Original Contribution
How stylet use can effect confirmation of endotracheal tube position using ultrasound

https://doi.org/10.1016/j.ajem.2008.09.024Get rights and content

Abstract

Introduction

None of the techniques used for confirmation of endotracheal tube (ET) placement are proven reliable 100% of the time. The purpose of our study is to determine whether ultrasound can accurately detect the passage of ET through the trachea and esophagus and to see whether this visualization is augmented with the use of a metal stylet.

Methods

A total of 7 physicians made assessments of ET positions using an ultrasound during their passage through the trachea or esophagus. A total of 40 esophageal and 40 tracheal intubations were performed randomly in a blinded fashion on a fresh, unfrozen human cadaver. Half were performed with a metal stylet and the other half without a stylet.

Results

During transtracheal assessment regardless of stylet use, correct identification of ET position was achieved in 275 of 280 esophageal intubations and 268 of 280 tracheal intubations. The overall sensitivity was 95.7%, and specificity was 98.2%. The presence and the absence of stylet was identified in 109 of 280 and in 155 of 280 attempts, respectively. Correct identification of stylet presence yielded a sensitivity of 38.9% and a specificity of 55.4%.

Ultrasound can be used by emergency physicians to accurately detect the passage of ET through the trachea and esophagus; however, stylet use did not augment ET visualization.

Introduction

Esophageal intubation is more likely to occur in critical care environments such as emergency departments (EDs). It may be rapidly fatal if it is not recognized in a proper and timely manner. The properly placed endotracheal tube (ET) provides a definitive protected airway and is vital for ensuring adequate ventilation in the event of cardiac arrest, respiratory failure, or significant trauma. However, recent studies in an urban emergency medical system found that up to 25% of medical or pediatric and adult trauma patients had esophageal intubations on presentation to the ED [1], [2].

There are numerous methods to confirm the position of the ET as follows: detection of exhaled CO2 by capnography (qualitative/quantitative), direct visualization of the ET passing through the vocal cords, revisualization with direct laryngoscopy, gurgling over the epigastrium, auscultating breath sounds, fogging in the ET, esophageal detection device, visualization of chest movement, pulse oximetry, and chest radiograph [3].

Although numerous techniques have been described to confirm ET placement, there is no perfect confirmation tool, and many methods are less reliable or some are unavailable in the ED. A meta-analysis demonstrated capnography to be only 93% sensitive [4]. In addition, detection of end-tidal CO2 by either capnography or colorimetric measurement depends on adequate pulmonary blood flow. Therefore, it is unreliable in patients with cardiac arrest or those in a low-flow state, with a sensitivity of only 72% [5]. Secretions, blood, and anatomical variations can obscure the direct visualization of the trachea and vocal cords. Listening over the epigastrium may be helpful but cannot provide the proper positioning with 100% sensitivity and specificity. Auscultation of lungs to verify for breath sounds may be limited if the patient is an infant or a small child. Fogging in the ET can occur even with esophageal intubation [6]. Esophageal detection device can be misinterpreted in patients with morbid obesity, late pregnancy, status asthmaticus, or copious tracheal secretions [7].

Ultrasound (US) is being used by the emergency physicians for a variety of conditions. Virtually all foreign bodies are hyperechoic and appear as bright structures that are distinct from their surrounding tissues. Disposable plastic ET and metal stylets produce acoustic shadowing and reverberation or comet-tail artifacts, which can facilitate visualization [8].

In this study, we sought to determine if US can accurately detect the passage of the ET through the trachea or esophagus in real time fresh cadaver model and if this visualization is augmented with the use of a metal stylet.

Section snippets

Materials and methods

This prospective randomized trial was done using only one human cadaver model in the cadaver laboratory of a university hospital. A total of 7 physicians, 1 faculty physician of the Department of Emergency Medicine and 6 residents of various postgraduate years, participated in the study. Two residents from the first and the third years and 1 resident from the second and forth years were recruited. All physicians were experienced with the use of US in daily practice. Participants were given a

Results

In this study, 6 emergency medicine residents (2 first year, 1 second year, 2 third year, and 1 fourth year) and a faculty emergency physician completed 80 (20 esophageal without stylet, 20 tracheal without stylet, 20 tracheal with stylet, 20 esophageal with stylet) assessments of ET placement by placing a probe over the transtracheal region above the sternoclavicular notch.

During transtracheal assessment regardless of stylet use, correct identification of ET position was achieved in 275 of 280

Discussion

None of the techniques used for confirmation of ET placement is proven reliable 100% of the time. Although the direct visualization of the ET passing through the vocal cords is said to be the gold standard, it still requires firm evidence of correct placement and needs to be verified with other techniques. The American College of Emergency Physicians Policy Statement recommends the confirmation of ET position with additional techniques before securing the airway [3]. These techniques can be

Acknowledgment

This study was supported by Akdeniz University Foundation.

References (9)

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