Airways ultrasound in predicting difficult face mask ventilation

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.

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 factor, 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.

Airway management of lingual tonsillar hypertrophy: A narrative review

Lingual tonsillar hypertrophy is rarely identified on routine airway assessment but may cause difficulties in airway management. We conducted a narrative review of case reports of lingual tonsillar hypertrophy to examine associated patient factors, success rates of airway management techniques and complications. We searched the literature for anaesthetic management of cases with lingual tonsillar hypertrophy. We found 89 patients in various case reports, from which we derived 92 cases to analyse. 64% of cases were assessed as having a normal airway. Difficult and impossible face mask ventilation occurred in 29.6% and 1.4% of cases, respectively. Difficult intubation and failed intubation occurred in 89.1% and 21.7% of cases, respectively. Multiple attempts (up to six) at intubation were performed, with no successful intubation after the third attempt with direct laryngoscopy. Some 16.5% of patients were woken up and 4.3% required emergency front of neck access. Complications included oesophageal intubation (10.9%), bleeding (9.8%) and severe hypoxia (3.2%). Our findings show that severe cases of lingual hypertrophy may cause an unanticipated difficult airway and serious complications, including hypoxic brain damage and death. A robust airway strategy is required which includes limiting the number of attempts at laryngoscopy, and early priming and performance of emergency front of neck access if required. In patients with known severe lingual tonsillar hypertrophy, awake intubation should be considered.

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.

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.

Airway ultrasound for patients anticipated to have a difficult airway: Perspective for personalized medicine

Airway ultrasound allows for precise airway evaluation, particularly for assessing the difficult airway and the potential for front of neck access. Many studies have shown that identification of the cricothyroid membrane by airway ultrasound is more accurate than digital palpation. However, no reports to date have provided clinical evidence that ultrasound identification of the cricothyroid membrane increases the success rate of cricothyroidotomy. This is a narrative review which describes patients with difficult airways for whom airway ultrasound may have been useful for clinical decision making. The role of airway ultrasound for the evaluation of difficult airways is summarized and an approach to the use of ultrasound for airway management is proposed. The goal of this review is to present practical applications of airway ultrasound for patients predicted to have a difficult airway and who undergo cricothyroidotomy.

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.

Predicting Difficult Intubation: The Hyomental Distance Ultrasound Evaluation is Superior to the Thyromental Distance

BACKGROUND

Hyomental distance (HMD), an anatomical feature of the upper airway, can be measured precisely by ultrasonography. But the sensitivity and specificity of HMD compared to thyromental distance (TMD) to predict difficult airways is still unknown.

METHODS

A cases cohort study was conducted. The written informed consent was obtained. Elective surgery adult patients undergoing general anaesthesia and tracheal intubation were recruited. The other inclusion criteria: no maxillofacial deformity, trauma, airway stenosis, known difficult airway. The exclusion criteria: tracheal intubations were canceled, or operations were canceled, or patients' data were missing. HMD ultrasound measurements of patients in a sniffing position and other usual airway evaluations were performed before general anaesthesia induction. The primary outcome was the intubation difficulty level. Predictive values were calculated.

RESULTS

We successfully enrolled 2357 patients (62 difficult intubation patients) in the cohort study for analysis. The area under the receiver operating characteristic curve (AUC) of the HMD and TMD for predicting difficult intubation was 0.86 (95% CI, 0.84-0.87) and 0.77 (95% CI, 0.75-0.78) respectively (comparison: P <  0.001). With an optimal cutoff value of HMD ≤ 4.9 cm, we observed a sensitivity and specificity of 0.90 (95% CI, 0.80-0.96) and 0.73 (95% CI, 0.71-0.75). Meanwhile, of TMD ≤ 7.0 cm, the sensitivity and specificity were 0.77 (95% CI, 0.65-0.87) and 0.65 (95% CI, 0.63-0.67) respectively.

CONCLUSION

In comparison to TMD, HMD measured by ultrasound was more sensitive in predicting difficult intubation.

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.