Validation of modified Mallampati test with addition of thyromental distance and sternomental distance to predict difficult endotracheal intubation in adults

Evaluation of preoperative difficult airway prediction methods for adult patients without obvious airway abnormalities: a systematic review and meta-analysis

BACKGROUND

This systematic review aims to assist clinical decision-making in selecting appropriate preoperative prediction methods for difficult tracheal intubation by identifying and synthesizing literature on these methods in adult patients undergoing all types of surgery.

METHODS

A systematic review and meta-analysis were conducted following PRISMA guidelines. Comprehensive electronic searches across multiple databases were completed on March 28, 2023. Two researchers independently screened, selected studies, and extracted data. A total of 227 articles representing 526 studies were included and evaluated for bias using the QUADAS-2 tool. Meta-Disc software computed pooled sensitivity (SEN), specificity (SPC), positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR). Heterogeneity was assessed using the Spearman correlation coefficient, Cochran's-Q, and I2 index, with meta-regression exploring sources of heterogeneity. Publication bias was evaluated using Deeks' funnel plot.

RESULTS

Out of 2906 articles retrieved, 227 met the inclusion criteria, encompassing a total of 686,089 patients. The review examined 11 methods for predicting difficult tracheal intubation, categorized into physical examination, multivariate scoring system, and imaging test. The modified Mallampati test (MMT) showed a SEN of 0.39 and SPC of 0.86, while the thyromental distance (TMD) had a SEN of 0.38 and SPC of 0.83. The upper lip bite test (ULBT) presented a SEN of 0.52 and SPC of 0.84. Multivariate scoring systems like LEMON and Wilson's risk score demonstrated moderate sensitivity and specificity. Imaging tests, particularly ultrasound-based methods such as the distance from the skin to the epiglottis (US-DSE), exhibited higher sensitivity (0.80) and specificity (0.77). Significant heterogeneity was identified across studies, influenced by factors such as sample size and study design.

CONCLUSION

No single preoperative prediction method shows clear superiority for predicting difficult tracheal intubation. The evidence supports a combined approach using multiple methods tailored to specific patient demographics and clinical contexts. Future research should focus on integrating advanced technologies like artificial intelligence and deep learning to improve predictive models. Standardizing testing procedures and establishing clear cut-off values are essential for enhancing prediction reliability and accuracy. Implementing a multi-modal predictive approach may reduce unanticipated difficult intubations, improving patient safety and outcomes.

Multivariable prediction models for difficult direct laryngoscopy: Systematic review and literature metasynthesis

CONTEXT

The difficult airway is an important scenario in anaesthesia due to the impact of its potential complications, and the difficulty in predicting its presence in current clinical practice.

METHODS

Systematic review of articles in English and Spanish retrieved from MEDLINE (Ovid), LILACS and EMBASE up to March 2018. The search strategy was defined by the authors. The reviewers uploaded the studies to specially designed tables in order to qualitatively analyse the results of each paper.

RESULTS

A total of 3602 studies were identified. Thirty-four of these were included in the qualitative review. The most commonly used definition of difficulty was the Cormack-Lehane 3 or 4 classification, with a weighted mean incidence of 7.23%. The most relevant finding was the methodological weaknesses in obtaining these scales.

CONCLUSIONS

Available prediction models show limited discrimination, and weaknesses were detected in the methodology used to develop these prediction rules.

Airway Management: Difficulty of Intubation and Range of Movement of the Thyroid Cartilage

PURPOSE

Difficult endotracheal intubation has been associated with a number of anatomic factors. According to our experience, the range of movement of thyroid cartilage can be used as a useful test to determine the difficulty in endotracheal intubation. The aim of this study was to evaluate the association between the range of movement of thyroid cartilage and difficulty in intubation.

DESIGN

Cross-sectional study.

METHODS

This study was carried out on 400 patients at (Shohada Ashayer Hospital, Khorramabad). After obtaining consent letters from the patients who were between 18 and 60 years of age, the patients underwent general anesthesia. The participants were evaluated by Mallampati and other evaluating tests. The range of movement of thyroid cartilage from the midline was measured and recorded.

FINDINGS

There were significant correlation between the range of movement of thyroid cartilage and thyromental distance. In addition, in patients with Cormack-Lehane class 1, the mean range of movement of thyroid cartilage was significantly more than the patients with Cormack-Lehane class 3 and 4.

CONCLUSIONS

The outcomes of our study indicate that the range of movement of thyroid cartilage can be used for predication of difficult intubation. However, further randomized trials should be conducted in this regard.

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.

Evaluation of thyromental height as a predictor of difficult laryngoscopy and difficult intubation: a cross-sectional observational study

BACKGROUND AND OBJECTIVES

Several anthropometric measurements have been suggested to identify a potentially difficult airway. We studied thyromental height (TMH) as a predictor of difficult laryngoscopy and difficult intubation. We also compared TMH, ratio of height to thyromental distance (RHTMD), and thyromental distance (TMD) as predictors of difficult airway.

METHODS

This cross-sectional observational study was conducted in 300 adult surgical patients requiring tracheal intubation. Preoperatively airway characteristics were assessed. Standard anesthesia was administered. Degree of difficulty with mask ventilation, laryngoscopic view, duration of laryngoscopy, and difficulty in tracheal intubation (intubation difficulty scale score) were noted. Multivariate logistics regression analysis was performed to identify independent predictors for difficult laryngoscopy.

RESULTS

Laryngoscopy was difficult in 46 of 300 (15.3%) patients; all 46 patients had Cormack-Lehane grade 3 view. Duration of laryngoscopy was 27 ± 11 s in patients with difficult laryngoscopy and 12.7 ± 3.9 s in easy laryngoscopy; p = 0.001. Multivariate analysis identified that TMH, presence of short neck, and history of snoring were independently associated with difficult laryngoscopy. Incidence of difficult intubation was 17.0%. A shorter TMH was associated with higher IDS scores; r = -0.16, p = 0.001. TMH and duration of laryngoscopy were found to be negatively correlated; a shorter TMH was associated with a longer duration of laryngoscopy; r = -0.13, p = 0.03. The cut-off threshold value for TMH in our study is 4.4 cm with a sensitivity of 66% and a specificity of 54%.

CONCLUSION

Thyromental height predicts difficult laryngoscopy and difficult intubation. TMD and RHTMD did not prove to be useful as predictors of difficult airway.

Multivariable prediction models for difficult direct laryngoscopy: Systematic review and literature metasynthesis

CONTEXT

The difficult airway is an important scenario in anaesthesia due to the impact of its potential complications, and the difficulty in predicting its presence in current clinical practice.

METHODS

Systematic review of articles in English and Spanish retrieved from MEDLINE (Ovid), LILACS and Embase up to March 2018. The search strategy was defined by the authors. The reviewers uploaded the studies to specially designed tables in order to qualitatively analyse the results of each paper.

RESULTS

A total of 3602 studies were identified. Thirty-four of these were included in the qualitative review. The most commonly used definition of difficulty was the Cormack-Lehane3 or 4 classification, with a weighted mean incidence of 7.23%. The most relevant finding was the methodological weaknesses in obtaining these scales.

CONCLUSIONS

Available prediction models show limited discrimination, and weaknesses were detected in the methodology used to develop these prediction rules.

Assessment of Airway in Patients with Acromegaly Undergoing Surgery: Predicting Successful Tracheal Intubation

Background In the field of anesthesia, acromegaly is considered a cause of difficult tracheal intubation and airway management. There is a high probability of unanticipated difficult intubation in acromegalic patients despite a lower percentage of patients being identified preoperatively as having a difficult airway. In this study, we carried out various airway assessment tests preoperatively and during induction of anesthesia to find out the predictors of easy tracheal intubation in patients with acromegaly.

Methods All patients of either sex, diagnosed as a case of acromegaly and scheduled to undergo pituitary surgery were enrolled over a period of 3 years. Various airway assessment tests were performed prior to surgery, which included modified Mallampati (MP) classification (sitting and supine), mouth opening (MO), upper lip bite test (ULBT), neck movement (NM), thyromental (TM) distance, thyrohyoid (TH) distance, sternomental (SM) distance, hyomental (HM) distance, length of upper incisors (IL), receding mandible (RM), any history of obstructive sleep apnea (OSA), mask ventilation (MV), Cormack-Lehane (CL) III and IV, and external laryngeal manipulation (ELM). Results were reported as odds ratios (95% confidence interval [CI]). The p-value < 0.05 was considered statistically significant.

Results A total of 42 patients were enrolled over a period of 3 years. The male-to-female ratio was 19:23 with a mean age of 37.95 years and mean weight of 72.7 kg. Out of 15 airway assessment parameters, only ULBT and CL grade showed significant results.

Conclusion We conclude that ULBT and CL grading are reliable predictors of easy intubation in patients with acromegaly undergoing surgery.

Predictive Values of Preoperative Tests for Difficult Laryngoscopy and Intubation in Adult Patients at Tikur Anbessa Specialized Hospital

Introduction

The significance of difficult or failed tracheal intubation following induction is a well-recognized cause of morbidity and mortality in anesthetic practice. Nevertheless, the need to predict potentially difficult tracheal intubation has received a little attention. During routine anesthesia, the incidence of difficult tracheal intubation has been estimated at 1.5%–8% of general anesthetics. Difficulties in intubation have been associated with serious complications, such as brain damage or death, particularly when failed intubation has occurred. Occasionally, in a patient with a difficult airway, the anesthetist is faced with the situation where mask ventilation proves difficult or impossible. This is one of the most critical emergencies that may be faced in the practice of anesthesia. If the anesthetist can predict which patients are likely to prove difficult to intubate, he/she may reduce the risks of anesthesia considerably. In Ethiopia, there are no data on the magnitude of difficult laryngoscopic tracheal intubation and no standard guidelines for preoperative tests. The main concern of this study was to provide information on the magnitude of difficult laryngoscopic intubation and to determine valuable preoperative tests to predict difficult laryngoscopy and intubation in patients with apparently normal airways which can help anesthetists to improve preoperative airway assessment and contribute to decrease anesthesia-related morbidity and mortality.

Objective

The main objective of this study was to assess the magnitude and predictive values of preoperative tests for difficult laryngoscopy and intubation, among surgical patients who underwent elective surgery under general anesthesia with endotracheal intubation in Tikur Anbessa Hospital from February 1 to March 30, 2016.

Study Design

A facility-based cross-sectional study design was used.

Result

In this study, we found the magnitude of difficult laryngoscopy and intubation as 13.6% and 5%, respectively. 33.3% of patients with difficult laryngoscopy were found to be difficult for intubation. Mallampati test, interincisor distance, and thyromental distance were identified to be good preoperative tests to predict difficult laryngoscopic intubation when used in combination.

Recommendation

We recommend anesthesia professionals to use combination of MMC/TMD/IID for their routine preoperative airway assessment.

Correlation of preoperative findings in computed axial tomography with the presence of difficult airway in patients undergoing head and neck otorhinolaryngological surgery

OBJECTIVES

To establish a correlation between 4 measurements made on preoperative computed axial tomography and the presence of difficult airway, as well as its clinical prediction in patients undergoing otorhinolaryngological surgery.

MATERIAL AND METHODS

A retrospective, observational study was carried out using the information gathered from the clinical notes of 104 patients undergoing general anaesthesia and endotracheal intubation for oncological otorhinolaryngological surgery over a period of 36 months. Based on the findings in the preoperative imaging tests, a multivariate logistic regression analysis was performed, where the dependent variable was the presence of extreme grades of visualization of the glottis visualisation (Cormack III-IV) or the presence of predictors of difficult intubation (Mallampati III-IV). This resulted in a total of 4 tomographic and clinical factors of difficult airway being introduced in this model.

RESULTS

In the Cormack III-IV group, the results were not statistically significant in the multivariate model when compared to the tomography predictors, distance from epiglottis to posterior pharyngeal wall (95% CI; 0.030 - 2.31, P<.05), and the distance from the base of the tongue to the posterior pharyngeal wall (95% CI; 0.018-1.37, P<.05). In the Mallampati III-IV group, in the multivariate model only the distance from the vocal cords to the posterior pharyngeal wall showed clinically significant results (95% CI; 0.104 - 8.53, P<.05).

CONCLUSIONS

In the approach to the airway, reliance on predictors is based on physical examination to anticipate situations that put oxygenation and ventilation of the patients at risk. There are still insufficient data to recommend imaging tests in this area, however it seems that in the future they may be added to the diagnostic performance of physical examination as predictors of difficult airway.

Are cardiac surgical patients at increased risk of difficult intubation?

Background and Aims:

Safe airway management is the cornerstone of contemporary anaesthesia practice, and difficult intubation (DI) remains a major cause of anaesthetic morbidity and mortality. The surgical category, particularly cardiac surgery as a risk factor for DI has not been studied extensively. The aim of this study was to test the hypothesis whether cardiac surgical patients are at increased risk of DI.

Methods:

During the study, 627 patients (329 cardiac and 298 non-cardiac surgical) were enrolled. Pre-operative demographic and other variables associated with DI were assessed. Patients with Cormack Lehane grade III and IV or use of bougie in Cormack grade II were defined as DI. The incidence of anticipated and unanticipated DI was assessed. Factors associated with DI were described using univariate and multivariate logistic regression models.

Results:

The overall incidence of DI was 122/627 (19.46%). The incidence of DI was higher in cardiac surgery patients (24%) as compared to non-cardiac surgery patients (14.4% P = 0.002). On multivariate analysis, factors independently associated with DI were greater age, male sex, higher Mallampati grade, and anticipated DI, but not cardiac surgery. The incidence of unanticipated DI was 48.1% and 53.4% in cardiac and non-cardiac surgery patients, respectively.

Conclusion:

Although there was a higher incidence of DI in cardiac surgical patients, cardiac surgery is not an independent risk factor for DI. Rather, other factors play more important role. About half of the DI both in cardiac and non-cardiac surgeries were unanticipated.

Endotracheal Intubation in a Down Syndrome Adult Undergoing Cataract Surgery - a Multidisciplinary Approach

The present case report aims to describe and discuss the approach for the management of difficult endotracheal intubation in an adult with Down syndrome undergoing cataract surgery. A 26-year-old female with Down syndrome and a validated diagnosis of cataract requiring surgery was examined in order to assess the degree of difficulty of endotracheal intubation. Patients with Down syndrome have characteristic craniofacial abnormalities which require a thorough pre-operative assessment to anticipate and prepare for a difficult endotracheal intubation. Before the surgery, a series of clinical and paraclinical examinations were conducted. Although cataract surgery generally requires loco-regional anesthesia, in our case it was performed under general anesthesia. Indicators of potentially difficult intubation were macroglossia, prognathism, short neck, limited degree of head extension and obesity. The pre-operative examinations, which revealed a high degree of endotracheal intubation, allowed the anesthetist to achieve a better peri- and intra-operative management of the patient.

Indirect laryngoscopic assessment for the diagnosis of difficult intubation in patients undergoing microlaryngeal surgery

BACKGROUND

The aim of this study is to investigate the feasibility of using indirect laryngoscopy for the diagnosis of difficult intubations in patients who are undergoing microlaryngeal surgery.

METHODS

In the pre-anesthetic examination the thyromental distance, sternomental distance, interincisor distance, neck circumference, modified Mallampati scores, and Wilson risk scores were measured. An otolaryngologist conducted an indirect laryngoscopic assessment. Direct laryngoscopic profiles were classified according to their Cormack-Lehane scores.

RESULTS

Forty patients underwent microlaryngeal surgery. Their mean ages, neck circumferences, Cormack-Lehane scores of the patients who had intubation difficulties were statistically significantly higher than those who did not have intubation difficulties (p < 0.05). The significant differences between the indirect laryngoscopic assessment distributions of patients who either had or did not have intubation difficulty were assessed (p < 0.05).

CONCLUSIONS

Indirect laryngoscopic assessment is a simple and valuable technique that can be used for the diagnosis of difficult intubation in patients who are undergoing microlaryngeal surgery.