Use of sonography for airway assessment: an observational study

Real-time ultrasound-guided laryngeal mask assisted percutaneous dilatational tracheostomy versus bronchoscopy-guided percutaneous dilatational tracheostomy in critically ill patients: a randomized controlled trial

BACKGROUND

Percutaneous dilatational tracheostomy (PDT) is a common procedure for mechanically ventilated patients in the intensive care unit (ICU). This study compared the real-time ultrasound-guided PDT using a laryngeal mask airway (LMA) with the standard bronchoscopy-guided PDT technique in ICU patients requiring elective tracheostomy.

METHODS

This randomized controlled study was conducted at Ain Shams University Hospital's Critical Care Department from December 4th, 2021, to December 3rd, 2022. The study population included 60 critically ill patients admitted to the ICU. Thirty patients were randomly assigned to the real-time ultrasound-guided LMA-assisted group, and 30 patients were randomly assigned to the bronchoscopy-guided technique. The primary study outcome was the procedure time, and the secondary outcomes included procedure-related complications rate and cost-effectiveness.

RESULTS

The real-time ultrasound-guided LMA-assisted group had significantly shorter procedure time (median 17 [IQR: 15-20] min vs. 35 [IQR: 28-39] min, p < 0.001) and lower equipment damage (0% vs. 20%, p = 0.024) during the procedure compared to the bronchoscopy-guided group. Additionally, the cost of tracheostomy was significantly lower in the real-time ultrasound-guided LMA-assisted group (median: 300 vs. 800 USD, p < 0.001). The real-time ultrasound-guided LMA group had a lower major complications rate than the bronchoscopy-guided group (36.7%) vs. 3.3%, p = 0.002).

CONCLUSIONS

The study demonstrated that real-time ultrasound-guided LMA-assisted PDT had shorter procedure time, reduced equipment damage, lower costs, and was associated with lower complications when compared to the bronchoscopy-guided technique. These findings suggest that ultrasound guidance can enhance the efficiency and cost-effectiveness of PDT procedures.

Waves of Precision: A Practical Guide for Reviewing New Tools to Evaluate Mechanical In-Exsufflation Efficacy in Neuromuscular Disorders

Mechanical insufflation-exsufflation (MI-E) is essential for secretion clearance, especially in neuromuscular disorders. For the best outcomes, initiation of MI-E should be started at the correct time with regular evaluation to the response to treatment. Typically, cough peak flow has been used to evaluate cough effectiveness with and without MI-E. This review highlights the limitations of this and discussed other tools to evaluate MI-E efficacy in this rapidly developing field. Such tools include the interpretation of parameters (like pressure, flow and volumes) that derive from the MI-E device and external methods to evaluate upper airway closure. In this review we pinpoint the differences between different devices in the market and discuss new tools to better titrate MI-E and detect pathological responses of the upper airway. We discuss the importance of point of care ultrasound (POCUS), transnasal fiberoptic laryngoscopy and wave form analysis in this setting. To improve clinical practice newer generation MI-E devices should allow real-time evaluation of waveforms and standardize some of the derived parameters.

Determinants of difficult laryngoscopy based on upper airway indicators: a prospective observational study

BACKGROUND

The main cause of anesthesia-related deaths is the failure to manage difficult airways. Difficult laryngoscopic exposure is a major cause of unsuccessful management of difficult airways. Inadequate preoperative airway assessment hinders the clinical management of difficult airways cases, emphasizing the critical need for accurate identification of difficult airways. Currently, no definitive and reliable indicators are available to predict a difficult airway. Our study aims to predict laryngoscope exposure risk factors by combining ultrasonically measured upper airway anatomic parameters with physical examination indicators.

METHODS

Patients aged 18 to 75 years, classified as American Standards Association (ASA) I-III, and scheduled for elective general anesthesia with endotracheal intubation were included. All patients received the upper airway and ultrasonographic measurements. After anesthesia induction, laryngoscope exposure was analyzed using the Cormack-Lehane grading system, with Grades III and IV as indicative of difficult laryngoscopy. Univariate and multivariate logistic regression analyses were performed to identify reliable indicators for predicting difficult laryngoscopy. Receiver Operating Characteristic (ROC) curve analysis was utilized to assess the predictive performance of each indicator.

RESULTS

A total of 1120 patients finished the study, with 710 cases found in Grade I laryngoscopic exposure group, 360 cases in Grade II group, and 50 cases in Grade III group. There was no case observed in Grade IV group, thereby resulting in an incidence of difficult laryngoscopy of 4.46%. Univariate logistic regression analysis revealed that several parameters including age, Body Mass Index (BMI), neck circumference, neck mobility, snoring intensity, as well as ultrasound measurements of the pre-epiglottic space and thyromental distance were identified as significant risk factors for difficult laryngoscopy (P < 0.05). Among these, BMI, and neck circumference exhibited notable predictive value, with Area Under The Curve (AUC) values of 0.746 (95%CI 0.649-0.842) and 0.732 (95%CI 0.638-0.827), respectively. Neck mobility was also identified as an independent risk factor for predicting difficult laryngoscopy (P = 0.009) in multivariate logistic regression analysis, with an AUC of 0.672 (0.562-0.782) in the ROC curve.

CONCLUSIONS

Our findings revealed a direct correlation between difficult laryngoscopy and age, BMI, neck circumference, neck mobility, snoring intensity, as well as ultrasound measurements of the pre-epiglottic space and thyromental distance. Furthermore, neck mobility was identified as an independent predictive factor.

TRIAL REGISTRATION

The trial was registered prior to patient enrollment at clinicaltrials.gov (register no. ChiCTR2100053826, Date of registration: November 30, 2021).

A pilot observation using ultrasonography and vowel articulation to investigate the influence of suspected obstructive sleep apnea on upper airway

Failure to employ suitable measures before administering full anesthesia to patients with obstructive sleep apnea (OSA) who are undergoing surgery may lead to developing complications after surgery. Therefore, it is very important to screen OSA before performing a surgery, which is currently done by subjective questionnaires such as STOP-Bang, Berlin scores. These questionnaires have 10-36% specificity in detecting sleep apnea, along with no information given on anatomy of upper airway, which is important for intubation. To address these challenges, we performed a pilot study to understand the utility of ultrasonography and vowel articulation in screening OSA. Our objective was to investigate the influence of OSA risk factors in vowel articulation through ultrasonography and acoustic features analysis. To accomplish this, we recruited 18 individuals with no risk of OSA and 13 individuals with high risk of OSA and asked them to utter vowels, such as /a/ (as in "Sah"), /e/ (as in "See"). An expert ultra-sonographer measured the parasagittal anterior-posterior (PAP) and transverse diameter of the upper airway. From the recorded vowel sounds, we extracted 106 features, including power, pitch, formant, and Mel frequency cepstral coefficients (MFCC). We analyzed the variation of the PAP diameters and vowel features from "See: /i/" to "Sah /a/" between control and OSA groups by two-way repeated measures ANOVA. We found that, there was a variation of upper airway diameter from "See" to "Sah" was significantly smaller in OSA group than control group (OSA: ∆12.8 ± 5.3 mm vs. control: ∆22.5 ± 3.9 mm OSA, p < 0.01). Moreover, we found several vowel features showed the exact same or opposite trend as PAP diameter variation, which led us to build a machine learning model to estimate PAP diameter from vowel features. We found a correlation coefficient of 0.75 between the estimated and measured PAP diameter after applying four estimation models and combining their output with a random forest model, which showed the feasibility of using acoustic features of vowel sounds to monitor upper airway diameter. Overall, this study has proven the concept that ultrasonography and vowel sounds analysis may be useful as an easily accessible imaging tool of upper airway.

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.

Ultrasonography Imaging versus Waveform Capnography in Detecting Endotracheal Tube Placement during Intubation at a Tertiary Hospital

Background

There is continued research to find new faster, highly accurate, easily accessible, and portable methods of confirming endotracheal tube position during intubation. A newer modality for visualizing endotracheal tube location is transtracheal or transcricothyroid ultrasonography. The aim of this study was to see if ultrasound machine can also be routinely used for the confirmation of endotracheal tube position in operating theaters along with capnograph.

Methods

The study was observational and prospective, conducted from January 2017 to July 2017. Study locations were at the Tribhuvan University Teaching Hospital and Manmohan Cardiothoracic Vascular and Transplant Center operating rooms. Sample size taken was 95.

Results

In the study, 11 patients had esophageal intubation out of the 95. The accuracy of both ultrasonography and capnography was found to be 96.84%. For ultrasonography, the sensitivity, specificity, along with positive predictive value and negative predictive value were 97.62%, 90.91%, 98.80%, and 83.33%, respectively, while that for capnography were found to be 96.43%, 100%, 100%, and 78.57%, respectively. The kappa value was calculated to be 0.749, which suggested the degree of agreement of result between the methods to be good. Compared to capnography, ultrasonography was found to be significantly faster for the confirmation of endotracheal tube location by 16.36 s (15.70-17.02) (P = 0.011).

Conclusion

Both waveform capnography and ultrasonography were found to be accurate and reliable in confirming endotracheal tube location. The use of ultrasound during intubation can help confirm endotracheal tube location faster and also aid in precision when used along with capnography. Manual bag ventilations are not necessary when confirming endotracheal tube position by ultrasonography and thus may help in preventing aspiration of gastric contents into the lungs of the patient.

Ultrasound-Guided Airway Evaluation: Is It a Game Changer for Predicting Difficult Endotracheal Intubation?

INTRODUCTION

Airway ultrasound has recently promised to be a valuable addition to preoperative airway assessment tools. This study was undertaken to determine the efficacy of ultrasound-guided measurement of soft tissue thickness (STT) at various levels of the anterior neck in predicting difficult airways in an eastern Indian population.

OBJECTIVE

 The primary objective was to find out the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of anterior neck soft tissue thickness at the level of the hyoid (STT-Hyoid) and vocal cords (STT-VC), distance from the skin to the epiglottis midway (DSEM), and the ratio of the depth of the pre-epiglottic space (Pre-E) to the distance from the epiglottis to the mid-point of the vocal cords (E-VC). The secondary objective was to develop a scoring system using these parameters.

MATERIALS AND METHODS

One hundred eighty-eight patients aged 18-65 years who received general anesthesia and endotracheal intubation for surgery were included in the study. Anterior neck soft tissue thickness measurements were done preoperatively using ultrasound. The actual difficulty of the airway was graded by the anesthesiologist while performing endotracheal intubation using the intubation difficulty scale (IDS).

RESULTS

The incidence of a difficult airway (IDS > 5) was 9.04%. The STT-Hyoid and STT-VC had a moderate correlation with IDS. The DSEM and Pre-E/E-VC ratios had a weak correlation with IDS. For difficult airway prediction, the cutoff points of STT-Hyoid and STT-VC were 7.95 mm and 24.25 mm, respectively. The combined cutoff measurements of STT-Hyoid and STT-VC (29.95 mm) were better predictors of difficult airway.

CONCLUSION

Preoperative airway ultrasound examination measuring the soft tissue thickness at the hyoid and vocal cord levels is an effective modality in predicting a difficult airway. However, further studies are needed to validate this finding in populations of varied ethnicity and demographic distribution.

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.

Ultrasound Elastography Detects Age-Related Changes in Adult False Vocal Folds

PURPOSE

To investigate the feasibility of ultrasound elastography for assessing the symmetry in stiffness values and movements of both false vocal folds (FVFs).

METHODS

After Institutional Review Board's approval and written informed consent obtained, we measured ultrasound strain and shear wave velocity (SWV) of the bilateral FVF in vocal fold abduction and adduction in 30 participants using a linear array transducer (4-10 MHz). Twenty-eight participants met inclusion criteria as healthy subjects for analysis. Mean strain of FVF produced by FVF movement from abduction to adduction was analyzed using 2D speckle-tracking software offline. A SWV ratio ([SWV_adduction - SW_abduction ]/SW_abduction ) was developed to test the contractibility of FVF. Statistical analysis included one-way ANOVA to test the difference in mean strain, SWV (adduction and abduction), and SWV ratio among the three age groups; linear regression to analyze correlations of stiffness and movement between the right and left FVF; and intraclass correlation coefficient (ICC) to examine intra- and interobserver reliability in performing shear wave elastography (SWE) of FVF.

RESULTS

The 28 healthy participants were divided into 3 age groups (10 of young 20-44 years; 9 of mid-age 45-64 years; and 9 of senior ≥65 years). The SWV in FVF abduction was higher and the SWV ratio was lower in seniors compared to young participants (P < .05). Good to excellent correlation of mean strain and SWV between both FVFs (R²  > 0.89). The reliability of performing SWE of FVF was moderate to excellent.

CONCLUSION

Ultrasound elastography is feasible to assess the stiffness, dynamic movement, and symmetry of adult FVF, and healthy seniors may exhibit increased FVF stiffness.

Dynamic assessment of oropharynx with ultrasonography as a screening tool for obstructive sleep apnea

Ultrasonography is an easily available and portable tool to assess the dynamic changes in the upper airway and surrounding soft tissue. This study aimed to evaluate the utility of oropharynx ultrasonography as a screening tool for obstructive sleep apnea (OSA). The study sequentially enrolled overweight individuals (body mass index >25 kg/m² ) and subjected them to OSA screening tools (Berlin questionnaire, Epworth Sleepiness Scale and STOP-Bang scores), ultrasonography of the oropharynx followed by overnight polysomnography. A total of 30 healthy individuals were also recruited as controls. Detailed dynamic and static ultrasonography measurements of the oropharynx and surrounding tissue were done. The diagnostic ability of various ultrasonography parameters to detect OSA was determined using receiver operating characteristic curve analysis. A total of 63 subjects were enrolled, with 33 in the OSA group and 30 in non-OSA overweight group. All baseline characteristics were similar in the two groups. Except for the dynamic measurements of oropharynx (Retropalatal% change-inspiration, retropalatal% change-Muller manoeuvre, retroglossal% change-inspiration, and retroglossal% change-Muller manoeuvre) all other parameters were similar in the OSA and non-OSA overweight subjects. The area under the receiver operating characteristic curve was highest for retropalatal% change-inspiration: 0.989, followed by retropalatal% change-Muller manoeuvre: 0.988. Both were also significant predictors of OSA with odds ratios of 0.338 (p = 0.003; 95% confidence interval [CI] 0.164-0.696) and 0.346 (p = 0.018; 95% CI 0.143-0.837), respectively. Ultrasonography provides a near complete picture of the dynamic changes and collapsibility of the oropharynx and can be an effective tool in screening for OSA.

Mini-probe endoscopic ultrasound for the diagnosis of congenital esophageal or duodenal stenosis

PURPOSE

The usefulness of endoscopic ultrasound (EUS) in pediatric populations has been recently appreciated; however, published studies on mini-probe EUS in the diagnosis of congenital esophageal stenosis (CES) or congenital duodenal stenosis (CDS) in pre-school patients remain scarce. This study aimed to report the utility of mini-probe EUS for the diagnosis of CES or CDS in pre-school patients based on the etiology.

METHODS

We retrospectively reviewed the medical records of pediatric patients with CES or CDS who underwent mini-probe EUS through the stenotic segments at our hospital between December 2006 and December 2021.

RESULTS

Five patients with CES and one with CDS were enrolled. The median age and body weight when EUS was performed were 12.5 months and 8.5 kg, respectively. Hypoechoic lesions were observed on EUS in three patients, which were assessed as cartilage; one patient had no hypoechoic lesion but had a focal thickness of the muscular layer. They were diagnosed with tracheobronchial remnants based on EUS. The full circumferential wall thickness of the esophagus was visualized in one patient with fibromuscular hypertrophy. The histopathological findings confirmed the diagnoses. In the patient with CDS, EUS findings revealed pancreatic parenchyma encircling the stenotic part of the duodenum. The preoperative diagnosis was annular pancreas. The patient underwent duodenoduodenostomy, and intraoperative findings confirmed the diagnosis.

CONCLUSION

Mini-probe EUS can be recommended as a feasible and safe technique for infants and toddlers. It can effectively diagnose CES or CDS based on etiology and can inform treatment strategies for pre-school patients.

Cervical ultrasound for the evaluation of the vocal cords: A pilot study in an endocrine surgery unit

INTRODUCTION

Cervical ultrasound (CE) has emerged as a promising tool in recent years for vocal cord (VC) assessment in patients undergoing thyroid surgery. Our aim is to assess the reliability of CE once implemented in an endocrine surgery unit and performed by the surgeons themselves.

MATERIAL AND METHOD

86 participants with no history of laryngeal pathology or cervical surgery underwent CE by three independent endocrine surgeons. Laryngeal structures and specifically the VCs were analysed. To consider the examination as diagnostic, the VCs had to be visualised statically and during phonation. The time taken to perform the technique and the interobserver variability were also analysed.

RESULTS

Of the 86 participants, 51.2% were male with a mean age of 43 years. The range of diagnostic examinations between surgeons was 60-68%, with substantial agreement between the 3 explorers (Fleiss's K-value = .714). Male sex and advanced age were factors associated with non-assessability of the technique. The mean procedure time was 72 s.

CONCLUSIONS

CE is a fast, non-invasive, feasible bedside tool useful for the assessment of VCs prior to thyroid surgery, mainly in young women.

Mortality Risk Factors in Patients Admitted with the Primary Diagnosis of Tracheostomy Complications: An Analysis of 8026 Patients

Background: Tracheostomy is a procedure commonly conducted in patients undergoing emergency admission and requires prolonged mechanical ventilation. In the present study, the aim was to determine the prevalence and risk factors of mortality among emergently admitted patients with tracheostomy complications, during the years 2005−2014. Methods: This was a retrospective cohort study. Demographics and clinical data were obtained from the National Inpatient Sample, 2005−2014, to evaluate elderly (65+ years) and non-elderly adult patients (18−64 years) with tracheostomy complications (ICD-9 code, 519) who underwent emergency admission. A multivariable logistic regression model with backward elimination was used to identify the association between predictors and in-hospital mortality. Results: A total of 4711 non-elderly and 3315 elderly patients were included. Females included 44.5% of the non-elderly patients and 47.6% of the elderly patients. In total, 181 (3.8%) non-elderly patients died, of which 48.1% were female, and 163 (4.9%) elderly patients died, of which 48.5% were female. The mean (SD) age of the non-elderly patients was 50 years and for elderly patients was 74 years. The mean age at the time of death of non-elderly patients was 53 years and for elderly patients was 75 years. The odds ratio (95% confidence interval, p-value) of some of the pertinent risk factors for mortality showed by the final regression model were older age (OR = 1.007, 95% CI: 1.001−1.013, p < 0.02), longer hospital length of stay (OR = 1.008, 95% CI: 1.001−1.016, p < 0.18), cardiac disease (OR = 3.21, 95% CI: 2.48−4.15, p < 0.001), and liver disease (OR = 2.61, 95% CI: 1.73−3.93, p < 0.001). Conclusion: Age, hospital length of stay, and several comorbidities have been shown to be significant risk factors in in-hospital mortality in patients admitted emergently with the primary diagnosis of tracheostomy complications. Each year of age increased the risk of mortality by 0.7% and each additional day in the hospital increased it by 0.8%.

Application of POCUS in patients with COVID-19 for acute respiratory distress syndrome management: a narrative review

COVID-19 has inflicted the world for over two years. The recent mutant virus strains pose greater challenges to disease prevention and treatment. COVID-19 can cause acute respiratory distress syndrome (ARDS) and extrapulmonary injury. Dynamic monitoring of each patient's condition is necessary to timely tailor treatments, improve prognosis and reduce mortality. Point-of-care ultrasound (POCUS) is broadly used in patients with ARDS. POCUS is recommended to be performed regularly in COVID-19 patients for respiratory failure management. In this review, we summarized the ultrasound characteristics of COVID-19 patients, mainly focusing on lung ultrasound and echocardiography. Furthermore, we also provided the experience of using POCUS to manage COVID-19-related ARDS.

Radiological versus traditional parameters for airway assessment: A comparison

Background:

Aim:

Settings and Design:

Materials and Methods:

Statistical Analysis Used:

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Comparison of landmark guided and ultrasound guided percutaneous dilatational tracheostomy: Efficiency, efficacy and accuracy in critically ill patients

Background and Aims:

To overcome the procedure-related complications associated with landmark-guided percutaneous dilatational tracheostomy (PDT) ultrasound is emerging as a promising tool. Present study was designed to compare landmark-guided PDT and ultrasound-guided PDT in terms of efficiency, efficacy, and accuracy.

Material and Methods:

Hundred intensive care unit patients requiring prolonged mechanical ventilation were prospectively randomized into 2 groups of 50 patients each. In land mark guided (LMG) group, patients underwent landmark-guided PDT, whereas in ultrasound guided (USG) group, patients underwent ultrasound-guided PDT.

Results:

Both the groups were comparable in terms of demographic data, sequential organ failure assessment score, ventilator settings, and mean days on mechanical ventilation prior to PDT. The mean assessment time in the ultrasound-guided group (1.56 ± 1 min) was significantly more (P-value = 0.000) than in the landmark-guided group (0.84 ± 0.72 min). The mean total procedure time for the USG group (5.98 ± 10.23 min) was more than that for the LMG group (4.86 ± 8.03 min) (P-value 0.542). Deviation of puncture site from the midline was seen in two patients in group A as compared to none in the USG group (P-value = 0.153). The number of patients requiring more than one attempt for successful needle insertion was more (P-value = 0.148) in the LMG group (20%) as compared to USG group (8%). Incidence of complications, like bleeding and desaturation was more in the LMG group as compared to the USG group.

Conclusion:

Ultrasound-guided PDT is associated with reduction in periprocedural complications as compared to landmark technique, although it takes slightly longer time.

Age-Related Changes in Upper Airway Anatomy Via Ultrasonography in Pediatric Patients

PURPOSE

Ultrasonography is a portable, noninvasive tool that may be used to evaluate the upper airway. The purpose of our study was to present a systematic approach to identify salient features of the pediatric airway and determine whether ultrasonography can identify anatomical changes that occur with growth and development.

METHODS

We present a prospective, observational trial where patients included were between 1 day and 10 years of age presenting for elective surgery who had no known history of unfavorable airway pathology. We sequentially obtained 5 ultrasound views under anesthesia: (1) sagittal sternal notch view of the trachea, (2) sagittal longitudinal view of trachea (LT), (3) axial view at the level of the vocal cords (AVC), (4) axial view at the level of the cricoid membrane (AC), and (5) sagittal longitudinal submental space view (SM). A broadband linear array transducer was used to identify airway structures and perform measurements.

RESULTS

Eighty-four percent of enrolled patients underwent airway imaging and were analyzed using multiple regression and Spearman correlation (ρ). In view 1, tracheal diameter via sagittal sternal notch view was immeasurable because of air disturbance. In the LT view, the distance from the skin to the cricothyroid membrane (LT1) did not statistically increase with age in days (P = 0.06); however, the distance from the cricoid to thyroid cartilage (LT2) did correlate to age (P < 0.001; 99% confidence interval [CI], 1.8 × 10-5, 7.7 × 10-5; ρ = 0.77, P = 0.001). We found a statistically significant relationship between age and the distance between the anterior and posterior commissures (AVC2; P < 0.001; 99% CI, 1.0 × 10-4, 1.7 × 10-4; ρ = 0.80, P < 0.001), the distance from the skin to the posterior commissure (AVC3; P < 0.001; 99% CI, 9.6 × 10-5, 2.0 × 10-4; ρ = 0.73, P < 0.001), the distance to the cricoid cartilage (AC; P < 0.001; 99% CI, 2.0 × 10-5, 7.7 × 10-5; ρ = 0.66, P < 0.001), and the distance from the tongue base to the soft palate (SM2; P < 0.001; 9% CI, 1.8 × 10-4, 3.9 × 10-4; ρ = 0.85, P < 0.001). There were no significant relationships between age and AVC1 (P = 0.16) and SM1 (P = 0.44).

CONCLUSIONS

Airway ultrasound is a feasible tool to evaluate the pediatric airway in children younger than 10 years; however, the detection of age-related changes of certain structures is limited to select measurements.

Ultrasound Shear Wave Elastography of the Tongue during Selective Hypoglossal Nerve Stimulation in Patients with Obstructive Sleep Apnea Syndrome

Currently, there is no established technique to directly measure extrinsic tongue muscle activation during selective hypoglossal stimulation therapy (sHNS) in patients with obstructive sleep apnea syndrome (OSAS) in a simple, non-invasive clinical setting. Ultrasound shear-wave elastography (US-SWE) enables quantitative measurement of tissue stiffness. We investigated whether US-SWE is able to detect changes in muscle stiffness of the tongue during sHNS. Patients with OSAS treated with sHNS were prospectively enrolled. A standardized US-SWE protocol was used to selectively measure tissue stiffness of the geniohyoid muscle (GH) and genioglossus (GG) muscles on the side of stimulator implantation (sGH, sGG) and on the contralateral side (nGH, nGG) without and with sHNS. Eighteen patients were included (median age = 62 years, interquartile range: 56-65, 83.3% male). Median shear-wave velocity (SWV) increased during contraction with each patient's clinically prescribed therapeutic regimen in the sGH (+19%, p = 0.020) and sGG (+81%, p < 0.001) and decreased during contraction in the nGH (-8%, p = 0.107) and nGG (-8%, p = 0.396). Differences in SWV during contraction were significant only on the side of stimulation (sGG +81%, sGH +19%). SWE measurements had excellent reliability as reflected by a Cronbach α value ≥0.9 for all target muscles pre- and post-contraction and an item-total correlation ≥0.5. US-SWE allows reliable measurement of SWV as an indicator of muscle stiffness of extrinsic tongue muscles. This non-invasive method provides new possibilities to distinguish and characterize responders from non-responders in hypoglossal stimulation therapy. Compared with the regular visual assessment of tongue movement, US-SWE of individual muscle groups provides a new non-invasive imaging tool in patients with OSAS.

Ultrasound: Reliability of a Pocket-Sized System in the Assessment of Swallowing

Purpose Ultrasound imaging offers a noninvasive adjunct to clinical swallowing assessment. Published reliability of sophisticated ultrasound systems is promising; however, no data exist for reliability using more affordable, pocket-sized devices. This study explored intrarater, interrater, and test-retest reliability of swallowing measures acquired with pocket-sized ultrasound technology. Method Five participants collected measures of swallowing from 20 healthy individuals using the Clarius ultrasound. Hyoid excursion and thyrohyoid approximation were derived during saliva, liquid, and puree swallowing. The cross-sectional area of the floor of mouth muscles and tongue thickness were obtained at rest. Measures were collected at two occasions minimum 11 days apart. Reliability was assessed for the entire process of data acquisition including scanning and online measurement, and for offline measurement of saved images. Results For most measures, reliability was poor (ICC [intraclass correlation coefficient] < .50) to moderate (ICC = .50-.75) for the entire process of data acquisition and poor to good (ICC > .75) when measuring saved images. Conclusion Further work is needed to elucidate whether our study findings apply to the Clarius system only or the data suggest a general limitation of pocket-sized ultrasound technology.

Assessing the accuracy of ultrasound measurements of tracheal diameter: an in vitro experimental study

Background

Recent studies indicate that ultrasound can detect changes in tracheal diameter during endotracheal tube (ETT) cuff inflation. We sought to assess the accuracy of ultrasound measurement of tracheal diameter, and to determine the relationship between tracheal wall pressure (TWP), cuff inflation volume (CIV), and the degree of tracheal deformation.

Methods

Our study comprised two parts: the first included 45 porcine tracheas, the second 41 porcine tracheas. Each trachea was intubated with a cuffed ETT, which was connected to an injector and the manometer via a three-way tap. The cuff was inflated and the cuff pressure recorded before and after intubation. The tracheal diameter was measured using ultrasound. This included three separate measurements: outer transverse diameter (OTD), internal transverse diameter (ITD), and anterior tracheal wall thicknesses (ATWT). A precision electronic Vernier caliper was also used to measure tracheal diameter. We calculated TWP and the percentage change of tracheal diameter. The Bland–Altman method, linear regression, and locally weighted regression (LOESS) were used to analyze the data.

Results

There were strong correlation and agreement for OTD (r = 0.97, P < 0.001) and ITD (r = 0.90, P < 0.001) as measured by ultrasound and by precision electronic Vernier caliper, but a poor correlation for ATWT (r = 0.58, P < 0.001). There was a strong correlation between the percentage change of OTD (OTD%, r = 0.75, P < 0.001) and CIV, the percentage change of ITD (ITD%, r = 0.77, P < 0.001) and CIV, TWP (r = 0.75, P < 0.001) and CIV. And a strong correlation was also found between TWP and OTD% (r = 0.84, P < 0.001), TWP and ITD% (r = 0.84, P < 0.001).

Conclusions

Use of ultrasound to measure OTD and ITD is accurate, but is less accurate for ATWT. There is a close correlation between OTD%, ITD%, CIV and TWP.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-021-01398-3.

The anatomic basis for ultrasound in the diagnosis and treatment of styloid process-related diseases

Background

The styloid process (SP), stylohyoid ligament and lesser horn of hyoid bone together form the stylohyoid chain. Differences in the ossification degree and the connection sites of each segment of the stylohyoid chain on both sides lead to variations in the length, orientation, thickness, and straightness of SP. The incidence of elongation of the SP, known as styloid process syndrome (SPS), is around 4%, with only 4% of patients showing elongation show symptoms. Computed tomography (CT) remains the first-choice auxiliary examination for diagnosing SPS, but its performance can be affected by a variety of factors. Ultrasound can reveal the parapharyngeal space and adjacent structures, which offer high consistency with CT findings. Here, we investigated the ultrasonographic features of the SP and its adjacent structures in normal adults and assessed the clinical utility of ultrasound assessment for SP-related diseases.

Methods

With the ramus of mandible, mastoid process, SP, and salivary gland as the anatomical landmarks, ultrasonography was conducted on the parapharyngeal space in 78 healthy adults. The scans were performed along the oblique coronal section of the ramus and the cross-sectional plane between the mastoid process and ramus to visualize the SP and its adjacent structures. The SP length, the shortest distance from the SP tip to the outer edge of tonsil (SP-tonsil distance), and the distance from SP to the internal carotid artery (SP–ICA distance) were measured.

Results

SP and its adjacent structures were successfully visualized on ultrasonography in all 78 subjects. The measured SP length was 2.65±0.48 cm. The SP–tonsil distance was 1.95±0.50 cm. The SP–ICA distance was 0.509±0.231 cm. The SP length and SP–tonsil distance measured by ultrasound were not significantly different from those measured by CT (P=0.071, P=0.053). Furthermore, the SP length and SP–tonsil distance measured by ultrasound were positively correlated with CT measurements (r=0.917, P=0.071; r=0.978, P=0.053, respectively). SP–tonsil distance was negatively correlated with SP length and SP inward deflection angle.

Conclusions

Ultrasound can accurately reveal the shape and size of SP and its adjacent structures and thus will be helpful for the diagnosis of SP-related diseases.

Ultrasonography of the larynx: Novel use during the SARS-CoV-2 pandemic (Review)

Few articles have been published on the subject of laryngeal ultrasonography. However, considering the increased power and accuracy of ultrasound technology, this imaging modality should be reevaluated. The present review aimed to increase the awareness of fellow specialists regarding the use of this imaging tool in healthcare units that do not benefit from onsite ear, nose and throat (ENT) service. We illustrate the ultrasonographic examination protocol for the larynx along with the relevant anatomic landmarks. We review cases with laryngeal tumoral pathology that underwent ultrasonographic examination for improved management. All findings were confirmed through computerized tomography (CT) and endoscopy performed by the ENT specialist. The ultrasound of the larynx has potential utility in diagnosis (e.g., laryngeal abnormalities, speech and swallowing abnormalities, identification of endotracheal tube placement), treatment (e.g., guidance of percutaneous tracheostomy and cricothyrotomy) and prognosis (e.g., prediction of postextubation stridor and difficult intubation). This imaging modality could be useful in the current SARS-CoV-2 pandemics in reducing the exposure to invasive maneuvers producing aerosol, such as endoscopy.

Point-of-Care Ultrasound (POCUS) for the Cardiothoracic Anesthesiologist

Point-of-Care Ultrasound (POCUS) is a valuable bedside diagnostic tool for a variety of expeditious clinical assessments or as guidance for a multitude of acute care procedures. Varying aspects of nearly all organ systems can be evaluated using POCUS and, with the increasing availability of affordable ultrasound systems over the past decade, many now refer to POCUS as the 21^st-century stethoscope. With the current available and growing evidence for the clinical value of POCUS, its utility across the perioperative arena adds enormous benefit to clinical decision-making. Cardiothoracic anesthesiologists routinely have used portable ultrasound systems for nearly as long as the technology has been available, making POCUS applications a natural extension of existing cardiothoracic anesthesia practice. This narrative review presents a broad discussion of the utility of POCUS for the cardiothoracic anesthesiologist in varying perioperative contexts, including the preoperative clinic, the operating room (OR), intensive care unit (ICU), and others. Furthermore, POCUS-related education, competence, and certification are addressed.

Ultrasonographic Measurement of Pharyngeal-Airway Dimension and Its Relationship with Obesity and Sleep-Disordered Breathing

Previous studies based on magnetic resonance imaging (MRI) or computed tomography (CT) have shown that pharyngeal airway diameter during wakefulness is different between healthy controls and patients with a high risk of sleep-disordered breathing (SDB). However, MRI and CT are expensive and not easily accessible. Conversely, ultrasonography is more accessible and is getting more attention as a point-of-care technology to assess physiologic systems, such as the pharynx. Thus, we aimed to evaluate the feasibility of ultrasonography in estimating the pharyngeal airway dimension. To evaluate the pharyngeal airway with ultrasonography, we measured the parasagittal anterior-posterior (PAP) diameter and transverse diameter. For PAP diameter measurements, the transducer probe was placed in a submandibular lateral oblique position, with its superior margin abutting the angle of the left mandible. For the transverse measurement, the ultrasound probe was positioned in a submandibular location, in a near-coronal plane, just above the hyoid bone so that the tongue could be seen in cross-section. The diameter measurements were performed manually by two technicians. The reliability of these measurements was assessed by the intra-class correlation coefficient (ICC). To validate our measurements, we compared the measured PAP diameter with the average pharyngeal airway cross-sectional area from vellum to glottis measured by acoustic pharyngometry. Furthermore, we compared the influence of obesity and SDB in the measured pharyngeal diameters. Eighteen controls and 13 individuals with a high risk of SDB participated in this study. Reliability analysis of the PAP measurements yielded an ICC of 0.97 (95% confidence interval: 0.94-0.98). Furthermore, measured PAP diameters were significantly correlated with the pharyngeal airway cross-sectional area (r = 0.76, p < 0.01). Moreover, obesity and SDB were associated with decreases in PAP diameter. Our study shows that ultrasonography measurement of the PAP diameter may provide a quantitative assessment of the pharyngeal airway and may be useful for screening of SDB.

Comparison of leakage test and ultrasound imaging to validate ProSeal supraglottic airway device placement

Background and Aims:

To validate the placement of ProSeal supraglottic airway device using ultrasound (USG) with leakage test in adult population of both sexes.

Material and Methods:

This single-arm observational study was conducted on 80 American Society of Anesthesiology (ASA) I-III patients, undergoing elective surgery under general anesthesia with ProSeal supraglottic airway device. Leakage pressure test was conducted in all cases. The position of the ProSeal laryngeal mask airway (LMA) was assessed by USG in the pharyngeal, laryngeal, and the cranial-caudal axis plane. The fiberoptic examination was done to confirm the position of ProSeal if the seal pressure was <27 cm H₂O, to confirm suboptimal placement. The position of the ProSeal in the three USG planes was allocated a predetermined score. This score was compared with the leakage test to determine the strength of the correlation, sensitivity, and specificity for predicting a need for reinsertion.

Results:

Leakage seal pressure was recorded as <27 cm H₂O in 6 (7.5%) patients and fiberoptic bronchoscopy was done in these cases to determine the need for reinsertion. ProSeal was reinserted in 5 (6.25%) cases. Patients with a composite ultrasound score of 0–1 required ProSeal reinsertion while those with a score of 2–3 did not require reinsertion. Seventy-one patients had seal pressure >27 cm H₂O and a score of 3. USG examination is comparable with leakage test in predicting the requirement of reinsertion (P = 0.003) and a score of 19 equating 0–1 predicted the need for reinsertion with a sensitivity and specificity of 80% and 100%, respectively.

Conclusion:

USG is comparable with the leakage test for confirmation of ProSeal placement.

Ultrasound assessment of upper airway dilator muscle contraction during transcutaneous electrical stimulation in patients with obstructive sleep apnoea

Background

Electrical current can be used to stimulate upper airway dilator muscles to treat obstructive sleep apnoea (OSA). Ultrasound devices are widely available and may be used to detect contraction of the upper airway dilator muscles assessing the functionality of electrical stimulation (ES) used for this treatment.

Methods

In a physiological sub-study of a randomised controlled trial, patients with OSA underwent ultrasound examination to assess contraction of the upper airway dilator muscles in response to transcutaneous ES. Ultrasound scans were scored according to the picture quality (poor = '0', acceptable = '1' and good = '2'). Tongue base thickness was assessed in mid-sagittal and coronal planes with (D2, A2) and without ES (D1, A1), while awake and seated. The primary outcome was to determine the increase in tongue thickness during ES in both views (D2 - D1 = ΔD), as well as any increase in the cross-sectional area (CSA) in the coronal view (A2 - A1 = ΔA). Data were presented as mean and standard deviation (SD).

Results

Fourteen patients [eight male, age 57.5 (9.8) years, body mass index (BMI) 29.5 (2.8) kg/m²] with OSA [Apnea-Hypopnea Index (AHI) 19.5 (10.6) × hour^-1] were studied. Quality of the ultrasound scans was acceptable or good with 1.5 (0.5) points. In the mid-sagittal plane, ΔD was +0.17 (0.07) cm in midline and +0.21 (0.09) cm in the widest diameter, a percentual change of 12.2% (4%) and 12.8% (5.2%) (P<0.001, respectively). In the coronal plane, ΔD was +0.17 (0.04) cm, an increase of 12.3% (4.6%) (P<0.001, respectively), ΔA in the CSA increased by +18.9% (3.0%) with stimulation (P<0.001). There was a negative correlation between age and ΔA (r= -0.6, P=0.03), but no significant associations were found with gender, BMI, neck circumference, Epworth Sleepiness Scale (ESS), AHI, skin and subcutaneous tissue in the submental area.

Conclusions

Ultrasound can visualise upper airway dilator muscle contraction during transcutaneous ES in awake patients with OSA. Contraction is best detected in the CSA of the tongue base in the coronal plane.

Ability of Critical Care Medics to Confirm Endotracheal Tube Placement by Ultrasound

INTRODUCTION

The Advanced Cardiac Life Support (ACLS) guidelines were recently updated to include ultrasound confirmation of endotracheal tube (ETT) location as an adjunctive tool to verify placement. While this method is employed in the emergency department under the guidance of the most recent American College of Emergency Physicians (ACEP; Irving, Texas USA) guidelines, it has yet to gain wide acceptance in the prehospital setting where it has the potential for greater impact. The objective of this study to is determine if training critical care medics using simulation was a feasible and reliable method to learn this skill.

METHODS

Twenty critical care paramedics with no previous experience with point-of-care ultrasound volunteered for advanced training in prehospital ultrasound. Four ultrasound fellowship trained emergency physicians proctored two three-hour training sessions. Each session included a brief introduction to ultrasound "knobology," normal sonographic neck and lung anatomy, and how to identify ETT placement within the trachea or esophagus. Immediately following this, the paramedics were tested with five simulated case scenarios using pre-obtained images that demonstrated a correctly placed ETT, an esophageal intubation, a bronchial intubation, and an improperly functioning ETT. Their accuracy, length of time to respond, and comfort with using ultrasound were all assessed.

RESULTS

All 20 critical care medics completed the training and testing session. During the five scenarios, 37/40 (92.5%) identified the correct endotracheal placements, 18/20 (90.0%) identified the esophageal intubations, 18/20 (90.0%) identified the bronchial intubation, and 20/20 (100.0%) identified the ETT malfunctions correctly. The average time to diagnosis was 10.6 seconds for proper placement, 15.5 seconds for esophageal, 15.6 seconds for bronchial intubation, and 11.8 seconds for ETT malfunction.

CONCLUSIONS

The use of ultrasound to confirm ETT placement can be effectively taught to critical care medics using a short, simulation-based training session. Further studies on implementation into patient care scenarios are needed.

Measurement of subglottic diameter and distance to pre-epiglottic space among Chinese adults

Proper endotracheal tube (ETT) size selection and identification of potentially difficult airways are important to reduce laryngeal injury during intubation. However, controversies exist concerning transverse subglottic diameter—the narrowest part of the airway—and the distance to pre-epiglottic space. Because few studies have reported the distance from skin to the midpoint of the epiglottis (DSE) among normal individuals, whether the DSE varies between individuals and by ethnicity remains uncertain. The present study aims to investigate the sonographic subglottic diameter and DSE among healthy Chinese adults. Healthy volunteers were recruited at National Taiwan University Hospital between October and November 2019. Exclusion criteria included pre-existing airway or respiratory diseases, neck tumors, and a history of neck operation. Age, sex, height, weight, body mass index (BMI), sonographic DSE, and transverse subglottic diameter were recorded. A total of 124 participants were enrolled. The average age was 32.5 ± 10.4 years and 63 participants (51%) were males. The subglottic diameter was positively associated with sex (males, 14.40 mm; females, 11.10 mm, p < 0.001) and BMI (underweight, 12.13 mm; normal weight, 12.47 mm; overweight, 13.80 mm; obese, 13.67 mm, p = 0.007). Moreover, the DSE was shorter in males (male, 16.18 mm; females, 14.54 mm, p < 0.001) and participants with increased BMI (underweight, 13.70 mm; normal weight, 15.06 mm; overweight, 16.58 mm; obese, 18.18 mm, p < 0.001). As compared with other ethnicity, a smaller size of subglottic diameter and a shorter DSE were noted among Chinese participants, and we suggest that a relatively smaller size of endotracheal tube selection should be considered in tracheal intubations.

Effectiveness of four ultrasonographic parameters as predictors of difficult intubation in patients without anticipated difficult airway

Background

Predicting difficult intubation (DI) is a key challenge, as no single clinical predictor is sufficiently valid to predict the outcome. We evaluated the effectiveness of four upper airway ultrasonographic parameters in predicting DI. The validity of the models using combinations of ultrasonography-based parameters was also investigated.

Methods

This prospective, observational, double-blinded cohort trial enrolled 1,043 surgical patients classified as American Society of Anesthesiologists physical status I–III without anticipated difficult airway. Preoperatively, their tongue thickness (TT), invisibility of hyoid bone (VH), and anterior neck soft tissue thickness from the skin to thyrohyoid membrane (ST) and hyoid bone (SH) were measured by sublingual and submandibular ultrasonography. The logistic regression, Youden index, and receiver operator characteristic analysis results were reported.

Results

Overall, 58 (5.6%) patients were classified as DI. The TT, SH, ST, and VH had accuracies of 78.4%, 85.0%, 84.7%, and 84.9%, respectively. The optimal values of TT, SH, and ST for predicting DI were > 5.8 cm (sensitivity: 84.5%, specificity: 78.1%, AUC: 0.880), > 1.4 cm (sensitivity: 81%, specificity: 85.2%, AUC: 0.898) and > 2.4 cm (sensitivity: 75.9%, specificity: 85.2%, AUC: 0.885) respectively. VH had a sensitivity and specificity of 72.4% and 85.6% (AUC: 0.790). The AUC values of the five models (with combinations of three or four parameters) ranged from 0.975–0.992. ST and VH had a significant impact on the individual models.

Conclusions

SH had the best accuracy. Individual parameters showed limited validity. The model including all four parameters offered the best diagnostic value.

Ultrasound measurement of laryngeal structures in the parasagittal plane for the prediction of difficult laryngoscopies in Chinese adults

Background

Abnormal laryngeal structures are likely to be associated with a difficult laryngoscopy procedure. Currently, laryngeal structures can be measured by ultrasonography, however, little research has been performed on the potential role of ultrasound on the evaluation of a difficult laryngoscopy. The present study investigated the value of laryngeal structure measurements for predicting a difficult laryngoscopy.

Objective

The main objective of this study was to explore the value of laryngeal structure measurements for predicting a difficult laryngoscopy.

Methods

Two hundred and eleven adult patients (over 18 years old) were recruited to undergo elective surgery under general anesthesia via endotracheal intubation. Ultrasound was utilized to measure the distance between the skin and thyroid cartilage (DST), the distance between the thyroid cartilage and epiglottis (DTE), and the distance between the skin and epiglottis (DSE) in the parasagittal plane. These metrics were then investigated as predictors for classifying a laryngoscopy as difficult vs easy, as defined by the Cormack and Lehane grading scale.

Results

Multivariate logistic regression showed that the DSE, but not DST or DTE, was significantly related to difficult laryngoscopies. Specifically, a DSE ≥ 2.36 cm predicted difficult laryngoscopies with a sensitivity and specificity of 0.818 (95% CI: 0.766–0.870) and 0.856 (95% CI: 0.809–0.904). Furthermore, when combining the best model constructed of other indicators (i.e. sex, body mass index, modified Mallampati test) to predict the difficult laryngoscopy, the AUC reached 93.28%.

Conclusion

DSE is an independent predictor of a difficult laryngoscopy; a DSE cutoff value of 2.36 cm is a better predictor of a difficult laryngoscope than other ultrasound or physiological measurements for predicting a difficult laryngoscope. Nevertheless, it’s more valuable to apply the best model of this study, composed of various physiological measurements, for this prediction purpose.

Integration of Pre-intubation Ultrasound into Airway Management Course: A Novel Training Program

Objectives

To determine the feasibility of integrating pre-intubation ultrasound into airway course and assess emergency medicine (EM) residents’ confidence and comfort level in using ultrasound for pre-intubation hemodynamic stabilization and identifying cricothyroid membrane after the training session.

Materials and methods

This is a retrospective study. Pre-intubation ultrasound training was delivered with the following ultrasound components (didactics and hands-on sessions using human models) to EM residents: (1) sonoanatomy and scanning technique to identify cricothyroid membrane and (2) pre-intubation echocardiography for recognition of acute right ventricular failure and pre-intubation hemodynamic stabilization.

Results

A total of 56 EM residents participated in this study. Only 21% [95% confidence interval (CI), 10–31%] reported using ultrasound for pre-intubation hemodynamic stabilization. After the training session, 89% (95% CI, 81–97%) reported that ultrasound-based teaching increased their knowledge of pre-intubation hemodynamic stabilization compared with traditional teaching methods. On a scale of 1 (low) through 10 (high), the average comfort level for integrating ultrasound findings into medical decision making for pre-intubation hemodynamic stabilization was 6.8 (95% CI, 6.3–7.3). Seventy-nine percent (95% CI, 68–89%) reported that focused training in airway ultrasound is adequate to identify cricothyroid membrane. On a scale of 1 (low) through 10 (high), the average confidence level for identifying cricothyroid membrane using ultrasound was 6.6 (95% CI, 6.1–7.1).

Conclusion

At our institution, we successfully integrated pre-intubation ultrasound into an airway course. Emergency medicine residents had a moderate level of comfort and confidence level using ultrasound for pre-intubation hemodynamic stabilization and identifying cricothyroid membrane after the training session.

How to cite this article

Adhikari S, Situ-LaCasse E, Acuña J, Irving S, Weaver C, Samsel K, et al. Integration of Pre-intubation Ultrasound into Airway Management Course: A Novel Training Program. Indian J Crit Care Med 2020;24(3):179–183.

Point-of-care ultrasound in the preoperative setting

Point-of-care ultrasound (POCUS) is a widely used diagnostic tool, especially in emergency and critical care medicine, and it is increasingly being used in the perioperative setting. Its specific role in preoperative assessment of patients, however, has not yet been defined. While some data show innovative use of the technique in the preoperative setting, higher-level evidence to underscore potential advantages is still limited. We review and discuss a range of POCUS examinations which can potentially help anaesthesiologists in the preoperative clinic decide whether to perform additional testing, can assist in selecting the best anaesthetic approach, and can support perioperative and postoperative monitoring.

Pilot Study to Assess the Use of Ultrasound in Evaluating the Abnormal Pediatric Airway

In this study, we sought to explore the feasibility of using ultrasonography to evaluate airway anomalies in awake children with previous airway reconstruction. For the month of December 2018, we reviewed the medical records of patients aged <18 years old with prior airway reconstruction who had an outpatient appointment and a microlaryngoscopy and bronchoscopy within 24 hours of each other. Four patients met inclusion criteria and were enrolled. Sonographic airway images and measurements were obtained during the outpatient appointment and compared with those obtained during endoscopy. Ultrasound identified extraluminal stents and glottic, subglottic, and tracheal pathology. Subglottic measurements obtained sonographically were within 0.1 to 0.5 mm of the outer diameter of the appropriate endotracheal tubes. Ultrasound did not visualize tracheotomy tubes or posterolateral pathology. Our findings lay the foundation for expanding the role of ultrasound in pediatric airway assessment, keeping in mind its apparent inability to visualize posterolateral airway pathology.

Ultrasonography for predicting a difficult laryngoscopy. Getting closer

Our objective was to evaluate the usefulness of five ultrasound measurements to predict a difficult laryngoscopy (DL). Prospective observational study. 50 patients underwent scheduled surgery under general anesthesia with orotracheal intubation with classical laryngoscopy at the University Hospital of Jaén (Spain). Sociodemographic variables, classic preintubation screening tests and ultrasound measurements of the neck soft tissue from skin to hyoid (DSH), epiglottis (DSE) and glottis (DSG) were obtained, as well as two measurements derived from the above: DSH + DSE and DSE - DSG. The relationship between a DL and ultrasound measurements was evaluated using t student test. The ROC Curve was used to establish the diagnostic accuracy of ultrasound measurements to discriminate a DL and logistic regression was used to establish a cut-off point. Multivariate analysis was performed to assess the impact of these measures in clinical practice. Patients with DL showed greater thickness of DSE (2.9 ± 0.46 cm vs 2.32 ± 0.54 cm; p = 0.001), DSH + DSE (4.25 ± 0.45 cm vs 3.62 ± 0.77 cm; p = 0.001) and DSE - DSG (1.83 ± 0.54 cm vs 1.24 ± 0.46 cm; p = 0.001) than those with an easy laryngoscopy. DSE and DSE - DSG had the highest diagnostic accuracy for DL with an area under the ROC curve of 0.79 [95%IC 0.66-0.92] and 0.82 [95%IC 0.68-0.96], respectively. It was established that DSE ≥ 3 cm, could predict a DL with a positive predictive value (PPV) of 69.23% [95%CI 40.3-98.2], and DSE - DSG ≥ 1.9 cm would do so with a PPV of 78.57% [95%CI 53.31-100%]. The multivariate analysis endorsed that DSE and DSE - DSG combined with classic tests (the Modified Mallampati score, the thyromental distance and the upper lip bite test) improved the preoperative detection of a DL. The inclusion of DSE and DSE - DSG in a multivariate model with classic parameters may offer the anesthesiologist better information for detecting a DL preoperatively.

Ultrasound is a reliable and faster tool for confirmation of endotracheal intubation compared to chest auscultation and capnography when performed by novice anaesthesia residents - A prospective controlled clinical trial

Background

Anesthesia trainee may initially take longer time to intubate and unintentionally place the endotracheal tube (ETT) in the esophagus. The present study determined if ultrasound is the fastest method of confirmation of correct placement of ETT compared to capnography, and chest auscultation in trainees.

Methods

First year anesthesia residents performed intubation in 120 patients recruited after ethical clearance and informed consent. Time to visualize flutter in trachea, double trachea sign, time to appearance of first and sixth capnography, and time to execute chest auscultation was noted.

Results

Ultrasonography was statistically fastest method to determine endotracheal intubation (36.50 ± 15.14 seconds) vs unilateral chest auscultation (50.29 ± 15.50 seconds) vs bilateral chest auscultation (51.90 ± 15.98 seconds) vs capnography first waveform (53.57 ± 15.97 seconds) vs capnography sixth waveform (61.67 ± 15.88 seconds).

Conclusion

When teaching endotracheal intubation to novice anesthesia residents using conventional direct laryngoscopy, ultrasonography is the fastest method to confirm correct ETT placement compared to capnograph and chest auscultation. Mentor can guide trainee to direct ETT towards trachea and can promptly detect esophageal intubation by double trachea sign.

Ultrasonographic assessment of airway

Ultrasound is gaining increasing popularity among anesthesiologists as it is readily available and provides real-time imaging for various procedures. It is considered as a "visual stethoscope" of the anesthesiologist. After establishing its use in regional blocks and central venous catheter insertion, it is now finding increasing use in anticipation of difficult airway and securing and maintaining it. It has challenged the classical approach of clinical assessment of airway and allows more dynamic bedside assessment. This article attempts to briefly outline the role of ultrasound and its applications for airway management in patients.

Point-of-Care Ultrasound for Obstructive Sleep Apnea Screening: Are We There Yet? A Systematic Review and Meta-analysis

BACKGROUND

Perioperative diagnosis of obstructive sleep apnea (OSA) has important resource implications as screening questionnaires are overly sensitive, and sleep studies are expensive and time-consuming. Ultrasound (US) is a portable, noninvasive tool potentially useful for airway evaluation and OSA screening in the perioperative period. The objective of this systematic review was to evaluate the correlation of surface US with OSA diagnosis and to determine whether a point-of-care ultrasound (PoCUS) for OSA screening may help with improved screening in perioperative period.

METHODS

A search of all electronic databases including Medline, Embase, and Cochrane Database of Systematic Reviews was conducted from database inception to September 2017. Inclusion criteria were observational cohort studies and randomized controlled trials of known or suspected OSA patients undergoing surface US assessment. Article screening, data extraction, and summarization were conducted by 2 independent reviewers with ability to resolve conflict with supervising authors. Diagnostic properties and association between US parameters (index test) and OSA diagnosis using sleep study (reference standard) were evaluated. The US parameters were divided into airway and nonairway parameters. A random-effects meta-analysis was planned, wherever applicable.

RESULTS

Of the initial 3865 screened articles, 21 studies (7 airway and 14 nonairway) evaluating 3339 patients were included. Majority of studies were conducted in the general population (49%), respirology (23%), and sleep clinics (12%). No study evaluated the use of US for OSA in perioperative setting. Majority of included studies had low risk of bias for reference standard and flow and timing. Airway US parameters having moderate-good correlation with moderate-severe OSA were distance between lingual arteries (DLAs > 30 mm; sensitivity, 0.67; specificity, 0.59; 1 study/66 patients); mean resting tongue thickness (>60 mm; sensitivity, 0.85; specificity, 0.59; 1 study/66 patients); tongue base thickness during Muller maneuver (MM; sensitivity, 0.59; specificity, 0.78; 1 study/66 patients); and a combination of neck circumference and retropalatal (RP) diameter shortening during MM (sensitivity, 1.0; specificity, 0.65; 1 study/104 patients). Nonairway US parameters having a low-moderate correlation with moderate-severe OSA were carotid intimal thickness (pooled correlation coefficient, 0.444; 95% confidence interval [CI], 0.320-0.553; P value = .000, 8 studies/727 patients) and plaque presence (sensitivity, 0.24-0.75; specificity, 0.13-1.0; 4 studies/1183 patients).

CONCLUSIONS

We found that a number of airway and nonairway parameters were identified with moderate to good correlation with OSA diagnosis in the general population. In future studies, it remains to be seen whether PoCUS screening for a combination of these parameters can address the pitfalls of OSA screening questionnaires.

Sonographic Assessment of Oropharynx Movement During Deep Breathing

To investigate the feasibility of ultrasonography in detecting the oropharynx movement during deep breathing and to quantitatively analyze oropharynx airway lumen changes during deep breathing. The motions of oropharynx were monitored, and sonographic measurements of airway lumen were obtained during deep breathing in 448 healthy volunteers. Adequate visualization of oropharynx movement was obtained on all healthy volunteers. The anterior-posterior (AP) diameters and AP/transverse (T) diameter ratios were greater at the end of deep inspiration than that at the end of deep expiration for each sex (p < 0.01). The anterior-posterior dimensional changes were greater than lateral airway dimensional changes each sex (p < 0.05). Ultrasonography could provide realistic impression of the process on the oropharynx movement during deep breathing and perform the quantitative analysis of the oropharynx airway lumen changes during deep breathing. The results were encouraging and supported the utility of ultrasonography in future studies.

Ultrasound for diagnosing new difficult laryngoscopy indicator: a prospective, self-controlled, assessor blinded, observational study

BACKGROUND

Unpredictable difficult laryngoscopy (DL) remains a challenge for anesthesiologists, especially when difficult ventilation occurs during standard laryngoscopy. Accurate airway assessment should always be performed, but the common airway assessment methods only perform superficial screening. Thus, the deep laryngopharyngeal anatomy may not be evaluated. Ultrasound-based airway assessment has been recently proposed as a useful, simple, and non-invasive bedside tool as an adjunct to clinical methods, which may facilitate identification of DL. The present study aimed to determine the correlation between ultrasound-measured indicators and DL.

METHODS

Patients undergoing elective surgery under general anesthesia with tracheal intubation were enrolled. Ultrasonic airway assessments were performed before anesthesia induction. Ultrasound diagnostic indicators included the thickness and width of the base of the tongue, the angle between the epiglottis and glottis, the length of the thyrohyoid membrane, and the thickness of the lateral pharyngeal wall. A score of ≥3 in the Modified Cormack-Lehane Scoring System was used as a standard of DL and was also applied to divide patients into DL and non-DL groups. The area under the receiver operating characteristic (ROC) curve was used to evaluate the diagnostic ability of various diagnostic indicators.

RESULTS

A total of 499 patients were enrolled into non-DL and DL groups comprising 452 (452/499, 90.6%) and 47 (47/499, 9.4%) patients, respectively. One ultrasonic diagnoses indicator correlated with DL, namely, the angle between the epiglottis and glottis. When the angle between the epiglottis and glottis was 50°, the area under the ROC curve was maximum (0.902), and the best sensitivity (81%) and specificity (89%) were achieved.

CONCLUSIONS

Airway ultrasounds should be considered to identify DL. The ultrasonic angle measured between the epiglottis and glottis is highly associated with DL, which may occur when the angle is less than 50°.

CLINICAL TRIAL REGISTRATION

ChiCTR-DDT-13004102, http://www.chictr.org.cn/showproj.aspx?proj=5465.

RETRACTED: The role of laryngeal ultrasound in diagnosis of infant laryngomalacia

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Authors and the Editor-in-Chief. After a thorough investigation, the Editor-in-Chief has concluded that details in the origin of data and permissions integral to the article’s acceptance in the journal necessitate a retraction. A single hospital was mentioned in the article but this was not where the data was collected. Reviewers would have assumed that informed consent was received and properly reviewed by this institution, as it was not otherwise specified. Several oversights within the article that were brought forward by the Authors make it clear that the article that was accepted had misrepresentation of key data. While the Authors presented some differences of opinion about how these concerns about the key data originated, it is clear that when the manuscript was accepted that Reviewers and Editors would not have had knowledge of these difficulties, and this may have created a different review process and outcome for this manuscript. One of the Authors has requested an ability to provide additional information to address the concerns. However, the Editor-in-Chief has decided that this would not follow the process for accepted manuscripts or address some of the concerns presented and, therefore, has settled on the retraction of the manuscript as the final decision regarding this paper.

Unstable control of breathing can lead to ineffective noninvasive ventilation in amyotrophic lateral sclerosis

Upper airway obstruction with decreased central drive (ODCD) is one of the causes of ineffective noninvasive ventilation (NIV) in amyotrophic lateral sclerosis (ALS). The aim of this study is to determine the mechanism responsible for ODCD in ALS patients using NIV.

This is a prospective study that included ALS patients with home NIV. Severity of bulbar dysfunction was assessed with the Norris scale bulbar subscore; data on upper or lower bulbar motor neuron predominant dysfunction on physical examination were collected. Polysomnography was performed on every patient while using NIV and the ODCD index (ODCDI: number of ODCD events/total sleep time) was calculated. To determine the possible central origin of ODCD, controller gain was measured by inducing a hypocapnic hyperventilation apnoea. Sonography of the upper airway during NIV was performed to determine the location of the ODCD.

30 patients were enrolled; three (10%) had ODCDI >5 h⁻¹. The vast majority of ODCD events were produced during non-rapid eye movement sleep stages and were a consequence of an adduction of the vocal folds. Patients with ODCDI >5 h⁻¹ had upper motor neuron predominant dysfunction at the bulbar level, and had greater controller gain (1.97±0.33 versus 0.91±0.36 L·min⁻¹·mmHg⁻¹; p<0.001) and lower carbon dioxide (CO₂) reserve (4.00±0.00 versus 10.37±5.13 mmHg; p=0.043). ODCDI was correlated with the severity of bulbar dysfunction (r= −0.37; p=0.044), controller gain (r=0.59; p=0.001) and CO₂ reserve (r= −0.35; p=0.037).

ODCD events in ALS patients using NIV have a central origin, and are associated with instability in the control of breathing and an upper motor neuron predominant dysfunction at the bulbar level.

Upper airway obstructions in ALS patients using NIV have a central origin, and are associated with instability in the control of breathing and an upper motor neuron predominant dysfunction at the bulbar levelhttp://bit.ly/2WEMt28

Point of care ultrasound for the clinical anesthesiologist

Diagnostic ultrasonography was first utilized in the 1940s. The past 70+ years have seen an explosion in both ultrasound technology and availability of ultrasound technology to more and more clinicians. As ultrasound technology and availability have grown, the utility of ultrasound technology in the clinical setting as only been limited by clinicians' imagination. Due to its lack of radiation, non-invasive nature, and gentle learning curve, medical ultrasonography is now a tremendously useful Point of Care technology in the clinical arena. What follows is a discussion of Point of Care Ultrasound (PoCUS) and how it can be incorporated in the daily practice of any regional anesthesiology. While most regional anesthesiologists usually focus on the interventional aspects of ultrasonography (i.e. nerve blocks), our discussion will center on the diagnostic value of ultrasonography-especially concerning assessment of cardiac physiology and pathophysiology, gastric anatomy, airway anatomy, and intracranial pathophysiology. After reading and reviewing this chapter, the learner will have the knowledge to start training themselves in a variety of PoCUS exams that will allow rapid diagnosis of normal and abnormal patient conditions. Once an accurate diagnosis is established, the anesthesiologist and his/her team can then confidently optimize an anesthetic pain, prevent harm, and/or treat a patient condition. In this day and age, the ability to rapidly establish an accurate diagnosis cannot be overstated-especially in a critical situation. It is the authors' sincerest hope that the following discussion will help regional anesthesiologist to become even better and well-rounded clinical leaders.