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

Sonographic evidence of abnormal tracheal cartilage ring structure in cystic fibrosis

OBJECTIVES/HYPOTHESIS

Tracheal cartilage ring structural abnormalities have been reported in cystic fibrosis (CF) mice and pigs. Whether similar findings are present in humans with CF is unknown. We hypothesized that tracheal cartilage ring shape and size would be different in people with CF.

STUDY DESIGN

Tracheal cartilage ring size and shape were measured in adults with (n = 21) and without CF (n = 18).

METHODS

Ultrasonography was used in human subjects to noninvasively assess tracheal cartilage ring structure in both the sagittal and the transverse planes. Tracheal cartilage ring thickness was also determined from histological sections obtained from newborn non-CF and CF pigs. These values were compared with human data.

RESULTS

Human CF tracheas had a greater width and were less circular in shape compared to non-CF subjects. CF tracheal cartilage rings had a greater midline cross-sectional area and were thicker compared to non-CF rings. Maximal tracheal cartilage ring thickness was also greater in both newborn CF pigs and human adults with CF, compared to non-CF controls.

CONCLUSIONS

Our findings demonstrate that structural differences exist in tracheal cartilage rings in adults with CF. Comparison with newborn CF pig data suggests that some of these changes may be congenital in nature.

LEVEL OF EVIDENCE

3b

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.

Laryngo-tracheal ultrasonography to confirm correct endotracheal tube and laryngeal mask airway placement

Waveform capnography was recommended as the most reliable method to confirm correct endotracheal tube or laryngeal mask airway placements. However, capnography may be unreliable during cardiopulmonary resuscitation and during low flow states. It may lead to an unnecessary removal of a well-placed endotracheal tube, re-intubation and interruption of chest compressions. Real-time upper airway (laryngo-tracheal) ultrasonography to confirm correct endotracheal tube placement was shown to be very useful in cadaveric models and during emergency intubation. Tracheal ultrasonography does not interrupt chest compressions and is not affected by low pulmonary flow or airway obstruction, but is limited by ultrasonography scattering and acoustic artifacts generated in air – mucosa interfaces. Sonographic upper airway assessment emerges as a rapid and easily available method to predict difficult intubation, to assess the laryngeal and hypopharyngeal size and visualize the position of the laryngeal mask airway in situ. This study demonstrates that the replacement of air with saline in endotracheal tube or laryngeal mask airway cuffs and the use of the contrast agents enables detection of cuffs in the airway. It also allows visualization of the surrounding structures or tissues as the ultrasound beam can be transmitted through the fluid – filled cuffs without being reflected from air – mucosal interfaces.

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.

Utility of ultrasound in the ICU

PURPOSE OF REVIEW

Use of ultrasound in the acute care setting has become more common in recent years. However, it still remains underutilized in the perioperative management of critical patients. In this review, we aim to increase the awareness of ultrasound as an important diagnostic modality that can be used in the perioperative period to improve patient care. Our main focus will be in describing the diagnostic uses of ultrasound to identify cardiac, pulmonary, airway and vascular diseases commonly encountered in acute care settings.

RECENT FINDINGS

We find that ultrasound can be used in a quick fashion to assess a haemodynamically unstable patient. Protocols are available to use ultrasound as a part of cardiopulmonary resuscitation. Ultrasound can help in deciding fluid vs. pressor treatment by evaluating the inferior vena cava and other cardiac structures.Lung ultrasound can not only help in diagnosing pneumothoracies and effusions but also look at lung recruitment and diaphragmatic movement, hence can aid in deciding extubation strategies. This modality can be utilized for confirmation of endotracheal tube.Recent interest in axillary vein cannulation with ultrasound guidance has gained some momentum.

SUMMARY

This article covers the recent developments and literature available on point of care ultrasound and its utilization in the perioperative period. We have not covered some other important uses of ultrasound such as abdominal examination looking at the aorta and other abdominal organs. This was beyond the scope of this article.

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.

Sonographic confirmation of intubation: comparison of 3 methods in a pig model

OBJECTIVES

Several recent studies have investigated methods to confirm endotracheal tube (ETT) placement with sonography, using diaphragmatic movement, lung sliding, and transtracheal visualization of the ETT. To our knowledge, no studies have directly compared these 3 methods. This study aimed to directly compare the test characteristics of these 3 methods to determine ETT placement. Additionally, we compared the time required to complete the sonographic examination and the performers' confidence in their findings.

METHODS

We conducted a prospective randomized single-blinded study. Twenty-five recently euthanized pigs were intubated either in the esophagus or trachea, for a total of 50 intubations. Each of the 3 sonographic methods of intubation confirmation was performed by sonographers of different skill levels. Sonographic findings, the time to findings, and confidence in findings were recorded.

RESULTS

A total of 150 sonographic examinations were performed. There were no significant differences in the sensitivity, specificity, positive predictive value, negative predictive value, or accuracy for correct ETT placement between the 3 methods of intubation confirmation. On average, the transtracheal and thoracic methods were faster (12.5 and 14.0 seconds, respectively) than the diaphragmatic method (21.0 seconds; P < .01). There were no significant differences in operator confidence between the confirmation methods.

CONCLUSIONS

All 3 methods for determining ETT placement had similar test characteristics. Transtracheal and thoracic sonography were faster than diaphragmatic sonography for determining ETT placement in pigs.

The effect of sonologist experience on the ability to determine endotracheal tube location using transtracheal ultrasound

STUDY OBJECTIVE

Transtracheal ultrasound has been described as a method to evaluate endotracheal tube placement. Correlation between sonologist experience and the successful use of transtracheal ultrasound to identify endotracheal tube location has not been examined. Our objectives were to evaluate emergency physicians' ability to correctly identify endotracheal tube location using transtracheal ultrasound and to evaluate the role operator experience plays in successful identification of tube placement.

METHODS

This was a cross-sectional, single-blinded study conducted in a cadaver laboratory. Two cadavers were used as models. One cadaver had an endotracheal tube placed in the esophagus, and the second had the tube placed in the trachea. Participants were asked to evaluate tube placement using transtracheal ultrasound and to record their interpretation. Examination clips were reviewed by the emergency ultrasound fellowship director. Descriptive statistics and χ(2) test were used for analysis.

RESULTS

Twenty-nine participants were included, 8 (27.6%) of whom were considered to be "most experienced" based on previous ultrasound experience (>150 scans). Eleven of 29 correctly identified esophageal intubation and 18 of 29 correctly identified tracheal intubation, resulting in a sensitivity of 62.0% (95% confidence interval [CI], 42.3-79.3) and a specificity of 37.9% (95% CI, 20.7-57.7). Transtracheal ultrasound performed by the most experienced sonologists showed better sensitivity and specificity, 75.0% (95% CI, 34.9-96.8) and 62.5% (95% CI, 24.5-91.5), respectively.

CONCLUSION

Most participants obtained adequate images, but correct interpretation of the images was poor. The most experienced sonologists correctly identified tube location more often. Additional education would be required before adopting this method.

Bedside US imaging in multiple trauma patients. Part 1: US findings and techniques

OBJECTIVES

The aim of this review article is to present the current views and visions of the role of ultrasound (US) in the management of patients with multiple trauma. The article is divided into two parts. Part 1 (US findings and techniques) will mainly deal with the technical aspects of US imaging in trauma patients and is written also for educational purposes. Part 2 (pathophysiology and US imaging in trauma patients) will deal with integration of US in the clinical and pathophysiological management of multiple trauma patients.

METHODS

A non-systematic review of the literature through PubMed search (restricted to the last 10 years) of original articles and review articles.

RESULTS

80 publications were selected for Part 1. Of these 80 articles, the author selected 50 according to personal criteria on the basis of their innovative or original contents (48 original articles and 2 literature review articles); 19 articles were furthermore extracted from the references of the selected publications. The information extracted from these 69 publications was organized into sections dealing with different fields of applications of US imaging in multiple trauma patients.

CONCLUSIONS

US imaging in trauma has evolved from the initial use, i.e., early diagnosis of peritoneal effusion (focused abdominal sonography for trauma), to a wider use known as resuscitative ultrasonography, and is today considered as an extension of physical examination to implement a more effective approach to clinical problems and increase the timeliness and safety of interventions.

A novel airway device with tactile sensing capabilities for verifying correct endotracheal tube placement

We present a new device for verifying endotracheal tube (ETT) position that uses specialized sensors intended to distinguish anatomical features of the trachea and esophagus. This device has the potential to increase the safety of resuscitation, surgery, and mechanical ventilation and decrease the morbidity, mortality, and health care costs associated with esophageal intubation and unintended extubation by potentially improving the process and maintenance of endotracheal intubation. The device consists of a tactile sensor connected to the airway occlusion cuff of an ETT. It is intended to detect the presence or absence of tracheal rings immediately upon inflation of the airway occlusion cuff. The initial study detailed here verifies that a prototype device can detect contours similar to tracheal rings in a tracheal model.

Real-time tracheal ultrasonography for confirmation of endotracheal tube placement during cardiopulmonary resuscitation

OBJECTIVE

This study aimed to evaluate the accuracy of tracheal ultrasonography for assessing endotracheal tube position during cardiopulmonary resuscitation (CPR).

METHODS

We performed a prospective observational study of patients undergoing emergency intubation during CPR. Real-time tracheal ultrasonography was performed during the intubation with the transducer placed transversely just above the suprasternal notch, to assess for endotracheal tube positioning and exclude esophageal intubation. The position of trachea was identified by a hyperechoic air-mucosa (A-M) interface with posterior reverberation artifact (comet-tail artifact). The endotracheal tube position was defined as endotracheal if single A-M interface with comet-tail artifact was observed. Endotracheal tube position was defined as intraesophageal if a second A-M interface appeared, suggesting a false second airway (double tract sign). The gold standard of correct endotracheal intubation was the combination of clinical auscultation and quantitative waveform capnography. The main outcome was the accuracy of tracheal ultrasonography in assessing endotracheal tube position during CPR.

RESULTS

Among the 89 patients enrolled, 7 (7.8%) had esophageal intubations. The sensitivity, specificity, positive predictive value, and negative predictive value of tracheal ultrasonography were 100% (95% confidence interval [CI]: 94.4-100%), 85.7% (95% CI: 42.0-99.2%), 98.8% (95% CI: 92.5-99.0%) and 100% (95% CI: 54.7-100%), respectively. Positive and negative likelihood ratios were 7.0 (95% CI: 1.1-43.0) and 0.0, respectively.

CONCLUSIONS

Real-time tracheal ultrasonography is an accurate method for identifying endotracheal tube position during CPR without the need for interruption of chest compression. Tracheal ultrasonography in resuscitation management may serve as a powerful adjunct in trained hands.

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.

Ingested foreign bodies: a case series demonstrating a novel application of point-of-care ultrasonography in children

In an era of recognizing the risks of radiation exposure, it is important to develop alternatives to radiographs. Bedside ultrasound has become an important adjunct to clinical diagnoses and procedural guidance in the emergency department. We present a case series of two patients who presented to a pediatric emergency department after witnessed coin ingestions. Point-of-care ultrasonography was able to accurately identify the location of each of the coins, at the thoracic inlet and in the stomach, as confirmed by chest radiography. To our knowledge, point-of-care ultrasonography has not been previously utilized to detect and localize esophageal foreign bodies in the emergency department.

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.

Ultrasound-guided, Bougie-assisted cricothyroidotomy: a description of a novel technique in cadaveric models

BACKGROUND

Ultrasound (US) has well-documented utility in critical procedures performed in the emergency department. It has been described as a "skill integral to the practice of emergency medicine" in the 2007 Model of Clinical Practice of Emergency Medicine. One of the ideal uses for US in critical care may be in the performance of emergent cricothyroidotomy. To the best of our knowledge there is currently no description of how to perform an US-guided open cricothyroidotomy in the literature.

OBJECTIVES

This study aimed to develop and describe an US-guided technique for emergent open cricothyroidotomy and evaluate the time to completion and failure rate of this technique.

METHODS

This study was performed in a cadaver lab on 21 cadavers. The procedure was performed by two independent operators with US guidance using a linear transducer in the longitudinal orientation placed on the anterior midline of the neck. The cricothyroid membrane was incised with a No. 20 scalpel and a bougie with a coude tip was inserted into the trachea. A 6.0 endotracheal tube was then advanced over the bougie and the cuff was inflated. Endotracheal tube placement was confirmed by dissection. The procedure was timed to evaluate the length of time to identification of the cricothyroid membrane and completion of the procedure. There was no control group for this study.

RESULTS

There were 12 female and nine male cadavers. The mean body mass index (BMI) was 21.9 (range=12.2 to 44.9). There was a median time to identification of the cricothyroid membrane of 3.6 seconds (interquartile range [IQR]=1.9 to 15.3 seconds) and median time to completion of the procedure of 26.2 seconds (IQR=10.7 to 50.7 seconds). The failure rate was 1 out of 21, with one incision placed between the cricoid cartilage and the first tracheal ring. In this case, the trachea was still cannulated. Similar completion times were obtained with high- and low-BMI cadavers.

CONCLUSIONS

Ultrasound-guided bougie-assisted cricothyroidotomy is a novel technique that may be beneficial in emergent open cricothyroidotomy. The data suggest that this technique is rapid, with a median time to completion of 26.2 seconds. The data also suggest that the procedure may have a low failure rate, with 20 of 21 cadavers undergoing successful cricothyroidotomy.

Ultrasonographic lung sliding sign in confirming proper endotracheal intubation during emergency intubation

AIM OF STUDY

Unrecognized one-lung intubations (also known as main-stem intubation) can lead to hypoventilation, atelectasis, barotrauma, and even patient death. Many traditional methods can be employed to detect one-lung intubation; however, each of these methods has limitations and is not consistently reliable in emergency settings. This study aimed to assess the accuracy and timeliness of ultrasound to confirm proper endotracheal intubation.

METHODS

This was a prospective, single-center, observational study conducted at the emergency department of a national university teaching hospital. Patients received emergency tracheal intubation because of respiratory failure or cardiac arrest. After intubation, bedside ultrasound was performed with a transducer placed on the chest bilaterally at the mid-axillary line, to identify lung sliding over the lungs bilaterally during ventilation. Chest radiography was used as the criterion standard for confirmation of endotracheal tube position.

RESULTS

One hundred and fifteen patients needing tracheal intubation were included, and nine (7.8%) had one-lung intubations. The overall accuracy of ultrasound to confirm proper endotracheal intubation was 88.7% (95% confidence interval (CI): 81.6-93.3%). The positive predictive value was 94.7% (95% CI: 87.1-97.9%) in the non-cardiac-arrest group and 100% (95% CI: 87.1-100.0%) in the cardiac-arrest group. The median operating time of ultrasound was 88 s (interquartile range [IQR]: 55.0, 193.0), and of chest radiography was 1349 s (IQR: 879.0, 2221.0) post intubation.

CONCLUSIONS

In this study, the positive predictive value of bilateral lung sliding in confirming proper endotracheal intubation was high, especially among patients with cardiac arrest. Considerable time advantage of ultrasound over chest radiography was demonstrated.