Pilot study to evaluate the accuracy of ultrasonography in confirming endotracheal tube placement

Role of point-of-care ultrasound in critical care and emergency medicine: update and future perspective

Point-of-care ultrasound (POCUS) is a rapidly developing technology that has the potential to revolutionize emergency and critical care medicine. The use of POCUS can improve patient care by providing real-time clinical information. However, appropriate usage and proper training are crucial to ensure patient safety and reliability. This article discusses the various applications of POCUS in emergency and critical care medicine, the importance of training and education, and the future of POCUS in medicine.

Diagnostic Value of Epigastric Ultrasound and Suprasternal Notch Ultrasound in Comparison with Standard Capnography in Confirmation of Endotracheal Tube Placement after Intubation

Background

Endotracheal intubation is the basic method of providing a safe cross-sectional airway area and the incorrect placement can be dangerous and causes complications. So this study aimed to access the diagnostic value of color Doppler epigastric ultrasound and linear probe suprasternal notch ultrasound in comparison with standard capnography in confirmation of endotracheal tube (ETT) placement after intubation.

Materials and Methods

This diagnostic value study was conducted on 104 patients requiring intubation who were referred to the Emergency Department. After the intubation, color Doppler epigastric ultrasound and suprasternal notch ultrasound as well as the standard capnography were used to confirm the placement ETT.

Results

The sensitivity and specificity of color Doppler epigastric ultrasound were 97.96% and 100%, for suprasternal notch ultrasound were 98.98% and 66.67%, and for combination of the both methods were 96.94% and 100% respectively that showed the significant diagnostic value in the confirmation of ETT placement (P < 0.001). The mean of elapsed time to confirm the ETT placement by the standard capnography method (17.95 ± 2.45 s) was significantly more than the two methods of epigastric ultrasound (10.38 ± 4.65 s) and suprasternal notch ultrasound (5.08 ± 4.45 s) as well as the combined method with the mean of 15.46 ± 8.31 s (P < 0.001).

Conclusion

The results of this study showed that although ultrasound is a potentially accurate, fast, and reliable method to confirm the endotracheal tube placement, but suprasternal notch ultrasound is considered to be a more appropriate diagnostic technique due to its higher sensitivity and less detection time compared to epigastric ultrasound and combined method.

Diagnostic Accuracy of Suprasternal Versus Subxiphoid Ultrasonography for Endotracheal Intubation

Background

Airway management is an important skill for emergency physicians, and confirmation of correct endotracheal tube (ETT) placement is a crucial component of airway management.

Objectives

Due to the occurrence of incorrect ETT positioning in emergency departments, the present study aimed to compare the diagnostic sensitivity of ultrasound using suprasternal and subxiphoid methods for confirming the correct placement of ETT compared to capnography.

Methods

This cross-sectional study was conducted by examining patients requiring intubation. Ultrasound was performed by two independent emergency medical assistants using two suprasternal and subxiphoid methods to confirm correct ETT placement; the results were then interpreted. To observe the tube passage through the vocal cords, capnography and lung auscultation were applied as the gold standards, and the results of two ultrasound methods were compared.

Results

A total of 66 patients, who were intubated in the emergency department, participated in this study. The positive and negative predictive values, sensitivity, and specificity of supernatural ultrasound were 96.72%, 80%, 98.33%, and 66.67%, respectively. Also, positive and negative predictive values, sensitivity, and specificity of subxiphoid ultrasound were 97.95%, 29.41%, 80%, and 83.33%, respectively. The diagnostic odds ratios of suprasternal and subxiphoid ultrasounds were 1.026 and 1.024 compared to capnography, respectively.

Conclusions

Ultrasonography using the suprasternal method was feasible. Considering the high sensitivity and specificity of this method in confirming correct ETT placement, it produced reliable results. Overall, this modality can be used as one of the main methods to verify correct ETT placement in emergency departments.

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.

The Use of POCUS to Manage ICU Patients With COVID-19

Since the advent of SARS-CoV-2, the virus that causes COVID-19, clinicians have had to modify how they provide high-value care while mitigating the risk of viral spread. Routine imaging studies have been discouraged due to elevated transmission risk. Patients who have been diagnosed with COVID-19 often have a protracted hospital course with progression of disease. Given the need for close follow-up of patients, we recommend the use of ultrasonography, particularly point-of-care ultrasound (POCUS), to manage patients with COVID-19 through their entire ICU course. POCUS will allow a clinician to evaluate and monitor cardiac and pulmonary function, as well as evaluate for thromboembolic disease, place an endotracheal tube, confirm central venous catheter placement, and rule out a pneumothorax. If a patient improves sufficiently to perform weaning trials, POCUS can also help evaluate readiness for ventilator liberation.

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.

Selective Computed Tomography (CT) Imaging is Superior to Liberal CT Imaging in the Hemodynamically Normal Pediatric Blunt Trauma Patient

BACKGROUND

The optimal imaging strategy in hemodynamically stable pediatric blunt trauma remains to be defined. The purpose of this study was to determine the differences between selective and liberal computed tomography (CT) strategy in a pediatric trauma population with respect to radiation exposure and outcomes.

METHODS

We performed a retrospective analysis of hemodynamically stable blunt pediatric trauma patients (≤16 y) who were admitted to a Level I trauma center between 2013-2016. Patients were stratified into selective and liberal imaging cohorts. Univariate and multivariate regression analyses were used to compare outcomes between the groups. Outcomes included radiation dose, hospital and ICU length of stay, complications and mortality.

RESULTS

Of the 485 patients included, 176 underwent liberal and 309 selective CT imaging. The liberal cohort were more likely to be severely injured (ISS>15: 34.1 versus 8.4%, P< 0.001). The odds of exposure to a radiation dose of >15 mSv were higher with liberal scanning in patients with both ISS > 15 (OR 2.78, 95% CI 1.76-5.19, P< 0.001) and ISS ≤ 15 (OR 3.41, 95% CI 2.19-8.44, P < 0.001). Adjusted outcomes regarding mortality, ICU length of stay, and complications were similar between the cohorts.

CONCLUSION

Selective CT imaging in hemodynamically stable blunt pediatric trauma patients was associated with reduced radiation exposure and similar outcomes when compared to a liberal CT strategy.

Ultrasonography for airway management

Ultrasonography (USG) allows a new approach to the airway in anaesthesia and intensive care. USG visualises the airway from the mouth to the lungs. By exploring the entire airway, USG proposes new criteria (1) to assess the risk of difficult laryngoscopy, (2) to anticipate the management of a difficult airway, (3) to confirm the position of the endotracheal tube (ETT), and (4) to confirm that the lungs are effectively ventilated. Intraoperatively, USG may also help to resolve acute ventilatory problems such as pneumothorax, delayed selective bronchial intubation after patient positioning (Trendelenburg, prone or lateral position) or acute pulmonary oedema.

Ultrasound for Intubation Confirmation: A Randomized Controlled Study among Emergency Medicine Residents

Confirmation of endotracheal tube (ETT) placement during intubation is a critical skill for emergency medicine (EM) residents; airway ultrasonography has been suggested as an accessible and accurate method of ETT confirmation. Here, we investigated the accuracy with which EM residents could identify ETT location in cadavers using different ultrasound modes. EM attendings intubated either the trachea or the esophagus of a cadaver, and blinded residents identified ETT position using either B-mode or B-mode plus color Doppler. Residents correctly identified ETT location in 1075 of 1203 trials (89.4%); performance improved with post-graduate year (residents in post-graduate year 3 had 97.8% accurate identifications). There were 556 (91.7%) correct identifications made with B-mode and 519 (86.9%) with B-mode plus color Doppler (p value = 0.007); thus, accuracy did not improve with addition of color Doppler to B-mode. Further research is needed on the efficacy of different ultrasound modes in confirming ETT placement in live intubations.

Feasibility of using ultrasound in ambulances in Saudi Arabia

BACKGROUND

In developed countries, the economic feasibility of using ultrasound in ambulances before arriving at the hospital has been achieved through comprehensive studies, and this of course does not apply to Arab countries, as there are no current studies to support this. Therefore, this study is a preliminary measure of the economic feasibility of using ultrasound in ambulances in Saudi Arabia.

AIM

To measure the demand for ultrasound equipment in ambulances in Saudi Arabia.

METHODS

A cross-sectional study of five different groups of participants including radiation technologists, emergency physicians, paramedics, Red Crescent managers and the public. Email and social media were used to deliver a questionnaire to these groups. The questionnaire included specific questions to measure the purpose of ultrasound use in each group of participants.

RESULTS

Each group had some knowledge on ultrasound and its benefits. More than 50% in each study group supported the availability of ultrasound in ambulances. Additionally, 60% of emergency physicians reported that they had difficulties in venous access, checking the presence of internal bleeding, recognizing pregnancy in trauma cases, and inserting endotracheal tubes, and the majority of them confirmed the effective role of ultrasound in achieving such tasks. Almost all paramedics (93.33%), physicians (98.89%), and Saudi Red Crescent managers (96.3%) emphasized the importance of communication between ambulance staff and emergency departments. Moreover, most physicians (77.78%), and technologists (82.73%) supported the presence of paramedics in ambulances to operate ultrasound in order to improve patient outcomes.

CONCLUSION

Most of the study groups evaluated had knowledge on ultrasound and supported the presence of ultrasound devices in ambulances.

Point-of-Care Ultrasound for Pediatric Endotracheal Tube Placement Confirmation by Advanced Practice Transport Nurses

OBJECTIVE

This study aimed to identify which point-of-care ultrasound (POCUS) techniques and sonographic signs were reliably acquired and interpreted by transport nurses for the confirmation of endotracheal tube placement in children.

METHODS

We developed and assessed a multimodal POCUS training curriculum for transport nurses that evaluated 5 sonographic signs using 3 scanning techniques.

RESULTS

Twenty-one transport nurses were enrolled in the curriculum. The mean scores (95% confidence interval [CI]) of the knowledge test were 82% (95% CI, 63%-93%), 88% (95% CI, 68%-95%), and 74% (95% CI, 53%-87%) for tracheal, lung, and hemidiaphragmatic scans, respectively. For the simulation image evaluation, 94% (95% CI, 77%-99%) of tracheal scan images, 97% (95% CI, 81%-99%) of lung scan images, and 88% (95% CI, 69%-96%) of hemidiaphragmatic scan images were determined clinically useful. For the pediatric intensive care unit image evaluation, 100% (95% CI, 86%-100%) of tracheal scan images, 100% (95% CI, 86%-100%) of lung scan images, and 79% (95% CI, 59%-91%) of hemidiaphragmatic scan images were determined clinically useful. A tracheal dilation sign was rarely captured by POCUS.

CONCLUSION

Transport nurses can acquire POCUS skills to confirm endotracheal tube placement in children. A combination of a double trachea sign, a lung sliding sign, and a lung pulse sign could be a feasible POCUS approach.

Lung sonography can improve the specificity of determination of left-sided double-lumen tracheal tube position in both novices and experts: a randomised prospective study

Objective

Lung sonography can be helpful to determine the position of a left-sided double-lumen tube (DLT). However, clinical experience is required for correct assessment. We investigated whether lung sonography can improve the diagnostic efficacy of determining the DLT position in novices and experts.

Methods

In this randomised prospective clinical study, 88 patients were allocated to two groups using auscultation or lung sonography for initial assessment of the DLT position. In each group, two repeated assessments were performed; the first was performed by a novice, and the second was performed by an expert. The final DLT position was confirmed by fibre-optic bronchoscopy. The primary outcome was the diagnostic efficacy (including overall accuracy, sensitivity, and specificity) in confirming the DLT position.

Results

In both the novices and experts, the specificity of determining the DLT position was significantly higher with lung sonography than auscultation (60.0% vs. 21.7% and 66.7% vs. 37.5%, respectively). Additionally, the predictability of an incorrect position was similar between the novices and experts using lung sonography (area under the curve of 0.665 and 0.690, respectively).

Conclusions

Lung sonography can improve the diagnostic efficacy of detecting an incorrect DLT position in both novices and experts.

Transtracheal ultrasonographic confirmation of endotracheal intubation using I-gel and an endotracheal tube introducer

BACKGROUND

This study aimed to investigate the efficacy of transtracheal ultrasonography in confirming the placement of an endotracheal tube introducer during endotracheal intubation using the I-gel supraglottic airway as a guide.

METHODS

In this prospective study, endotracheal intubation using an endotracheal tube introducer through the I-gel was performed in patients with return of spontaneous circulation after I-gel insertion for out-of-hospital cardiac arrest. The introducer placement was assessed by the occurrence of hyperechoic artifacts within the trachea or esophagus in transtracheal ultrasonography. Results of ultrasonography were confirmed by waveform capnography in the case of tracheal artifacts and direct visualization by laryngoscopy in the case of esophageal artifacts.

RESULTS

One hundred and six patients were enrolled in this study. In transtracheal ultrasonography, artifacts of introducer in the trachea and esophagus were observed in 80 (75.5%) and 26 (24.5%) patients, respectively. Transtracheal ultrasonography in identifying the placement of introducers revealed a sensitivity of 100% (95% CI 95.4 to 100), specificity of 96.3% (95% CI 81.0 to 99.9), a PPV of 98.7% (95% CI 92.0 to 99.8), and a NPV of 100% (95% CI 94.8 to 99.9).

CONCLUSION

Transtracheal ultrasonography is an accurate method for identifying introducer placement during endotracheal intubation using an endotracheal tube introducer through the I-gel.

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.

The Utility of Color Doppler to Confirm Endotracheal Tube Placement: A Pilot Study

Introduction

Grayscale ultrasound (US) imaging has been used as an adjunct for confirming endotracheal tube (ETT) placement in recent years. The addition of color Doppler imaging (CDI) has been proposed to improve identification but has not been well studied. The aim of this study was to assess whether CDI improves correct localization of ETT placement.

Methods

A convenience sample of emergency and critical care physicians at various levels of training and experience participated in an online assessment. Participants viewed US video clips of patients, which included either tracheal or esophageal intubations captured in grayscale or with CDI; there were five videos of each for a total of 20 videos. Participants were asked to watch each clip and then assess the location of the ETT.

Results

Thirty-eight subjects participated in the online assessment. Levels of training included medical students (13%), emergency medicine (EM) residents (50%), EM attendings (32%), and critical care attendings (5%). The odds ratio of properly assessing tracheal placement using color relative to a grayscale imaging technique was 1.5 (p = 0.21). Regarding the correct assessment of esophageal placement, CDI had 1.4 times the odds of being correctly assessed relative to grayscale (p = 0.26). The relationship between training level and correct assessments was not significant for either tracheal or esophageal placements.

Conclusion

In this pilot study we found no significant improvement in correct identification of ETT placement using color Doppler compared to grayscale ultrasound; however, there was a trend toward improvement that might be better elucidated in a larger study.

Ultrasound guided tracheal intubation with a styleted tracheal tube in anticipated difficult airway

Ultrasonography is a simple, reliable, non-invasive technique which helps in real-time assessment of airway anatomy and contributes to safer airway management in various settings like operating rooms, intensive care units and emergency departments. It also helps us to plan the appropriate anesthetic technique especially in difficult airway cases. Here, we discuss the importance of styleted tracheal tube in improving the accuracy of ultrasound guided tracheal intubation in anticipated difficult airway.

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.

Application of bedside real-time tracheal ultrasonography for confirmation of emergency endotracheal intubation in patients in the intensive care unit

OBJECTIVE

Critically ill patients often require emergency endotracheal intubation and mechanical ventilation. When esophageal intubation is not confirmed early, treatment may be delayed, even for life-threatening conditions. We examined the accuracy of bedside real-time airway ultrasonography in confirming the endotracheal tube (ETT) position during emergency endotracheal intubation in patients in the intensive care unit (ICU).

METHODS

This single-center prospective observational study included 118 patients who underwent urgent endotracheal intubation in the ICU of Taizhou Hospital of Integrated Traditional Chinese and Western Medicine. Tracheal ultrasonography was used to confirm the ETT position during endotracheal intubation, after which fiberoptic bronchoscopy was performed. The accuracy of bedside real-time tracheal ultrasonography in determining the ETT position was examined.

RESULTS

Twelve (10.2%) patients underwent endotracheal intubation. The kappa value was 0.844, indicating perfect consistency between tracheal ultrasonography and fiberoptic bronchoscopy in identifying esophageal intubation. The sensitivity, specificity, and positive and negative predictive values of tracheal ultrasonography in determining the ETT position were 75.0%, 100%, 100%, and 97.2%, respectively.

CONCLUSIONS

Bedside real-time tracheal ultrasonography accurately assesses the ETT position in the ICU and can identify the ETT position during intubation. These findings have important clinical applications and are of great significance for treatment of ICU patients.

A New Formula for Confirmation of Proper Endotracheal Tube Placement with Ultrasonography

Background:

Endotracheal intubation is an important procedure in critical care and emergency medicine settings. Optimal depth of the tube placement has been a serious concern because of several complications associated with its malposition.

Objective:

The aim of the current study was to find a new formula to estimate the proper endotracheal tube depth when using ultrasonography or lighted stylet device in order to increase the accuracy of determining Endotracheal tube (ETT) depth and decrease the side effects of ETT misplacement.

Method:

Patients older than 18 years of age admitted to Imam emergency department who needed tracheal intubation were included. Tube’s length at the angle of the mouth while the tube passed the suprasternal notch, ETT depth after insertion and the distance from ETT’s tip to carina were recorded. Ultrasonography and portable chest x-ray were used as tools for measuring these lengths.

Results:

A total number of 91 patients including 55 men and 36 women were eligible for inclusion in the study. Not placing the tube at proper depth was considered as the failure of intubation. This failure rate was 9.9% in the standard method which would have been 1.1% if our proposed formula was used.

Conclusion:

The findings of this study suggest that the use of this new formula may help in predicting the proper intubation tube placement. Further studies are warranted to confirm these findings.

Real-time Tracheal Ultrasound for the Confirmation of Endotracheal Intubations in the Intensive Care Unit: An Observational Study

OBJECTIVES

Current methods to confirm endotracheal tube (ETT) placement have varying degrees of effectiveness and time to completion. We aimed to study the accuracy of real-time tracheal ultrasound (US) to confirm ETT placement in the intensive care unit (ICU) setting.

METHODS

This work was a prospective study completed at 2 academic tertiary care centers. Patients in the adult ICU requiring emergent intubation were enrolled in the trial. During the intubation process, a US team performed a tracheal US examination to determine, in real time, whether the ETT was placed into the trachea or the esophagus.

RESULTS

A total of 75 patients were enrolled in the study and were available for analysis. There were 12 (16%) esophageal intubations and 63 (84%) tracheal intubations. One hundred percent of the tracheal intubations and 83% of the esophageal intubations were correctly identified. The positive and negative predictive values of US to detect an esophageal intubation were 100% and 97%, respectively.

CONCLUSIONS

Tracheal US can be highly accurate in identifying the location of the ETT, in real time, in ICU patients undergoing emergent intubation. Although our study shows a great potential of real-time US use during emergent intubations, larger studies would be needed to further evaluate the accuracy of this technique.

Confirmation of placement of endotracheal tube - A comparative observational pilot study of three ultrasound methods

Background and Aims

Confirmation of endotracheal tube (ETT) position is necessary to ensure proper ventilation. The present study was conducted with the aim to compare the efficacy of three ultrasonographic (USG) techniques in terms of time taken for confirmation of ETT position. The time taken by each USG technique was also compared with that for auscultation and capnography. The ability of the three USG techniques to identify tracheal placement of ETT was evaluated in all patients.

Material and Methods

Ninety adult American Society of Anesthesiologists (ASA) I/II patients requiring general anaesthesia with tracheal intubation were randomised into three groups (n = 30 each) depending upon the initial USG transducer position used to confirm tracheal placement of ETT: group T (tracheal), group P (pleural) and group D (diaphragm). The time taken for confirmation of tracheal placement of ETT by USG, auscultation and capnography was recorded for each of the groups. Subsequently, USG confirmation of ETT placement was performed with the other two USG techniques in all patients.

Results

The time taken for USG in group T was significantly less (3.8 ± 0.9 s) compared to group P (12.1 ± 1.6 s) and group D (13.8 ± 1.7 s); P < 0.001. USG was significantly faster than both auscultation and capnography in group T (P < 0.001), whereas in group P and group D, USG took longer time compared to auscultation (P = 0.014 and P < 0.001, respectively) but lesser time than capnography (P < 0.001 in both groups).

Conclusion

USG is a rapid technique for identification of ETT placement. All the three USG techniques are reliable in identifying the tracheal placement of ETT.

Avoid the Goose! Paramedic Identification of Esophageal Intubation by Ultrasound

OBJECTIVES

Rapid identification of esophageal intubations is critical to avoid patient morbidity and mortality. Continuous waveform capnography remains the gold standard for endotracheal tube (ETT) confirmation, but it has limitations. Point-of-care ultrasound (POCUS) may be a useful alternative for confirming ETT placement. The objective of this study was to determine the accuracy of paramedic-performed POCUS identification of esophageal intubations with and without ETT manipulation.

METHODS

A prospective, observational study using a cadaver model was conducted. Local paramedics were recruited as subjects and each completed a survey of their demographics, employment history, intubation experience, and prior POCUS training. Subjects participated in a didactic session in which they learned POCUS identification of ETT location. During each study session, investigators randomly placed an ETT in either the trachea or esophagus of four cadavers, confirmed with direct laryngoscopy. Subjects then attempted to determine position using POCUS both without and with manipulation of the ETT. Manipulation of the tube was performed by twisting the tube. Descriptive statistics and logistic regression were used to assess the results and the effects of previous paramedic experience.

RESULTS

During 12 study sessions, from March 2014 through December 2015, 57 subjects participated, evaluating a total of 228 intubations: 113 tracheal and 115 esophageal. Subjects were 84.0% male, mean age of 39 years (range: 22 - 62 years), with median experience of seven years (range: 0.6 - 39 years). Paramedics correctly identified ETT location in 158 (69.3%) cases without and 194 (85.1%) with ETT manipulation. The sensitivity and specificity of identifying esophageal location without ETT manipulation increased from 52.2% (95% confidence interval [CI], 43.0-61.0) and 86.7% (95% CI, 81.0-93.0) to 87.0% (95% CI, 81.0-93.0) and 83.2% (95% CI, 0.76-0.90) after manipulation (P<.0001), without affecting specificity (P=.45). Subjects correctly identified 41 previously incorrectly identified esophageal intubations. Paramedic experience, previous intubations, and POCUS experience did not correlate with ability to identify tube location.

CONCLUSION

Paramedics can accurately identify esophageal intubations with POCUS, and manipulation improves identification. Further studies of paramedic use of dynamic POCUS to identify inadvertent esophageal intubations are needed. LemaPC, O'BrienM, WilsonJ, St. JamesE, LindstromH, DeAngelisJ, CaldwellJ, MayP, ClemencyB. Avoid the goose! Paramedic identification of esophageal intubation by ultrasound. Prehosp Disaster Med. 2018;33(4):406-410.

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.

Airway ultrasound for the confirmation of endotracheal tube placement in cadavers by military flight medic trainees - A pilot study

OBJECTIVE

Confirming correct endotracheal tube (ETT) placement is a key component of successful airway management. Ultrasound (US) as a tool for the confirmation of ETT placement has been investigated in the hospital setting but not in the pre-hospital setting. We hypothesized that after a short educational session, military flight medic trainees would be able to accurately identify ETT placement in a cadaver model.

METHODS

We conducted a prospective, randomized trial in a human cadaver model. Participants received a brief didactic and hands-on presentation on airway US techniques. Each participant then performed transtracheal US on cadaver models which were randomly assigned to tracheal or esophageal intubation; time to verbalize ETT location was also recorded. Participants were then asked whether they felt airway US would be a useful adjunctive skill in their practice.

RESULTS

Thirty-two military flight medic trainees were enrolled. US had a sensitivity of 66.7% and a specificity of 76.4% for identification of esophageal intubations. The positive predictive value was 71.4% and the negative predictive value was 72.2%. Mean time to report ETT placement was 47.3s. Time did not vary between medics with accurate identification versus inaccurate identification (p=0.176). 83% of participants felt airway US would be a useful adjunctive skill for the confirmation of ETT placement.

CONCLUSIONS

Military flight medic trainees can rapidly use airway US to identify ETT placement after a short educational session with moderate sensitivity and specificity. These advanced military medics are interested in learning and implementing this skill into their practice.

Point-of-care ultrasound (POCUS) of the upper airway

Airway management is a critical skill in the practice of several medical specialities including anesthesia, emergency medicine, and critical care. Over the years mounting evidence has showed an increasing role of ultrasound (US) in airway management. The objective of this narrative review is to provide an overview of the indications for point-of-care ultrasound (POCUS) of the upper airway. The use of US to guide and assist clinical airway management has potential benefits for both provider and patient. Ultrasound can be utilized to determine airway size and predict the appropriate diameter of single-lumen endotracheal tubes (ETTs), double-lumen ETTs, and tracheostomy tubes. Ultrasonography can differentiate tracheal, esophageal, and endobronchial intubation. Ultrasonography of the neck can accurately localize the cricothyroid membrane for emergency airway access and similarly identify tracheal rings for US-guided tracheostomy. In addition, US can identify vocal cord dysfunction and pathology before induction of anesthesia. A rapidly growing body of evidence showing ultrasonography used in conjunction with hands-on management of the airway may benefit patient care. Increasing awareness and use of POCUS for many indications have resulted in technologic advancements and increased accessibility and portability. Upper airway POCUS has the potential to become the first-line non-invasive adjunct assessment tool in airway management.

Diagnostic Value of Sonography for Confirmation of Endotracheal Intubation in the Emergency Department

Background

Intubation and maintaining airway are crucial in the management of critically ill patients in the emergency department. Correct tracheal intubation should be confirmed by the physician, otherwise oesophageal intubation could lead to hypoxia with detrimental consequences and even death. Sonography can be used to determine proper placement of the tracheal tube.

Methods

In this study, 75 patients, with an indication of intubation and age older than 18 years entered the study. An emergency medicine performed real-time sonography of the trachea to evaluate the correct placement of endotracheal tube. Tube passage (snowstorm) and vocal cord angel widening (bullet sign) were evaluated, and then both lungs sliding and diaphragm movement were evaluated to confirm correct tube placement and ventilation.

Results

In this study, 75 patients entered the study. The mean age of the patients was 61.12; 47 patients (62.7%) were male and 28 (37.3%) were female. The reason of intubation was the decreased level of consciousness in 22 cases (29.3%), cardiopulmonary arrest in 22 patients (29.3%), respiratory distress in 9 patients (12%), shock in 10 patients (13.3%), and seizure in 1 case. Snowstorm sign was seen in 72 patients (96%). Bullet sign was objected in 24 cases (32%). Lung sliding was seen bilaterally in 63 patients (84%) and unilaterally in 7 patients (9.3 %), but it was not noticed in 6.7% of the patients (5 patients).

Conclusions

Transverse tracheal and lung sonography in the emergency department can be a fast measure to confirm correct endotracheal intubation.

A Prospective Evaluation of Transverse Tracheal Sonography During Emergent Intubation by Emergency Medicine Resident Physicians

OBJECTIVES

Establishing a definitive airway is often the first step in emergency department treatment of critically ill patients. Currently, there is no agreed upon consensus as to the most efficacious method of airway confirmation. Our objective was to determine the diagnostic accuracy of real-time sonography performed by resident physicians to confirm placement of the endotracheal tube during emergent intubation.

METHODS

We performed a prospective cohort study of adult patients in the emergency department undergoing emergent endotracheal intubation. Thirty emergency medicine residents, who were blinded to end-tidal carbon dioxide detection results, performed real-time transverse tracheal sonography during intubation to evaluate correct endotracheal tube placement.

RESULTS

Seventy-two patients were enrolled in the study. Sixty-eight instances (94.4%) were interpreted as correct placement in the trachea; 4 (5.6%) were interpreted as esophageal, of which 1 was a false-negative finding, therefore conferring sensitivity of 98.5% (95% confidence interval, 92.1%-99.9%) and specificity of 75.0% (95% confidence interval, 19.4%-99.4%) for correct placement. There was no significant difference in accuracy among resident sonographers with different levels of residency training.

CONCLUSIONS

A simple transverse tracheal sonographic examination performed by emergency medicine resident physicians can be used as an adjunct to help confirm correct endotracheal tube placement during intubation. In our cohort, the level of training did not appear to affect the ability of residents to correctly identify the endotracheal tube position.

Diagnostic Imaging in pediatric thoracic trauma

Thoracic trauma accounts for approximately 14% of blunt force traumatic deaths, second only to head injuries. Chest trauma can be blunt (90% of cases) or penetrating. In young patients, between 60 and 80% of chest injuries result from blunt trauma, with over half as a consequence of impact with motor vehicles, whereas in adolescents and adults, penetrating trauma has a statistically more prominent role. Pulmonary contusions and rib fractures are the most frequent injuries occurring. Chest X-ray is the first imaging modality of choice to identify patients presenting with life-threatening conditions (i.e., tension pneumothorax, huge hemothorax, and mediastinal hematoma) and those who require a CT examination. Multi-Slice Computed Tomography is the gold standard to evaluate chest injuries. In fact, the high spatial resolution, along with multiplanar reformation and three-dimensional (3D) reconstructions, makes MDCT the ideal imaging method to recognize several chest injuries such as rib fractures, pneumothorax, hemothorax, lung contusions and lacerations, diaphragmatic rupture, and aortic injuries. Nevertheless, when imaging a young patient, one should always keep into account the ALARA concept, to balance an appropriate and low-dose technique with imaging quality and to reduce the amount of ionizing radiation exposure. According to this concept, in the recent years, the current trends in pediatric imaging support the rising use of alternative imaging modalities, such as US and MRI, to decrease radiation exposure and to answer specific clinical questions and during the observation period also. As an example, ultrasound is the first technique of choice for the diagnosis and treatment of pleural and pericardial effusion; its emerging indications include the evaluation of pneumothoraces, costocondral and rib fractures, and even pulmonary contusions.

Predictive Value of Tracheal Rapid Ultrasound Exam Performed in the Emergency Department for Verification of Tracheal Intubation

BACKGROUND

Verification of the correct placement of the endotracheal tube (ETT) has been one of the most challenging issues of airway management in the field of emergency medicine. Early detection of oesophagal intubation through a reliable method is important for emergency physicians.

AIM

The aim of this study was to assess the diagnostic accuracy of tracheal rapid ultrasound exam (TRUE) to assess endotracheal tube misplacement during emergency intubation.

METHODS

This was an observational prospective study performed in the emergency department of the major tertiary referral hospital in the city. We included a consecutive selection of 100 patients. TRUE was performed for all these patients, and subsequently, quantitative waveform capnography was done. The later test is considered as the gold standard.

RESULTS

From our total 100 eligible patients, 93 (93%) participants had positive TRUE results (tracheal intubation) and 7 (7%) patients have negative TRUE results (esophageal intubation). Quantitative waveform capnography report of all 93 (100%) patients who had positive TRUE was positive (appropriate tracheal placement). Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of TRUE for detecting appropriate tracheal placement of ETT were 98.9% (95% CI, 93.3% to 99.8%), 100% (95% CI, 51.6% to 100%), 100% (95% CI, 95.1% to 100%) and 85.7% (95% CI, 42% to 99.2%) respectively.

CONCLUSIONS

Performing TRUE is convenient and feasible in many emergency departments and pre-hospital settings. We would recommend emergency units explore the possibility of using TRUE as a method in the assessment of proper ETT placement.

Ultrasonography for endotracheal tube position in infants and children

Ultrasonography (US) has been shown to be effective for verifying endotracheal tube (ETT) position in adults but has been less studied in infants and children. We review the literature regarding US for ETT positioning in the pediatric population. A literature search was conducted using the Ovid and MEDLINE databases with search terms regarding US relating to ETT intubation and positioning in infants and children. Most studies in neonates and infants used the midsagittal suprasternal view. Studies reported >80% visualization of the ETT tip by US, and US interpretation of the ETT position correlated with the XR position in 73-100% of cases. Studies of older children used the suprasternal views, substernal views, and mid-axillary intercostal views. US appears comparable to XR and capnography in determining ETT position in this population.

CONCLUSION

US for ETT verification appears to be well tolerated in infants and children and may augment determination of proper ETT position in combination with other ETT verification modalities. Further studies are needed regarding technique and training. What is Known: • Point-of-care ultrasonography is realizing increased availability and use in several pediatric specialties. • Ultrasonography has been shown to be effective for verifying ETT position in adults but have been less studied in infants and children. What is New: • Ultrasonography for endotracheal tube verification appears to be well tolerated in infants and children. • Ultrasonography may augment determination of proper endotracheal tube position in combination with other verification modalities such as radiography and capnography in the pediatric population.

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.

End-tidal capnography and upper airway ultrasonography in the rapid confirmation of endotracheal tube placement in patients requiring intubation for general anaesthesia

Background and Aims:

Confirmation of correct endotracheal tube placement is essential immediately after intubation for general anaesthesia. In this study, we have compared upper airway ultrasonography (USG) with reference to capnography for rapid confirmation of endotracheal tube placement after general anaesthesia.

Methods:

A prospective, single centre, observational study was conducted on 100 patients requiring tracheal intubation for general anaesthesia. Both capnography and upper airway USG were performed immediately after intubation to confirm the endotracheal tube (ETT) placement. Sensitivity, specificity, and positive and negative predictive values of upper airway USG were determined against capnography as the reference method. Agreement between the methods and time required to determine ETT placement by the two methods were assessed with kappa statistics and Student's t-test.

Results:

Upper airway USG detected all five cases of oesophageal intubation, but could not detect five patients with correct tracheal intubation. Upper airway USG had a sensitivity of 96.84% (95% confidence interval [CI]: 94.25%–96.84%), specificity of 100% (95% CI: 50.6%–100%), positive predictive value of 100% (95% CI: 97.3%–100%) and negative predictive value of 62.5% (95% CI: 31.6%–62.5%). Kappa value was found to be 0.76, indicating a good agreement between upper airway USG and capnography for confirmation of ETT placement. Time taken for confirmation of ETT by capnography was 8.989 ± 1.043 s vs. 12.0 ± 1.318 s for upper airway USG (P < 0.001).

Conclusion:

Both capnography and upper airway USG may be used as primary procedures for the confirmation of ETT placement.

Sonography for Complete Evaluation of Neonatal Intensive Care Unit Central Support Devices: A Pilot Study

OBJECTIVES

Neonates in the neonatal intensive care unit often require considerable support with endotracheal tubes, umbilical arterial and venous catheters, and peripherally inserted central venous catheters. Support device evaluation with radiography exposes neonates to ionizing radiation. This study evaluated the effectiveness of sonographic localization for endotracheal tubes, umbilical arterial and venous catheters, and peripherally inserted central venous catheters.

METHODS

This blinded prospective Institutional Review Board-approved, Health Insurance Portability and Accountability Act-compliant study with informed consent compared sonography to radiography for endotracheal tube, umbilical arterial and venous catheter, and peripherally inserted central venous catheter localization. Participants were consecutively recruited NICU patients of any weight, gestation, and chronologic age who had an endotracheal tube, umbilical arterial catheter, umbilical venous catheter, or peripherally inserted central venous catheter placed or adjusted and had subsequent radiographic confirmation within 24 hours. Sonographic evaluation was obtained as soon as possible, without prior review of the radiograph, and results were compared.

RESULTS

Thirty sonographic studies were performed in 25 patients (14 male and 11 female), for a total of 50 lines and tubes: 18 umbilical venous catheters, 12 umbilical arterial catheters, 11 peripherally inserted central venous catheters, and 9 endotracheal tubes. Forty-nine support devices (98%) were visualized with sonography, all concordant with radiography. Forty-four were correctly positioned, and 6 were malpositioned. Sonography identified the location of umbilical venous catheters in all 18 cases (100%), umbilical arterial catheters in all 12 (100%), peripherally inserted central venous catheters in 10 (91%), and endotracheal tubes in 9 (100%).

CONCLUSIONS

The effectiveness of sonography was excellent for evaluation of umbilical arterial and venous catheters, endotracheal tubes, and peripherally inserted central venous catheters. These results support the goal of further point-of-care training and accreditation to use sonography as a primary modality for complete evaluation of NICU support devices.

Verification of endotracheal tube placement using electrical stimulation through electrodes placed on the endotracheal tube cuff

BACKGROUND

Current methods for verification of endotracheal intubation can fail, particularly in emergency settings. We investigated whether a verification method using electrical stimulation through electrodes placed on the endotracheal tube cuff could distinguish endotracheal and esophageal intubations in an experimental setting.

METHODS

During three sequential sessions simulating emergency intubation without paralysis, rapid sequence intubation (RSI) with neuromuscular blockade, and intubation during cardiopulmonary resuscitation, eight pigs were intubated with an endotracheal tube fitted with two electrodes exposed on the cuff of the tube, first in the esophagus and next in the trachea or in reverse sequence. Cuff pressure was monitored during a 5-s electrical stimulation (20 mA, 80 Hz, 500 μs), and delta pressure was calculated as the difference between baseline cuff pressure and maximum cuff pressure during the electrical stimulation.

RESULTS

Delta pressure was significantly higher in esophageal than in tracheal placements in all three sequential sessions (86.0 [78.3-89.7] vs. 6.5 [2.0-7.9] mmHg, P = 0.001; 16.6 [13.2-22.8] vs. 0.8 [0.3-2.6] mmHg, P = 0.004; 66.1 [60.0-84.7] vs. 2.7 [0.7-9.7] mmHg, P = 0.001). The delta pressure did not overlap between tracheal and esophageal intubations except for the session simulating RSI with neuromuscular blockade, in which one of eight esophageal placements showed a delta pressure within the delta pressure range of tracheal placements.

CONCLUSION

Electrical stimulation through electrodes placed on the endotracheal tube cuff produced remarkably greater increases in cuff pressure in esophageal intubations than in tracheal intubations in an experimental setting.