Useful Ultrasonographic Parameters to Predict Difficult Laryngoscopy and Difficult Tracheal Intubation-A Systematic Review and Meta-Analysis

Pilot multicenter study to determine the utility of point-of-care ultrasound to predict difficulty of tracheal intubation using videolaryngoscopy with the McGrath™ Mac videolaryngoscope

Background

Clinical airway screening tests used to predict difficulties during airway management have low sensitivity and specificity. Point-of-care airway ultrasound has described measurements related to problems with difficult direct laryngoscopy. Nevertheless, the correlation between ultrasound parameters and videolaryngoscopy has not been published yet. The aim of this multicenter, prospective observational pilot study was to evaluate the applicability of clinical parameters and ultrasound measurements to find potential tracheal intubation difficulties when videolaryngoscopy is used.

Methods

Preoperatively, six clinical airway assessments were performed: (1) modified Mallampati score, (2) thyromental distance, (3) sternomental distance, (4) interincisal distance, (5) upper lip bite test, and (6) neck circumference. Six ultrasound parameters were measured in awake patients: (1) distance from skin to hyoid bone, (2) distance from skin to epiglottis, (3) hyomental distance in neutral head position, (4) hyomental distance in head-extended position, (5) distance from skin to the deepest part of the palate, and (6) sagittal tongue area. And finally, there was one ultrasound measure obtained in anesthetized patients, the compressed sagittal tongue area during videolaryngoscopy. The difficulty for tracheal intubation using a McGrath™ Mac videolaryngoscope, the percentage of glottic opening, and Cormack-Lehane grade were also assessed.

Results

In this cohort of 119 subjects, tongue dimensions, particularly the sagittal tongue area, showed a robust association with increased intubation difficulty using videolaryngoscopy. A multiparametric model combining the following three ultrasound variables in awake patients: (a) the distance from skin to epiglottis, (b) the distance from skin to the deepest part of the palate, and (c) the sagittal tongue area, yielded a sensitivity of 92.3%, specificity of 94.5%, positive predictive value of 82.8%, and negative predictive value of 97.8% (p < 0.001).

Conclusion

Point-of-care airway ultrasound emerges as a more useful tool compared to traditional clinical scales to anticipate possible challenges during videolaryngoscopic intubation.

Preoperative point-of-care neck ultrasound: beyond the airway

PURPOSE

A preoperative point-of-care neck ultrasound, carried out during preoperative airway evaluation by extending the scans to the regions close to the larynx and trachea, can allow for the rapid identification of unknown pathologies or abnormalities in a cost-effective and non-invasive manner. This prospective, observational study examines a series of ultrasound findings in structures close to the airway, made through preoperative point-of-care neck ultrasound in a cohort of 230 patients.

METHODS

We conducted a prospective observational study, enrolling 230 adult patients selected for elective abdominal surgery. The primary goal was to verify the predictive role of airway ultrasound in identifying difficult airways, while the secondary goal was to evaluate structures close to the airway such as jugular veins, carotid arteries, thyroid gland and soft tissues.

RESULTS

Overall, preoperative point-of-care neck ultrasound proved to be an effective and reliable method of obtaining details about local or systemic pathologies, which could affect perioperative care. For example, the exam consistently revealed the presence of carotid plaques or venous congestion, which could be used to best determine the patient's cardiovascular risk or to instigate further investigations. It also allowed for more accurate central venous catheter placement planning and better airway management and it warned about possible thyroid or neoplastic pathologies that would have otherwise remained unknown. In some cases, information from preoperative point-of-care neck ultrasound has even led to modifications in perioperative therapy.

CONCLUSION

Preoperative point-of-care neck ultrasound is fast, inexpensive, and non-invasive, and it can be easily performed by a properly trained professional during the preoperative airway ultrasound evaluation. It can be considered as a new preoperative assessment tool.

Point-of-care ultrasound for airway management in the emergency and critical care setting

Airway management is a common procedure within emergency and critical care medicine. Traditional techniques for predicting and managing a difficult airway each have important limitations. As the field has evolved, point-of-care ultrasound has been increasingly utilized for this application. Several measures can be used to sonographically predict a difficult airway, including skin to epiglottis, hyomental distance, and tongue thickness. Ultrasound can also be used to confirm endotracheal tube intubation and assess endotracheal tube depth. Ultrasound is superior to the landmark-based approach for locating the cricothyroid membrane, particularly in patients with difficult anatomy. Finally, we provide an algorithm for using ultrasound to manage the crashing patient on mechanical ventilation. After reading this article, readers will have an enhanced understanding of the role of ultrasound in airway management.

A new score for airway assessment using clinical and ultrasound parameters

Background

Over the last few years, ultrasonography has been introduced as the fifth pillar to patient's bedside physical examination. Clinical assessments aim to screen and look for airway difficulties to predict difficult intubations, but none have demonstrated a significant predictive capacity. Recent systematic reviews have established a correlation between ultrasound imaging and difficult direct laryngoscopy. The primary objective of this study was to determine whether the utilization of ultrasonography to examine the upper airway could accurately predict difficult direct laryngoscopy.

Methods

This is a prospective observational study including 102 adult patients that required general anesthesia for elective surgery. Preoperatively, clinical airway assessments were performed. Data such as Mallampati-Samsoon grade (MS), upper lip bite test (ULBT), thyromental (TMD) and sternomental distance (SMD), cervical circumference (CC) and the Arné risk index were collected. Ultrasound evaluation was taken at five different levels in two planes, parasagittal and transverse. Therefore, the following measurements were registered: distance from skin to hyoid bone (DSHB), distance from skin to thyrohyoid membrane (DSTHM), distance from skin to epiglottis (DSE), distance from skin to thyroid cartilage (DSTC) and distance from hyoid bone and thyroid cartilage (DHBTC). Patients were divided into two groups based on the difficulty to perform direct laryngoscopy, according to Cormack-Lehane (C-L) classification. Grades I and II were classified as easy laryngoscopy and grades III or IV as difficult. Logistic regression models and the Receiver Operating Characteristic (ROC) curve was employed to determine the diagnostic precision of ultrasound measurements to distinguish difficult laryngoscopy (DL).

Results

The following risk score for DL was obtained, DSTHM ≥ 1.60 cm (2 points), DSTC ≥ 0.78 cm (3 points) and gender (2 points for males). The score can range from 0 to 7 points, and showed and AUC (95% CI) of 0.84 (0.74-0.95). A score of 5 points or higher indicates a 34-fold increase in the risk of finding DL (p = 0.0010), sensitivity of 91.67, specificity of 75.56, positive predictive value of 33.33, and negative predictive value of 98.55.

Conclusion

The use of ultrasonography combined with classic clinical screening tests are useful tools to predict difficult direct laryngoscopy.

The diagnostic accuracy of point-of-care ultrasound parameters for airway assessment in patients undergoing intubation in emergency department-an observational study

BACKGROUND

Endotracheal intubation is an essential resuscitative procedure in the emergency setting. Airway assessment parameters such as the Mallampati classification are difficult to perform in an emergency setting. As point-of-care ultrasound (POCUS) assessment of airway parameters does not require patients to perform any mandatory action, ultrasound may become the potential first-line noninvasive airway assessment tool in the emergency department (ED). The use of POCUS in the ED has not been sufficiently studied. Using POCUS in airway assessment for predicting difficult intubation may be the next step in successful airway management.

METHODOLOGY

The study was an observational study conducted at the ED of the All India Institute of Medical Sciences (Rishikesh). The treating emergency physician recorded the patient history and systemic examination along with an indication for intubation. The POCUS assessment of airway parameters pre-epiglottis to epiglottic vocal cord ratio (Pre-E/E-VC), tongue thickness, hyomental distance, and distance from skin to the hyoid bone was performed by the study investigator. During laryngoscopy, Cormack-Lehane (CL) grading was assessed. The data was entered and analyzed.

RESULTS

Seventy patients who required intubation in the ED were enrolled in the study. Among the study population, 48.6%, 28.6%, 14.3%, 1.4%, and 7.1% were classified with the following CL grading: 1, 2a, 2b, 3a, and 3b, respectively. At a cutoff of ≥ 1.86, Pre-E/E-VC predicts difficult laryngoscopy (AUC 0.835) with a sensitivity of 83% and a specificity of 94%. At a cutoff of ≥ 5.98 cm, tongue thickness predicts difficult laryngoscopy (AUC 0.78) with a sensitivity of 83% and a specificity of 88%. At a cutoff of hyomental distance ≤ 6 cm, it predicts difficult laryngoscopy with a sensitivity of 83% and a specificity of 88%. All parameters can act as a promising tool for predicting difficult laryngoscopy, with the single best parameter being Pre-E/E-VC.

CONCLUSION

Assessment of the airway with POCUS may be helpful to the emergency physician when the clinical airway assessment parameters fail to predict difficult laryngoscopy as most patients requiring intubation are uncooperative. Assessment of the parameters in our study Pre-E/E-VC, tongue thickness, and hyomental distance can act as a promising tool for predicting difficult laryngoscopy in the emergency scenario.

[Recommendations for Education in Sonography in Prehospital Emergency Medicine (pPOCUS): Consensus paper of DGINA, DGAI, BAND, BV-ÄLRD, DGU, DIVI and DGIIN]

Point-of-care sonography is a precondition in acute and emergency medicine for the diagnosis and initiation of therapy for critically ill and injured patients. While emergency sonography is a mandatory part of the training for clinical acute and emergency medicine, it is not everywhere required for prehospital emergency medicine. Although some medical societies in Germany have already established their own learning concepts for emergency ultrasound, a uniform national training concept for the use of emergency sonography in the out-of-hospital setting is still lacking. Experts of several professional medical societies have therefore joined forces and developed a structured training concept for emergency sonography in the prehospital setting. The consensus paper serves as quality assurance in prehospital emergency sonography.

Training Requirements in Point-of-Care Ultrasonography of the Upper Airway: A Feasibility Study

OBJECTIVES

Point-of-care ultrasonography of the upper airway can be a useful supplement to conventional pre-anesthetic clinical evaluations. However, the reliability of such examinations is highly operator-dependent and proper training in sonoanatomy and ultrasound operational skills are required. The objective of this study aims to assess the minimum training requirements for applying a predefined upper airway scanning protocol in healthy volunteers by anesthesia trainees.

METHODS

Twenty-two healthy volunteer members of the Operating Room staff participated in the study. A predefined scanning protocol that included the identification of specific structures (hyoid bone, vocal cords, thyrohyoid membrane/epiglottis/pre-epiglottic space, cricothyroid membrane, and thyroid gland), as well as the performance of specific measurements (distance from the hyoid bone to skin, anterior commissure to skin, epiglottis to skin, and thyroid isthmus to skin) was taught in a single-day training course. The trainees' competence was assessed after multiple scanning repetitions performed over a week. Mixed effects regression models were applied for the trainee-instructor differences in all ultrasound measurements.

RESULTS

Cricothyroid membrane visualization had the lowest success rate (88%). Trainee-instructor differences were statistically significant for hyoid bone-to-skin (P < .001) and epiglottis-to-skin distances (P = .016). Measurement of the distance from the epiglottis to the skin required more scanning repetitions to achieve minimum deviance compared with other measurements. Ten or fewer scanning repetitions were sufficient to achieve minimum deviance for all four measurements.

CONCLUSIONS

At least 10 scanning repetitions of a pre-defined upper airway scanning protocol can be used as the minimum standard for training.

A Scoping Review of Ultrasonographic Techniques in the Evaluation of the Pediatric Airway

Point-of-care ultrasound is making rapid advancements in pediatrics, and ultrasonographic assessment of the airway is being employed in many specialties such as the pediatric, cardiac, and neonatal intensive care units, emergency department, pulmonary clinic, and the perioperative setting. This scoping review provides a technical description of image acquisition and interpretation, accompanying ultrasound images of the hallmark airway applications in pediatrics, and supporting evidence when available. We describe and illustrate ultrasound-determined endotracheal tube (ETT) sizing, ETT placement and depth confirmation, vocal fold assessment, prediction of post-extubation stridor, difficult laryngoscopy prediction, and cricothyrotomy guidance. This review aims to provide the descriptions and images necessary to learn and apply these skills at the point of care in the pediatric patient.

Development and validation of a screening method for difficult tracheal intubation based on geometric simulation and computer technology

BACKGROUND

The anatomical characteristics of difficult airways can be analysed geometrically. This study aims to develop and validate a geometry-assisted difficult airway screening method (GADAS method) for difficult tracheal intubation.

METHODS

In the GADAS method, a geometric simulated model was established based on computer graphics. According to the law of deformation of the upper airway on laryngoscopy, the expected visibility of the glottis was calculated to simulate the real visibility on laryngoscopy. Validation of the new method: Approved by the Ethics Committee of Yijishan Hospital of Wannan Medical College. Adult patients who needed tracheal intubation under general anaesthesia for elective surgery were enrolled. The data of patients were input into the computer software to calculate the expected visibility of the glottis. The results of tracheal intubation were recorded by anaesthesiologists. The primary observation outcome was the screening performance of the expected visibility of the glottis for difficult tracheal intubation.

RESULTS

The geometric model and software of the GADAS method were successfully developed and are available for use. We successfully observed 2068 patients, of whom 56 patients had difficult intubation. The area under the receiver operating characteristic curve of low expected glottis visibility for predicting difficult laryngoscopy was 0.96 (95% confidence interval [CI]: 0.95-0.96). The sensitivity and specificity were 89.3% (95% CI: 78.1-96.0%) and 94.3% (95% CI: 93.2%-95.3), respectively.

CONCLUSIONS

It is feasible to screen difficult-airway patients by applying computer techniques to simulate geometric changes in the upper airway.

[Recommendations for Education in Sonography in Prehospital Emergency Medicine (pPOCUS): Consensus paper of DGINA, DGAI, BAND, BV-ÄLRD, DGU, DIVI and DGIIN]

Point-of-care sonography is a precondition in acute and emergency medicine for the diagnosis and initiation of therapy for critically ill and injured patients. While emergency sonography is a mandatory part of the training for clinical acute and emergency medicine, it is not everywhere required for prehospital emergency medicine. Although some medical societies in Germany have already established their own learning concepts for emergency ultrasound, a uniform national training concept for the use of emergency sonography in the out-of-hospital setting is still lacking. Experts of several professional medical societies have therefore joined forces and developed a structured training concept for emergency sonography in the prehospital setting. The consensus paper serves as quality assurance in prehospital emergency sonography.

Preoperative airway ultrasound assessment in the sniffing position: a prospective observational study

BACKGROUND

Clinical airway screening tests intend to predict difficult airways, but none have a high predictive value. Recent systematic reviews correlate ultrasound with difficult laryngoscopy. This study aimed primarily to correlate ultrasound measurements of anatomical upper airway structures in the sniffing position with difficult direct laryngoscopy. The secondary aim was to observe gender-based differences.

METHODS

This prospective, cross-sectional, single-center observational study included 209 patients requiring general anesthesia for elective surgery. Preoperatively, we performed six clinical airway assessments and three ultrasound measurements, which were the Distance from Skin to the Hyoid Bone (DSHB), to the Epiglottis (DSE), and to the anterior commissure of the vocal cords (DSAC) in a sniffing position. Benumof's criteria for the "best view at the first attempt" for direct laryngoscopy assessed the difficulty of laryngoscopy.

RESULTS

The distance from skin to the epiglottis was the best predictor of direct difficult laryngoscopy (defined as Cormack-Lehane grade ≥ 2b) with a minimum thickness cut-off at 2.70 ± 0.19 cm (sensitivity 91.3%; specificity 96.9%). The skin to the hyoid bone distance cut-off was 1.41 ± 0.30 cm with moderate correlation (sensitivity 80.4%; specificity 60.1%). No correlation was found for the distance to the anterior commissure of the vocal cords. In women compared to men, the skin to the epiglottis distance was more sensitive (92.3% vs. 90.9%) and specific (98.8% vs. 95.2%).

CONCLUSIONS

DSE in the sniffing position is the most reliable parameter for preoperative airway ultrasound assessment in the Caucasian population, with higher sensitivity and specificity in women, and might be considered as an independent predictor for direct difficult laryngoscopy.

Empfehlungen zur Sonografieausbildung in der prähospitalen Notfallmedizin (pPOCUS): Konsensuspapier von DGINA, DGAI, BAND, BV-ÄLRD, DGU, DIVI und DGIIN

Die Point-of-Care-Sonografie ist in der Akut- und Notfallmedizin ein fester Bestandteil der Diagnostik und Therapieeinleitung von kritisch kranken und verletzten Patienten. Während die Notfallsonografie im Rahmen der Zusatzweiterbildung für klinische Akut- und Notfallmedizin vorausgesetzt wird, wird diese für die prähospitale Notfallmedizin lediglich im (Muster-)Kursbuch Allgemeine und spezielle Notfallbehandlung als Weiterbildungsinhalt definiert. Obwohl einige Fachgesellschaften in Deutschland bereits eigene Lernkonzepte für die Notfallsonografie etabliert haben, fehlt bis dato ein einheitliches nationales Ausbildungskonzept für den Einsatz der Notfallsonografie im prähospitalem Umfeld. Experten mehrerer Fachgesellschaften haben daher als Empfehlung für die notfallmedizinische Weiterbildung ein Kurskonzept für die spezielle Ausbildung in der prähospitalen Notfallsonografie erarbeitet, welche gleichermaßen zu deren Qualitätssicherung beitragen soll.

Prediction of difficult laryngoscopy / difficult intubation cases using upper airway ultrasound measurements in emergency department: a prospective observational study

INTRODUCTION

Difficult laryngoscopy and intubation are serious problems among critically ill patients in emergency department (ED) so utility of a rapid, accurate and noninvasive method for predicting of these patients are necessary. Ultrasonography has been recently used in this regard and this study was conducted to investigate the correlation of some introduced upper airway ultrasound parameters with difficult laryngoscopy / difficult intubation in patients referred to the ED.

METHOD

In this prospective observational study all patients ≥ 18-year-old who had an indication for rapid sequence intubation (RSI) were included. Ultrasound parameters including Hyoid Bone Visibility (HBV), Distance from Skin to Hyoid Bone (DSHB), Distance from Skin to Vocal Cords (DSVC), Distance from Skin to Thyroid Isthmus (DSTI), and Distance between Arytenoids Cartilages (DBAC) were measured in all cases. The patients underwent RSI and thereafter the patients' baseline characteristics, Cormack-Lehane grade, number of attempted laryngoscopy were recorded in a pre-prepared check list and compared with measured ultrasound parameters. The "difficult laryngoscopy" was defined as Cormack-Lehane classification grades III/IV; and need for more than 3 intubation attempts was considered as "difficult intubation".

RESULTS

One hundred and twenty-three patients (52% male) were included of whom 10 patients (8.1%) were categorized as difficult laryngoscopy cases; and just 4 (3.3%) cases underwent more than 3 laryngoscopy attempts who considered as difficult intubation cases. The mean age of the patients in non-difficult and difficult intubation groups were 69.2 ± 15.16 and 68.77 ± 17.37 years, respectively (p > 0.05). There was no significant relationship between difficult laryngoscopy and HBV (p = 0.381) but has significant correlation with difficult intubation (p = 0.004). The DSHB had a significant correlation with difficult laryngoscopy (p = 0.002) but its correlation with difficult intubation was not significant (p = 0.629). The DSVC and DSTI had a significant relationship with both difficult laryngoscopy (p = 0.003 and p = 0.001), and difficult intubation (p = 0.025 and p = 0.001). The DBAC had not significant correlation neither with the difficult laryngoscopy (p = 0.142), nor with difficult intubation (p = 0.526).

CONCLUSION

The findings showed that ultrasound parameters including soft tissue DSHB, DSVC and DSTI could be proper predictors of difficult laryngoscopy. Also, HBV, DSVC and DSTI may be proper predictors for difficult intubation. But DBAC was not useful in this regard.

Development and Internal Validation of a Prediction Model for Difficult Laryngoscopy Using Ultrasound-Derived Factor in Comatose Patients

OBJECTIVES

The distance from skin to the hyoid bone (DSHB) and skin to the anterior commissure of vocal cords (DSAC) are reliable parameters for pre-operative airway ultrasound assessment in awake patients and can be assessed in comatose patients. This study aimed to inspect its feasibility and accuracy in predicting difficult laryngoscopy for comatose patients.

METHODS

A prospective cohort study included patients with a Glasgow Coma Scale (GCS) of ≤8 who underwent emergency tracheal intubation between November 2019 and August 2020. The outcome was difficult laryngoscopy and classified according to the Cormack-Lehane grading.

RESULTS

A total of 151 patients were included in the study. Fifty-two (34.4%) patients were categorized as having difficult laryngoscopy. The DSHB add DSAC (hereinafter referred to as the "DSBAC") was superior to either parameter alone in the predictive performance, and the optimal cut-off value was 1.90. To optimize the predictive value, DSBAC (adjusted odds ratio [OR]: 7.76; 95% confidence interval [CI]: 2.88-20.94; P < .001), GCS (adjusted OR: 1.39; 95% CI: 3.93-26.28; P = .039), mandibular retraction (adjusted OR: 8.20; 95% CI: 1.92-35.09; P = .005) and edentulous (adjusted OR: 4.23; 95% CI: 1.40-12.80; P = .011) were included in a multivariable model and constructed a nomogram. Discrimination and calibration statistics were satisfactory, with C-index above 0.80 from both model development and internal validation.

CONCLUSIONS

Ultrasound-derived factor, DSBAC, can be easily assessed and help predict difficult laryngoscopy among comatose patients. A simple nomogram including only four clinical items exhibited excellent discrimination performance and was useful when comatose patients underwent emergency tracheal intubation.

Pre-operative ultrasound prediction of difficult airway management in adult patients: A systematic review of clinical evidence

BACKGROUND

Predicting a difficult airway, including difficult laryngoscopy, intubation or mask ventilation, is paramount in peri-operative management. As clinical predictors are only partially reliable, ultrasound-based measurements might be useful in evaluating anterior neck fat tissues depth.

OBJECTIVES

The aim of this systematic review is to report clinical evidence on pre-operative ultrasound as a predictor of difficult laryngoscopy, difficult intubation or difficult mask ventilation.

DESIGN

A systematic review of randomised controlled trials and observational studies.

DATA SOURCES

The MEDLINE, EMBASE and Google Scholar databases were queried from inception until 28 February 2022.

ELIGIBILITY CRITERIA

Studies involving adult patients who had undergone orotracheal intubation after evaluation with airways ultrasound were considered suitable. Exclusion criteria were a clinical history of difficult airways, cancer or trauma, pregnancy, supraglottic airway devices, video-laryngoscopy. Parameters were classified by reporting their accuracy in discriminating 'difficult' vs. 'not difficult' laryngoscopy, intubation or mask ventilation.

RESULTS

Thirty-one observational studies were included and a total of 41 single parameters and 12 different combinations of clinical and ultrasound parameters were reported. The distance from skin to epiglottis midway with neutral position of head and neck, the distance from hyoid bone to skin surface with a neutral position of head and neck and the hyomental distance extended/neutral ratio are the most associated with difficult laryngoscopy or difficult intubation. A combination of clinical and ultrasound parameters (a modified Mallampati score, the distance from the skin to the epiglottis midway with neutral position of the head and neck, and the USED-MSH score) showed high accuracy. Only two studies reported the role of ultrasound in predicting difficult mask ventilation: the distance from hyoid bone to skin surface with neutral position of head and neck, the thickness of the base of the tongue with hyperextension of the head, and the hyomental distance with hyperextension of the head and active subluxation of the mandible are the parameters with the highest correlation.

CONCLUSIONS

The use of ultrasound parameters might be useful in predicting difficult laryngoscopy or difficult intubation. Several ultrasound parameters and combinations have been associated with difficult laryngoscopy or difficult intubation prediction. The use of scores combining clinical predictors and ultrasound measures are very promising. Data on difficult mask ventilation are scarce and the role of ultrasound is still controversial. Future studies are needed.

CLINICAL TRIAL REGISTRATION

CRD42021250574.

Point-of-Care Ultrasound in Airway Evaluation and Management: A Comprehensive Review

Airway management is a common and critical procedure in acute settings, such as the Emergency Department (ED) or Intensive Care Unit (ICU) of hospitals. Many of the traditional physical examination methods have limitations in airway assessment. Point-of-care ultrasound (POCUS) has emerged as a promising tool for airway management due to its familiarity, accessibility, safety, and non-invasive nature. It can assist physicians in identifying relevant anatomy of the upper airway with objective measurements of airway parameters, and it can guide airway interventions with dynamic real-time images. To date, ultrasound has been considered highly accurate for assessment of the difficult airway, confirmation of proper endotracheal intubation, prediction of post-extubation laryngeal edema, and preparation for cricothyrotomy by identifying the cricothyroid membrane. This review aims to provide a comprehensive overview of the key evidence on the use of ultrasound in airway management. Databases including PubMed and Embase were systematically searched. A search strategy using a combination of the term "ultrasound" combined with several search terms, i.e., "probe", "anatomy", "difficult airway", "endotracheal intubation", "laryngeal edema", and "cricothyrotomy" was performed. In conclusion, POCUS is a valuable tool with multiple applications ranging from pre- and post-intubation management. Clinicians should consider using POCUS in conjunction with traditional exam techniques to manage the airway more efficiently in the acute setting.

Current status of point of care ultrasonography for the perioperative care of trauma patients

PURPOSE OF REVIEW

The incorporation of point of care ultrasound into the field of anesthesiology and perioperative medicine is growing at rapid pace. The benefits of this modality align with the acuity of patient care and decision-making in anesthetic care of a trauma patient.

RECENT FINDINGS

Cardiac ultrasound can be used to diagnose cardiac tamponade or investigate the inferior vena cava to assess volume status in patients who may suffer from hemorrhagic shock. Thoracic ultrasound may be used to rapidly identify pneumothorax or hemothorax in a patient suffering chest wall trauma. In addition, investigators are exploring the utility of ultrasonography in traumatic airway management and elevated intracranial pressure. In addition, the utility of gastric ultrasound on trauma patients is briefly discussed.

SUMMARY

Incorporation of point of care ultrasound techniques into the practice of trauma anesthesiology is important for noninvasive, mobile and expeditious assessment of trauma patients. In addition, further large-scale studies are needed to investigate how point of care ultrasound impacts outcomes in trauma patients.

Objective structured assessment ultrasound skill scale for hyomental distance competence - psychometric study

BACKGROUND

Ultrasound assessment of the airway recently integrates the point-of-care approach to patient evaluation since ultrasound measurements can predict a difficult laryngoscopy and tracheal intubation. Because ultrasonography is performer-dependent, a proper training and assessment tool is needed to increase diagnostic accuracy. An objective, structured assessment ultrasound skill (OSAUS) scale was recently developed to guide training and assess competence. This work aims to study the psychometric properties of OSAUS Scale when used to evaluate competence in ultrasound hyomental distance (HMD) measurement.

METHODS

Prospective and experimental study. Volunteers were recruited and enrolled in groups with different expertise. Each participant performed three ultrasonographic HMD evaluation. The performance was videorecorded and anonymized. Five assessors blindly rated participants' performance using OSAUS scale and a Global Rating Scale (GRS). A psychometric study of OSAUS scale as assessment tool for ultrasound HMD competence was done.

RESULTS

Fifteen voluntaries participated on the study. Psychometric analysis of OSAUS showed strong internal consistency (Cronbach's alpha 0.916) and inter-rater reliability (ICC 0.720; p < 0.001). The novice group scored 15.4±0.18 (mean±SD), the intermediate 14.3±0.75 and expert 13.6±0.1.25, with a significant difference between novice and expert groups (p = 0.036). The time in seconds to complete the task was evaluated: novice (90±34) (mean±SD), intermediate (84±23) and experts (83±15), with no significant differences between groups. A strong correlation was observed between OSAUS and global rating scale (r = 0.970, p < 0.001).

CONCLUSION

The study demonstrated evidence of validity and reliability. Further studies are needed to implement OSAUS scale in the clinical setting for training and assessment of airway ultrasound competence.

Prediction of Difficult Laryngoscopy Using Ultrasound: A Systematic Review and Meta-Analysis

OBJECTIVES

Evaluate associations between ultrasound measures and difficult laryngoscopy.

DATA SOURCES

MEDLINE, Embase, Google Scholar, Web of Science, and the Cochrane Library were searched using MeSH terms and keywords.

STUDY SELECTION

Studies published in English describing the use of airway ultrasound for identifying difficult laryngoscopy, with sufficient data to calculate sensitivity and specificity using 2 × 2 tables.

DATA EXTRACTION

We assigned the described indices of airway dimension to one of three domains based on methodology characteristics: anterior tissue thickness domain, anatomical position domain, and oral space domain. We then performed a bivariate random-effects meta-analysis, deriving pooled sensitivity, specificity, diagnostic odds ratio, positive likelihood ratio, and negative likelihood ratio estimates. We assessed risks of bias using Quality Assessment of Diagnostic Accuracy Studies-2 analysis.

DATA SYNTHESIS

Thirty-three studies evaluating 27 unique indices were included in the meta-analysis. The ultrasound protocols of the included studies were heterogeneous. Anterior tissue thickness demonstrated a pooled sensitivity of 76% (95% CI, 71-81%), specificity of 77% (95% CI, 72-81%), and an area under the receiver operating characteristic curve (AUROC) of 0.83 (95% CI, 0.80-0.86). Anatomical position demonstrated a pooled sensitivity of 74% (95% CI, 61-84%), specificity of 86% (95% CI, 78-91%), and an AUROC of 0.87 (95% CI, 0.84-0.90). Oral space demonstrated a pooled sensitivity of 53% (95% CI, 0.36-0.69), specificity of 77% (95% CI, 0.67-0.85), and an AUROC of 0.73 (95% CI, 0.69-0.77).

CONCLUSIONS

Airway ultrasound metrics associate with difficult laryngoscopy in three domains: anterior tissue thickness, anatomic position, and oral space. An assessment instrument combining clinical and ultrasound assessments may be an accurate screening tool for difficult laryngoscopy.

Morphometric and ultrasonographic determinants of difficult laryngoscopy in obese patients: A prospective observational study

BACKGROUND

Obese people have a higher risk of difficult laryngoscopy due to their thick neck, large tongue, and redundant pharyngeal soft tissue. However, there is still no established predictive factor for difficult laryngoscopy in obese population.

METHODS

We conducted a prospective assessor-blind observational study to enroll adult patients with a body mass index of 30 kg·m-2 or higher undergoing laparoscopic sleeve gastrectomy at a medical center between May 2020 and August 2021. Conventional morphometric characteristics along with ultrasonographic airway parameters were evaluated before surgery. The primary outcome was difficult laryngoscopy, defined as a Cormack and Lehane's grade III or IV during direct laryngoscopy. Logistic regression analyses were performed to evaluate the association between included factors and difficult laryngoscopy. Discrimination performance of predictive factors was assessed using area under the receiver operating characteristic curve (AUC).

RESULTS

A total of 80 patients were evaluated, and 17 (21.3%) developed an event of difficult laryngoscopy. Univariate analyses identified five factors associated with difficult laryngoscopy, including age, sex, hypertension, neck circumference, and cross-sectional area of tongue base. After adjusting for these variables, neck circumference was the only independent influential factor, adjusted odds ratio: 1.227 (95% confidence interval, 1.009-1.491). Based on Youden's index, the optimal cutoff of neck circumference was 49.1 cm with AUC: 0.739 (sensitivity: 0.588, specificity: 0.889; absolute risk difference: 0.477, and number needed to treat: 3).

CONCLUSION

Greater neck circumference was an independent risk factor for difficult laryngoscopy in obese patients. This finding provides a way of reducing unanticipated difficult airway in this high-risk population.

Point-of-Care Ultrasound in the Pediatric Intensive Care Unit

Ultrasonography has been widely used in medicine for decades but often by specific users such as cardiologists, obstetricians, and radiologists. In the last several years, the use of this imaging modality has moved to the bedside, with clinicians performing and interpreting focused point of care ultrasonography to aid in immediate assessment and management of their patients. The growth of point of care ultrasonography has been facilitated by advancement in ultrasound-related technology and emerging studies and protocols demonstrating its utility in clinical practice. However, considerable challenges remain before this modality can be adopted across the spectrum of disciplines, primarily as it relates to training, competency, and standardization of usage. This review outlines the history, current state, challenges and the future direction of point of care ultrasonography specifically in the field of pediatric critical care medicine.

Point-of-Care Ultrasound for the Trauma Anesthesiologist

Purpose of Review

With advances in technology and availability of handheld ultrasound probes, studies are focusing on the perioperative care of patients, but a limited number specifically on trauma patients. This review highlights recent findings from studies using point of care ultrasound (POCUS) to improve the care of trauma patients.

Recent Findings

Major findings include the use of POCUS to assess volume status of trauma patients upon arrival to measure the major vasculature. Additionally, several studies have advanced the use of POCUS to identify pneumothorax in trauma patients. Finally, the ASA POCUS certification and ASRA expert guidelines are examples of international organizations establishing guidelines for utilization and training of anesthesiologists in the field of POCUS, which will be discussed.

Summary

Despite the COVID-19 pandemic, and considerable resources being diverted to fight this global healthcare crisis, advances are being made in utilization of POCUS to aid the care of trauma patients.