Minor Variations in Electrode Pad Placement Impact Defibrillation Success

Remote synchronous usability testing of public access defibrillators during social distancing in a pandemic

Public access automated external defibrillators (AEDs) represent emergency medical devices that may be used by untrained lay-persons in a life-critical event. As such their usability must be confirmed through simulation testing. In 2020 the novel coronavirus caused a global pandemic. In order to reduce the spread of the virus, many restrictions such as social distancing and travel bans were enforced. Usability testing of AEDs is typically conducted in-person, but due to these restrictions, other usability solutions must be investigated. Two studies were conducted, each with 18 participants: (1) an in-person usability study of an AED conducted in an office space, and (2) a synchronous remote usability study of the same AED conducted using video conferencing software. Key metrics associated with AED use, such as time to turn on, time to place pads and time to deliver a shock, were assessed in both studies. There was no difference in time taken to turn the AED on in the in-person study compared to the remote study, but the time to place electrode pads and to deliver a shock were significantly lower in the in-person study than in the remote study. Overall, the results of this study indicate that remote user testing of public access defibrillators may be appropriate in formative usability studies for determining understanding of the user interface.

Effect of Shock Vector Orientation in Modulating and Terminating Rotors - a Simulation Study

The main treatment option for Ventricular Fibrillation (VF), especially in out-of-hospital cardiac arrests (OHCA) is defibrillation. Typically, the survival-to-discharge rates are very poor for OHCA. Existing studies have shown that rotors may be the sources of arrhythmia and ablating them could modulate or terminate VF. However, tracking rotors and ablating them is not a feasible solution in a OHCA scenario. Hence, if the sources (or rotors) can be regionally localized non-invasively and this information can be used to direct the orientation of the shock vectors, it may aid the termination of rotors and defibrillation success. In this work, using computational modeling, we present our initial results on testing the effect of shock vector orientation on modulating (or) terminating rotors. A combination of Sovilj's and Aliev Panfilov's monodomain cardiac models were used in inducing rotors and testing the effect of shock vector magnitude and direction. Based on our simulation results on an average with four experimental trials, a shock vector directed in the perpendicular direction along the axis of the rotor terminated the rotor with 16% lesser magnitude than parallel direction and 38% lesser magnitude than in oblique direction.Clinical Relevance- A rotor localization dependent defibrillation strategy may aid the defibrillation protocol procedures to improve the survival rates. Based on the four experimental trials, the results indicate shock vectors oriented perpendicular to the axis of the rotors were efficient in modulating or terminating rotors with lower magnitude than other directions.

Basic life support skills can be improved among certified basic life support instructors

Background

A correct visual skill demonstration is important when learning cardiopulmonary resuscitation (CPR) and the use of an automated external defibrillator (AED). Basic life support (BLS) instructors are expected to master and demonstrate CPR/AED skills correctly. The aim of this study was to evaluate certified BLS instructors’ competencies in demonstrating CPR and the use of an AED.

Methods

Certified BLS instructors demonstrated CPR and the use of an AED on a resuscitation manikin. Skills were evaluated using data collected from the manikin and video recordings and compared to resuscitation guidelines. Further, instructors completed questionnaires on resuscitation guidelines and rating of their own CPR/AED skills.

Results

Overall, we analyzed data from 125 instructors. Of all chest compressions, only 22% were within guideline recommendations regarding depth. Instructors performed chest compressions with excessive depth (mean depth 64 mm (7.3)) and a mean rate of 115 min⁻¹ (10.8). Only 25% of instructors placed the left AED electrode correctly (median distance 7.6 cm (5.0;10.5)), while the right AED electrode usually was placed correctly (median distance 2.9 cm (1.5;4.0), 85% placed correctly). Nearly half of the instructors failed to state correct answers regarding how to diagnose a cardiac arrest and where to place the AED electrodes. Despite their performance, instructors rated their BLS skills as good.

Conclusion

Certified BLS instructors’ have poor CPR/AED skills and several important knowledge gaps on CPR/AED guidelines in contrast to instructors’ self-reported skills. This highlights a need for improving BLS instructor education, including continuous faculty development to ensure optimal learning conditions for BLS course participants.

Can Mobile Videocall Assist Laypersons' Use of Automated External Defibrillators? A Randomized Simulation Study and Qualitative Analysis

Objective

To investigate the feasibility of mobile videocall guidance to facilitate AED use by laypersons. Design, setting, and participants. A total of 90 laypersons were randomized into three groups: the mobile video call-guided, voice call-guided, and non-guided groups. Participants were exposed to simulated cardiac arrest to use an AED, and guided by video calls, voice calls, or were not guided. We recorded the simulation experiments as a videoclip, and other researchers who were blinded to the simulation assessed the performance according to the prespecified checklist after simulations. Outcomes measure and analysis. We compared the performance score and time intervals from AED arrival to defibrillation among the three groups and analyzed the common errors.

Results

There was no significant difference among the three groups in terms of baseline characteristics. Performance scores in the checklist for using AED were higher in the mobile video call-guided group, especially in the category of "Power on AED" and "Correctly attaches pads" than in the other groups. However, the time interval to defibrillation was significantly longer in the mobile video call-guided group.

Conclusions

Mobile video call guidance might be an alternative method to facilitate AED use by laypersons. Therefore, further well-designed research is needed to evaluate the feasibility of this approach in OHCA.

The general public's ability to operate automated external defibrillator: A controlled simulation study

BACKGROUND

Automated external defibrillators (AEDs) enable laypeople to provide early defibrillations to patients undergoing cardiac arrest, but scant information is available on the general public's ability to use AEDs. This study assessed the ability of laypeople to operate AEDs, the effect of a 15-minute training, and whether skills differed by age.

METHODS

From May 1 to December 31, 2018, a prospective simulation study was conducted with 94 laypeople aged 18-65 years (32 aged 18-24 years, 34 aged 25-54 years, and 28 aged 55-65 years) with no prior AED training. The participants' AED skills were assessed individually pre-training, post-training, and at a three-month follow-up using a simulated cardiac arrest scenario. The critical actions and time intervals were evaluated during the AED operating process.

RESULTS

Only 14 (14.9%) participants (eight aged 18-24 years, four aged 25-54 years, and two aged 55-65 years) successfully delivered defibrillations before training. AED operation errors were more likely to occur among the participants aged 55-65 years than among other age groups. After training, the proportion of successful defibrillations increased significantly (18-24 years old: 25.0% vs. 71.9%, P<0.01; 25-54 years old: 11.8% vs. 70.6%, P<0.01; 55-65 years old: 7.1% vs. 67.9%, P<0.01). After three months, 26.1% of the participants aged 55-65 years successfully delivered defibrillations, which was significantly lower than that of participants aged 18-24 years (54.8%) and 25-54 years (64.3%) (P=0.02). There were no differences in time measures among three age groups in each test.

CONCLUSIONS

The majority of untrained laypeople cannot effectively operate AEDs. More frequent training and refresher courses are crucial to improve AED skills.

Accuracy of instructional diagrams for automated external defibrillator pad positioning

INTRODUCTION

Correct defibrillation pad positioning optimises the chances of successful defibrillation. AEDs have pictoral representation to guide untrained bystanders in correct pad positioning. There is a wide variation in this pictoral guidance and evidence suggests that correct anatomical pad placement is poor. We reviewed all currently available diagrams and assessed the resultant pad placement achieved by untrained bystanders following these instructions.

METHODS

Twenty untrained bystanders were presented with a total of 27 different pad placement diagrams (including one designed by the researchers) in a random sequence and were asked to apply them to the chest of an adult manikin. The lateral/medial and cranial/caudal position in relation to the optimal position recommended by the European Resuscitation Council guidelines was then measured for each pair of pads.

RESULTS

Overall, the sternal pad was placed an average of 6.0 mm cranial to, and 3.2 mm medial to, the optimal position. The apical pad was placed an average of 78.2 mm caudal to, and 59.3 mm medial to, the optimal position. The pad position diagram we designed and assessed out performed existing diagrams.

CONCLUSION

All current defibrillation pad diagrams fail to achieve accurate defibrillation pad placement. A clearer, more effective diagram, such as the one we designed, is urgently needed to ensure bystander defibrillation is effective as possible.

Automated external defibrillation training on the left or the right side - a randomized simulation study

Background

Correct placement of the left automated external defibrillator (AED) electrode is rarely achieved. AED electrode placement is predominantly illustrated and trained with the rescuer sitting on the right side of the patient. Placement of the AED electrodes from the left side of the patient may result in a better overview of and access to the left lateral side of the thorax. This study aimed to investigate if training in automated external defibrillation on the left side compared to the right side of a manikin improves left AED electrode placement.

Methods

Laypeople attending basic life support training were randomized to learn automated external defibrillation from the left or right side of a manikin. After course completion, participants used an AED and placed AED electrodes in a simulated cardiac arrest scenario.

Results

In total, 40 laypersons were randomized to AED training on the left (n=19 [missing data =1], 63% female, mean age: 47.3 years) and right (n=20, 75% female, mean age: 48.7 years) sides of a manikin. There was no difference in left AED electrode placement when trained on the left or right side: the mean (SD) distances to the recommended left AED electrode position were 5.9 (2.1) cm vs 6.9 (2.2) cm (p=0.15) and to the recommended right AED electrode position were 2.6 (1.5) cm vs 1.8 (0.8) cm (p=0.06), respectively.

Conclusion

Training in automated external defibrillation on the left side of a manikin does not improve left AED electrode placement compared to training on the right side.