Abstract
Background Endotracheal intubation (ETI) is the gold standard for the out-of-hospital emergency airway management in severely injured patients. Due to time-critical circumstances, poor patient presentation and hostile environments, it may be prone for mechanical complications and failure.
Methods In a retrospective study (January 2011 to December 2013), all patients who underwent out-of-hospital ETI before admittance to a level 1 trauma center were analyzed consecutively. Patients with supraglottic airways, being under cardiopulmonary resuscitation and interfacility transports were excluded. The main study endpoint was the incidence of unrecognized tube malposition; secondary endpoints were Glasgow Outcome Scale (GOS) and in-hospital mortality adjusted to on-scene Glasgow Coma Scale (GCS), Injury Severity Score (ISS), Abbreviated Injury Scale head (AIS head), and on-scene time.
Results Out of 1176 patients, 151 underwent out-of-hospital ETI. At hospital admission, tube malpositions were recognized in nine patients (5.9%). Accidental and unrecognized esophageal intubation was detected in five patients (3.3%) and bronchial intubation in four patients (2.7%). Although ISS (p=0.053), AIS head (p=0.469), on-scene GCS (p=0.151), on-scene time (p=0.530), GOS (p=0.748) and in-hospital mortality (p=0.431) were similar compared with correctly positioned ETI tubes, three esophageal intubation patients died due to hypoxemic complications.
Discussion In our study sample, out-of-hospital emergency ETI in severely injured patients was associated with a considerable tube misplacement rate. For safety, increased compliance to consequently use available technologies (eg, capnography, video laryngoscopy) for emergency ETI should be warranted.
Level of evidence Level of Evidence IIA.
Background
Out-of-hospital emergency endotracheal intubation (ETI) is the gold standard in severely injured patients who require advanced airway management.1–3 It represents an important skill in emergency medical service (EMS) and is recognized as a quality indicator.4 Due to potential risk of severe complications which includes multiple intubation attempts, inadvertent esophageal or bronchial intubation, transient hypoxia, airway edema and bleeding, and tracheal aspiration, out-of-hospital ETI is discussed controversially.5 6 The aim of our study was to determine the prevalence and outcomes of patients who experienced tube malpositioning after emergency out-of-hospital ETI due to severe injuries.
Methods
After approval by the ethical committee of the Medical Faculty of the University Hospital Leipzig (No 137-15-20042015), we analyzed all electronic and paper-based medical charts of patients who were admitted to our university emergency department (ED) with trauma team activation between January 1, 2011 and December 31, 2013.
Investigated variables
Patient characteristics included age, gender, injury patterns, Abbreviated Injury Scale head, Injury Severity Score (ISS), Glasgow Coma Scale (GCS) on scene, and on-scene time (OST, time from EMS arrival until hospital admission). Patients <16 years, with supraglottic airways, being under cardiopulmonary resuscitation and interfacility transports were excluded. The main study endpoint was the incidence of unrecognized tube malposition (esophageal and endobronchial intubation); secondary endpoints were Glasgow Outcome Scale (GOS) and in-hospital mortality adjusted to injury severity, head injury and OST.
Setting
In Germany, out-of-hospital emergency treatment of patients with major trauma is provided by EMS physicians. In the current ‘Guideline on the Treatment of the Severely Injured’ the intubation is indicated in polytraumatized patients with apnea or snap breathing and recommended in patients with hypoxia (SpO2<90%), a traumatic brain injury (GCS <9), a trauma-associated hemodynamic instability (RR systolic <90 mm Hg) or after severe thorax trauma with respiratory insufficiency. However, some EMS physicians perform out-of-hospital intubation in case of severe pain after major trauma.7 In the receiving ED, the trauma team consists of traumatologists, visceral surgeons, neurosurgeons, anesthetists and radiologists due to national recommendations.7 Primary and secondary surveys are performed according to advanced trauma life support standard. All major trauma patients undergo multislice CT after focused assessment of sonography for trauma.
Statistics
Descriptive statistics was performed using numbers (percentage) and mean values (±SD). Computations used SPSS V.20 (SPSS) for Windows using X2 test or Fisher’s test for categorical variables. Normal distribution was tested using Student’s t-test or Mann-Whitney test. Differences between the two groups were compared by using X2 test for categorical variables and the t-test for continuous variables. The significance level was set up at p<0.05. Multivariate analysis was not performed due to low sample sizes.
Results
During the 3-year study period, 1176 patients were admitted to our center and presented to our trauma team. One hundred and fifty-one patients (12.8%) underwent emergency out-of-hospital ETI by EMS physicians. Demographic data and patient’s characteristics are displayed in table 1. Context of injuries were motor vehicle crash in 85.1%, falls from height in 10.4%, and 4.5% other trauma mechanisms. After hospital admission, 139 patients (92.1%) were classified as successfully intubated and in nine patients (5.9%) tube malpositions were recognized. Five patients (3.3%) had esophageal malpositions and four patients (2.7%) had mainstem malpositions (three right side, one left side). Esophageal malpositions were associated with three fatal outcomes (60.0%) and two patients had a GOS score of 3 and 4, respectively (table 2). Four esophageal malpositions were detected during primary survey after connecting to capnography and in one patient after a whole-body CT scan (table 3).
Demographic data
Patients’ characteristics of esophageal misplacements
Use of medication, blood gas analysis and evidence of anoxia
Discussion
In this study, we investigated the prevalence and outcomes of tube malpositions of major trauma patients admitted to a level I trauma center after out-of-hospital ETI by EMS physicians. The incidence of misplaced ETI was 5.9% whereas esophageal misplacements are more likely to cause irreversible neurological sequelae and are often fatal due to inadvertent iatrogenic hypoxemia in contrast to mainstem bronchial misplacements. In the current literature, the reported incidence of unrecognized esophageal misplacements in out-of-hospital ETI is ranging from <1% up to 16.7% (table 4).
Case series of delayed detected or undetected inadvertent esophageal misplacement of tracheal tubes in out-of-hospital emergency medical service since 2000
We did not select patients due to ISS, which can only be calculated after completion of diagnostic and thus may not be applied appropriately for acute patient triage. The study population reflected real-life presentations to the trauma team.
EMS physicians usually do not work in EMS only but attend several days per month. Thus, the performance of emergency ETI may vary considerably. EMS physicians perform ETI only once every 0.5–1.5 months depending on the type of EMS program (ground vs. helicopter EMS).6 8 The needed number of ETIs prior to the active participation in EMS is still an area of debate: studies found between 75 and 150 performed ETI as a prerequisite to reach a high first-pass success.8–10 Furthermore, video laryngoscopy showed improved intubation success rates in trauma patients.11 Therefore, the recently revised German guideline on treatment of patients with severe and multiple injuries particularly recommends video laryngoscopy use and frequent training in emergency anesthesia, ETI, and alternative ways of securing an airway (including bag valve mask, supraglottic airway devices, and emergency cricothyrotomy).11
Detailed neurological outcomes of patients with delayed or unrecognized malpositioned tubes are not available.2 7 12 In our study, patients who suffered from unrecognized tube misplacement had more unfavorable GOS in comparison to patients with successful airway management.
Esophageal intubation can be survived when spontaneous breathing is warranted. Due to the use of paralytics and anesthetic drugs, this may be impaired or impossible. Furthermore, the risk of tracheobronchial aspiration may be increased when the tube is removed from the esophagus. Therefore, direct laryngoscopy and ETI should be performed before esophageal placed tube removal. In four cases, the fatal esophageal misplacement was detected immediately after admission, but in one case due to spontaneous breathing despite tube obstruction the misplacement was found after a whole-body CT scan.
Limitations of this study include the retrospective design which may have caused a study bias. The study was conducted at a single trauma center, and local structures can limit the interpretation of the results. Furthermore, the sample size is too small for multivariate logistic regression analysis. We did not include patients undergoing alternative airway devices (eg, laryngeal masks, laryngeal tubes or Combitubes) which may impair the interpretation of our results. Although all patients with tube malpositions underwent direct laryngoscopy using Macintosh blades, we did not investigate the rate of video laryngoscopy in our whole study collective and patients in the successful intubation group may have had more frequent use of video laryngoscopy. We did not particularly analyze the training levels of EMS physicians regarding ETI performance, which may have varied considerably. However, we present real-world data with all strengths and weaknesses.
Conclusion
We found a considerable incidence of unrecognized misplacements of endotracheal tube emergency ETI of severely injured patients in a physician-based out-of-hospital EMS setting. Further studies should be warranted to develop strategies for an improved ETI performance of EMS providers by consequent application of available technologies.
Acknowledgments
We acknowledge the support from the German Research Foundation (DFG) and Leipzig University within the program of Open Access Publishing.
Footnotes
Contributors OÖ conceived the study and designed the protocol. OÖ, SS and JF collected the data. OÖ, MFS and MB analyzed the data. CJ and HW supervised the conduct of the study and data collection. OÖ, MFS and MB drafted the article, and all authors contributed substantially to its revision. OÖ take responsibility for the article as a whole. All authors read and approved the final article.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval The study was performed in accordance with the Declaration of Helsinki and approved by the ethics committee of the Medical Faculty of the University of Leipzig with the reference number 137-15-20042015.
Provenance and peer review Not commissioned; externally peer reviewed.
This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.
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