| | Interruptions in Cardiopulmonary Resuscitation From Paramedic Endotracheal IntubationPresented at the Society for Academic Emergency Medicine annual meeting, May 2008, Washington, DC. Received 16 December 2008; received in revised form 1 March 2009 and 14 May 2009; accepted 21 May 2009. published online 03 July 2009.
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Do Not Pardon the Interruption
, 03 August 2009
Bentley J. Bobrow, Daniel W. Spaite
Annals of Emergency Medicine
November 2009 (Vol. 54, Issue 5, Pages 653-655)
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Study objectiveEmergency cardiac care guidelines emphasize treatment of cardiopulmonary arrest with continuous uninterrupted cardiopulmonary resuscitation (CPR) chest compressions. Paramedics in the United States perform endotracheal intubation on nearly all victims of out-of-hospital cardiopulmonary arrest. We quantified the frequency and duration of CPR chest compression interruptions associated with paramedic endotracheal intubation efforts during out-of-hospital cardiopulmonary arrest. MethodsWe studied adult out-of-hospital cardiopulmonary arrest treated by an urban and a rural emergency medical services agency from the Resuscitation Outcomes Consortium during November 2006 to June 2007. Cardiac monitors with compression sensors continuously recorded rescuer CPR chest compressions. A digital audio channel recorded all resuscitation events. We identified CPR interruptions related to endotracheal intubation efforts, including airway suctioning, laryngoscopy, endotracheal tube placement, confirmation and adjustment, securing the tube in place, bag-valve-mask ventilation between intubation attempts, and alternate airway insertion. We identified the number and duration of CPR interruptions associated with endotracheal intubation efforts. ResultsWe included 100 of 182 out-of-hospital cardiopulmonary arrests in the analysis. The median number of endotracheal intubation–associated CPR interruption was 2 (interquartile range [IQR] 1 to 3; range 1 to 9). The median duration of the first endotracheal intubation–associated CPR interruption was 46.5 seconds (IQR 23.5 to 73 seconds; range 7 to 221 seconds); almost one third exceeded 1 minute. The median total duration of all endotracheal intubation–associated CPR interruptions was 109.5 seconds (IQR 54 to 198 seconds; range 13 to 446 seconds); one fourth exceeded 3 minutes. Endotracheal intubation–associated CPR pauses composed approximately 22.8% (IQR 12.6-36.5%; range 1.0% to 93.4%) of all CPR interruptions. ConclusionIn this series, paramedic out-of-hospital endotracheal intubation efforts were associated with multiple and prolonged CPR interruptions. SEE EDITORIAL, P. 653. Introduction  Background In the United States, emergency medical services (EMS) treat almost 300,000 out-of-hospital cardiopulmonary arrests annually, with few patients surviving to hospital discharge.1 Clinicians in both hospital and out-of-hospital settings view airway management as an essential element of out-of-hospital cardiopulmonary arrest resuscitation. The most common method of airway management in these settings is endotracheal intubation. In the United States, paramedics attempt endotracheal intubation on nearly all comatose victims of out-of-hospital cardiopulmonary arrest.2, 3, 4, 5 Editor's Capsule SummaryWhat is already known on this topic Decreased interruption of chest compressions in out-of-hospital cardiac arrest is strongly associated with increased survival in animal models and clinical trials. Little is known, however, about the specific issues that lead to interruptions. What question this study addressed What are the frequency and duration of cardiopulmonary resuscitation chest compression interruptions associated with paramedic endotracheal intubation during out-of-hospital cardiac arrest? What this study adds to our knowledge In 100 out-of-hospital cardiac arrests, patients' chest compressions were interrupted twice, on average, because of efforts to intubate, with a mean total interruption time of nearly 2 minutes. How this might change clinical practice This adds support for the current movement to deemphasize intubation and delay it until later in resuscitation attempts for out-of-hospital cardiac arrest. Previous studies suggest that paramedic endotracheal intubation may interfere with other key aspects of resuscitation; for example, endotracheal intubation may lead to inadvertent hyperventilation, adversely affecting cerebral perfusion in traumatic brain injury or coronary perfusion pressure during cardiopulmonary resuscitation (CPR).6, 7, 8 Importance Current emergency cardiac care guidelines emphasize the delivery of continuous CPR chest compressions with as few interruptions as possible, including pauses for airway management efforts.9 However, endotracheal intubation often requires multiple actions, including laryngoscopy and intubation, airway suctioning, tube confirmation and adjustment, securing the tube in place, bag-valve-mask ventilation between intubation attempts, and alternate airway insertion in the event of failed endotracheal intubation, among others.10 Paramedic endotracheal intubation may also require multiple laryngoscopy attempts.11 In a simulation study, paramedic endotracheal intubation resulted in more than 1 minute of CPR interruption.12 To minimize CPR interruptions, some EMS agencies have substituted endotracheal intubation with esophageal-tracheal twin-lumen airway device (Combitube; Kendall-Sheridan Catheter Corp, Argyle, NY) or King LT airway (King Systems, Noblesville, IN) insertion.13 Although these collective observations point to the strong potential for paramedic endotracheal intubation efforts to interfere with CPR chest compression continuity, no clinical studies have quantified this phenomenon. Goals of This Investigation The objective of this study was to characterize the frequency and duration of CPR interruptions associated with paramedic endotracheal intubation efforts during out-of-hospital cardiopulmonary arrest. Materials and Methods Study Design and Setting This study was approved by the University of Pittsburgh Institutional Review Board. We conducted a prospective observational study involving EMS agencies from the Pittsburgh arm of the Resuscitation Outcomes Consortium, which is a North American consortium dedicated to the study of the out-of-hospital care of out-of-hospital cardiopulmonary arrest and severe traumatic injury.14, 15 The consortium includes EMS agencies in the Birmingham, Dallas, Milwaukee, Pittsburgh, Portland, San Diego, Seattle, Toronto, Ottawa, and British Columbia regions. The consortium collects prospective data on out-of-hospital cardiopulmonary arrest by using a standardized registry system (ROC Epistry-Cardiac Arrest).1 For this study, we used data from 2 EMS agencies associated with the Pittsburgh regional Resuscitation Outcomes Consortium center. One EMS agency (A) consisted of a large, urban paramedic service with 14 2-paramedic ambulances responding to more than 65,000 annual dispatches. Fire fighter first responders supplemented paramedic teams at out-of-hospital cardiopulmonary arrest. The other EMS agency (B) consisted of a large county-based rural EMS agency with 27 single-paramedic ambulances responding to more than 60,000 dispatches annually. For out-of-hospital cardiopulmonary arrest, both EMS agencies used conventional advanced airway management protocols consisting of initial conventional endotracheal intubation efforts, followed by alternate airway techniques in the event of failed endotracheal intubation. EMS agency A used Combitube or King LT airway insertion or cricothyroidotomy in the event of failed endotracheal intubation. EMS agency B used only cricothyroidotomy in the event of failed endotracheal intubation. Although EMS agency A used waveform end-tidal capnography to verify endotracheal tube placement, EMS agency B did not use this technique at the time of this study. Although permitted in practice, EMS agency A did not include primary use of Combitube or King LT airway insertion in its protocols at the time of this study. Selection of Participants We included out-of-hospital cardiopulmonary arrest patients receiving attempted EMS resuscitation and endotracheal intubation or other advanced airway insertion efforts. We included consecutive out-of-hospital cardiopulmonary arrest patients treated during November 1, 2006, through June 20, 2007, coinciding with the implementation of Philips MRX (Phillips Healthcare, Andover, MA) portable cardiac monitors at both EMS agencies. This period did not overlap with concurrent consortium interventional out-of-hospital cardiopulmonary arrest study protocols. We excluded pediatric patients (aged <18 years), victims of major trauma, and instances without attempted resuscitation or advanced airway management. Data Collection and Processing We obtained CPR chest compression process data by using Philips MRX portable cardiac monitors, which continuously record electrocardiographic rhythm, ventilations, end-tidal carbon dioxide levels, and chest compressions by a sternal detector.16, 17 The monitor digital audio records all on-scene events. Standard manufacturer software converts raw digital data into synchronized graphic and audio process logs. We linked CPR process data with clinical information for each patient, including patient age, sex, bystander- or EMS-witnessed arrest, bystander or first responder CPR, bystander or first responder automated external defibrillator use, initial electrocardiographic rhythm, type of airway inserted, and initial patient outcome. These clinical data comprised part of the standard consortium data registry.1 Methods of Measurement Using the chest compression channel of the graphic log, we identified all CPR interruptions, defined by study team consensus as a chest compression discontinuity greater than or equal to 5 seconds. We defined the end of a CPR interruption as the resumption of chest compressions for greater than or equal to 5 seconds. We defined the CPR discontinuity duration as the elapsed time between the peak of the last compression preceding and the peak of the first compression after the interruption. Endotracheal intubation efforts often involve multiple actions in addition to laryngoscopy and endotracheal tube placement; for example, airway suctioning, tube confirmation and adjustment, securing the tube in place, and alternate airway insertion in the event of failed endotracheal intubation.10 Because it is standard procedure after failed laryngoscopy, we included CPR interruptions caused by bag-valve-mask ventilation between intubation attempts. We also included any instances of primary alternate airway insertion without laryngoscopy. We used the digital audio channel to identify events related to endotracheal intubation efforts. Examples of phrases associated with endotracheal intubation efforts included, “He's very anterior…,” “There's lots of emesis in his airway…,” “Good breath sounds bilaterally…,” “The belly's quiet…,” and “Hold compressions, please… I can't visualize the airway…” (Appendix E1, available online at http://www.annemergmed.com). An example of a distinct endotracheal intubation–associated sound included the sound of bag-valve-mask ventilation through an endotracheal tube. Combining the graphic and audio information, we identified the number and duration of CPR interruptions associated with endotracheal intubation efforts. Two reviewers independently reviewed and abstracted all data. If the reviewers disagreed, they collectively rereviewed the case to reach consensus. Although the EMS agencies did not include the narration of on-scene events as part of their protocols, during pilot efforts we observed that EMS personnel in the study agencies customarily verbalized their airway management actions. We excluded cases with insufficient data to define endotracheal intubation–associated events, such as those missing audio recording, noisy audio recordings, or missing chest compression channel data. Outcome Measures The primary outcomes of this analysis were number and durations of CPR interruptions associated with endotracheal intubation efforts. Specifically, we determined the total number of endotracheal intubation–associated CPR interruptions for each patient. We determined the duration of each endotracheal intubation–associated CPR interruption. Because the first endotracheal intubation-related CPR interruption typically reflected initial laryngoscopy and because of common clinical emphasis on first-attempt endotracheal intubation success, we analyzed the first CPR pause separately from subsequent pauses. We also determined the total duration of endotracheal intubation–associated CPR interruptions by summing the individual CPR pauses for each patient. Primary Data Analysis We evaluated interrater agreement using Cohen's κ and interclass correlation coefficients. We characterized the number and duration of endotracheal intubation–associated CPR interruptions by using descriptive techniques (median, interquartile range, and minimum and maximum values). The endotracheal intubation–associated CPR pauses comprised a portion of the total CPR interruption time. To estimate the fraction of the CPR interruptions attributable to endotracheal intubation efforts, we divided the total endotracheal intubation-association CPR interruption time by the automated total CPR interruption (“no-flow”) time reported by the manufacturer software program. The automatic tabulation overestimated the total CPR interruption time, incorporating periods with sternal sensor malfunction or displacement or the period after the termination of resuscitation efforts. We therefore adjusted the estimated total CPR interruption times by manually subtracting periods of artifactual CPR pauses. We performed all analyses with Stata, version 10.0 (StataCorp, College Station, TX). Sensitivity Analyses The primary analysis defined a CPR interruption as a chest compression discontinuity greater than or equal to 5 seconds. We repeated the analysis including only chest compression interruptions greater than or equal to 10 seconds and greater than or equal to 20 seconds. Results During the study period, there were 182 out-of-hospital cardiopulmonary arrests. We excluded 82 cases, including 38 (46%) with incomplete or insufficient data (Figure 1). These latter cases resulted from failure to apply or activate the sternal detector or instances in which the audio recorder failed or was inadvertently muted. The 100 out-of-hospital cardiopulmonary arrest patients included in the analysis were mostly elderly and men (Table). Less than half were bystander witnessed, and approximately one third received bystander CPR. Most patients presented in asystole or with pulseless electrical activity. The 13 patients receiving Combitube or King LT airway use all received initial endotracheal intubation attempts. According to the definition of a CPR interruption as a chest compression discontinuity greater than or equal to 5 seconds, endotracheal intubation efforts were associated with a median of 2 CPR interruptions per patient (interquartile range [IQR] 1 to 3 interruptions; range 1 to 9 interruptions) (Figure 2). In more than one third of the cases, there were more than 2 endotracheal intubation–associated CPR interruptions. In select cases, there were as many as 9 endotracheal intubation–associated CPR interruptions. The median elapsed time from monitor activation to the first endotracheal intubation–associated CPR interruption was 246 seconds (IQR 176.5 to 366.5 seconds). The median duration of the first endotracheal intubation–associated CPR interruption was 46.5 seconds per patient (IQR 23.5 to 73 seconds; range 7 to 221 seconds) (Figure 3). In approximately 30% of cases, the first endotracheal intubation–associated CPR interruption exceeded 1 minute. Select cases exhibited endotracheal intubation–associated CPR interruptions lasting almost 4 minutes. Among the 100 patients, subsequent (second through ninth) endotracheal intubation–associated CPR interruptions comprised a total of 171 pauses, of which the median duration was 35 seconds per CPR interruption (IQR 21 to 58 seconds; range 7 to 199 seconds) (Figure 4). The median total duration (sum) of endotracheal intubation–associated CPR interruptions was 109.5 seconds per patient (IQR 54 to 198 seconds; range 13 to 446 seconds) (Figure 5). The total duration of endotracheal intubation–associated CPR interruptions exceeded 3 minutes in more than one fourth of cases and 7 minutes in select cases. The total endotracheal intubation–associated CPR interruption time composed approximately one fourth of the total CPR interruptions (median 22.8%; IQR 12.6% to 36.5%; range 1.0% to 93.9%). The number and durations of endotracheal intubation–associated CPR interruptions were not associated with patient age, sex, bystander- or EMS-witnessed out-of-hospital cardiopulmonary arrest, bystander or first responder CPR, automated external defibrillator use, initial ECG rhythm, or type of advanced airway. For EMS agency A, interrater agreement was very good for case inclusion/exclusion (κ=0.87), the number of endotracheal intubation–associated CPR interruptions (interclass correlation coefficient=0.68), the time to (interclass correlation coefficient=0.87) and duration of (interclass correlation coefficient=0.87) the first endotracheal intubation–associated CPR interruption, and total duration of all endotracheal intubation–associated CPR interruptions (interclass correlation coefficient=0.59). Because of the strong observed agreement, we did not formally calculate interrater statistics for EMS agency B. Including only chest compression discontinuities greater than or equal to 10 seconds did not alter the median number or total duration of CPR interruptions. Including only chest compression discontinuities greater than or equal to 20 seconds did not change the median number of CPR interruptions. However, the total duration of endotracheal intubation–associated CPR interruptions decreased slightly (median 102 seconds; IQR 51 to 181.5 seconds). Limitations We selected a convenience sample of data from 2 EMS agencies by using conventional endotracheal intubation–based advanced airway management strategies. We limited the study period to avoid overlapping with other consortium research protocols. The quality and availability of data varied as EMS personnel learned to properly activate and operate the monitors. If available, CPR process data for excluded cases may have altered the results. Our observations originate from well-trained EMS services practicing in high-acuity settings and may reflect typical or best-case clinical practice. Additional study with a broader range of EMS agencies is needed to confirm these results in other clinical, geographic, and educational settings. Although potentially subject to classification bias, digital audio review represented the best option for identifying airway management events in the uncontrolled out-of-hospital setting. Systematic out-of-hospital videotaping is not possible because of ethical and logistic barriers. Self-reports would likely underestimate the magnitude and extent of the CPR interruptions. Although we did not formally validate the associations between paramedics' statements and their executed actions, we selected terms most clearly related to endotracheal intubation efforts. We did not examine the effect of the number of rescuers on scene. We surmise that a larger number of rescuers may have reduced the number and duration of CPR interruptions. We could not determine whether endotracheal intubation occurred without CPR interruption. We did not examine the depth or quality of CPR chest compressions as in previous studies.16, 17 Although we shared the results of the study with the EMS agencies, we did not formally evaluate resulting changes in practice. Anecdotally, according to these observations one EMS agency instituted a quality improvement effort to limit endotracheal intubation–related interruptions and to increase primary use of the King LT airway. The effect of these efforts on reducing CPR interruptions is an area for future study. Discussion Current emergency cardiac care guidelines recommend limiting the number and duration of CPR chest compression interruptions during resuscitative efforts, including those associated with airway management.9 In the United States, paramedics customarily attempt endotracheal intubation on nearly all comatose victims of out-of-hospital cardiopulmonary arrest. In this series, paramedic endotracheal intubation efforts were associated with more than 1.5 minutes of CPR interruptions. Select endotracheal intubation efforts resulted in more than 6 minutes of CPR interruptions. The endotracheal intubation–associated CPR pauses composed almost one fourth of the total CPR interruption for each patient. Our observations highlight an unintended consequence of paramedic endotracheal intubation. Numerous studies highlight the pitfalls of paramedic endotracheal intubation, including unrecognized endotracheal tube misplacement or dislodgement, multiple, and failed laryngoscopy efforts and iatrogenic oxygen desaturation and bradycardia.11, 18, 19, 20, 21 Endotracheal intubation may also indirectly affect other key resuscitation actions. For example, Aufderheide and Lurie6 and Aufderheide et al7 associated paramedic endotracheal intubation with inadvertent hyperventilation and impaired CPR coronary perfusion pressure in out-of-hospital cardiopulmonary arrest patients. Davis et al8 observed inadvertent hyperventilation in patients with traumatic brain injury after paramedic neuromuscular-blockade–assisted endotracheal intubation. These observations collectively highlight that even properly performed endotracheal intubation may inadvertently affect other resuscitation elements. Resuscitation strategies must account for these important interactions. Previous studies suggest links between CPR chest compression continuity and out-of-hospital cardiopulmonary arrest outcomes. For example, Christenson et al22 associated out-of-hospital cardiopulmonary arrest survival with the fraction of resuscitation time with CPR chest compressions. Bobrow et al23 reported a 3-fold increase in out-of-hospital cardiopulmonary arrest survival to hospital discharge with a paramedic strategy of minimally interrupted CPR. Because of the limited size of this series, we decided a priori not to draw formal associations with out-of-hospital cardiopulmonary arrest outcomes. However, animal studies suggest that even brief pauses (3 to 5 seconds) may impair CPR coronary perfusion.24, 25 Additional studies with a larger series could evaluate the connections between endotracheal intubation–associated CPR interruptions and patient outcomes. According to aggregate data provided by the manufacturer software, the observed endotracheal intubation–associated pauses represented approximately one fourth of all CPR interruptions. We did not broaden the analysis to classify all CPR interruptions because in pilot efforts we could not easily identify other clinical events. Additional study with protocolized narration of on-scene events could provide important perspectives. Assuming the need to reduce endotracheal intubation–associated CPR interruptions, potential strategies include improving paramedic endotracheal intubation skill or altering out-of-hospital airway management techniques. Improving endotracheal intubation skill may prove difficult, given limits in the quantity of paramedic student training and clinical endotracheal intubation experience in the United States.26, 27, 28 Although select paramedics attempt endotracheal intubation without stopping CPR chest compressions, the broader feasibility of this technique remains unclear. To minimize CPR interruptions, many EMS agencies have substituted endotracheal intubation with Combitube or King LT airway insertion.13 Select studies suggest the viability of CPR without ventilation, potentially obviating the need for airway management interventions.29, 30 The relative effectiveness of these techniques remains unknown. In this series, paramedic out-of-hospital endotracheal intubation efforts were associated with multiple and prolonged CPR interruptions. Appendix E1. Examples of key phrases or events on audio recording indicating actions related to endotracheal intubation efforts Distinct sound of suctioning Distinct sound of bag-valve-mask device attached to endotracheal tube “He's very anterior…” “There's lots of emesis in his airway…” “Good breath sounds bilaterally…” “The belly's quiet…” “Hold compressions, please…I can't visualize the airway…” “I can't see the cords…” “Try pulling back a little…” “OK, bag him up…” “You might be a little right mainstem…” “Good end-tidal wave…” “We've got an end-tidal reading of ___…” “I'll take some cricoid pressure…” “We're currently attempting intubation…” “He's verifying the tube…” References 1. 1Nichol G, Thomas E, Callaway CW, et al. Regional variation in out-of-hospital cardiac arrest incidence and outcome. JAMA. 2008;300:1423–1431.
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Department of Emergency Medicine, University of Pittsburgh, Pittsburgh, PA  Address for correspondence: Henry E. Wang, MD, MS, Department of Emergency Medicine, University of Alabama at Birmingham, 619 19th St South, JTN 266, Birmingham, AL 35249; 205-996-6526, fax 205-975-4662
Dr. Wang is now affiliated with the Department of Emergency Medicine, University of Alabama at Birmingham, Birmingham, AL. Supervising editor: Daniel W. Spaite, MD Author contributions: HEW and CWC conceived the study. HEW, SJS, and CWC designed the study. SJS and MDW abstracted the data. HEW, SJS, and MDW analyzed the data. HEW drafted the article, and all authors contributed substantially to its revision. HEW had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. HEW takes responsibility for the paper as a whole. Funding and support: By Annals policy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article that might create any potential conflict of interest. See the Manuscript Submission Agreement in this issue for examples of specific conflicts covered by this statement. This study was supported by National Heart, Lung, and Blood Institute grant U01-HL077871. Dr. Wang received support from Clinical Scientist Development Award K08-HS013628 from the Agency for Health Care Research and Quality, Rockville, MD. The funders had no direct role in the design or execution of the study or the composition of the resulting article. Reprints not available from authors. PII: S0196-0644(09)00534-4 doi:10.1016/j.annemergmed.2009.05.024 © 2009 American College of Emergency Physicians. Published by Elsevier Inc. All rights reserved. | |
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