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The Cochrane Database of Systematic... May 2018The unanticipated difficult airway is a potentially life-threatening event during anaesthesia or acute conditions. An unsuccessfully managed upper airway is associated... (Meta-Analysis)
Meta-Analysis Review
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.
Topics: Adult; Airway Management; Humans; Intubation, Intratracheal; Laryngoscopy; Physical Examination; Point-of-Care Systems; Sensitivity and Specificity; Treatment Failure
PubMed: 29761867
DOI: 10.1002/14651858.CD008874.pub2 -
Anesthesia and Analgesia Apr 2022Despite several clinical index tests that are currently applied for airway assessment, unpredicted difficult laryngoscopy may still represent a serious problem in... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Despite several clinical index tests that are currently applied for airway assessment, unpredicted difficult laryngoscopy may still represent a serious problem in anesthesia practice. The aim of this systematic review and meta-analysis was to evaluate whether preoperative airway ultrasound can predict difficult direct laryngoscopy in adult patients undergoing elective surgery under general anesthesia.
METHODS
We searched the Medline, Scopus, and Web of Science databases from their inception to December 2020. The population of interest included adults who required tracheal intubation for elective surgery under general anesthesia without clear anatomical abnormalities suggesting difficult laryngoscopy. A bivariate model has been used to assess the accuracy of each ultrasound index test to predict difficult direct laryngoscopy.
RESULTS
Fifteen studies have been considered for quantitative analysis of summary receiver operating characteristic (SROC). The sensitivity for distance from skin to epiglottis (DSE), distance from skin to hyoid bone (DSHB), and distance from skin to vocal cords (DSVC) was 0.82 (0.74-0.87), 0.71 (0.58-0.82), and 0.75 (0.62-0.84), respectively. The specificity for DSE, DSHB, and DSVC was 0.79 (0.70-0.87), 0.71 (0.57-0.82), and 0.72 (0.45-0.89), respectively. The area under the curve (AUC) for DSE, DSHB, DSVC, and ratio between the depth of the pre-epiglottic space and the distance from the epiglottis to the vocal cords (Pre-E/E-VC) was 0.87 (0.84-0.90), 0.77 (0.73-0.81), 0.78 (0.74-0.81), and 0.71 (0.67-0.75), respectively. Patients with difficult direct laryngoscopy have higher DSE, DSVC, and DSHB values than patients with easy laryngoscopy, with a mean difference of 0.38 cm (95% confidence interval [CI], 0.17-0.58 cm; P = .0004), 0.18 cm (95% CI, 0.01-0.35 cm; P = .04), and 0.23 cm (95% CI, 0.08-0.39 cm; P = .004), respectively.
CONCLUSIONS
Our study demonstrates that airway ultrasound index tests are significantly different between patients with easy versus difficult direct laryngoscopy, and the DSE is the most studied index test in literature to predict difficult direct laryngoscopy. However, it is not currently possible to reach a definitive conclusion. Further studies are needed with better standardization of ultrasound assessment to limit all possible sources of heterogeneity.
Topics: Adult; Anesthesia, General; Humans; Intubation, Intratracheal; Laryngoscopy; Respiratory System; Ultrasonography
PubMed: 34914641
DOI: 10.1213/ANE.0000000000005839 -
Pediatric Pulmonology May 2021Airway anomalies are accountable for a substantial part of morbidity and mortality in children with Down syndrome (DS). Although tracheal anomalies occur more often in... (Review)
Review
INTRODUCTION
Airway anomalies are accountable for a substantial part of morbidity and mortality in children with Down syndrome (DS). Although tracheal anomalies occur more often in DS children, a structured overview on the topic is lacking. We systematically reviewed the characteristics of tracheal anomalies in DS children.
METHODS
A MEDLINE and EMBASE search for DS and tracheal anomalies was performed. Tracheal anomalies included tracheal stenosis, complete tracheal ring deformity (CTRD), tracheal bronchus, tracheomalacia, tracheal web, tracheal agenesis or atresia, laryngotracheoesophageal cleft type 3 or 4, trachea sleeve, and absent tracheal rings.
RESULTS
Fifty-nine articles were included. The trachea of DS children is significantly smaller than non-DS children. Tracheomalacia and tracheal bronchus are seen significantly more often in DS children. Furthermore, tracheal stenosis, CTRD, and tracheal compression by vascular structures are seen regularly in children with DS. These findings are reflected by the significantly higher frequency of tracheostomy and tracheoplasty performed in DS children.
CONCLUSION
In children with DS, tracheal anomalies occur more frequently and tracheal surgery is performed more frequently than in non-DS children. When complaints indicative of tracheal airway obstruction like biphasic stridor, dyspnea, or wheezing are present in children with DS, diagnostic rigid laryngotracheobronchoscopy with special attention to the trachea is indicated. Furthermore, imaging studies (computed tomography, magnetic resonance imaging, and ultrasound) play an important role in the workup of DS children with airway symptoms. Management depends on the type, number, and extent of tracheal anomalies. Surgical treatment seems to be the mainstay in severe cases.
Topics: Child; Down Syndrome; Humans; Infant; Larynx; Trachea; Tracheal Diseases; Tracheal Stenosis
PubMed: 33434377
DOI: 10.1002/ppul.25203 -
Clinical Dysmorphology Oct 2012The VATER/VACTERL association is typically defined by the presence of at least three of the following congenital malformations: vertebral anomalies, anal atresia,... (Review)
Review
The VATER/VACTERL association is typically defined by the presence of at least three of the following congenital malformations: vertebral anomalies, anal atresia, cardiac malformations, tracheo-esophageal fistula, renal anomalies, and limb abnormalities. The identification of 14 twin pairs with an initial diagnosis of VATER/VACTERL association at our clinical centers led to the performance of a classical twin study. This involved a thorough evaluation of these 14 twin pairs and a further 55 twin pairs identified from a systematic review of the literature. The zygosity, concordance, and malformation status of all 69 twin pairs were evaluated. Twenty-four twin pairs fulfilled the criteria for inclusion in a comparison of the concordance rates between monozygous (MZ) and dizygous (DZ) twin pairs. The pairwise concordance rates were 15% [95% confidence interval (CI) 4-42%] for MZ and 18% (95% CI 5-48%) for DZ twin pairs (P=0.53). The probandwise concordance rates were 27% (95% CI 11-52%) for MZ and 31% (95% CI 13-58%) for DZ twin pairs (P=0.40). Although based on a limited number of twin pairs, the findings of the present study are consistent with the low number of familial cases reported to date, and suggest that the role of inherited genetic factors in the majority of VATER/VACTERL cases is limited.
Topics: Anus, Imperforate; Diseases in Twins; Esophagus; Heart Defects, Congenital; Humans; Radius; Spine; Trachea; Twins, Dizygotic; Twins, Monozygotic
PubMed: 22895008
DOI: 10.1097/MCD.0b013e328358243c -
The Laryngoscope Sep 2021To examine the clinical features of benign intratracheal thyroid (ITT) and their management strategies and outcomes.
OBJECTIVE/HYPOTHESIS
To examine the clinical features of benign intratracheal thyroid (ITT) and their management strategies and outcomes.
STUDY DESIGN
Case series study.
METHODS
This systemic review was conducted in two international academic centers. This review includes 43 patients: one new case from the Massachusetts Eye and Ear Infirmary, four new cases from Beijing Tongren Hospital, and 38 previously published cases. We analyzed these 43 cases and summarized the patients' epidemiological data, clinical features, and treatment regimens.
RESULTS
ITTs were less common in men than in women (male:female ratio of 3:10). ITT was observed in patients as young as neonates and as old as 85 years. Orthotopic thyroid nodules were present in 55.8% of the patients with ITT. Malignancy was incidentally found in 4.6% of all ITTs. Imaging examinations showed that the ITTs were typically attached to the posterolateral/lateral tracheal wall of the first, second, or third tracheal rings. Tissue attachment between the ITT and normal thyroid lobes was seen in 59.5% of the patients. Thirty-seven patients underwent surgery: 30 underwent open surgery, and seven underwent endoscopic debulking resections. One neonate received thyroid suppression therapy. One patient with ITT and papillary thyroid cancer was treated with radiotherapy and ultimately died after recurrence.
CONCLUSIONS
Surgical resection is an effective treatment for benign ITT. We hypothesized that abnormalities during the embryonic development of Berry's ligament might play a role in ITT pathogenesis.
LEVEL OF EVIDENCE
NA Laryngoscope, 131:E2609-E2617, 2021.
Topics: Choristoma; Humans; Thyroid Gland; Tracheal Diseases
PubMed: 34184770
DOI: 10.1002/lary.29678 -
Anaesthesia Jul 2019Although bedside screening tests are routinely used to identify people at high risk of having a difficult airway, their clinical utility is unclear. We estimated the...
Although bedside screening tests are routinely used to identify people at high risk of having a difficult airway, their clinical utility is unclear. We estimated the diagnostic accuracy of commonly used bedside examination tests for assessing the airway in adult patients without apparent anatomical abnormalities scheduled to undergo general anaesthesia. We searched for studies that reported our pre-specified bedside index screening tests against a reference standard, published in any language, from date of inception to 16 December 2016, in seven bibliographic databases. We included 133 studies (127 cohort type and 6 case-control) involving 844,206 participants. Overall, their methodological quality (according to QUADAS-2, a standard tool for assessing quality of diagnostic accuracy studies) was moderate to high. Our pre-specified tests were: the Mallampati test (6 studies); modified Mallampati test (105 studies); Wilson risk score (6 studies); thyromental distance (52 studies); sternomental distance (18 studies); mouth opening test (34 studies); and the upper lip bite test (30 studies). Difficult facemask ventilation, difficult laryngoscopy, difficult intubation and failed intubation were the reference standards in seven, 92, 50 and two studies, respectively. Across all reference standards, we found all index tests had relatively low sensitivities, with high variability, but specificities were consistently and markedly higher than sensitivities. For difficult laryngoscopy, the sensitivity and specificity (95%CI) of the upper lip bite test were 0.67 (0.45-0.83) and 0.92 (0.86-0.95), respectively; upper lip bite test sensitivity (95%CI) was significantly higher than that for the mouth opening test (0.22, 0.13-0.33; p < 0.001). For difficult tracheal intubation, the modified Mallampati test had a significantly higher sensitivity (95%CI) at 0.51 (0.40-0.61) compared with mouth opening (0.27, 0.16-0.41; p < 0.001) and thyromental distance (0.24, 0.12-0.43; p < 0.001). Although the upper lip bite test showed the most favourable diagnostic test accuracy properties, none of the common bedside screening tests is well suited for detecting unanticipated difficult airways, as many of them are missed.
Topics: Airway Management; Humans; Intubation, Intratracheal; Laryngeal Masks; Point-of-Care Testing; Predictive Value of Tests; Reproducibility of Results; Sensitivity and Specificity
PubMed: 30843190
DOI: 10.1111/anae.14608