Above or below the vocal cords; the never-ending question
Marc Giménez-Milà MD
Maylin Koo MD, PhD
There exist few clinical situations as acute and potentially fatal as cardiac arrest in an extra-hospital scenario, whereby specialised clinical teams will perform different interventions in order to treat while diagnosing the cause of the arrest. In this heavily stressful setting, diagnosis depends on non-technical skills such as leadership and communication capabilities married with technical ones such as airway management, chest compression, and vascular access, and be based on high quality scientific clinical evidence. Moreover, despite continuous developments in acute medicine, intensive care and cardiology non-traumatic out-of-hospital cardiac arrest (OHCA) is described to remain with a hospital discharge survival of around 10%.1
In this line, Wang et al.2provide us with a randomised controlled trial comparing endotracheal intubation (ETI) with laryngeal tube (LT) insertion in non-traumatic OHCA adult patients in United States. The authors present a well-structured cluster-crossover trial over a 2-year period, recruiting 3000 patients in total (1495 in ETI and 1505 in LT). Twenty-seven emergency medical services agencies participated and no extra training was given to staff in order to avoid bias and to obtain results that represent clinical practice. Randomisation was limited to the 2 airway options and hospital management; target temperature management, neuroprognostication, change of supraglottic device upon arrival at the Emergency Department; was not part of the study protocol.
Patients in the ETI group remained longer without airway management from arrival of EMS crew – median of 12.5 minutes compared with 9.8 minutes in LT. Also, only 51.6% of patients in the ETI group were successfully intubated vs. 90.3% success rate in the LT group. Patients who were approached with an LT showed better 72-h survival, which was defined as the primary outcome, compared with ETI (18.3% vs. 15.4%; p=0.04). In secondary outcomes LT also offered benefit in return of spontaneous circulation (27.9% vs 24.3%; p= 0.03), survival to hospital discharge (10.8% vs 8.1%; p= 0.01), and favourable neurological outcome at discharge (7.1% vs 5%; p= 0.02). No significant differences were obtained in rate of pneumonia or pneumonitis, airway swelling, and hypopharyngeal injury.
Although we do appreciate quality of trial, reproducibility may be affected by each country’s National Health system and organisation of Extra-hospital Emergency services.
Factors such as degree of training of EMS staff, physician vs. paramedic services, distance to local hospital, and type of supraglottic device used may hamper world-wide conclusions. Also, we would have liked to learn the aetiology of OHCA in each group (acute coronary syndrome, pulmonary embolism, intoxication, cerebral events), how ETI malposition was diagnosed, and whether capnography was used routinely in all patients for assessing quality of chest compressions as recommended by recent European Resuscitation Council Guidelines.3
In the group of patients with ETI, basic life-support clinicians that arrived first to the scene proceeded to face mask ventilation until advanced life support arrived to proceed to tracheal intubation. Meanwhile in LT, the basic life-support team inserted the supraglottic device with no need to wait for the advanced team. The difference of approach in the 2 groups may have induced a benefit of unknown magnitude to the LT group. It is important to mention that after post hoc multivariable regression adjustment, the 72-hour survival was not statistically significantly differentbetween thegroups, which suggests over-scoring of benefit of LT in some of the cluster groups.
The question of how applicable this study is in our European setting is difficult to answer, even though a recent trial was performed in France and Belgium.4A large OHCA cohort was enrolled into this RCT comparing ETI with face-mask ventilation in a physician-based EMS. The RCT showed a 28-day survival of 5.3% and 5.4%, respectively, and no differences in neurological outcomes at day 28. We are hoping to learn results of the Airway-2 trial, which is happening in the United Kingdom comparing i-gel laryngeal mask with ETI.5
Meanwhile, debate regarding use of supraglottic devices in OHCA is bound to remain open. Probably as important as airway management are minimisation of chest compressions, early defibrillation, and transfer to hospital with capabilities for directed treatment of cause of arrest.
1. Benjamin EJ, Virani SS, Callaway CW, et al; American Heart Association Council on Epidemiology and Prevention Statistics Committee and Stroke Statistics Subcommittee. Circulation2018;137(12):e67-e492.
2. Wang HE, Schmicker RH, Daya MR, et al.
3. Perkins GD, Olasveengen TM, Maconochie I, et al.; European Resuscitation Council.
4. Jabre P, Penaloza A, Pinero D, et al.