22.8i Verification of Proper Tube Placement

It is absolutely imperative that endotracheal placement of the tube be objectively confirmed immediately after placement and continuously throughout care, particularly if the patient is moved or deteriorates.

You should employ a number of methods in the field to confirm correct ETT placement.

The patient’s clinical condition should be the deciding factor in your patient management decisions.

Continually assess your patient’s clinical condition.

Countless EMS airway disasters related to unrecognized esophageal intubation have occurred.

The common theme in these situations is excessive confidence, inappropriate reliance on subjective measures, and ignoring or not using waveform capnography.

Subjective methods of tube placement confirmation include direct visualization, tube misting, and auscultation for breath sounds.

Well-performed EMS studies have demonstrated that reliance on subjective means alone results in a 10 to 20 percent rate of missed esophageal intubations.

Therefore you should not rely solely on subjective observations for confirmation of correct tube placement although they are important when combined with other methods.

Some subjective methods follow.

Direct visualization.

Although you must see the tube pass through the cords, this method of tube confirmation has failed for at least three possible reasons.

First, in the emergency situation, visualization of the tube’s passage through the cords is often unsatisfactory as a result of patient immobilization, positioning, or blood/vomitus in the airway.

Second, the tube itself often obscures visualization.

Third, even if the tube is observed to pass through the cords, it can become dislodged when the stylet is removed and/or if end-tidal and BVM are attached before the tube has been secured.

Video laryngoscopy allows multiple practitioners to visualize tube placement, which increases the value of direct visual confirmation, but this is still not perfect.

For these reasons, direct visualization alone cannot be relied on to confirm tube placement.

Tube misting.

Observing mist or condensation in the tube, or a “vapor trail,” has long been held as a means to confirm tracheal placement of the tube, but it is not reliable.

There have been many cases of a vapor trail noted with an esophageal intubation as well as cases when the vapor trail is missing with a correctly placed tracheal tube.

Never make any decisions on tube placement based solely on tube misting.

Auscultation.

After intubation, breath sounds should be checked bilaterally and compared with pre-intubation breath sounds unless ambient noise makes this impossible.

Sounds should be present bilaterally if they were present bilaterally before intubation.

Newly diminished sounds on the left with strong breath sounds on the right strongly suggest right mainstem intubation.

Absence of sounds over the epigastrium should be confirmed.

(Epigastric sounds suggest esophageal placement.) It is important to recognize that breath sounds have proved unreliable many times.

This is particularly common in children (sounds are easily transmitted throughout the pediatric thorax), in patients who are obese, and in those with lung pathology.

Like the other subjective means of tube confirmation, breath sounds should be neither relied on entirely nor ignored.

As another subjective finding, the rise and fall of the chest indicates correct endotracheal intubation.

As the number of obese patients increases, however, it becomes more difficult to determine chest rise and fall.

Worsening gastric distention can indicate esophageal placement.

Any gastric distention should be investigated.

Remember, though, that it is not uncommon for gastric distention to develop prior to endotracheal intubation from mechanical ventilation.

Even in experienced hands, it is very difficult to avoid gastric distention with mechanical ventilation until an endotracheal tube is placed.

Objective methods of tube confirmation include capnography, esophageal detector device (EDD), endotracheal tube introducer, and pulse oximetry.

Remember that objective methods such as these must be used in addition to subjective observations to confirm proper tube placement.

Use of four-phase waveform end-tidal CO2 (capnography) is the gold standard for tube confirmation.

Concern that patients in cardiac arrest will not produce any detectable CO2 is likely misplaced.

Recent literature has documented sustained ETCO2 values in intubated cadavers.

In the absence of a four-phase waveform capnograph, we must assume that the tube is not in the trachea.

Case studies have reported deaths that incorrectly described the lack of waveform capnography seen as being caused by cardiac arrest, not the esophageal intubation that, in fact, was present.

As detailed previously, there are two types of end-tidal CO2 detection: qualitative (indicating only whether CO2 is present or absent) and quantitative (providing a measure, usually with a waveform for analysis, of how much CO2 is present).

While waveform capnography (a quantitative procedure) is the gold standard for tube placement confirmation, qualitative detectors are still often used in clinical practice.

The quantitative detectors are better for ongoing monitoring, especially during air medical transport where clinical means are limited.

Waveform detectors produce virtually no false positive readings.

This means that if the quantitative waveform detector says that CO2 is present, then you are not in the esophagus.

Keep in mind, however that you might be above the trachea in the hypopharynx.

Esophageal detector device.

Use of an EDD is another means of objective tube verification; however, its use has fallen out of favor given the ready availability and superior performance of waveform capnography.

A syringe device or bulb is placed on the end of the endotracheal tube to create suction (Figure 22-90).

If the tube is correctly placed in the trachea, the cartilaginous rings keep the trachea patent when suction is applied, so there is rapid air return into the device.

If the tube is incorrectly placed in the esophagus, the soft distensible tissues occlude the end of the tube when suction is applied, so air return does not occur or occurs very slowly.

Though principally used to facilitate difficult intubations, an endotracheal tube introducer (bougie) can be used in addition to waveform capnography to confirm tube placement.

When a well-lubricated introducer is passed through an endotracheal tube that is correctly placed in the trachea, you should be able to feel it “hold up” (meet resistance) in the smaller airways within approximately 40 cm of the teeth or about 50 cm from the tube end.

(It has been said that you should also be able to feel “clicks” as the introducer passes over the tracheal rings.

However, clicks may not be detectable because the tube bypasses most of the large rings of the trachea.) Absence of hold-ups at the depth where you would expect to feel them with a tracheal placement is an indication of incorrect esophageal placement.

Pulse oximetry readings can be a late indicator of tube placement.

As noted earlier, pulse oximetry values are a lagging indicator of actual SpO2.

A patient who has falling saturations and then is successfully intubated (as confirmed by waveform ETCO2) will continue to have falling SPO2 levels for some time despite correct ETT placement.

Likewise, a high SPO2 level (as in a well preoxygenated patient) can remain high for some time despite having a known esophageal intubation.

For these reasons, pulse oximetry should always be only an adjunct to other methods, including waveform ETCO2.