Clinical paperEffect of airway management strategies during resuscitation from out-of-hospital cardiac arrest on clinical outcome: A registry-based analysis
Introduction
Morbidity and mortality rates are still markedly high in patients sustaining out-of-hospital cardiac arrest (OHCA).1, 2, 3 The two priorities during cardiopulmonary resuscitation (CPR) lie in high quality chest compressions to maintain blood flow and in effective ventilation, providing reoxygenation and decarboxylation to ischaemic and acidotic tissues.4 In an out-of-hospital CPR setting, the airway can be managed by bag-mask valve ventilation, via supraglottic airway devices (SAD), and through intubation of the trachea. However, the optimal approach to airway management in OHCA has not yet been established.5
Since its introduction in 2002, the laryngeal tube (LT) has been implemented as a frequently used SAD during OHCA.6 Even the European Resuscitation Council (ERC) Guidelines advocates the use of SAD as well as the endotracheal tube (ETT) for experienced performers.4 Since its market launch, several studies have been published pertaining to the effectiveness and safety of the LT.7, 8 as compared to other SAD (e.g., laryngeal mask airway, i-gel).9 The studies showed divergent results: in a retrospective study from an Austrian physician staffed emergency medical system (EMS), Sulzgruber et al.10 showed that out-of-hospital airway management using endotracheal intubation was associated with better 30-day survival and favourable neurological outcomes in comparison to the LT. An Anglo-American randomized clinical trial by Wang et al.11 found a significantly greater 72-h survival and a better neurological long-term outcome when airways were secured by paramedics with an LT instead of an ETT.
The aim of the present study was to compare the effectiveness of an airway strategy using initial LT insertion versus ETT in OHCA patients, analysing the data of the German Resuscitation Registry (GRR) from EMS physician staffed EMS systems. Moreover, the effects on clinical outcome of an early switch from LT to ETT in the out-of-hospital setting were investigated.
Section snippets
Methods
The success of out-of-hospital CPR in cardiac arrest (CA) patients depends on several factors. Many of these factors are well-known.12 Within the scope of this study, treatment of OHCA patients followed the ERC guidelines.4 Registry based risk-adjusted matched-pair analysis was chosen to compare different interventional groups.13 The data of the GRR were analyzed in a retrospective case-control design, using a matched-pair analysis. The GRR was started in 2007 by the German Society for
Results
During the study period from January 1st 2007 to December 31st 2017, a total of 89,220 patients with attempted CPR were included in the GRR (Fig. 1). All relevant and complete data were available for 19,196 patients (21.5%). 4391 patients did not meet the inclusion criteria (e.g. due to use of laryngeal mask, bag-mask-valve ventilation only, unknown airway technique). The remaining 14,805 patients were defined as the study cohort (Fig. 2).
Out of these patients, 10,610 received an ETT (71.7%),
Discussion
In this matched-pair analysis of the GRR registry on 14,805 adult OHCA patients, the main result was that an airway strategy of “ETT” was associated with higher survival rates and a better neurological outcome at hospital discharge, than a strategy relying fully on the laryngeal tube (“LT only”).
The “LTEX”-strategy (laryngeal tube placed initially by paramedic with subsequent endotracheal intubation by EMS physician“) was associated with better short term outcomes than “LT only” and “ETT”. No
Limitations
Although we managed to show the association between endotracheal intubation and neurologically intact survival for the first time on the GRR, and although Sulzgruber's findings10 could also apply to our results, this study must consider the limitations of retrospective registry analyses. While it can show associations, the causes of the seen effects remain unknown and need further inquiry. The matched pair design adjusted the study groups to known influence factors, but these are likely to be
Conclusions
“ETT” was associated with higher survival rates and better neurological outcomes in comparison to “LT_only”. The strategy of “LTEX” versus “LT_only” or “ETT” was only associated with better short-term outcomes. Our observational registry data suggests that endotracheal intubation by physician staffed EMS is the optimal airway strategy for OHCA in our system.
Authors’ contributions
Niels-Henning Behrens: Formal analysis, Investigation, Validation, Writing – Original Draft,
Writing – Review & Editing, Visualization
Matthias Fischer: Conceptualization, Methodology, Formal analysis, Investigation, Validation, Writing – Review & Editing, Visualization, Supervision
Tobias Krieger: Writing – Original Draft, Writing – Review & Editing
Kathleen Monaco: Writing – Review & Editing
Jan Wnent: Writing – Review & Editing
Stephan Seewald: Writing – Review & Editing
Jan-Thorsten Gräsner:
Conflict of interest
The authors declared that they have no competing interests. All authors were or are involved in one or more of the following: construction, data collection (present and past), data evaluation and future development of the German Resuscitation Registry.
Funding
Steffen Keller received an expense allowance from the German Society for Anaesthesiology and Intensive Care Medicine (Deutsche Gesellschaft für Anästhesiologie und Intensivmedizin) for developing the PairMatcher, the software for performing matched pair analysis and comparable groups. There was no further funding.
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- 1
Authors are members of the Steering Committee of the German Resuscitation Registry Study.
- 2
N. Behrens and M. Fischer have contributed equally to this manuscript.