Misplaced endotracheal tubes by paramedics in an urban emergency medical service system

Also posted over at Rogue Medic and at Research Blogging.

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We don’t need to improve airway management. We were placing tubes correctly 30 years ago without waveform capnography, so we certainly don’t need any technology to substitute for a competent assessment.

Right?

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Placement of endotracheal tubes (ETTs) in the field by paramedics is a well-accepted out-of-hospital procedure used to obtain definitive airway control. Several studies have reported the incidence of unrecognized, misplaced endotracheal intubations in the field to be low, typically 1% to 5% ^1-5 (Table 1). In the majority of these studies, verification of tube placement was performed in the field. It was our clinical impression before conducting our study that the incidence of patients with misplaced ETTs on arrival to our emergency department was substantially higher than that reported in the literature. To our knowledge, no study had investigated the actual incidence of misplaced ETTs on patient arrival to an ED.^[1]

Here is a study that sets out to determine if one part of my statement is correct. Were we correctly placing endotracheal tubes before we even had the fancy technology of waveform capnography?

Click on images to make larger.

These results suggest that there is not a huge problem with the ability of paramedics to recognize the correct placement of endotracheal tubes. The rate of unrecognized esophageal intubation should be zero, but these are close and zero might be within reach even without waveform capnography.

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Trauma patients were significantly more likely to have misplaced ETTs than medical patients (37% versus 14%, P<.01). With one exception, all the patients found to have esophageal tube placement exhibited the absence of ETCO₂ on patient arrival. In the exception, the patient was found to be breathing spontaneously despite a nasotracheal tube placed in the esophagus.^[1]

We assume that what we are doing is helping patients.

We have a bias toward treating, rather than benign neglect.

We are repeatedly told that we need to do everything we can do.

In the exception, the patient was found to be breathing spontaneously despite a nasotracheal tube placed in the esophagus.

This patient did not survive to the hospital because of EMS.

This patient survived to the hospital in spite of EMS.

What more could EMS have done to this patient to find out how much it will take to kill the patient? We are only limited by our imagination.

What could EMS have done to minimize the harm to the 25% of patients with misplaced tubes?

One of the problems is too much treatment and not enough discretion.

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In the group of patients found to have tube placement in the hypopharynx, 44.4% (4/9) exhibited the absence of ETCO₂ on patient arrival.^[1]

These are the patients more likely to actually have the tube dislodged by movement. The tube is not that far from the right place. These patients may have oxygen delivered to the lungs, but the lack of ETCO₂ suggests that the CO₂ is not being removed by a tube just above the vocal cords.

How low were the patients’ pH levels due to the inability to remove CO₂?

How many of these patients were not capable of producing CO₂ at high enough levels to register ETCO₂ levels?

How many of these patients would have survived if EMS had not done all it could?

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The incidence of unrecognized, misplaced endotracheal intubations in the present study is alarming, and substantially higher than in previously reported series. We believe there may be several explanations for this discrepancy. All of the previously published series^1-5 were conducted in EMS systems directed by academic EMS directors with tightly controlled oversight of paramedic training and practice. Evaluation occurred in the field with researchers present during the procedures. Eligible patients included only selected subsets of the total intubated populations. In the previous studies, the status of tube position at EDD arrival was not reported.^[1]

In the last sentence, EDD should probably be ED (Emergency Department).

My reading of this is –

Absentee medical directors kill.

I do not mean that the lack of involvement of medical directors is the sole cause of these iatrogenic deaths, but I do not see any way of expecting any good outcome from authorizing intubation by personnel with minimal training and continuing education that makes the initial minimal training seem exhaustive. This is not oversight.

At least there is interest in improving things in this system.

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But is waveform capnography needed?

Endotracheal intubation is a psychomotor skill. Even under ideal conditions with the procedure performed by qualified anesthesiologists, it may be difficult to recognize esophageal intubations.¹² Adverse conditions in the field may make intubation even more difficult than in a hospital setting. Skill levels of various paramedic providers within a community may differ sharply.²⁰ Assessing tube position after intubation in this setting requires rigorous training and adherence to protocol.^11,16 Standard physical assessment techniques for verifying tube placement may be unreliable.^12,14,17 Auscultation over the chest can fail to detect esophageal placement in 15% of patients, and fogging of the tube has been shown to be present in 85% of esophageal intubations.^14[1]

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WWAD?

What Would Anesthesiologists Do?

After all, if we are going to claim that what we are doing is right, shouldn’t we look at what is done by those most experienced at intubation?

ETCO₂ monitoring is routinely used by anesthesiologists to verify proper ETT position. Since 1990, the American Society of Anesthesiologists has considered this to be the standard of care in the operating room, and has now extended that standard to include all anesthetic practice irrespective of geographic location.^10[1]

Irrespective of geographic location?

Not just in the OR (Operating Room).

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The rate of unrecognized, misplaced ETTs found in our community is alarmingly high. There are several factors that may have contributed to this problem. Despite written protocols requiring the out-of-hospital use of ETCO₂ devices in our community, we anecdotally found their use to be sporadic. To avoid the Hawthorne effect, we chose not to query paramedics regarding verification techniques used in the field. Accordingly, we were unable to document the frequency of field ETCO₂ device use during the study period.^[1]

we anecdotally found their use to be sporadic.

In other words –

We don’t know how often ETCO₂ is measured, but we do know that it is not enough.

Is it 90%?

Is it 50%?

Is it 10%?

The only thing we can tell from the term sporadic is that it is not 100% and it is not 0%.

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A significant limitation of the study was the lack of uniformity of direct laryngoscopy on all tube verifications. All but 4 of the tubes deemed to be misplaced were confirmed by laryngoscopy. In each of these 4 cases, there was vomitus in the ETT and absent breath sounds on examination. The attending physician in each case promptly removed the tube and replaced it. In each of these cases, tube placement was deemed esophageal.^[1]

Unless there is a good reason to believe that the vomitus is coming from the lungs, removing the tube should be the highest priority.

On the other hand, I have seen a paramedic recognize an esophageal intubation, decide to leave the esophageal tube in place, and move the patient from the floor of a clean home to the ambulance before doing anything to correct the esophageal intubation. Getting the patient to the hospital was considered more important than providing a patent airway.

One shortcoming not mentioned is that the assessment of tube placement was probably done on the ED stretcher after movement. the proper place to assess the placement of the tube by EMS is on the EMS stretcher. I do not believe that tubes are dislodged frequently by this movement, but the number dislodged by moving the patient to the ED stretcher should not be assumed to be zero just because the movement happens in the hospital.

We should be reassessing the placement of the tube with every movement, so it should only be after EMS reassesses the tube placement that the emergency physician is allowed to assess the tube. Even so, unless they are lifting the patient by the tube, this should not produce a significant number of intubations. The problem is that this introduces an uncontrolled variable. This is an easily controlled variable, but it does not appear to have been controlled for.

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Our data may differ from data in the EMS literature because this is one of the few studies undertaken in an EMS system not organized and run by academic emergency physicians with strong out-of-hospital care training and interest. No one is comfortable in reporting difficulty and poor performance in patient care activities. These data may be reflective of an unspoken, pervasive national problem in serious need of attention. Accordingly, we urge our colleagues across the country to review their experience in their own communities.^[1]

How many systems do not measure their intubation failure rate, or their unrecognized esophageal intubation rate?

If we do not know what the intubation failure rate is in our system, we cannot honestly claim that we are not killing patients.

If we do not know what the unrecognized esophageal intubation rate is in our system, we cannot honestly claim that we are not killing patients.

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Footnotes:

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^[1] Misplaced endotracheal tubes by paramedics in an urban emergency medical services system.
Katz SH, Falk JL.
Ann Emerg Med. 2001 Jan;37(1):32-7.
PMID: 11145768 [PubMed - indexed for MEDLINE]

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