We found that use of the I-gel was associated with a higher success rate and lower complication rate than use of the LTS-D by ambulance personnel during resuscitation from OHCA. The most frequent complication regarding LTS-D was anatomical conditions and problematic insertion, which may explain why the LTS-D may be harder to insert than the I-gel. In our study airway leakage was found to be the most frequent complication regarding use of I-gel.
Endotracheal intubation is the gold standard in prehospital advanced airway management, but requires a level of experience and training often not achievable for ambulance personnel [14]. Several studies show that, at least in hands of less experienced personnel, SAD has a higher insertion success rate and reduced time to secured airway compared to ETI [9, 15, 16]. Skill retention is also high for SAD, showing that less continuous training is needed to adequately use the SAD [15, 17]. When the patient is suboptimal positioned, SAD has an increased success rate compared to ETI, even when being used by skilled anaesthesiologists [18]. During a randomized controlled trial comparing SAD or ETI, fewer of the patients in the ETI group received any advanced airway interventions, which might be associated with SAD being easier to use. In the same study, they noted that among the patients receiving advanced airway management, the patients who received SAD had a higher survival compared to ETI – independent of which group they initially were allocated to [19]. A meta-analysis showed better survival and neurological outcome by the use of ETI compared to SAD, but this included no randomized controlled trials, and did not specify if the personnel using ETI and SAD had the same experience level [6].
In studies comparing I-gel and LTS-D during elective surgery, on cadavers or on manikins most studies are in favour of I-gel when it comes to successful insertions and time to airway control [20-26]. This is consistent with our study results, but it’s important to note that during elective surgery, treatment occurs in a more controlled environment than in the prehospital setting; with more knowledge of the patient in advance, optimal positioning of the patient, optimally anesthetized patient, optimal working height, good lighting, and sufficient personnel present and necessary equipment available. The prehospital setting is often characterized by austere conditions and an unpredictable treatment situation; the lighting conditions may be poor, the space conditions and positioning may be challenging, the patient is unknown, and the personnel resources are limited. The importance of an easy-to-use airway management tool is essential, as it is necessary to share the attention between airway management and other work tasks. We have not found any studies comparing the two SADs in out-of-hospital cardiac arrests.
We recognize some limitations in our study. First, the type of airway device used depended on which ambulance service the ambulance personnel belonged to, thus there was two groups with I-gel and one with LTS-D. Second, the three separate services had the same certification requirements and monthly case training on cardiac arrest situations and airway administration, but one would expect that educational motivation and updating would differ a little between ambulance bases in the same service. Third, the level of competence and experience of the ambulance personnel being responsible for each airway administration was not recorded in this study. All personnel have completed training in supraglottic airway administration, but personal education and experience may differ based on years in service and the local incidence of OHCA. This was not further investigated, which cannot exclude the possibility of results being affected by differences in overall competence in the three ambulance services. Fourth, the population density differs within the three health trusts. In services close to the cities, in Trondheim in particular, the population density is significantly larger than in the rural areas. This may affect the experience, and thus the competence of the individual ambulance personnel. Differences in geography may also affect ambulance response times, which may affect the probability of survival after cardiac arrest. Extended use of time before the initiation of resuscitation reduces the likelihood of survival [27]. However, we assumed that this would not affect the primary endpoints.
Despite some limitations, the data in this study reflect real-life situations and how the two different devices perform in pre-hospital clinical services. There are several environmental differences affecting practice when comparing the pre- and in-hospital setting. Results from previous studies performed in the in-hospital setting (i.e. operating room) might therefore not be directly transferrable to the pre-hospital setting. By conducting a telephone interview of all involved ambulance workers, the quality data could be validated. As an example, several ambulance personnel did initially not register the use of SAD as an airway intervention if they did not achieve a successful insertion. Without a telephone interview, the number of missed interventions would potentially have been substantially higher.
