Chapter 22

Endotracheal intubation can be one of the more challenging tasks in emergency medicine and critical care. Misplacement of the tube, most often into the right main stem bronchus or esophagus, has been reported in up to 8% of cases in the literature. Secondary confirmation of tube placement also presents various challenges to the practitioner. Traditionally, direct visualization of the endotracheal tube followed by at least one or more secondary confirmations is required to confirm tube placement. End-tidal colorimetric devices are most frequently used in the acute care setting, as well as auscultation of the thorax and epigastrium. Esophageal bulb detectors, visualization of mist in the endotracheal tube, and bilateral chest rise are also employed. Each of these techniques and devices has specific limitations and pitfalls. Bedside ultrasound may also be used to dynamically observe tube passage into the trachea or esophagus, providing an additional method of confirmation. Following successful intubation, bedside ultrasound may also be used to visualize the presence of bilateral lung sliding and comet-tail artifact, additional indicators of correct placement, and lung expansion post-intubation.

Bedside ultrasound is a rapid and reliable way to confirm proper endotracheal intubation. Sensitivity and specificity are high, especially when compared to end-tidal colorimetry in the acute care setting.

Direct ultrasound visualization of the endotracheal tube passing through the trachea may be particularly helpful for physicians who are supervising a trainee performing an intubation, allowing real-time confirmation of correct placement. Bedside ultrasound gives the senior physician the ability to instantly determine the location of the endotracheal tube, prior to bagging one that is incorrectly placed into the esophagus.

Bedside ultrasound evaluation of endotracheal intubation should be performed in:

• Any patient undergoing intubation, including pediatrics and trauma, if a difficult airway is anticipated
• Training situations, where a physician is supervising a less-experienced performer

### Linear Probe with a Frequency of 6.0–12.0 MHz

To visualize the trachea and thorax, a linear probe with a high frequency such as 6.0–12.0 MHz should be utilized. A lower frequency, microconvex or curvilinear probe may be helpful in more obese patients.

### Machine Preset

The machine should be set to a superficial or small parts setting.

### Focal Zone

The focal zone should be placed at the depth of the trachea or pleural line in order to optimize the lateral resolution.

### Time-Gain Compensation

The far gain or time-gain compensation may need to be adjusted in order to enhance and brighten signals returning to the machine monitor. This will help the sonographer observe the shadow created by the tracheal cartilage and endotracheal tube in the far field.

### Depth

An image that is either too deep or too shallow can be disorienting. Generally, it is better to start deeper than necessary, and once the appropriate anatomy ...

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