Use of Handheld Point-of-Care Ultrasound in Emergency Airway Management

[Ultrasound supported identification of the ligamentum conicum in teaching head and neck sonography]

OBJECTIVE

Upper airway obstructions are usually acute emergencies. Coniotomy is the last option to secure the airway and can be supported by sonography. The aim of this study was to establish a training program to teach these skills.

MATERIAL AND METHODS

The training consisted of theoretical training with an additional video presentation (10 minutes each) and practical training (45 minutes). Evaluations were completed before (T1) and after (T2) the training to measure prior experience and satisfaction with the training as well as subjective and objective competence levels. At T2, a practical test was also completed by n=113 participants. A standardized evaluation form was used to document the results of the practical test.

RESULTS

A large proportion of the participants had neither seen a coniotomy (64.6%) nor performed one independently (79.6%). Significant improvement (T1 to T2) was measured with regard to the subjective assessment of competence (p<0.001). The training received positive ratings for all items tested (scale ranges 1-2). During practical tests, the participants achieved an average of 89.2% of the possible points and needed a mean of 101 ±23 seconds to identify the conic ligament.

CONCLUSION

Structured training for sonographic identification of the conic ligament leads to significant improvement in the subjective assessment of competence and a high objective competence level in a short period of time. This type of training should be standardized in head and neck ultrasound training in the future.

Executive Summary of the Spanish Society of Anesthesiology, Reanimation and Pain Therapy (SEDAR) Spanish Society of Emergency and Emergency Medicine (SEMES) and Spanish Society of Otolaryngology, Head and Neck Surgery (SEORL-CCC) Guideline for difficult airway management

The Airway section of the Spanish Society of Anesthesiology, Reanimation and Pain Therapy (SEDAR), Spanish Society of Emergency and Emergency Medicine (SEMES) and Spanish Society of Otolaryngology, Head and Neck Surgery (SEORL-CCC) present the Guidelines for the integral management of difficult airway in adult patients. This document provides recommendations based on current scientific evidence, theoretical-educational tools and implementation tools, mainly cognitive aids, applicable to the treatment of the airway in the field of anesthesiology, critical care, emergencies and prehospital medicine. Its principles are focused on the human factors, cognitive processes for decision-making in critical situations and optimization in the progression of the application of strategies to preserve adequate alveolar oxygenation in order to improve safety and quality of care.

Spanish Society of Anesthesiology, Reanimation and Pain Therapy (SEDAR), Spanish Society of Emergency and Emergency Medicine (SEMES) and Spanish Society of Otolaryngology, Head and Neck Surgery (SEORL-CCC) Guideline for difficult airway management. Part II

The Airway Management section of the Spanish Society of Anesthesiology, Resuscitation, and Pain Therapy (SEDAR), the Spanish Society of Emergency Medicine (SEMES), and the Spanish Society of Otorhinolaryngology and Head and Neck Surgery (SEORL-CCC) present the Guide for the comprehensive management of difficult airway in adult patients. Its principles are focused on the human factors, cognitive processes for decision-making in critical situations, and optimization in the progression of strategies application to preserve adequate alveolar oxygenation in order to enhance safety and the quality of care. The document provides evidence-based recommendations, theoretical-educational tools, and implementation tools, mainly cognitive aids, applicable to airway management in the fields of anesthesiology, critical care, emergencies, and prehospital medicine. For this purpose, an extensive literature search was conducted following PRISMA-R guidelines and was analyzed using the GRADE methodology. Recommendations were formulated according to the GRADE methodology. Recommendations for sections with low-quality evidence were based on expert opinion through consensus reached via a Delphi questionnaire.

Spanish Society of Anesthesiology, Reanimation and Pain Therapy (SEDAR), Spanish Society of Emergency and Emergency Medicine (SEMES) and Spanish Society of Otolaryngology, Head and Neck Surgery (SEORL-CCC) Guideline for difficult airway management. Part I

The Airway Management section of the Spanish Society of Anesthesiology, Resuscitation, and Pain Therapy (SEDAR), the Spanish Society of Emergency Medicine (SEMES), and the Spanish Society of Otorhinolaryngology and Head and Neck Surgery (SEORL-CCC) present the Guide for the comprehensive management of difficult airway in adult patients. Its principles are focused on the human factors, cognitive processes for decision-making in critical situations, and optimization in the progression of strategies application to preserve adequate alveolar oxygenation in order to enhance safety and the quality of care. The document provides evidence-based recommendations, theoretical-educational tools, and implementation tools, mainly cognitive aids, applicable to airway management in the fields of anesthesiology, critical care, emergencies, and prehospital medicine. For this purpose, an extensive literature search was conducted following PRISMA-R guidelines and was analyzed using the GRADE methodology. Recommendations were formulated according to the GRADE methodology. Recommendations for sections with low-quality evidence were based on expert opinion through consensus reached via a Delphi questionnaire.

Bedside Ultrasound: The Silent Guardian for Upper Airway Assessment and Management

Ultrasound evaluation of the upper airway has emerged as an essential instrument for clinicians, offering real-time assessment that can help to guide interventions and improve patient outcomes. This review aims to provide health care providers with a practical approach to performing ultrasound evaluation of the upper airway, covering basic physics relevant to upper airway ultrasound, the identification of key anatomical structures, and elucidating its various clinical applications, such as prediction of difficult airway, confirmation of endotracheal intubation, and guidance for surgical airway procedures and airway blocks. We also discuss evidence-based training programs, limitations, and future directions of ultrasound imaging of the upper airway.

Recommendations from the Brazilian Society of Anesthesiology (SBA) for difficult airway management in adults

Difficult airway management represents a major challenge, requiring a careful approach, advanced technical expertise, and accurate protocols. The task force of the Brazilian Society of Anesthesiology (SBA) presents a report with updated recommendations for the management of difficult airway in adults. These recommendations were developed based on the consensus of a group of expert anesthesiologists, aiming to provide strategies for managing difficulties during tracheal intubation. They are based on evidence published in international guidelines and opinions of experts. The report underlines the essential steps for proper difficult airway management, encompassing assessment, preparation, positioning, pre-oxygenation, minimizing trauma, and maintaining arterial oxygenation. Additional strategies for using advanced tools, such as video laryngoscopy, flexible bronchoscopy, and supraglottic devices, are discussed. The report considers recent advances in understanding crisis management, and the implementation seeks to further patient safety and improve clinical outcomes. The recommendations are outlined to be uncomplicated and easy to implement. The report underscores the importance of ongoing education, training in realistic simulations, and familiarity with the latest technologies available.

Inter-System Variability of Eight Different Handheld Ultrasound (HHUS) Devices-A Prospective Comparison of B-Scan Quality and Clinical Significance in Intensive Care

BACKGROUND

the use of handheld ultrasonography (HHUS) devices is well established in prehospital emergency diagnostics, as well as in intensive care settings. This is based on several studies in which HHUS devices were compared to conventional high-end ultrasonography (HEUS) devices. Nonetheless, there is limited evidence regarding potential variations in B-scan quality among HHUS devices from various manufacturers, and regarding whether any such differences hold clinical significance in intensive care medicine settings.

METHODS

this study included the evaluation of eight HHUS devices sourced from diverse manufacturers. Ultrasound videos of five previously defined sonographic questions (volume status/inferior vena cava, pleural effusion, pulmonary B-lines, gallbladder, and needle tracking in situ) were recorded with all devices. The analogue recording of the same pathologies with a HEUS device served as gold standard. The corresponding findings (HHUS and HEUS) were then played side by side and evaluated by sixteen intensive care physicians experienced in sonography. The B-scan quality and the clinical significance of the HHUS were assessed using a five-point Likert scale (5 points = very good; 1 point = insufficient).

RESULTS

both in assessing the quality of B-scans and in their ability to answer clinical questions, the HHUS achieved convincing results-regardless of the manufacturer. For example, only 8.6% (B-scan quality) and 9.8% (clinical question) of all submitted assessments received an "insufficient" rating. One HHUS device showed a significantly higher (p < 0.01) average points score in the assessment of B-scan quality (3.9 ± 0.65 points) and in the evaluation of clinical significance (4.03 ± 0.73 points), compared to the other devices.

CONCLUSIONS

HHUS systems are able to reliably answer various clinical intensive care questions and are-while bearing their limitations in mind-an acceptable alternative to conventional HEUS devices. Irrespective of this, the present study was able to demonstrate relevant differences in the B-scan quality of HHUS devices from different manufacturers.

The Performance Characteristics of Handheld, Non-Piezoelectric Point-of-Care Ultrasound (POCUS) in the Emergency Department

The use of handheld point-of-care ultrasound (HH-POCUS) platforms is rapidly increasing, but the diagnostic performance of HH-POCUS in the emergency department (ED) has not been well-studied. For a period of one year, only a HH-POCUS system that uses a non-piezoelectric array (Butterfly iQ+™) was available for clinical POCUS examinations in our ED. We performed a retrospective observational study of patients who underwent cardiac, thoracic, renal, biliary, or lower extremity venous (DVT) examinations from November 2021-November 2022 and calculated performance characteristics of HH-POCUS relative to radiology imaging. A total of 381 HH-POCUS studies were evaluated. Cardiac image quality was significantly lower than lung (p = 0.002). Over half of the studies (213/381) had imaging available for comparison, and HH-POCUS identified 86.5% (32/37, (95%CI) 70.4-94.9) of prespecified emergent diagnoses, including acute cholecystitis, severely reduced left ventricular ejection fraction, pericardial effusion or tamponade, moderate or larger pleural effusion, pneumothorax, moderate or larger hydronephrosis, and DVT. For less emergent diagnoses, 84.3% (43/51, (95%CI) 70.9-92.5) were identified. Overall, HH-POCUS using a non-piezoelectric array showed modest real-world performance in the ED for cardiac, thoracic, renal, biliary, and DVT examinations. HH-POCUS may be inadequate to rule out some common ED diagnoses, but had good specificity for certain conditions such as pericardial effusion.

Identifying commonalities in definition and governance of point-of-care ultrasound within statements from medical organizations in the United States: A scoping review for a shared understanding

This scoping review analyzed statements from 22 medical organizations in the United States to identify commonalities in the definition and governance of point-of-care ultrasound (POCUS). A total of 41 statements were included. The review found that the most commonly used elements in defining POCUS were "focused," "bedside," and "patient care." In terms of governance, consistent requirements included specific training programs, documentation in medical records, continuous quality assurance, and standards for credentialing and privileging. These findings suggest the existence of essential commonalities that could facilitate communication and the development of standardized POCUS programs in the future.

A quantitative study of airway ultrasound in predicting difficult laryngoscopy: A prospective study

PURPOSE

As common clinical screening tests cannot effectively predict a difficult airway, and unanticipated difficult laryngoscopy remains a challenge for physicians. We herein used ultrasound to develop some point-of-care predictors for difficult laryngoscopy.

METHODS

This prospective observational study included 502 patients who underwent laryngoscopy and a detailed sonographic assessment. Patients under 18 years old, or with maxillofacial deformities or fractures, limited mouth opening, limited neck movement or history of neck surgery were excluded from the study. Laryngoscopic views of all patients were scored and grouping using the modified Cormack-Lehane (CL) scoring system. The measurements acquired comprised tongue width, the longitudinal cross-sectional area of the tongue, tongue volume, the mandible-hyoid bone distance, the hyoid bone-glottis distance, the mandible-hyoid bone-glottis angle, the skin-thyrohyoid membrane distance, the glottis-superior edge of the thyroid cartilage distance (DGTC), the skin-hyoid bone distance, and the epiglottis midway-skin distance. ANOVA and Chi-square were used to compare differences between groups. Logistic regression was used to identify risk factors for difficult laryngoscopy and it was visualized by receiver operating characteristic curves and nomogram. R version 3.6.3 and SPSS version 26.0 were used for statistical analyses.

RESULTS

Difficult laryngoscopy was indicated in 49 patients (CL grade Ⅲ - Ⅳ) and easy laryngoscopy in 453 patients (CL grade Ⅰ - Ⅱ). The ultrasound-measured mandible-hyoid bone-glottis angle and DGTC significantly differed between the 2 groups (p < 0.001). Difficult laryngoscopy was predicted by an area under the curve (AUC) of 0.930 with a threshold mandible-hyoid bone-glottis angle of 125.5° and by an AUC of 0.722 with a threshold DGTC of 1.22 cm. The longitudinal cross-sectional area of the tongue, tongue width, tongue volume, the mandible-hyoid distance, and the hyoid-glottis distance did not significantly differ between the groups.

CONCLUSION

Difficult laryngoscopy may be anticipated in patients in whom the mandible-hyoid bone-glottis angle is smaller than 125.5° or DGTC is larger than 1.22 cm.

Utilization of submandibular ultrasound in assessing upper airway changes following the administration of propofol

Background and Aims

Our study aimed to use submandibular ultrasound to measure upper airway parameters before and after induction dose of propofol in order to further understand upper airway changes that occur during induction of anesthesia. Measuring the changes that occur in airway anatomy due to the hypotonic effects of induction agents will allow for a deeper understanding of airway management.

Material and Methods

We enrolled 39 patients between November 2021 and January 2022. Submandibular ultrasound was used to measure tongue thickness, geniohyoid muscle thickness, the distance between the lingual arteries (DLA), lateral pharyngeal wall thickness, and hyomental distance before and after administration of induction doses of the commonly used, sedative-hypnotic agent, propofol.

Results

The mean DLA increased significantly after propofol administration, from 3.62 ± 0.63 cm to 3.79 ± 0.56 cm (P < 0.001). The mean tongue thickness was 4.89 ± 0.51 cm and decreased significantly to a mean of 4.62 ± 0.50 cm after propofol administration (P < 0.001). The change in DLA measurements after propofol administration decreased significantly as STOP-BANG score increased (r = -0.344, P = 0.037). However, DLA measurements when patients were awake increased significantly with an increase in the STOP-BANG score (r = 0.351, P = 0.031).

Conclusion

These findings suggest that propofol widens and flattens the tongue, which are changes that may contribute to difficult airway management. Given the quick and non-invasive nature of ultrasound, further studies should evaluate the role of submandibular ultrasound for understanding the upper airway and airway management in various populations.

[Ultrasound systems for abdominal diagnostics - current methods, clinical applications and new technologies]

Abdominal ultrasound is the method of first choice in many clinical situations. Gray scale imaging (B-mode) and conventional Doppler techniques are nowadays complemented by contrast-enhanced ultrasound (CEUS), elastography, fat quantification and further technologies which allow multimodal characterization of organs and tissue structure using panoramic imaging, 3D-techniques and image fusion. The development of small portable devices augments the spectrum for sonographic diagnostics. In this review, we describe the current status of ultrasound technology based on published evidence. In addition, we provide guidance for quality assurance.

Role of Point-of-Care Ultrasound in Emergency Airway Management Outside the Operating Room

Tracheal intubation is one of the most frequently performed procedures in critically ill patients, and is associated with significant morbidity and mortality. Hemodynamic instability and cardiovascular collapse are common complications associated with the procedure, and are likely in patients with a physiologically difficult airway. Bedside point-of-care ultrasound (POCUS) can help identify patients with high risk of cardiovascular collapse, provide opportunity for hemodynamic and respiratory optimization, and help tailor airway management plans to meet individual patient needs. This review discusses the role of POCUS in emergency airway management, provides an algorithm to facilitate its incorporation into existing practice, and provides a framework for future studies.

Developing a magnetic POCUS-guided bronchoscope for patients with suspected difficult endotracheal intubation in a general tertiary hospital: protocol for a randomised controlled study

INTRODUCTION

Endotracheal intubation (ETI) is a crucial but risky procedure, especially among patients suspected of difficult endotracheal intubation (DTI). Bronchoscope, as an improved technique commonly used in DTI, might encounter visualisation difficulties. The magnetic point-of-care ultrasound (MGPOCUS) provides a novel visualisation from the outside and enables estimation of the relative position and trajectory of the bronchoscope. The purpose of the study was to evaluate the efficiency of MGPOCUS-guided bronchoscopy, including the time required for successful ETI, the first attempt and overall success rate, the number of attempts, complications, and satisfaction with the visualization of the procedures.

METHODS AND ANALYSIS

The study is a randomised, parallel-group, single-blinded, single-centre study. Participants (n=108) will be recruited by the primary anaesthesiologist and randomised to groups of ETI with bronchoscope or MGPOCUS-guided bronchoscope. The primary outcome is the time taken to the first-attempt success ETI. Secondary outcomes include procedure time, the first-attempt and overall success, complications, and satisfaction of visualisation. Cox regression with Bonferroni correction and linear mixed regression will be used to analyse the outcomes.

ETHICS AND DISSEMINATION

The trial protocol was approved by the ethics committees at the Peking Union Medical College Hospital (Institutional Review Board #ZS-3428). Findings will be disseminated through conference presentations and peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT05647174.

Point-of-care ultrasound-guided submucosal paclitaxel injection in tracheal stenosis model

Background and Objectives

Transcutaneous point-of-care ultrasound (POCUS) is a good tool to monitor the trachea in many clinical practices. The aim of our study is to verify the feasibility of POCUS-guided submucosal injection as a potential drug delivery method for the treatment of tracheal stenosis.

Materials and methods

The inner wall of the trachea was monitored via a bronchoscope during the POCUS-guided submucosal injection of methylene blue in fresh ex vivo porcine trachea to evaluate the distribution of methylene blue. The feasibility and eficacy of POCUS-guided submucosal injection were evaluated in a tracheal stenosis rabbit model. Animals were divided into sham group, tracheal stenosis group, and treatment group. Ten days after the scraping of the tracheal mucosa or sham operation, POCUS-guided submucosal injection of paclitaxel or saline was performed. Seven days after the submucosal injection, the trachea was assessed by cervical computed tomography (CT) scan and ultrasound.

Results

The distribution of methylene blue in trachea proved the technical feasibility of POCUS-guided submucosal injection. CT evaluation revealed that the tracheal stenosis index and the degree of tracheal stenosis increased significantly in the stenosis group, while POCUS-guided submucosal injection of paclitaxel partially reversed the tracheal stenosis. POCUS-guided submucosal injection of paclitaxel also decreased the lamina propria thickness and collagen deposition in the stenosed trachea.

Conclusion

POCUS-guided submucosal paclitaxel injection alleviated tracheal stenosis induced by scraping of the tracheal mucosa. POCUS-guided submucosal injection might be a potential method for the treatment of tracheal stenosis.

Point-of-care ultrasound use in emergencies: what every anaesthetist should know

Point-of-care ultrasound has been embraced by anaesthetists as an invaluable tool for rapid diagnosis of haemodynamic instability, to ensure procedural safety and monitor response to treatments. Increasingly available, affordable and portable, with emerging evidence of improved patient outcomes, point-of-care ultrasound has become a valuable tool in the emergency setting. This state-of-the-art review describes the feasibility of point-of-care ultrasound practice, training and maintenance of competence. It also describes the many uses of point-of-care ultrasound for the anaesthetist and describes the most salient point-of-care ultrasound views for anaesthetic emergencies including: undifferentiated shock; hypoxemia; and trauma. Procedural safety is also discussed in addition to relevant important governance aspects. Cardiac function should be assessed using the parasternal long axis, parasternal short basal/mid-papillary/apical, apical four chamber and subcostal four chamber views, and should include a visual estimation of global left ventricular ejection fraction. Other cardiovascular conditions that can be identified using point-of-care ultrasound include: pericardial effusion; cardiac tamponade; and pulmonary embolism. Pulmonary emergency conditions that can be diagnosed using point-of-care ultrasound include pneumothorax; pleural effusion; and interstitial syndrome. The extended focused assessment with sonography for trauma examination may of value in patients who are hypotensive in order to identify intra-abdominal haemorrhage, pneumothoraces and haemothoraces.

New technologies in airway management: A review

The evolution of medical knowledge and technological growth have contributed to the development of different techniques and devices for airway management. These appear to play a role in optimizing the number of attempts and overall success, ultimately reducing the negative consequences of airway manipulation. In this literature review, we highlight the recent evidence regarding new technologies applied to airway management. Before intubation, every patient should have an individualized structured airway management plan. Technology can help with both airway evaluation and tracheal intubation. Point-of-care cervical ultrasound and artificial intelligence models with automated facial analysis have been used to predict difficult airways. Various devices can be used in airway management. This includes a robotic video endoscope that guides intubation based on real image recognition, a laryngeal mask with a non-inflatable cuff that tries to reduce local complications, video laryngeal masks that are able to confirm the correct position and facilitate intubation, Viescope™, a videolaryngoscope developed for combat medicine with a unique circular blade, a system that uses cervical transillumination for glottis identification in difficult airways and Vivasight SL™ tracheal tube, which has a high-resolution camera at its tip guaranteeing visual assurance of tube position as well as guiding bronchial blocker position. To conclude, we detailed the challenges in airway management outside the operating room as well as described suction-assisted laryngoscopy and airway decontamination technique for contaminated airways. Further research in the clinical setting is recommended to better support the use of these technologies.

Ultrasound measurements for evaluation of changes in upper airway during anaesthesia induction and prediction difficult laryngoscopy: a prospective observational study

Upper airway collapsibility after anaesthesia induction may be associated with unpredictable difficult airway. However, most works on airway anatomy are tended to morphological description before anaesthesia. This study aimed to evaluate the changes of upper airway after anaesthesia induction and using pre-anesthetic ultrasound measurements to predict Difficult Laryngoscopy (DL). We included 104 eligible subjects with complete data, who were performed tracheal intubations under general anaesthesia in the study. The upper airway changes before and after anaesthesia induction were determined by seven neck ultrasound measurements, included as follow: (1) Distance from skin to under surface of Tongue (DT), (2) Thickness of the thickest part of Tongue body (TT), (3) Hyoid Mental Distance (HMD), (4) Depth of Hyoid (DH), (5) Width of Hyoid (WH), (6) Distance from Skin to Epiglottis (DSE), (7) Depth of the anterior combination of the Vocal Cords (DVC). DL was evaluated with Cormack-Lehane (CL). Data regarding HMD [from 45.3 (42.4-48.5) to 41.1 (38.5-44.9) mm], DH [from 8.7 (6.6-10.9) to 7.0 (5.3-9.1) mm], DSE [from 20.1 (16.6-22.5) to 19.5 (16.5-21.6) mm] and the DVC [from 7.1 (5.7-8.3) to 6.8 (5.7-7.9) mm] were decreased (P < 0.05), while the DT [from 15.9 (13.1-18.4) to 17.4 (14.5-19.8) mm] was increased (P > 0.05) after anaesthesia induction. Additionally, when cut-off value of DSE was 21.25 mm before anaesthesia, it may be better predicted to DL [sensitivity 80.0% (95% CI: 60.7-91.6%) and specificity 83.8% (95% CI: 73.0-91.0%)]. The upper airway after induction showed the propensity of collapsibility by ultrasound measurements. Compared with other indicators, the DSE assessed by ultrasound might be considered to a valuable predictor of DL.Trial registration: The study was registered in ClinicalTrials.gov on 23th Jan 2019, ChiCTR1900021123.

Design and Implementation of Airway Response Teams to Improve the Practice of Emergency Airway Management

Emergency airway management (EAM) is a commonly performed procedure in the critical care setting. Despite clinical advances that help practitioners identify patients at risk for having a difficult airway, improved airway management tools, and algorithms that guide clinical decision-making, the practice of EAM is associated with significant morbidity and mortality. Evidence suggests that a dedicated airway response team (ART) can help mitigate the risks associated with EAM and provide a framework for airway management in acute settings. We review the risks and challenges related to EAM and describe strategies to improve patient care and outcomes via implementation of an ART.

The value of multiparameter combinations for predicting difficult airways by ultrasound

Background

Based on the upper airway anatomy and joint function parameters examined by ultrasound, a multiparameter ultrasound model for difficult airway assessment (ultrasound model) was established, and we evaluated its ability to predict difficult airways.

Methods

A prospective case-cohort study of difficult airway prediction in adult patients undergoing elective surgery with endotracheal intubation under general anesthesia, and ultrasound phantom examination for difficult airway assessment before anesthesia, including hyomental distance, tongue thickness, mandibular condylar mobility, mouth opening, thyromental distance, and modified Mallampati tests, was performed. Receiver operating characteristic (ROC) curve analysis was used to evaluate the effectiveness of the ultrasound model and conventional airway assessment methods in predicting difficult airways.

Results

We successfully enrolled 1000 patients, including 51 with difficult laryngoscopy (DL) and 26 with difficult tracheal intubation (DTI). The area under the ROC curve (AUC) for the ultrasound model to predict DL was 0.84 (95% confidence interval [CI]: 0.82–0.87), and the sensitivity and specificity were 0.75 (95% CI: 0.60–0.86) and 0.82 (95% CI: 0.79–0.84), respectively. The AUC for predicting DTI was 0.89 (95% CI: 0.87–0.91), and the sensitivity and specificity were 0.85 (95% CI: 0.65–0.96) and 0.81 (95% CI: 0.78–0.83), respectively. Compared with mouth opening, thyromental distance, and modified Mallampati tests, the ultrasound model predicted a greater AUC for DL (P < 0.05). Compared with mouth opening and modified Mallampati tests, the ultrasound model predicted a greater AUC for DTI (P < 0.05).

Conclusions

The ultrasound model has good predictive performance for difficult airways.

Trial registration

This study is registered on chictr.org.cn (ChiCTR-ROC-17013258); principal investigator: Jianling Xu; registration date: 06/11/2017).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-022-01840-0.

Nomograms for predicting difficult airway based on ultrasound assessment

Background

Accurate prediction of the difficult airway (DA) could help to prevent catastrophic consequences in emergency resuscitation, intensive care, and general anesthesia. Until now, there is no nomogram prediction model for DA based on ultrasound assessment. In this study, we aimed to develop a predictive model for difficult tracheal intubation (DTI) and difficult laryngoscopy (DL) using nomogram based on ultrasound measurement. We hypothesized that nomogram could utilize multivariate data to predict DTI and DL.

Methods

A prospective observational DA study was designed. This study included 2254 patients underwent tracheal intubation. Common and airway ultrasound indicators were used for the prediction, including thyromental distance (TMD), modified Mallampati test (MMT) score, upper lip bite test (ULBT) score temporomandibular joint (TMJ) mobility and tongue thickness (TT). Univariate and the Akaike information criterion (AIC) stepwise logistic regression were used to identify independent predictors of DTI and DL. Nomograms were constructed to predict DL and DTL based on the AIC stepwise analysis results. Receiver operating characteristic (ROC) curves were used to evaluate the accuracy of the nomograms.

Results

Among the 2254 patients enrolled in this study, 142 (6.30%) patients had DL and 51 (2.26%) patients had DTI. After AIC stepwise analysis, ULBT, MMT, sex, TMJ, age, BMI, TMD, IID, and TT were integrated for DL nomogram; ULBT, TMJ, age, IID, TT were integrated for DTI nomogram. The areas under the ROC curves were 0.933 [95% confidence interval (CI), 0.912–0.954] and 0.974 (95% CI, 0.954–0.995) for DL and DTI, respectively.

Conclusion

Nomograms based on airway ultrasonography could be a reliable tool in predicting DA.

Trial registration

Chinese Clinical Trial Registry (No. ChiCTR-RCS-14004539), registered on 13th April 2014.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-022-01567-y.