by previous meta-analyses. Our assessment shows that the modified Mallampati score is inadequate as a stand-alone test of a difficult laryngoscopy or tracheal intubation, but it may well be a part of a multivariate model for the prediction of a difficult tracheal intubation.

Tongue traction is as effective as jaw lift maneuver for Trachlight-guided orotracheal intubation

OBJECTIVE

The jaw lift maneuver has been traditionally used to facilitate Trachlight-guided orotracheal intubation. The aim of this study was to compare the jaw lift maneuver with another potentially useful maneuver, tongue traction, for facilitating Trachlight-guided orotracheal intubation.

METHODS

This study was prospective and randomized in design. A single experienced investigator performed Trachlight-guided orotracheal intubations in 100 adult patients with clinically normal airways undergoing elective surgeries under general anesthesia with paralysis. Patients were divided into two groups: Group J (jaw lift); and Group T (tongue traction using a padded artery forceps). Three parameters were recorded: search time (device insertion to midline glow); time to intubate (device insertion to glow at suprasternal notch); and time to confirm (device insertion to confirmation of placement by capnography).

RESULTS

All patients were intubated successfully using the Trachlight. Only one patient in Group J required more than two attempts for successful intubation. First and second attempt success rates were, respectively, 86% and 98% in Group J, and 92% and 100% in Group T. Mean search time, time to intubate and time to confirm were comparable: 6.36 ± 4.20 seconds, 11.23 ± 6.69 seconds and 21.59 ± 7.69 seconds, respectively, in Group J, and 6.81 ± 4.53 seconds, 10.79 ± 6.02 seconds and 22.80 ± 7.85 seconds, respectively, in Group T.

CONCLUSION

The tongue traction maneuver is as good as the jaw lift maneuver with regard to the success rate and time taken for Trachlight-guided orotracheal intubation.

Emergency department management of the airway in obese adults

Airway management in obese adults can be challenging, and much of the literature on this subject focuses on elective surgical cases, rather than acutely ill patients. In this article, we review the emergency department evaluation of the airway in obesity, discussing anatomy, physiology, and pharmacology. In addition, we describe techniques and devices used to improve intubating conditions in the obese patient. After our review of the relevant literature, we conclude that research in this particular area of acute care remains in its infancy.

Obstructive sleep apnea is not a risk factor for difficult intubation in morbidly obese patients

BACKGROUND

Morbid obesity (MO), obstructive sleep apnea (OSA), and neck circumference (NC) are widely believed to be independent risk factors for difficult tracheal intubation. In this study, we sought to determine whether these factors were associated with increased risk of difficult intubation in patients undergoing bariatric surgery. The predictive factors tested were OSA and its severity, as determined by apnea-hypopnea index (AHI), gender, NC, and body mass index (BMI).

METHODS

All sequentially enrolled MO patients underwent preoperative polysomnography. Severity of OSA was quantified using AHI and the American Society of Anesthesiologists' OSA severity scale. All patients had a standardized anesthetic that included positioning in the "ramped position" for direct laryngoscopy.

RESULTS

One hundred eighty consecutive patients were recruited, 140 women and 40 men. The incidence of OSA was 68%. The mean BMI was 49.4 kg/m(2). The mean AHI was 31.3 (range, 0-135). All the patients' tracheas were intubated successfully without the aid of rescue airways by anesthesiology residents. Six patients required three or more intubation attempts, a difficult intubation rate of 3.3%. There was an 8.3% incidence of difficult laryngoscopy, defined as a Cormack and Lehane Grade 3 or 4 view. There was no relationship between NC and difficult intubation (odds ratio 1.02, 95% confidence interval 0.93-1.1), between the diagnosis of OSA and difficult intubation (P = 0.09), or between BMI and difficult intubation (odds ratio 0.99, 95% confidence interval 0.92-1.06, P = 0.8). There was no relationship between number of intubation attempts and BMI (P = 0.8), AHI (P = 0.82), or NC (P = 0.3). Mallampati Grade III or more predicted difficult intubation (P = 0.02), as did male gender (P = 0.02). Finally, there was no relationship between Cormack and Lehane grade and BMI (P = 0.88), AHI (P = 0.93), or OSA (P = 0.6). Increasing NC was associated with difficult laryngoscopy but not difficult intubation (P = 0.02).

CONCLUSIONS

In MO patients undergoing bariatric surgery in the "ramped position," there was no relationship between the presence and severity of OSA, BMI, or NC and difficulty of intubation or laryngoscopy grade. Only a Mallampati score of 3 or 4 or male gender predicted difficult intubation.