Introduction

The prognosis of out-of-hospital cardiac arrest (CA) is determined by many well-studied factors^1-3, including the ability of the witness to quickly start cardiopulmonary resuscitation (CPR) maneuvers of sufficient quality as to generate cerebral blood flow, and continue them until the ambulance’s arrival.

Some of the strategies implemented in Spain to help laypersons act correctly in the event of an out-of-hospital CA include the regulation and installation of publicly accessible automated external defibrillators (AED)⁴, as well as dispatcher assistance from the Emergency Dispatch Centre (EDC) on the steps to follow in initiating CPR⁵.

Since it is reasonable to think that the dispatcher-assisted technique will directly affect the performance of CPR being performed by the witness, the objective of this paper is to focus on analysing the content of the CPR telephone instructions issued to untrained laypersons by an EDC during out-of-hospital cardiac arrest.

Methods

A descriptive post hoc analysis of a randomized clinical simulation study evaluated the quality of CPR performed by laypersons without prior training in life support maneouvers (NCT03771911)⁶.

Participants, with the support of an AED trainer (Philips HeartStart FR2) and EDC telephone instructions, carried out a simulation of cardiac arrest on a true-to-life mannequin without the possibility of being relieved by another person. The scenario was introduced by describing a case (briefing), in which the participant found a person lying supine on the floor, and was only equipped with a mobile phone that could be used to request help and a publicly accessible AED within their reach.

Phone calls were received at the corresponding EDC by an operator who, after initial questioning, transferred the communication to the center’s health care coordinator for case management. The telephone instructions were given by eleven different dispatchers at the EDC (emergency team of physicians and nurses with at least five years of professional experience), following the recommendations of the Spanish Resuscitation Council⁵.

Each simulation lasted nine minutes (approximately the time required for emergency resources to arrive at the site) in a high-fidelity simulated environment, which allowed observation of the situation and its recording on audio and video without interfering with its implementation. The simulation sessions took place on days and at times of low assistance load at the EDC, which was reinforced with additional personnel to avoid affecting the normal performance of the service.

For the descriptive analysis of the content of the dispatcher-assisted cardiopulmonary resuscitation instructions, a checklist of fourteen indicators was used, prepared on the basis of the recommendations proposed in the literature^{5 7}, in which the response was did or did not do. At the same time, the intervals of the call management process to the EDC were timed. Data collection was carried out independently by two researchers, while a third acted as an evaluator by comparing the information that they gathered, with agreement reached on the content of the final template.

The number of times that each of the telephone instructions described in the checklist were indicated was counted and their percentage was calculated. The timing of the telephone calls is displayed in the form of mean and standard deviation (SD). Inter-rater reliability was assessed using Cohen’s kappa and its 95% confidence interval (95%CI). Statistical analysis was performed using IBM SPSS Version 25, thereby setting the level of statistical significance at p <0.05.

Results

Twenty-one volunteers participated in the study, of which ten (47.6%) were women. The average age of the participants was 39.1 years (SD: 8.2).

The initial inter-rater agreement between researchers in content analysis related to dispatcher instructions was very high (k = 0.73; 95%CI: 0.65-0.81; p <0.001).

All the participants were able to initiate CPR maneuvers. In general, the instructions on how to proceed in the CPR technique were verbalized in very heterogeneous ways, and the prompts were not standardized. Half of the proposed indicators exceeded 90% compliance. The most frequently omitted instructions corresponded to the need to push hard and fast on the patient’s chest and the recommendation to activate the hands-free phone system. The most deficient instructions were those referring to the compression rate (with a tendency to mark slower rates). Table 1 summarizes how often dispatchers gave key instructions for performing CPR.

As shown in Table 2, the mean time between the emergency call and the start of chest compressions or turning on the AED was 3 min 33 s (SD 1 min 7 s).

Discussion

This paper represents an approximation of the actual performance of EDC as a telephone assistance provider for laypersons who are faced with the challenge of performing CPR without having specific training. The results of this simulation show that the EDC is capable of getting an untrained layperson to begin life support maneuvers, regardless of the quality thereof.

Papers evaluating the quality or content of dispatcher-assisted CPR are not abundant in the literature, thereby making it difficult to compare results; however, a previous study carried out in Asturias (Spain), based on twenty-eight recordings of calls received at the EDC about CA, detected a proportion of compliance with the indicators and some points of improvement close to those observed in our paper⁸.

The aspects that deserve more attention in this study, due to their low emphasis on dispatcher-assisted CPR instructions, are those that address the depth and rate of compressions. One of the most reiterative quality parameters in the latest international recommendations refers to chest compression depths⁷, since a compression of less than 5 cm does not generate cerebral blood flow. Overall, the dispatcher assistance during our simulations showed no emphasis in indicating the need to press hard, like in the movies; it should be noted that in less than half of the cases, the EDC told the rescuer to put the phone in hands-free mode. It is necessary to bear in mind that the evident discomfort of holding the phone close to the ear while performing compressions could affect their quality.

In addition to pressing hard, the EDC must urge the rescuer to press fast, with the intention of achieving a compression rate of between 100 and 120 per minute. The vocal marking of the compression rate from the EDC was inadequate in most cases, which is a result that corresponds to the observations made in previous publications⁹ and has led to solutions such as the integration of a metronome during dispatcher-assisted telephone CPR instructions^10-11; however, this option is not without its detractors, considering the possible negative effect compared to the usual practice¹².

Another aspect of our results that should be discussed is the EDC’s vague description of the correct way to position the CPR provider and prepare the patient. It must be considered that for the experienced professional caregiver, it may be obvious that the patient must be placed in a supine position, the provider must kneel next to the victim for cardiac massage, and this must be performed on the bare chest of the patient, but these details may not be known or deduced by the layperson raising the alarm, especially in a stressful situation.

Lastly, the timing of calls deserves special attention. Considering that the prognosis of CA is time-dependent, the strategies of the EDC must be oriented to preferentially handling calls that are suspected of being about CA and minimizing the time until CPR is initiated. In comparison with the results of Roza et al⁸, in this case lower mean times were achieved until the start of resuscitation, although three and a half minutes may be considered excessive from a clinical point of view.

Despite efforts aimed at possibly reproducing the most realistic situation, it is necessary to point out, as a limitation, that the study was carried out in a simulation space on a mannequin. This fact may obscure some reactions, which in a real situation might have led the layperson to act in a different way, such as the state of anxiety and nervousness that an emergency produces, and the reticence to perform CPR on a real person. In addition, the contextualization of the case during the briefing can help the participant to quickly identify the CA, when in a real situation there might be doubts or setbacks.

The overall conclusion of this paper shows that there is room for improvement in dispatcher-assisted services. EDC professionals must be aware of the need to provide clear, concise and homogeneous CPR telephone instructions, with the aim of reducing the time until the start of life support maneuvers, getting the rescuer to adopt a comfortable position (including the recommendation of activating the hands-free option of the phone), clearly indicating the way to prepare oneself and get into position to perform a heart massage, and reinforcing the need for hard and fast compression (perhaps marking the compression rate aided by a metronome).