Introduction

Cardiac Arrest (CA) carries a significant disease burden worldwide with an incidence of 81.6 Out-Of-Hospital Cardiac Arrest (OHCA) per 100,000 adult inhabitants in Europe [1]. Given the survival rate of approximately 10% for OHCA, efforts are continuously being made to improve outcomes, with research focusing on the timely and effective delivery of several critical interventions (such as administration of epinephrine, defibrillation, and advanced airway placement) during Advanced Life Support (ALS) next to Basic Life Support (BLS) in Cardiopulmonary Resuscitation (CPR) [2,3]. Outcome seems to be influenced by the intervals between collapse and the delivery of basic and advanced interventions, thus suggesting that the passage of time is an important factor in the survival of CA patients. The ideal timing and sequence of every critical step, however, seems to be rather unclear. The International Liaison Committee on Resuscitation (ILCOR) recommendations for adult ALS advise giving an intravenous push dose of epinephrine as soon as feasible in case of a non-shockable rhythm, whereas early defibrillation is advised in case of a shockable rhythm, keeping interruptions of chest compressions to a minimum and placing an advanced airway in time, using a stepwise approach [4–11]. Consequently, different key interventions must take place in a timely fashion, leading to questions regarding priority and sequence. To lead healthcare professionals through this process in an evidence-based manner, the European Resuscitation Council (ERC) provides updated guidelines every five years based on recommendations by ILCOR [12]. Adherence to these guidelines implies good quality of resuscitation, which is presumed to lead to better survival [13]. The evidence-base supporting this thesis, however, is not extensive nor unequivocal. Studies concerning In-Hospital Cardiac Arrest (IHCA) found a positive correlation between guideline adherence and Return of Spontaneous Circulation (ROSC), whereas other investigations were Inconclusive [14–17]. Studies investigating regional variability in outcomes of CA patients suggest, however, that these guidelines are not always met in real life [2,18-21]. When addressing CPR quality, many investigators have divided the adult CA algorithm into key components [22-24]. To our knowledge, no study has tried to investigate the compliance to the recommended timings for the critical actions visualized in the CA algorithm diagram in a prospective video recording-based manner. The main objective of this study was to evaluate the timings of each critical intervention during ALS. Prospective data derived from OHCA video recordings were analyzed and real-life timings were compared with the 2015 ERC guidelines for Resuscitation algorithm [12].

Materials and Methods

Setting

This prospective observational study was conducted by the Emergency Medical Services (EMS) connected to the Emergency Department (ED) of the University Hospital UZ Leuven, a tertiary referral center in Belgium. Mobile Medical Teams (MMT), consisting of at least an emergency physician and an emergency nurse, accompanied by an intern, manages patients sustaining an OHCA. At least two paramedics, trained in intermediate life support, reinforce the out-of-hospital team. All emergency medicine attending physicians and residents (minimum 3years of clinical experience) in this study have an ALS certificate and regular experience in handling CAs. During the study period, the MMTs used the 2015 ERC guideline algorithms for CA resuscitation efforts. A defibrillator (Philips Heart Start MRx) was available for rhythm analysis and defibrillation, if needed. There was no ‘point of care’-ultrasound or -testing available prehospital.

Study population

All adult patients (≥ 18years) who sustained an OHCA and were treated by a MMT from July 1, 2016 to June 31, 2018, were eligible for inclusion in the study. The MMT had to consist of at least three resuscitation members (including an emergency physician) (Figure 1). Patients were excluded if

1. The video recording of the CA was not complete,
2. The quality of video recording did not allow for reliable data collection or
3. The patient was found with rigor mortis or other obvious signs of irreversible death.

Figure 1: Flow diagram of video-recorded resuscitations. Abbreviations: OHCA: Out-Of-Hospital Cardiac Arrest. ECMO: Extracorporeal Membrane Oxygenation.

Data collection

A mobile digital real-time video recording GoPro HERO 4 device (black edition) was used. The GoPro was body-mounted on the team leader with a chest harness (Chesty) or on a participating emergency medicine intern who then oriented the camera to the team leader’s perspective. The team leader was responsible for recording the resuscitation process and the security of the videotape afterwards. The recording was started upon arrival at the scene.

Two physicians, who were not involved in prehospital care, independently reviewed video recordings of all included resuscitations. For privacy reasons, video recordings were erased within two weeks after the CA event. All study data were stored on a secure, hospital-based protected server.

The following demographic characteristics and CA event data were collected: age, gender, witnessed arrest (yes/no), bystander CPR (yes/no), arrival time of the MMT, time to first rhythm, initially detected cardiac rhythm, time to first defibrillation, time to first epinephrine administration, time to advanced airway placement, time to etiology questioning and treatment, CA event duration and patient outcome according to the Utstein criteria (Return of spontaneous circulation (ROSC)) [25]. Additionally time to subsequent doses of epinephrine and subsequent timings of rhythm checks, defibrillations and time to amiodarone where gathered. The absolute timings of critical actions were recorded and adjusted to set the first rhythm check as Time point zero (T₀).

Table 1: Overview of 2015 guidelines.

Data analysis

All data were imported into Microsoft Excel for Mac OS, version 16.8 (Microsoft Corp., Redmond, Washington, USA).

Data were described as percentage and frequency of occurrence for categorical variables and as central tendency measures for continuous data. Median times were calculated for all time critical actions. Based on the 2015 ERC guidelines, a guidance table was created including the recommended timings for each time critical action (Shown in Table 1) [26]. For each of them, the percentage of critical actions taking place within the proposed time interval was calculated. For airway management and treatment of reversible causes, the ERC does not make clear timing recommendations, so we looked at the timings proposed by ILCOR.

Results

From July 1, 2016, to June 31, 2018, the MMTs from UZ Leuven were dispatched 244 times for patients experiencing an OHCA. Of these, 85 resuscitations were not video recorded since there was no evidence of a need of resuscitation prior to arrival on scene. From the 159 cases where the prehospital teams planned to film, 31 video recordings were excluded due to poor video quality, memory card problems, battery issues, unavailability of the GoPro, irreversible death, or Extracorporeal Membrane Oxygenation (ECMO) placement (shown in Figure 1). In total 128 recordings were deemed valid for evaluation, but not all recordings gave clear and concise audio or video proof regarding all data, so each intervention was assessed individually. Figure 1 shows the number of resuscitations for which a timing was obtained for each intervention.

Resuscitation characteristics

The mean age of patients sustaining an OHCA was 69.4 years (range 25 to 95 years). The large majority was male (87 out of 128). Return of Spontaneous Circulation (ROSC) occurred in 53 patients. In 60.2% of all OHCAs, the arrest was witnessed and in 68.8%, patients received bystander CPR. The initial rhythm on arrival was in 18.0% shockable (shown in Table 2). Of all included patients, 27.3% survived one day. The one-month and one year survival rates were 10.2%, and 5.5%, respectively.

Continuous variables are expressed as medians with their interquartile ranges. Categorical variables are expressed as frequencies with percentages.

Resuscitation time frame

The median time from call to EMS to arrival at the patient’s side was 877s (15min 24s). A first rhythm check occurred at a median time of 64 s after arrival at the patient’s side. After the first rhythm check (T₀-Time 0s), a distinction was made between patients with an initial shockable (n=21) and non-shockable rhythm (n=107).

Defibrillation

In the shockable group, the first shock was administered at a median time of 26s after the first rhythm check (T₀). The second and third shock were administered after 224s (3min 44s), and 321s (5min 21s), respectively.

Epinephrine administration

The first dose of epinephrine was administered at a median time of 190s (3min 10s) after the first rhythm check (T₀) in the non-shockable patient group and 207s (3min 27s) in the shockable group. In 27.8% of all non-shockable OHCAs, the MMT was able to administer epinephrine in the first cycle, as advised in the ALS guidelines. In 73.74% of shockable OHCA’s, epinephrine was administered before the third cycle. Subsequent doses in the nonshockable group followed at a median time of 578 s (2^nd cycle) (9 min 38 s), and a median time of 1,139s (3^rd cycle) (18 min 59s) after the first rhythm check. In the shockable group subsequent doses of epinephrine followed at a median time of 551s (9min 11s) and 989s (16min 29s) in the 2^nd, and 3^rd cycle, respectively.

Advanced Airway Placement

The elapsed median time from first rhythm check to successful placement of an advanced airway was 265s (4min 25s) for shockable rhythms, and 240s (4min) for non-shockable rhythms, respectively. The percentages of correct AA placement in relation to the suggested CPR-cycles can be found in Figures 3 and

4. Initial Endotracheal Intubation (ETI) success rate was 69.5%. In 20.3% of the resuscitations, the physician needed more than two attempts for ETI. All attempts are summarized in Table 2. In two cases, it was unclear whether an attempt for an Advanced Airway was made due to unclear video footage. In 7 cases, it was clear no attempt to placement of an AA was made. Reasons reported for Bag Valve Mask (BVM) usage only included death prior to airway insertion attempt (1x) and adequate ventilation with BVM (4x). In 2 cases, the reason was unclear. During five OHCAs, a Laryngeal Tube (LT) was used, one time after 1 ETI attempt, one after 2 attempts, 1 time after 3 attempts and 2 times after 5 attempts.

All other advanced airway placement attempts ended with an ETI. In total 190 attempts were made during 119 OHCAs. In 31.6% (60 out of 190) of the ETI attempts, chest compressions were interrupted for more than 10 s (median: 31s-IQR: 14-32). In 41 resuscitations one prolonged attempt (>10s) was made, in 6 cases two prolonged attempts were needed, in one resuscitation 3 prolonged attempts and in one resuscitation 4 attempts were made. In 63% (75 out of 119) of all ETIs capnography was used.

Table 3: Attempts for Endotracheal Tube (ETT) placement.

Etiologic evaluation and treatment of reversible causes

In 85 resuscitations, a clear timing for etiology questioning could be discerned. Therefore, only 85 were included in the final analysis. The median times to etiology questioning for the non-shockable and shockable groups were 242s (4min 2s), and 240s (4min) after T₀, respectively. The median time to treatment of a reversible etiology (without the standard treatment with shock or ETI) after finding the first rhythm was 492s (8min 12s) for the non-shockable group and 422s (7min 2s) for the shockable group. More than 60% of treatment of reversible causes took place after the recommended cycle in the non-shockable group. For obvious reasons, time to first shock was omitted from treatment of reversible causes.

All gathered date were visualized using an adapted flowchart, based on the 2015 ERC Adult CA algorithm, with median timings from daily practice based on the OHCA video recordings (shown in Figure 2).

Figure 2: Resuscitation time frame, including median timings from daily practice based on the OHCA video recordings.

Comparison of the resuscitation guidelines with daily practice

Based on the 2015 ERC and ILCOR recommendations a guidance table was created including the recommended timings for each time critical action (shown in Table 1) [26]. In Figures 3 and 4, the percentages of critical actions taking place within the proposed time intervals are reported.

For resuscitations with an initial shockable rhythm, the percentages of resuscitations for which the critical actions were performed within the recommended time frames were the following:

1. Time to second rhythm check: 11.1% (2 out of 1),
2. Time to second shock 0% (0 out of 10),
3. Time to first dose of epinephrine: 0% (0 out of 19),
4. Time to advanced airway: 17.6% (3 out of 17),
5. Time to amiodarone: 0% (0 out of 10).

For resuscitations with an initial non-shockable rhythm, the percentages of resuscitations for which the critical actions were performed within the recommended time frames were the following:

1. Time to second rhythm check: 7.9% (8 out of 101),
2. Time to first dose of epinephrine: 24.7% (24 out of 97),
3. Time to advanced airway: 17.6% (13 out of 74),
4. Time to treatment of reversible causes: 10.7% (3 out of 28).

Figure 3: Guidelines versus reality for patients with an initial shockable rhythm. The red frame indicates the advised timing according to the guidelines. For each time critical action, the percentage of resuscitations following and deviating from the guidelines is shown. A) Time to second rhythm check; B) Time to second shock; C) Time to first dose of epinephrine; D) Time to advanced airway and E) Time to amiodarone.

Figure 4: Guidelines versus reality for patients with an initial non-shockable rhythm. The red frame indicates the advised timing according to the guidelines. For each time critical action, the percentage of resuscitations following and deviating from the guidelines is shown. A) Time to second rhythm check; B) Time to first dose of epinephrine; C) Time to advanced airway; D) Time to treatment of reversible causes.