Original Research
The Effectiveness of Out-of-Hospital Use of Continuous End-Tidal Carbon Dioxide Monitoring on the Rate of Unrecognized Misplaced Intubation Within a Regional Emergency Medical Services System

https://doi.org/10.1016/j.annemergmed.2004.09.014Get rights and content

Study objective

We evaluate the association between out-of-hospital use of continuous end-tidal carbon dioxide (etco2) monitoring and unrecognized misplaced intubations within a regional emergency medical services (EMS) system.

Methods

This was a prospective, observational study, conducted during a 10-month period, on all patients arriving at a regional Level I trauma center emergency department who underwent out-of-hospital endotracheal intubation. The regional EMS system that serves the trauma service area is composed of multiple countywide systems containing numerous EMS agencies. Some of the EMS agencies had independently implemented continuous etco2 monitoring before the start of the study. The main outcome measure was the unrecognized misplaced intubation rate with and without use of continuous etco2 monitoring.

Results

Two hundred forty-eight patients received out-of-hospital airway management, of whom 153 received intubation. Of the 153 patients, 93 (61%) had continuous etco2 monitoring, and 60 (39%) did not. Forty-nine (32%) were medical patients, 104 (68%) were trauma patients, and 51 (33%) were in cardiac arrest. The overall incidence of unrecognized misplaced intubations was 9%. The rate of unrecognized misplaced intubations in the group for whom continuous etco2 monitoring was used was zero, and the rate in the group for whom continuous etco2 monitoring was not used was 23.3% (95% confidence interval 13.4% to 36.0%).

Conclusion

No unrecognized misplaced intubations were found in patients for whom paramedics used continuous etco2 monitoring. Failure to use continuous etco2 monitoring was associated with a 23% unrecognized misplaced intubation rate.

Introduction

Endotracheal intubation is considered standard of care in the United States for management of out-of-hospital respiratory failure. Emergency medical services (EMS) personnel in the United States perform this procedure routinely under difficult and uncontrolled conditions not encountered when endotracheal intubation is performed in a hospital setting. The most serious complication associated with endotracheal intubation in the out-of-hospital setting is unrecognized misplaced intubation. Unrecognized misplaced intubation has been documented as an issue in EMS since 1984, with early studies showing a unrecognized misplaced intubation rate of 0.4% to 8%.1, 2, 3, 4, 5, 6, 7, 8 A previous study from 1997, conducted at the same regional Level I trauma center emergency department (ED) as our study, reported an unrecognized misplaced intubation incidence of 25%.9 Most recently, unrecognized misplaced intubation rates of 7% and 10% have been reported.10, 11, 12 Although these descriptive studies of out-of-hospital systems documented the rate of unrecognized misplaced intubation, none were designed to evaluate the association between a specific intervention and the rate of unrecognized misplaced intubation.

Identifying processes or interventions that could affect the rate of unrecognized misplaced intubation is a critical step toward eliminating this problem in EMS systems. End-tidal carbon dioxide (etco2) monitoring has been recommended as a standard practice for reducing unrecognized misplaced intubation in the out-of-hospital setting. etco2 confirmation of tube placement and continuous monitoring of endotracheal tube position is an accepted standard of care by the American Society of Anesthesiologists13 and is recommended by the American Heart Association for secondary confirmation of endotracheal tube placement.14 As a result, use of etco2 monitoring has gained acceptance in emergency medicine and EMS.

We studied the effectiveness of continuous etco2 monitoring on the incidence of unrecognized misplaced intubation within a regional EMS system. We hypothesized that the use of continuous etco2 monitoring would be associated with a lower rate of unrecognized misplaced intubation. Our primary outcome measure was the rate of unrecognized misplaced intubations.

Section snippets

Study Design and Setting

A prospective observational study was conducted during a 10-month period (March to December 2002) on all patients arriving at a regional trauma center ED who underwent out-of-hospital endotracheal intubation. The study ED is a Level I trauma center, geographically located within a designated regional trauma service area. This ED treats pediatric and adult patients and receives patients from numerous EMS agencies operating within this multicounty regional EMS system. During the study period,

Characteristics of Study Subjects

During the study period, 248 patients who received airway management in the out-of-hospital setting arrived at the study ED. One hundred fifty-three patients arrived with an endotracheal tube in place and were eligible for the study. Ninety-five patients received other means of airway management and were excluded from the study (bag-valve-mask: 79, laryngeal mask airway: 8, Combitube: 6, cricothyrotomy: 2). Data from 153 consecutive patients who arrived with an endotracheal tube in place were

Limitations

The limitations of our study include lack of randomization, not controlling for confounding variables, and paramedic self-reporting. The lack of randomization affects the ability to determine the independent effect of continuous etco2 monitoring on misplaced intubations. However, given standards used for capnography in the operating room and American Heart Association Guidelines 2000, we thought that withholding etco2 monitoring from one group in a truly randomized design would present

Discussion

Endotracheal intubation is an established standard of care for the management of respiratory failure in the out-of-hospital setting. Determining the safety and efficacy of this procedure has been problematic in EMS because of the lack of a consistent and objective database that eliminates the errors of EMS provider self-reporting. Studies performed using physician confirmation of endotracheal tube position on ED arrival have reported high rates of unrecognized misplaced intubations (7% to 25%).9

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    Author contributions: SS, GAR, and JT conceived the study and designed the trial. SS, GAR, JT, and JF developed the study protocol and data collection forms. SS, GAR, EC, and JF supervised the conduct of the trial and data collection. EC and AS ensured completeness of patient enrollment data forms. AS established and managed the database, including quality control. BK and SGR provided statistical consultation on the data analysis. SS and GAR chaired the data oversight committee. SS, GAR, and BK drafted the manuscript, and all authors contributed substantially to its revision. SS takes responsibility for the paper as a whole.

    Funding and support: Dr. Krauss is a consultant for Oridion Medical, a capnography manufacturer.

    Presented at the Society for Academic Emergency Medicine annual meeting, Boston, MA, May 2003.

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