We received approval for this study from The Medical University of Lodz Ethics Board (Protocol Signature: RNN/06/20/KE). Trial was registered in Clinical Trials : NCT05607836. The study adheres to CONSORT guidelines.
Study design
A multitude of observational evidence has suggested a possible survival advantage for tracheal intubation as compared with other airway management methods. However, instrumental airway management during OHCA still requires high-quality research on which to base treatment recommendations.
We designed a prospective observational study to compare INT (IntuBrite®, LLC; Vista, CA, USA) and MCL for ETI performed by paramedics in OHCA without an emergency physician on the scene. Our main goal was to determine whether INT is superior to using an MCL laryngoscope during a tracheal intubation attempt in nontraumatic OHCA, in terms of time and effectiveness.
The INT has changed the lighting method used – the commonly used white light is replaced by a system of two different light sources: ultraviolet light and light emitting diode type light. This type of lighting increases the image contrast and reduces glare on wet mucous membranes during DL. The laryngoscope handle is made from aluminium, thereby making it lightweight, and the ergonomic shape with finger embossing makes the laryngoscope comfortable and intuitive to use. The arched profile of the handle allows for improved manoeuvring during the intubation procedure which is important for less experienced operators (Fig. 1.).
Paramedics enrolled in the study were recruited from among the large EMS ambulance services operating in Poland, which respond to emergencies for approximately 1.5 million people. All of the study participants were qualified to perform tracheal intubation in their current scope of practice. The paramedics were randomized to use 1 of the 2 laryngoscopes in the study for the purposes of advanced airway management for the eligible patients in OHCA that they treated.
We conducted our study under actual field conditions over a period of 3 years to include a sufficient number of cases. Therefore, two INT devices were allocated to two of the 34 ambulances used in the study for three-months to assure experience and rotated after 3 months to the next two ambulances of the EMS agency until an appropriate number of cases had been achieved.
Setting and selection of patients
The trial population consisted of adults who had a nontraumatic OHCA. We included patients treated by paramedics employed in the Voivodeship Rescue Station (VRS) in Lodz City (Poland). VRS in Lodz responds to approximately 400,000 emergency calls per year.
We examined prospectively collected data from the Medical Rescue Card generated by the Emergency Medical Support Command System (described in data collection section).
Data were gathered from every eligible patient and stored in the VRS Lodz Data Warehouse.
We included all patients ≥ 18 years of age, treated by ground ambulances between 2016–2020, who experienced nontraumatic OHCA, as defined by all of the following: (A) absence of consciousness; (B) absence of palpable pulse; (C) absence of spontaneous breathing; and (D) Glasgow coma scale of 3; and initiation of chest compressions.
We excluded patients with confirmed or suspected traumatic cardiac arrest, those with missing data and the primary use of SGA by the paramedics. Patients with cardiac arrest occurring during hospital admission were excluded.
Following recommendations from The Medical University of Lodz Ethics Board (Protocol Signature: RNN/06/20/KE) the consent for publication was not obtained from patients nor next-of-kin of these participants.
Interventions
The current standard of care in Poland is tracheal intubation using DL with MCL.
The intervention consisted of an intubation attempt using the INT laryngoscope with a new type of lightning and an ergonomic handle shape.
A standard approach to airway management (from basic to advanced techniques) was agreed on by the participating paramedics. This included patient positioning, the use of bag-mask ventilation (BVM) and simple airway devices prior to advanced airway management.
Video assisted laryngoscopy is not used by paramedics in Poland.
For tracheal intubation in OHCA, a 2-person technique using DL was recommended. End-tidal carbon dioxide monitoring was used to confirm correct device placement in all patients.
All study participants followed the European Resuscitation Council Guidelines for Resuscitation 2015 [14].
Paramedics were allowed to adjust the airway management technique during OHCA to specific patient and perceived needs. The trial protocol specified 2 attempts using each laryngoscope before SGA devices were used. According to the terms of approval granted by the Ethics Board, paramedics were obliged to undertake every intervention that was in the patient’s best interest.
Outcome and other measures
All outcomes were collected for all eligible patients and were reported by the paramedics using the Medical Rescue Card and trial protocol.
The primary outcome was the time of the first ETI attempt performed by the paramedics.
The time was measured using an electronic stopwatch. Time measurement began when the paramedic held the selected laryngoscope and declared their readiness to perform the procedure.
The secondary outcome was the effectiveness of the first ETI attempt for instrumental airway management for nontraumatic adult OHCA. With the exception of standard clinical protocol, end-tidal carbon dioxide monitoring was used to confirm correct device placement in all patients.
As with other measures we collected the data concerning the degree difficulty of intubation attempts for all of the patients included in the study. A long-term survival and a cost-effectiveness analysis were not included within this trial.
Data collection and analysis
We obtained all of the relevant data from the Voivodeship Rescue Station in Lodz Data Warehouse. Outcome data were collected from the Medical Rescue Card and from trial protocol delivered by participating paramedics. The estimated time was counted to two decimal places. Efficacy was determined using the zero-one system. We abstracted basic demographic data including the sex and age of all of the patients.
All statistical analyses were performed using PQStat (Version 1.6.8.304.) and IBM SPSS (Version 24.0). We present the data as mean values, with standard deviation (SD), or medians, with interquartile range (IQR), where appropriate. The time (seconds) of the first ETI attempt, depending on the laryngoscope used, was compared using a Student’s t-test (parametric values) after verifying the normality of the distribution with the Kolmogorov-Smirnov test and the homogeneity of variance with the Fisher-Snedecor F-test. The effectiveness and the degree of difficulty of the ETI attempts depending on the laryngoscope used were compared using the chi-square test. We present adjusted odds ratios (aOR) with 95% confidence intervals.
A P value of ≤ 0.05 was considered statistically significant and a P value of < 0.01 was considered to be highly significant.
No randomisation was performed, operators choose device basing on their preference. No blinding was performed.
Data safety and monitoring
Data quality assessments are executed routinely by utilizing the Emergency Medical Support Command System, which is part of the National EMS Command System. Quality-assurance initiatives are conducted regularly to ensure completeness and accuracy. After every ETI attempt during CPR by paramedics, the research team sent a self-report questionnaire to the paramedic team to acquire specific data.