Endotracheal intubation (ETI) has long been defined as the “gold standard” for airway management to secure the airway. It is historically the “definitive airway” and, in the setting of cardiac arrest, a successfully placed and confirmed endotracheal tube connected to a well-managed ventilator removes the bulk of airway and breathing concerns from the Basic Life Support (BLS)/ Advanced Cardiovascular Life Support (ACLS) algorithms. For many emergency physicians and paramedics, intubation is a standard and satisfying procedure that not only secures a definitive airway but also patient disposition. For these reasons, we often tend to perform ETI as the default mechanism for cardiac arrest. The question remains as to whether it is always the best intervention for airway management in prehospital cardiac arrest.

ETI has a long list of potential medical complications including esophageal intubation, hypoxia, infectious disease exposure, and aspiration. In the setting of cardiac arrest, the interruption of chest compressions can be a significant detriment. ETI takes time: unzipping all the bags, opening the packages, connecting the syringe, checking the cuff, putting in the stylet, connecting one’s preferred blade to a laryngoscope, hooking up the suction, and, finally, positioning the patient. These are all more complicated when they are being performed by a three-person crew on a 90-foot high mezzanine at the brickyard, as opposed to a beautiful, spacious and well-lit resuscitation bay at the trauma center. One of the authors has been in both scenarios, and, unfortunately at the brickyard, the syringe happened to slip off and we had the pleasure of watching the thing fall through the perforated metal floor into a sandpit directly below. Yes, there was a backup in the bag, but digging it out took even more time.

Experience, Timing Matter

It is widely accepted that frequent experience in performing the complex procedure of ETI is what matters most in ascertaining competency. In a large emergency department, intubation is a frequent enough event to generate confidence. However, paramedic experience for intubation may entail one to eight attempts per year.

In a retrospective analysis from Victoria, Australia, it was demonstrated that paramedic intubation experience was associated with successful tube placement but not with cardiac arrest survival to discharge. This study involving highly trained paramedics demonstrated that previous experience correlated with intubation success, which in turn was correlated with return of spontaneous circulation (ROSC). Notably, the authors observed that first-pass success might be the key element in increasing both ROSC and survival to hospital discharge. The authors consequently suggested that paramedics who lack adequate experience should consider using supraglottic airway (SGA) devices.¹

Other studies validated this suggestion with mixed outcomes. The PART trial, a well conducted, pragmatic, cluster-crossover trial from 2018 evaluated outcomes of 3,000 out-of-hospital cardiac arrest (OHCA) patients in the United States. Approximately half of OHCA patients were randomly assigned to ETI, and half received a supraglottic laryngeal tube (King LT, often called King airways) as the intervention. Survival after 72 hours was 18.3 percent in the LT group compared with 15.4 percent in the ETI group, a statistically significant difference. Notably, however, the first airway attempt after EMS arrival in the LT group was 2.7 minutes shorter than with the ETI group. It is therefore possible that in this study, the timing mattered more than the specific intervention. Unsuccessful insertion for the ETI group was 44.1 percent compared with 11.8 percent in the LT group. Finally, it should be noted that EMS’s LTs were converted to ETI at the receiving emergency department 64.4 percent of the time.²

The AIRWAYS-2 trial was a massive cluster randomized controlled trial from the United Kingdom that evaluated 30-day good functional outcomes in OHCA survivors. The clusters were assigned to a specific type of SGA (iGel) versus ETI. The dataset was large enough to include 9,296 patients; no difference was found between the two groups. Although the study had limitations, it appears that it would be fair to conclude from AIRWAYS-2 that iGels are noninferior in the prehospital setting to ETI and vice-versa. Therefore, from this single study, we would be willing to challenge the “gold standard” idea when it comes to OHCA and paramedics. Subsequent three-month and six-month follow-up seems to corroborate the initial data of AIRWAYS-2, with the caveat that a very low percentage of patients responded to request for follow up.^3,4

Which is Best?

In an official position statement, the National Association of EMS Physicians (NAEMSP) favors the use of prehospital SGAs: “SGAs have utility as a primary or secondary EMS airway intervention.“

EMS agencies that perform endotracheal intubation must also equip their clinicians with SGA devices and ensure adequate training and competence.

In select situations, drug-assisted airway management may be used by properly credentialed EMS clinicians to facilitate SGA insertion.

Confirmation of initial and continuous SGA placement using waveform capnography is strongly encouraged as a best practice.⁵

If SGAs are as efficacious and safe as ETI, the question arises as to which type of SGA is the best. Several different styles are commercially available. A comparison between the King-LT and iGel was attempted in OHCA situations and, overall, the outcomes were not hugely different. There were some nuanced differences. Survival to discharge home was approximately the same between the two groups when the SGA was the primary airway device; but when the SGA was used as a rescue device for failed intubation, the iGel did better. The authors therefore concluded that the iGel for adult OHCA resuscitation had better outcomes as compared with the King-LT.⁶ It may be reasonable, as a conclusion, to keep it simple: Both devices are good, so one might choose the easiest one to use. The iGel does not have a cuff, meaning no syringe is required for insertion and it really has no failing parts.

From the articles cited above, a theme begins to emerge: Early placement of the airway, along with first-pass success, are important considerations. Practitioners must consider ROSC. Without ROSC, there really is no 72-hour or 30-day outcome at all. It is likely that the airway in the prehospital setting has something to do with ROSC. The time interval between EMS arrival and definitive airway placement is likely a key factor. In a striking secondary analysis of the ROC PRIMED data that included more than 7,000 patients, it was demonstrated that the earlier the airway is placed, the higher the likelihood there is of ROSC regardless of initial heart rhythm.⁷

In light of this data, it appears that ETI can be an appropriate EMS intervention in OHCA provided the following conditions are met: the paramedic is skilled and experienced; the endotracheal tube goes in on the first attempt without interrupting CPR or delaying defibrillation; and the airway is placed less than five minutes after EMS arrival. These conditions can exist in the real world but unfortunately may not apply for many reasons.

This leaves the emergency physician with a decision: When EMS brings in a well-ventilated OHCA patient who has an SGA in place, should they leave the iGel in or spend time replacing it with an endotracheal tube before either pronouncing the patient dead or sending the patient on to the cardiac cath lab in the case of ROSC? The case for removing the SGA may in some cases be a difficult one to make.

Dr. Miller is core faculty, EMS Fellowship at MetroHealth Medical Center, Cleveland, Ohio.

Dr. Glauser is professor of emergency medicine, Case Western Reserve University.

References

1. Dyson K, Bray JE, Smith K, et al. Paramedic Intubation Experience is Associated with Successful Tube Placement but not Cardiac Arrest Survival. Ann Emerg Med. 2017;70(3):382-390.e1.
2. Wang HE, Schmicker RH, Daya MR, et al. Effect of a Strategy of Initial Laryngeal Tube Insertion vs Endotracheal Intubation on 72-Hour Survival in Adults With Out-of-Hospital Cardiac Arrest: A Randomized Clinical Trial. JAMA. 2018;320(8):769-778.
3. Benger JR, Kirby K, Black S, et al. Effect of a Strategy of a Supraglottic Airway Device vs Tracheal Intubation During Out-of-Hospital Cardiac Arrest on Functional Outcome: The AIRWAYS-2 Randomized Clinical Trial. JAMA. 2018;320(8):779-791.
4. Benger JR, Lazaroo MJ, Crout M, et al. Randomised trial of the i-gel supraglottic airway device versus tracheal intubation during out of hospital cardiac arrest (AIRWAYS-2): Patient outcomes at three and six months. Resuscitation. 2020;157:74-82.
5. Lyng J, Baldino KT, Braude D, et al. Prehospital supraglottic airways: an NAEMSP position statement and resource document. Prehosp Emerg Care. 2022;26(1):32-41.
6. Smida T, Menegazzi J, Crowe R, et al. A retrospective nationwide comparison of the iGel and King laryngeal tube supraglottic airways for out-of-hospital cardiac arrest resuscitation. Prehosp Emerg Care. 2023;28(2):193-199.
7. Benoit JL, McMullan JT, Wang HE, et al. Timing of advanced airway placement after witnessed out-of-hospital cardiac arrest. Prehosp Emerg Care. 2019;23(6):838-846.