Confirmation of endotracheal intubation by combined ultrasonographic methods in the Emergency Department

Confirmatory methods for endotracheal tube placement in out-of-hospital settings: A systematic review of the literature

Background

Confirming proper placement of an endotracheal tube (ETT) is important, as accidental misplacements may occur and lead to critical injuries, potentially leading to adverse outcomes. Multiple methods are available for determining the correct ETT placement in prehospital care.

Objective

To assess the accuracy and reliability of the different methods used to confirm endotracheal intubation in prehospital settings.

Methods

A comprehensive literature search was performed in the MEDLINE, EMBASE, Scopus, and Web of Science databases for studies that were published between 1-June-1992 and 12-June-2022 using a combination of predetermined search terms. Studies that met the inclusion criteria were included and assessed for risk of bias using "Risk of Bias in Non-randomized Studies of Intervention" tool.

Results

Of the 1016 identified studies, nine met the inclusion criteria. Capnography and point-of-care ultrasound showed high sensitivity and specificity rates when applied to confirm ETT placement in prehospital care. Other methods including capnometry, colorimetric detectors, ODDs, and auscultation showed varied sensitivity and specificity. Patient comorbidities and device failure contributed to decreased accuracy rates in prehospital care. Capnography was less reliable in distinguishing between endotracheal intubation and right main stem intubation, which is known as a complication in out-of-hospital endotracheal intubation. Point-of-care ultrasound was more accurate and reliable in detecting oesophageal and endobronchial misplacements. ETCO2 monitors, i.e., capnometry and colorimetric detectors, were less reliable in patients with low perfusion states.

Conclusion

This systematic review showed that there is no single method with 100% accuracy in confirming the correct ETT placement and detecting the occurrence of accidental oesophageal or endobronchial misplacements in prehospital care. Further studies with a larger sample size are needed to assess the accuracy of multiple confirmatory methods in prehospital settings.

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

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

Comparison of Upper Airway Ultrasonography Against Quantitative Waveform Capnography for Validating Endotracheal Tube Position in a South Indian Population

INTRODUCTION

The utilization of ultrasonography (USG) is progressively growing to verify the accurate positioning of the endotracheal tube (ETT). Non-detection of the esophageal intubation can be fatal. Various techniques are employed to confirm the placement of the ETT, but none of them are considered optimal. Quantitative waveform capnography (qWC) is often regarded as the most reliable method for this purpose; however, it may not necessarily be accessible and can be expensive. Hence, this investigation was carried out to contrast the use of bedside upper airway USG with qWC in order to confirm the accurate positioning of the ETT following intubation.  Methods: A prospective validation study was undertaken in the emergency department (ED) of Lourdes Hospital, Kochi. This study includes subjects who are of the age group >18 years of either sex requiring intubation in the ED for causes like respiratory failure, cardiac arrest, coma, head injury, and poisoning and cases in which intubation was achieved in the first attempt. The sample size calculated was 77. Intubation in our ED includes both elective and emergency. For all the patients undergoing intubation, consent was taken before the procedure (from close relatives of the patients) by another staff after explaining the procedure to be conducted by the doctor. Following the acquisition of consent, the intubation procedure was executed in accordance with the established hospital protocol. This protocol included verifying the intubation's success as well as employing clinical techniques such as observing bilateral chest expansion, conducting a five-point auscultation, and monitoring pulse oximetry. Furthermore, USG was employed to assess the positioning of the ETT placement. The time taken by each of these methods to confirm tube placement was noted, and the findings were assessed for the sensitivity (SN) and specificity (SP) of USG against the gold standard qWC to confirm endotracheal intubation.

RESULTS

Eighty patients were enrolled in the study. All 80 patients were subjected to both ultrasound and end-tidal carbon dioxide (EtCO2). Of the 80 patients, six subjects (7.5%) underwent esophageal intubation, which was observed through the use of USG. Four patients had esophageal intubations and were correctly detected by EtCO2. All four esophageal intubations were correctly confirmed by EtCO2. Additionally, USG detected six intubations, out of which four were true and two were tracheal which was correctly confirmed by EtCO2. The bedside upper airway USG demonstrated an SN of 78 subjects at 97.4% (95% CI: 90.8-99.7%), an SP of 80 subjects at 100% (95% CI: 39.7-100%), a positive predictive value of 80 subjects at 100% (95% CI: 93.8-100%), and a negative predictive value of 53 subjects at 66.7% (95% CI: 33.7-88.7%). A positive test had an infinite likelihood ratio, whereas a negative test had a likelihood ratio of 0.03 (95% CI: 0.01-0.10). The average duration for confirmation by USG was 10.10 seconds.  Conclusion: The study's outcomes highlight the importance of incorporating USG into the clinical toolkit of ED physicians, ultimately contributing to enhanced patient safety and the optimization of endotracheal intubation procedures in the ED.

A comprehensive review of difficult airway management strategies for patient safety

Difficult airway management is critical to ensuring patient safety. It involves addressing the challenges and failures that can occur, even with skilled healthcare providers, during face mask ventilation, intubation, supraglottic airway placement, invasive airway procedures, or extubation. Although the incidence of the most critical situation in airway management, "cannot intubate, cannot oxygenate," is low at 0.0019-0.04%, its occurrence can have severe consequences, including dental injury, airway injury, hypoxic brain damage, and even death. This study aimed to offer healthcare providers a comprehensive and evidence-based approach for difficult airway management by reviewing recent guidelines and incorporating the latest evidence-based practices to improve their preparedness and competence in difficult airway management, and thus ultimately contribute to improved patient safety.

Screening Performance Characteristics of Ultrasonography in Confirmation of Endotracheal Intubation; a Systematic Review and Meta-analysis

Introduction:

Recent studies have suggested that point-of-care ultrasonography can be used for confirming the placement of endotracheal tube. This systematic review and meta-analysis aimed to investigate the sensitivity and specificity of ultrasonography for confirming endotracheal tube placement.

Methods:

In this meta-analysis, systematic search of the previous published papers investigating the diagnostic accuracy of ultrasonography for confirmation of endotracheal tube placement was performed. Seven electronic databases, including PubMed, Scopus, Google Scholar, EBSCO, EMBASE, Web of Science, and Cochrane Database were searched up to July 2021, for all relevant articles published in English on this topic. Meta-DiSc version 1.4 software was used for statistical analysis.

Results:

The estimated pooled sensitivity and specificity of ultrasonography for confirmation of endotracheal tube location were 0.98 (95% CI: 0.98–0.99) and 0.94 (95% CI 0.91–0.96), respectively. The pooled positive likelihood ratio and negative likelihood ratio were 5.94 (95% CI 4.41–7.98) and 0.03 (95% CI: 0.02-0.04), respectively. The diagnostic odds ratio of ultrasonography was 281.47 and the area under hierarchical summary receiver operating characteristic (HSROC) revealed an appropriate accuracy of 0.98.

Conclusion:

Ultrasonography has high diagnostic accuracy and can be used as a promising tool for confirmation of endotracheal tube placement, especially in critically ill patients or when capnography is not available, or its result is equivocal.

[Focused ultrasound in the emergency room]

Ultrasound is an important tool in diagnosis and treatment of critically ill patients. For trauma patients the eFAST (extended focused assessment with sonography for trauma) algorithm is already implemented in the diagnostic pathway. However, critically ill patients without trauma also need a structured approach including an early focused ultrasonographic exam. National and international guidelines regarding critical illnesses such as acute coronary syndrome, cardiogenic shock complicating myocardial infarction, pulmonary embolism or acute aortic syndromes recommend the use of ultrasound. We present pathways how ultrasound can be used in the diagnostic approach of common symptoms such as dyspnea, shock and abdominal pain. Using the ABCDE approach this article shows how ultrasound can be incorporated into the diagnostic pathway.

Unmasking the Lung Pulse for Detection of Endobronchial Intubation

The ultrasound lung pulse for detecting endobronchial intubation was first described in 2003 in the only study to date assessing its accuracy. It refers to rhythmic movement of the visceral pleura along the stationary parietal pleura as cardiac vibrations transmit through a motionless, airless lung. Compared to delayed visualization on chest radiography, this artifact immediately detects physiologic atelectasis. There is a scarcity of studies assessing the lung pulse, while several others that encountered this artifact did not even identify it. The lung pulse is useful for immediate detection of endobronchial intubation, but it remains unrecognized and underused by physicians.

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.

Point-of-Care Ultrasound for Intubation Confirmation of COVID-19 Patients

The novel coronavirus disease of 2019 (COVID-19) is associated with significant morbidity and mortality, as well as large numbers of patients requiring endotracheal intubation. While much of the literature has focused on the intubation technique, there is scant discussion of intubation confirmation. Herein, we discuss the limitations of traditional confirmatory approaches, summarize the literature supporting a role for point-of-care ultrasound in this application, and propose an algorithm for intubation confirmation among COVID-19 patients.

Accuracy of Real-time Intratracheal Bedside Ultrasonography and Waveform Capnography for Confirmation of Intubation in Multiple Trauma Patients

Background:

A secure airway and effective ventilation are key components of advanced life support, and misplacement of endotracheal tube (ETT) can lead to morbidity in multiple trauma patients. The purpose of this study was to investigate the accuracy of ultrasound in diagnosis of direction for tracheal intubation.

Materials and Methods:

This descriptive-analytical study was conducted on 100 traumatic patients requiring intubation in 2016 in the Emergency Department of Al-Zahra and Kashani Medical Education Centers in Isfahan. Surface probe was placed transversally in the front of the neck at the top of the suprasternal notch, and the position of trachea was specified by front of comet-tail artifact which is the contour between hyperechoic air–mucosa (A–M) and a posterior reverberation artifact. Intubation accuracy by capnography was investigated, and the results were recorded in each patient's profile. Tracheal sonography was done during placement, or as soon as, the ETT has been embedded. The scanning time was minimized and it was carried out in total time of 10 s.

Results:

The diagnosis of intubation accuracy indicated that it was successful in 94 individuals (94%) and unsuccessful in 6 ones (6%). Intubation accuracy in 93 people (93%) was confirmed, and inaccuracy of intubation in 7 people (7%) was diagnosed. Ultrasound sensitivity in diagnosis of intubation accuracy was 97.9% (92.94) with 83.3% (5.6%) specificity. The positive and negative predictive values were 98.9% (92.93) and 71.4% (5.7%) respectively.

Conclusion:

Ultrasound method has high sensitivity and specificity to determine the correct placement of the tracheal tube, and it can be implemented as a reliable method given the acceptable positive and negative predictive values.

Comparison of Static versus Dynamic Ultrasound for the Detection of Endotracheal Intubation

Introduction

In the emergency department setting, it is essential to rapidly and accurately confirm correct endotracheal tube (ETT) placement. Ultrasound is an increasingly studied modality for identifying ETT location. However, there has been significant variation in techniques between studies, with some using the dynamic technique, while others use a static approach. This study compared the static and dynamic techniques to determine which was more accurate for ETT identification.

Methods

We performed this study in a cadaver lab using three different cadavers to represent variations in neck circumference. Cadavers were randomized to either tracheal or esophageal intubation in equal proportions. Blinded sonographers then assessed the location of the ETT using either static or dynamic sonography. We assessed accuracy of sonographer identification of ETT location, time to identification, and operator confidence.

Results

A total of 120 intubations were performed: 62 tracheal intubations and 58 esophageal intubations. The static technique was 93.6% (95% confidence interval [CI] [84.3% to 98.2%]) sensitive and 98.3% specific (95% CI [90.8% to 99.9%]). The dynamic technique was 92.1% (95% CI [82.4% to 97.4%]) sensitive and 91.2% specific (95% CI [80.7% to 97.1%]). The mean time to identification was 6.72 seconds (95% CI [5.53 to 7.9] seconds) in the static technique and 6.4 seconds (95% CI [5.65 to 7.16] seconds) in the dynamic technique. Operator confidence was 4.9/5.0 (95% CI [4.83 to 4.97]) in the static technique and 4.86/5.0 (95% CI [4.78 to 4.94]) in the dynamic technique. There was no statistically significant difference between groups for any of the outcomes.

Conclusion

This study demonstrated that both the static and dynamic sonography approaches were rapid and accurate for confirming ETT location with no statistically significant difference between modalities. Further studies are recommended to compare these techniques in ED patients and with more novice sonographers.

Optimization of Ultrasound Transducer Positioning for Endotracheal Tube Placement Confirmation in Cadaveric Model

OBJECTIVES

Sonography has been suggested as a possible means of endotracheal tube (ETT) placement confirmation. However, optimum ultrasound transducer placement has not been established. Using a cadaveric model, ETT placement by the sonographic appearance at the thyroid cartilage, cricoid cartilage, and suprasternal notch in the upper airway was assessed to determine which ultrasound transducer placement offered the most optimal images for ETT confirmation in the airway.

METHODS

One provider intubated 5 cadavers, with the ultrasound transducer at each of the 3 levels, for a total of 30 intubations per specimen, while 2 providers assigned a visual score of 1 (subtle), 2 (clear), or 3 (pronounced) to each sonogram of the ETT in the airway.

RESULTS

At the level of the thyroid cartilage, tracheal intubation was detected at a rate of 40%, with a median visualization scale of 1 (subtle movement). At the level of the cricoid cartilage, the visualization scale improved to a median of 2 (clear movement), with a 70% intubation detection rate. At the level of the suprasternal notch, 100% of the tracheal intubations were visualized on sonography, with a median score of 3 (pronounced movement).

CONCLUSIONS

In comparing sonographic detection of ETT placement at 3 levels of the upper airway in a cadaveric model, our results clearly indicate that visualization was superior at the level of the suprasternal notch, with 100% of intubations detected with the best visualization scores.

Lung Sliding Identification Is Less Accurate in the Left Hemithorax

OBJECTIVES

The aim of our study was to compare the accuracy of lung sliding identification for the left and right hemithoraxes, using prerecorded short US sequences, in a group of physicians with mixed clinical and US training.

METHODS

A total of 140 US sequences of a complete respiratory cycle were recorded in the operating room. Each sequence was divided in two, yielding 140 sequences of present lung sliding and 140 sequences of absent lung sliding. Of these 280 sequences, 40 were randomly repeated to assess intraobserver variability, for a total of 320 sequences. Descriptive data, the mean accuracy of each participant, as well as the rate of correct answers for each of the original 280 sequences were tabulated and compared for different subgroups of clinical and US training. A video with examples of present and absent lung sliding and a lung pulse was shown before testing.

RESULTS

Two sessions were planned to facilitate the participation of 75 clinicians. In the first group, the rate of accurate lung sliding identification was lower in the left hemithorax than in the right (67.0% [interquartile range (IQR), 43.0-83.0] versus 80.0% [IQR, 57.0-95.0]; P < .001). In the second group, the rate of accurate lung sliding identification was also lower in the left hemithorax than in the right (76.3% [IQR, 42.9-90.9] versus 88.7% [IQR, 63.1-96.9]; P = .001). Mean accuracy rates were 67.5% (95% confidence interval, 65.7-69.4) in the first group and 73.1% (95% confidence interval, 70.7-75.5) in the second (P < .001).

CONCLUSIONS

Lung sliding identification seems less accurate in the left hemithorax when using a short US examination. This study was done on recorded US sequences and should be repeated in a live clinical situation to confirm our results.

Reliability of Ultrasonography in Confirming Endotracheal Tube Placement in an Emergency Setting

Background and Objectives:

Over the past few years, ultrasonography is increasingly being used to confirm the correct placement of endotracheal tube (ETT). In our study, we aimed to compare it with the traditional clinical methods and the gold standard quantitative waveform capnography. Two primary outcomes were measured in our study. First was the sensitivity and specificity of ultrasonography against the other two methods to confirm endotracheal intubation. The second primary outcome assessed was the time taken for each method to confirm tube placement in an emergency setting.

Methods:

This is a single-centered, prospective cohort study conducted in an emergency department of a tertiary care hospital. We included 100 patients with indication of emergency intubation by convenient sampling. The intubation was performed as per standard hospital protocol. As part of the study protocol, ultrasonography was used to identify ETT placement simultaneously with the intubation procedure along with quantitative waveform capnography (end-tidal carbon dioxide) and clinical methods. Confirmation of tube placement and time taken for the same were noted by three separate health-care staffs.

Results and Discussion:

Out of the 100 intubation attempts, five (5%) had esophageal intubations. The sensitivity and specificity of diagnosis using ultrasonography were 97.89% and 100%, respectively. This was statistically comparable with the other two modalities. The time taken to confirm tube placement with ultrasonography was 8.27 ± 1.54 s compared to waveform capnography and clinical methods which were 18.06 ± 2.58 and 20.72 ± 3.21 s, respectively. The time taken by ultrasonography was significantly less.

Conclusions:

Ultrasonography confirmed tube placement with comparable sensitivity and specificity to quantitative waveform capnography and clinical methods. But then, it yielded results considerably faster than the other two modalities.

Sonographic detection of tracheal or esophageal intubation: A cadaver study

Background:

The correct position of the endotracheal tube is confirmed by various modalities, most of which are not entirely reliable. Ultrasound is now increasingly available to anesthesiologists in the operating theater and is an attractive alternative. To investigate the usefulness of sonography in identifying the correct tracheal tube position in human cadavers.

Materials and Methods:

Endotracheal tubes placed randomly into trachea or esophagus was identified with a linear ultrasound probe placed transversely just above the suprasternal notch by a single anesthesiologist.

Results:

Of the 100 intubations performed at random, 99 were correctly identified to give a sensitivity of 100% and a specificity of 97.9%.

Conclusion:

Sonography is a useful technique to identify correct position of the tracheal tube.

The Role of Airway and Endobronchial Ultrasound in Perioperative Medicine

Recent years have witnessed an increased use of ultrasound in evaluation of the airway and the lower parts of the respiratory system. Ultrasound examination is fast and reliable and can be performed at the bedside and does not carry the risk of exposure to ionizing radiation. Apart from use in diagnostics it may also provide safe guidance for invasive and semi-invasive procedures. Ultrasound examination of the oral cavity structures, epiglottis, vocal cords, and subglottic space may help in the prediction of difficult intubation. Preoperative ultrasound may diagnose vocal cord palsy or deviation or stenosis of the trachea. Ultrasonography can also be used for confirmation of endotracheal tube, double-lumen tube, or laryngeal mask placement. This can be achieved by direct examination of the tube inside the trachea or by indirect methods evaluating lung movements. Postoperative airway ultrasound may reveal laryngeal pathology or subglottic oedema. Conventional ultrasound is a reliable real-time navigational tool for emergency cricothyrotomy or percutaneous dilational tracheostomy. Endobronchial ultrasound is a combination of bronchoscopy and ultrasonography and is used for preoperative examination of lung cancer and solitary pulmonary nodules. The method is also useful for real-time navigated biopsies of such pathological structures.

Ultrasound: A promising tool for contemporary airway management

Airway evaluation and its management remains an ever emerging clinical science. Present airway management tools are static and do not provide dynamic airway management option. Visualized procedures like ultrasound (US) provide point of care real time dynamic views of the airway in perioperative, emergency and critical care settings. US can provide dynamic anatomical assessment which is not possible by clinical examination alone. US aids in detecting gastric contents and the nature of gastric contents (clear fluid, thick turbid or solid) as well. US can help in predicting endotracheal tube size by measuring subglottic diameter and diameter of left main stem bronchus. US was found to be a sensitive in detecting rotational malposition of LMA in children. Also, US is the fastest and highly sensitive tool to rule out a suspected intraoperative pneumothorax. In intensive care units, US helps torule out causes of inadequate ventilation, determine the tracheal width and distance from the skin to predict tracheotomy tube size and shape and assist with percutaneous dilatational tracheostomy. US can help in confirming the correct tracheal tube placement by dynamic visualisation of the endotracheal tube insertion, widening of vocal cords (children), and bilateral lung-sliding and diaphragmatic movement. Thus, ultrasonography has brought a paradigm shift in the practise of airway management. With increasing awareness, portability, accessibility and further sophistication in technology, it is likely to find a place in routine airway management. We are not far from the time when all of us will be carrying a pocket US machine like stethoscopes to corroborate our clinical findings at point of care.

Defining the learning curve of point-of-care ultrasound for confirming endotracheal tube placement by emergency physicians

Background

Unrecognized esophageal intubations are associated with significant patient morbidity and mortality. No single confirmatory device has been shown to be 100 % accurate at ruling out esophageal intubations in the emergency department. Recent studies have demonstrated that point-of-care ultrasound (POCUS) may be a useful adjunct for confirming endotracheal tube placement; however, the amount of practice required to become proficient at this technique is unclear. The purpose of this study is to determine the amount of practice required by emergency physicians to become proficient at interpreting ultrasound video clips of esophageal and endotracheal intubations.

Methods

Emergency physicians and emergency medicine residents completed a baseline interpretation test followed by a 10 min online tutorial. They then interpreted POCUS clips of esophageal and endotracheal intubations in a randomly selected order. If an incorrect response was provided, the participant completed another practice session with feedback. This process continued until they correctly interpreted ten consecutive ultrasound clips. Descriptive statistics were used to summarize the data.

Results

Of the 87 eligible physicians, 66 (75.9 %) completed the study. The mean score on the baseline test was 42.9 % (SD 32.7 %). After the tutorial, 90.9 % (60/66) of the participants achieved proficiency after one practice attempt and 100 % achieved proficiency after two practice attempts. Six intubation ultrasound clips were misinterpreted, for a total error rate of 0.9 % (6/684). Overall, the participants had a sensitivity of 98.3 % (95 % CI 96.3–99.4 %) and specificity of 100 % (95 % CI 98.9–100 %) for detecting correct tube location. Scans were interpreted within an average of 4 s (SD 2.9 s) of the intubation.

Conclusions

After a brief online tutorial and only two practice attempts, emergency physicians were able to quickly and accurately interpret ultrasound intubation clips of esophageal and endotracheal intubations.

Electronic supplementary material

The online version of this article (doi:10.1186/s13089-015-0031-7) contains supplementary material, which is available to authorized users.

Ultrasonography for confirmation of endotracheal tube placement: a systematic review and meta-analysis

OBJECTIVE

This study aimed to undertake a systematic review and meta-analysis to summarize evidence on the diagnostic value of ultrasonography for the assessment of endotracheal tube placement in adult patients.

METHODS

The major databases, PubMed, EMBASE, and the Cochrane Library, were searched for studies published from inception to June 2014. We selected studies that used ultrasonography to confirm endotracheal tube placement. The search was limited to human studies, and had no publication date or country restrictions. Exclusion criteria included case reports, comments, reviews, guidelines and animal studies. Two reviewers extracted and verified the data independently. We summarized test performance characteristics with the use of forest plots, hierarchical summary receiver operating characteristic (HSROC) curves, and bivariate random effect models. Meta-regression analysis was performed to explore the source of heterogeneity. The methodological quality of individual studies was evaluated using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) tool.

RESULTS

A total of 12 eligible studies involving adult patients and cadaveric models were identified from 1488 references. For detection of esophageal intubation, the pooled sensitivity was 0.93 (95% CI: 0.86-0.96) and the specificity was 0.97 (95% CI: 0.95-0.98). The area under the summary ROC curve was 0.97 (95% CI: 0.95-0.98). The positive and negative likelihood ratios were 26.98 (95% CI: 19.32-37.66) and 0.08 (95% CI: 0.04-0.15), respectively.

CONCLUSIONS

Current evidence supports that ultrasonography has high diagnostic value for identifying esophageal intubation. With optimal sensitivity and specificity, ultrasonography can be a valuable adjunct in this aspect of airway assessment, especially in situations where capnography may be unreliable.

Transtracheal ultrasound for verification of endotracheal tube placement: a systematic review and meta-analysis

PURPOSE

Early confirmation of endotracheal tube placement is of paramount importance to prevent hypoxia and its catastrophic consequences. Despite certain limitations, capnography is considered the gold standard to evaluate the proper placement of an endotracheal tube. Ultrasound is a novel tool with some definitive advantages over capnography. It enables a real-time view and can be performed quickly; furthermore, it is independent of pulmonary blood flow and does not require lung ventilation. In this review, we aimed to evaluate the diagnostic accuracy of transtracheal ultrasound in detecting endotracheal intubation.

SOURCE

We completed an extensive search of MEDLINE®, EMBASE™, The Cochrane Library, KoreaMed, LILACS, OpenGrey, and the World Health Organization International Clinical Trials Registry from their inception to September 4, 2014. The studies that met the inclusion criteria were pooled and a meta-analysis was conducted.

PRINCIPAL FINDINGS

Eleven studies and 969 intubations were included in the final analysis. Eight studies and 713 intubations were performed in emergency situations and the others were carried out in elective situations. Transtracheal ultrasonography's pooled sensitivity and specificity with 95% confidence intervals (CIs) were 0.98 (95% CI 0.97 to 0.99) and 0.98 (95% CI 0.95 to 0.99), respectively. In emergency scenarios, transtracheal ultrasonography showed an aggregate sensitivity and specificity of 0.98 (95% CI 0.97 to 0.99) and 0.94 (95% CI 0.86 to 0.98), respectively.

CONCLUSION

Transtracheal ultrasound is a useful tool to confirm endotracheal intubation with an acceptable degree of sensitivity and specificity. It can be used in emergency situations as a preliminary test before final confirmation by capnography.

Accuracy of a novel ultrasound technique for confirmation of endotracheal intubation by expert and novice emergency physicians

Introduction

Recent research has investigated the use of ultrasound (US) for confirming endotracheal tube (ETT) placement with varying techniques, accuracies, and challenges. Our objective was to evaluate the accuracy of a novel, simplified, four-step (4S) technique.

Methods

We conducted a blinded, randomized trial of the 4S technique utilizing an adult human cadaver model. ETT placement was randomized to tracheal or esophageal location. Three US experts and 45 emergency medicine residents (EMR) performed a total of 150 scans. The primary outcome was the overall sensitivity and specificity of both experts and EMRs to detect location of ETT placement. Secondary outcomes included a priori subgroup comparison of experts and EMRs for thin and obese cadavers, time to detection, and level of operator confidence.

Results

Experts had a sensitivity of 100% (95% CI = 72% to 100%) and specificity of 100% (95% CI = 77% to 100%) on thin, and a sensitivity of 93% (95% CI = 66% to 100%) and specificity of 100% (95% CI = 75% to 100%) on obese cadavers. EMRs had a sensitivity of 91% (95% CI = 69% to 98%) and of specificity 96% (95% CI = 76% to 100%) on thin, and a sensitivity of 100% (95% CI = 82% to 100%) specificity of 48% (95% CI = 27% to 69%) on obese cadavers. The overall mean time to detection was 17 seconds (95% CI = 13 seconds to 20 seconds, range: 2 to 63 seconds) for US experts and 29 seconds (95% CI = 25 seconds to 33 seconds; range: 6 to 120 seconds) for EMRs. There was a statistically significant decrease in the specificity of this technique on obese cadavers when comparing the EMRs and experts, as well as an increased overall time to detection among the EMRs.

Conclusion

The simplified 4S technique was accurate and rapid for US experts. Among novices, the 4S technique was accurate in thin, but appears less accurate in obese cadavers. Further studies will determine optimal teaching time and accuracy in emergency department patients.

Ultrasonography for clinical decision-making and intervention in airway management: from the mouth to the lungs and pleurae

OBJECTIVES

To create a state-of-the-art overview of the new and expanding role of ultrasonography in clinical decision-making, intervention and management of the upper and lower airways, that is clinically relevant, up-to-date and practically useful for clinicians.

METHODS

This is a narrative review combined with a structured Medline literature search.

RESULTS

Ultrasonography can be utilised to predict airway difficulty during induction of anaesthesia, evaluate if the stomach is empty or possesses gastric content that poses an aspiration risk, localise the essential cricothyroid membrane prior to difficult airway management, perform nerve blocks for awake intubation, confirm tracheal or oesophageal intubation and facilitate localisation of tracheal rings for tracheostomy. Ultrasonography is an excellent diagnostic tool in intraoperative and emergency diagnosis of pneumothorax. It also enables diagnosis and treatment of interstitial syndrome, lung consolidation, atelectasis, pleural effusion and differentiates causes of acute breathlessness during pregnancy. Patient safety can be enhanced by performing procedures under ultrasound guidance, e.g. thoracocentesis, vascular line access and help guide timing of removal of chest tubes by quantification of residual pneumothorax size.

CONCLUSIONS

Ultrasonography used in conjunction with hands-on management of the upper and lower airways has multiple advantages. There is a rapidly growing body of evidence showing its benefits.

TEACHING POINTS

• Ultrasonography is becoming essential in management of the upper and lower airways. • The tracheal structures can be identified by ultrasonography, even when unidentifiable by palpation. • Ultrasonography is the primary diagnostic approach in suspicion of intraoperative pneumothorax. • Point-of-care ultrasonography of the airways has a steep learning curve. • Lung ultrasonography allows treatment of interstitial syndrome, consolidation, atelectasis and effusion.

A feasibility study on bedside upper airway ultrasonography compared to waveform capnography for verifying endotracheal tube location after intubation

Background

In emergency settings, verification of endotracheal tube (ETT) location is important for critically ill patients. Ignorance of oesophageal intubation can be disastrous. Many methods are used for verification of the endotracheal tube location; none are ideal. Quantitative waveform capnography is considered the standard of care for this purpose but is not always available and is expensive. Therefore, this feasibility study is conducted to compare a cheaper alternative, bedside upper airway ultrasonography to waveform capnography, for verification of endotracheal tube location after intubation.

Methods

This was a prospective, single-centre, observational study, conducted at the HRPB, Ipoh. It included patients who were intubated in the emergency department from 28 March 2012 to 17 August 2012. A waiver of consent had been obtained from the Medical Research Ethics Committee. Bedside upper airway ultrasonography was performed after intubation and compared to waveform capnography. Specificity, sensitivity, positive and negative predictive value and likelihood ratio are calculated.

Results

A sample of 107 patients were analysed, and 6 (5.6%) had oesophageal intubations. The overall accuracy of bedside upper airway ultrasonography was 98.1% (95% confidence interval (CI) 93.0% to 100.0%). The kappa value (Κ) was 0.85, indicating a very good agreement between the bedside upper airway ultrasonography and waveform capnography. Thus, bedside upper airway ultrasonography is in concordance with waveform capnography. The sensitivity, specificity, positive predictive value and negative predictive value of bedside upper airway ultrasonography were 98.0% (95% CI 93.0% to 99.8%), 100% (95% CI 54.1% to 100.0%), 100% (95% CI 96.3% to 100.0%) and 75.0% (95% CI 34.9% to 96.8%). The likelihood ratio of a positive test is infinite and the likelihood ratio of a negative test is 0.0198 (95% CI 0.005 to 0.0781). The mean confirmation time by ultrasound is 16.4 s. No adverse effects were recorded.

Conclusions

Our study shows that ultrasonography can replace waveform capnography in confirming ETT placement in centres without capnography. This can reduce incidence of unrecognised oesophageal intubation and prevent morbidity and mortality.

Trial registration

National Medical Research Register NMRR11100810230.

Dynamic anatomic relationship of the esophagus and trachea on sonography: implications for endotracheal tube confirmation in children

OBJECTIVES

Sonographic visualization of an empty esophagus to confirm endotracheal tube placement during intubation may be more reliable than identifying an endotracheal tube within the trachea. Our objective was to determine the frequency in which the normal empty esophagus can be identified at or below the level of the cricoid ring in children.

METHODS

A prospective cohort of children and young adults presenting to the emergency department were examined by sonography to determine the dynamic anatomic relationship of the trachea and esophagus at or below the level of the cricoid ring. For children with the esophagus behind or partially behind the trachea, cricoid pressure was applied using a linear array transducer to visualize the presence of lateral sliding of the esophagus from behind the trachea.

RESULTS

A total of 55 patients 21 years or younger were examined; 51% (28) were male. Sixty-two percent (34) had esophagi positioned partially to the left of the cricoid ring, 20% (11) completely to the left of the cricoid ring, 16% (9) behind the cricoid ring, and 2% (1) partially to the right of the cricoid ring. When cricoid pressure was applied using the ultrasound transducer, the esophagus was visualized lateral to the trachea in all patients (54 to the left and 1 to the right; n = 55 of 55; 95% confidence interval, 94%-100%).

CONCLUSIONS

With cricoid pressure applied using a linear transducer, the esophagus was visualized lateral to the trachea in all children and young adults. Visualizing an empty esophagus by point-of-care sonography may be feasible to confirm endotracheal tube placement by a process of elimination.

Verification of endotracheal intubation in obese patients - temporal comparison of ultrasound vs. auscultation and capnography

BACKGROUND

Ultrasound (US) may have an emerging role as an adjunct in verification of endotracheal intubation. Obtaining optimal US images in obese patients is generally regarded more difficult than for other patients. This study compared the time consumption of bilateral lung US with auscultation and capnography for verifying endotracheal intubation in obese patients.

METHODS

A prospective, paired and investigator-blinded study performed in the operating theatre. Twenty-four adult patients requiring endotracheal intubation for bariatric surgery were included. During post-intubation bag ventilation, bilateral lung US was performed for detection of lungsliding indicating lung ventilation simultaneous with capnography and auscultation of epigastrium and chest. Primary outcome measure was the time difference to confirmed endotracheal intubation between US and auscultation alone. The secondary outcome measure was time difference between US and auscultation combined with capnography.

RESULTS

Both methods verified endotracheal tube placement in all patients. No significant difference was found between US compared with auscultation alone. Median time for verification by auscultation alone was 47.5 s [interquartile (IQR) 40-51 s], with a mean difference of -0.3 s in favor of US (95% confidence interval -3.5-2.9 s) P = 0.87. Comparing US with the combination of auscultation and capnography, there was a significant difference between the two methods. Median time for verification by US was 43 s (IQR 40-51 s) vs. 55 s (IQR 46-65 s), P < 0.0001.

CONCLUSION

In obese patients, verification of endotracheal tube placement with US is as fast as auscultation alone and faster than the standard method of auscultation and capnography.

Ultrasonography in the management of the airway

In this study, it is described how to use ultrasonography (US) for real-time imaging of the airway from the mouth, over pharynx, larynx, and trachea to the peripheral alveoli, and how to use this in airway management. US has several advantages for imaging of the airway - it is safe, quick, repeatable, portable, widely available, and it must be used dynamically for maximum benefit in airway management, in direct conjunction with the airway management, i.e. immediately before, during, and after airway interventions. US can be used for direct observation of whether the tube enters the trachea or the esophagus by placing the ultrasound probe transversely on the neck at the level of the suprasternal notch during intubation, thus confirming intubation without the need for ventilation or circulation. US can be applied before anesthesia induction and diagnose several conditions that affect airway management, but it remains to be determined in which kind of patients the predictive value of such an examination is high enough to recommend this as a routine approach to airway management planning. US can identify the croicothyroid membrane prior to management of a difficult airway, can confirm ventilation by observing lung sliding bilaterally and should be the first diagnostic approach when a pneumothorax is suspected intraoperatively or during initial trauma-evaluation. US can improve percutaneous dilatational tracheostomy by identifying the correct tracheal-ring interspace, avoiding blood vessels and determining the depth from the skin to the tracheal wall.

Temporal comparison of ultrasound vs. auscultation and capnography in verification of endotracheal tube placement

BACKGROUND

This study compared the time consumption of bilateral lung ultrasound with auscultation and capnography for verifying endotracheal intubation.

METHODS

A prospective, paired, and investigator-blinded study carried out in the operating theatre. Twenty-five adult patients requiring endotracheal intubation were included. During intubation, transtracheal ultrasound was performed to visualize passage of the endotracheal tube. During bag ventilation, bilateral lung ultrasound was performed for the detection of lung sliding as a sign of ventilation simultaneous with capnography and auscultation of the epigastrium and chest. Primary outcome measure was time difference to confirmed endotracheal intubation between ultrasound and auscultation alone. Secondary outcome measure was time difference between ultrasound and auscultation combined with capnography.

RESULTS

Both methods verified endotracheal tube placement in all patients. In 68% of patients, endotracheal tube placement was visualized by real-time transtracheal ultrasound. Comparing ultrasound with the combination of auscultation and capnography, there was a significant difference between the two methods. Median time for ultrasound was 40 s [interquartile range (IQR) 35-48 s] vs. 48 s (IQR 45-53 s), P < 0.0001. Mean difference was -7.1 s in favour of ultrasound [95% confidence interval (CI) -9.4--4.8 s]. No significant difference was found between ultrasound compared with auscultation alone. Median time for auscultation alone was 42 s (IQR 37-47 s), P = 0.6, with a mean difference of -0.88 s in favour of ultrasound (95% CI -4.2-2.5 s).

CONCLUSIONS

Verification of endotracheal tube placement with ultrasound is as fast as auscultation alone and faster than the standard method of auscultation and capnography.

Tracheal rapid ultrasound exam (T.R.U.E.) for confirming endotracheal tube placement during emergency intubation

OBJECTIVES

This study aimed to assess the diagnostic accuracy and timeliness of using tracheal ultrasound to examine endotracheal tube placement during emergency intubation.

METHODS

This was a prospective, observational study, conducted at the emergency department of a national university teaching hospital. Patients received emergency intubation because of impending respiratory failure, cardiac arrest, or severe trauma. The tracheal rapid ultrasound exam (T.R.U.E.) was performed during emergency intubation with the transducer placed transversely at the trachea over the suprasternal notch. Quantitative waveform capnography was used as the criterion standard for confirmation of tracheal intubation. The main outcome was the concordance between the T.R.U.E. and the capnography.

RESULTS

A total of 112 patients were included in the analysis, and 17 (15.2%) had esophageal intubations. The overall accuracy of the T.R.U.E. was 98.2% (95% confidence interval [CI]: 93.7-99.5%). The kappa (κ) value was 0.93 (95% CI: 0.84-1.00), indicating a high degree of agreement between the T.R.U.E. and capnography. The sensitivity, specificity, positive predictive value, and negative predictive value of the T.R.U.E. were 98.9% (95% CI: 94.3-99.8%), 94.1% (95% CI: 73.0-99.0%), 98.9% (95% CI: 94.3-99.8%) and 94.1% (95% CI: 73.0-99.0%). The median operating time of the T.R.U.E. was 9.0s (interquartile range [IQR]: 6.0, 14.0).

CONCLUSIONS

The application of the T.R.U.E. to examine endotracheal tube placement during emergency intubation is feasible, and can be rapidly performed.