You have devoted a considerable amount of time and energy in training to be comfortable in airway management. As part of the care of the intubated patient, you want to make sure the endotracheal tube is correctly placed in the trachea and your patient’s airway is secure.

Verification of endotracheal tube placement is imperative for the oxygenation, ventilation, and airway protection of your patient. A tube in the esophagus, or in the hypopharyngeal space, may be incorrectly thought to be in position and may place your patient at undue risk of hypoxemia or aspiration.

Therefore, confirmation of proper endotracheal tube placement should be completed in all patients at the time of initial intubation. Unfortunately, at this time no technique used for confirmation of endotracheal tube placement has been proven to be 100% accurate.^1-7

A variety of techniques may enhance your ability to confirm airway placement; comfort with these techniques is essential to your practice.

Visualization of the endotracheal tube passing through the vocal cords remains the optimal method for initial endotracheal tube placement. Unfor-tunately, direct visualization is not always possible, especially in the anatomically difficult airway or an airway that is obscured by blood, secretions, or vomitus.

Other physical examination methods such as auscultation of the lungs and epigastrium, visualization of bilateral chest rise, and fogging of the tube may be helpful but are not sufficiently reliable to confirm placement of the tube between the vocal cords.

What makes confirmation even more difficult is that esophageal intubation may remain undetected despite chest radiography and pulse oximetry results that appear to confirm proper tube placement.^1-7

These methods cannot exclude esophageal intubation in all situations, and for this reason, additional methods should be used to verify correct initial placement of the endotracheal tube.

Techniques to Confirm Tube Placement

To supplement traditional methods, a variety of additional techniques and commercially available products help to identify misplaced tubes.

These include repeat direct laryngoscopy, qualitative and quantitative end-tidal carbon dioxide detection, esophageal detector devices, and, most recently, ultrasound, and transthoracic impedance.^8-21

The use of repeat direct laryngoscopy is invasive and impractical for continuous or frequent repetitive monitoring, because it may require repeat dosing of sedatives and paralytics.

Furthermore, if direct visualization of the tube was not possible initially, this method may not be confirmatory.

End-tidal carbon dioxide detection offers the best alternative for confirmation of endotracheal tube placement.

While the qualitative end-tidal carbon dioxide method gives a good initial assessment of tube position in the patient with adequate perfusion, quantitative and continuous carbon dioxide detection is a preferred method for the continuous monitoring of proper tube location.

This technique is relatively simple and requires a capnography device connected to the ventilator. The device will record ventilatory carbon dioxide quantitatively with a waveform on a monitor.

In a patient with good circulation and perfusion, the lack of end-tidal carbon dioxide delivery should immediately alert one to the misplacement or dislodgement of the endotracheal tube.

This method has been utilized in the operating room for some time, and has made its way both to the emergency department and prehospital setting for intubation as well as procedural sedation.

Capnography is a simple method to assure continuous tube placement and approaches 100% sensitivity and specificity in the patient with spontaneous circulation.

Confirmation of endotracheal tube placement in patients with poor circulatory perfusion, particularly those in cardiac arrest or with recent return of spontaneous circulation, can be difficult.

Essentially all reported occurrences of a correctly placed endotracheal tube without detection of exhaled carbon dioxide have occurred in the setting of a low perfusion state or that of pulmonary edema.^8-13

In these patients, delivery of carbon dioxide to the lungs may be insufficient to produce reliable confirmation, and alternative confirmation techniques may be necessary.

Esophageal detector devices have limited utility as a technique for endotracheal tube position assessment. While these devices are generally easy to use, are inexpensive, and have demonstrated reasonable utility in detecting esophageal intubations, there are a number of situations in which they have not been shown to be entirely accurate.

Erroneous findings can be observed in obese patients, those with a large amount of air in the esophagus or stomach, and patients with copious pulmonary secretions.^14-16

In addition, esophageal detector devices do not allow ongoing assessment of continued proper tube location.

For these reasons, esophageal detector devices are not routinely recommended, particularly as a sole method for confirmation of endotracheal tube placement.

New techniques such as ultrasound imaging and transthoracic impedance methods offer potential in the detection and monitoring of the proper location of the tube.^17-21

Although these techniques currently may be helpful as adjuncts, they are relatively unproven and may not be widely available.

Ultimately, the evidence is currently insufficient to endorse widespread implementation of these technologies for this purpose.

Intubated patients often require procedures, repositioning, transport, and other movement while in the emergency department.

These events create a substantial potential for dislodgement of the endotracheal tube. Given the increased frequency of movements and transport in the emergency and acute care setting, assessment techniques for tube position should be used frequently.

Continuous endotracheal tube monitoring, such as with capnography, is recommended to assure prompt detection of endotracheal tube dislodgement from the trachea.

If the equipment for continuous monitoring of endotracheal tube position is not available, other methods should be used.

At a minimum, endotracheal tube placement should be recon-firmed promptly if the patient’s condition deteriorates but preferably before such a condition materializes.

Summary

At the time of initial intubation, proper endotracheal tube location should be verified for all patients. Failure to do so can lead to poor ventilation and oxygenation, and ultimately patient injury.

Several techniques exist to assure proper placement.

Chest and abdomen auscultation, pulse oximetry, chest radiography, and esophageal detector devices are helpful but have not been shown to be accurate in 100% of clinical encounters.

In the patient who has adequate tissue perfusion, these techniques are not comparable to end-tidal carbon dioxide assessment for the verification of endotracheal tube placement.

End-tidal carbon dioxide assessment is the preferred method for initial verification and continuous monitoring to assure proper location of the endotracheal tube.

The patient with poor perfusion offers unique challenges and additional techniques are typically necessary in these patients.

Other techniques for assessment of endotracheal tube location, such as ultrasound imaging and transthoracic impedance offer potential for the future. However, they are not currently endorsed for widespread implementation.

References

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18. Bhende M.S., Thompson A.E., Cook D.R., et al. Validity of a disposable end-tidal CO₂ detector in verifying endotracheal tube placement in infants and children. Ann. Emerg. Med. 1992;21:142-5.
19. Ornato J.P., Shipley J.B., Racht E.M., et al. Multicenter study of a portable, hand-size, colorimetric end-tidal carbon dioxide detection device. Ann. Emerg. Med. 1992;21:518-23.
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