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Prove It: Real-time feedback devices improve CPR training

Researchers measured the impact several CPR feedback or prompt devices had on chest compression depth, compression rate recoil and hand position

Today is training day for the crew of station 27. After breakfast, dispatch places both the engine and the medic crews out of service and sends them to the training center. Today’s class is a CPR refresher course.

However, this refresher course is different than any previously taught. Today, the instructors are adding a new CPR feedback device to the manikin practice, which will provide real-time performance data to the crew. The instructor explains the devices will help insure everyone provides the correct rate, depth, and recoil. The device also provides an audible warning when a pause in chest compressions lasts for 10 or more seconds. The instructor explains the department will place one of these devices on every response vehicle in the city during the next week in the hopes of fine-tuning CPR performance and improving out-of-hospital cardiac arrest survival rates for the community. 

Initially, the devices are a bit cumbersome for the crew. No one has ever used one before and it takes some getting used to. As each of the firefighters and medics take turns on the manikin, they slowly begin to adjust their performance based on the feedback provided by the device.

However, one of the station officers is becoming increasingly frustrated with the device. He grumbles about being CPR certified for more than 25 years and he does not need a machine to tell him how to do CPR. He thinks his department could have saved the money spent for these devices on something with a greater benefit to the department.

Despite the best intentions of the training officer, the lieutenant remains unconvinced the device will actually change the way he and his crew perform CPR.

Study review: CPR performance with a feedback device
Using a manikin, researchers measured the impact that various CPR feedback or prompt devices had on specific CPR quality metrics, such as chest compression depth, compression rate, inadequate recoil and incorrect hand position [1]. The participants were all nurses who had previous experience with CPR, but had never used any type of feedback or prompt device. Each nurse either worked in the emergency department or as part of the EMS team with an average (mean) work experience of 12.4 years. Before starting the study, members of the research team trained the nurses to correctly use each of the devices.

The researchers compared manual CPR without the use of a device (standard CPR) to CPR using each of three commonly available devices; TrueCPR™ Coaching Device from Physio-Control, CPR-Ezy™ from Health Affairs, LTD. and the iCPR app from DSign S.r.l. Random assignment determined which device (or no device) each nurse would start with. Each nurse performed eight minutes of single rescuer CPR with the randomly assigned device (or no device).

Upon conclusion, the nurse rested for 20 minutes before being assigned to one of the remaining options. This process continued until each nurse performed eight minutes of CPR with each of the three devices and eight minutes of standard CPR without a device.

After completing all four CPR sessions, each nurse also completed a survey that described a personal level of confidence, whether each device was easy and comfortable to use and whether each device provided a distraction from performing CPR.

Researchers collected the data for this study during the summer of 2014, before the release of the 2015 AHA CPR Guidelines. As a result, the researchers compared all CPR quality measures to those recommended by the 2010 European Resuscitation Council (ERC) Guidelines, which called for a chest compression depth of at least 5 cm (50 mm), a rate between 100 and 120 compressions per minute, full chest recoil and hands positioned on the lower half of the sternum [2].

Results: Feedback device comparison
The only study condition to achieve the recommended chest compression depth of 50 mm was CPR performed while using the TrueCPR™ feedback device. With this device, nurses achieved significantly deeper chest compressions than with the other devices or no device at all. In decreasing order, nurses achieved a mean chest compression depth of 54.5 mm with TrueCPR™, 45.6 mm with CPR-Ezy™, 44.6 mm with standard CPR using no feedback device and 39.6 mm using the iCPR app. Not only did the TrueCPR™ device produce deeper average chest compressions, but the device also produced the highest proportion of compressions meeting the ERC depth recommendations.

All three of the devices had a significant impact on chest compression rate. The only condition that produced a chest compression rate outside of the recommended rate (100-120 per minute) was standard CPR without the use of a device. In decreasing order, nurses performed CPR at a mean rate of 129 compressions per minute using standard CPR with no device, 110 compressions per minute using TrueCPR™, 104 compressions per minute using the iCPR app, and 102 compressions per minute using CPR-Ezy™.

Since the ERC recommended a compression depth greater than 50 mm, full chest recoil should also be greater than 50 mm. Use of the TrueCPR™ device resulted in a significantly higher proportion of compressions meeting the recommendation for chest recoil. In decreasing order, the proportion of compressions meeting the ERC recommendations for chest recoil was 78 percent with TrueCPR™, 70 percent with CPR-Ezy™, 68 percent with standard CPR using no device, and 65 percent using the iCPR app.

The manikin and software program used in this study were able to measure whether the compression point was on the lower half of the sternum (correct), or in some other location, such as too far to one side or too high or low on the chest (incorrect). Use of the TrueCPR™ device resulted in the highest proportion of compressions in the correct position. In decreasing order, the proportion of chest compressions with the correct pressure point was 98 percent with TrueCPR™, 95 percent with standard CPR using no feedback device, 93 percent with CPR-Ezy™, and 77 percent using the iCPR app.

Finally, the researchers created a metric called effective compression, which was defined as the proportion of compressions meeting the ERC recommendations for depth, recoil, and hand position. TrueCPR™ significantly outperformed any of the other conditions. In decreasing order, the proportion of effective chest compressions was 86 percent with TrueCPR™, 40 percent with CPR-Ezy™, 38 percent with standard CPR using no device, and 33 percent using the iCPR app. The proportion of effective chest compressions associated with TrueCPR™ remained significantly better regardless of whether the measurement occurred at the beginning of the eight-minute CPR period (90 percent) or the end (76 percent).

In a head-to-head comparison of user satisfaction variables between the three devices, the study participants found the TrueCPR™ device easiest and most comfortable to use. The device also provided the user with the highest level of confidence and produced the least amount of distraction.

In the multivariate regression analysis, the researchers also found that both provider experience and work location influenced the overall proportion of effective chest compressions. Nurses with more experience outperformed those with less experience when performing standard CPR without a device and when using the iCPR app. Additionally, those nurses primarily assigned to EMS fieldwork outperformed those assigned to the ED when performing standard CPR without a device and when using the iCPR app.

What this means for you
The term feedback device is commonly used to describe a variety of tools with a common goal to improve the quality of CPR provided during a resuscitation attempt. However, the term may or may not actually describe the way the device works. True feedback devices offer information about what rescuers are actually doing, so they can make real time adjustments to CPR performance. In this study, the TrueCPR™ and the CPR-Ezy™ devices functioned as true feedback devices.

Prompt devices on the other hand do not provide information about how rescuers are performing. While the rescuer can make real-time adjustments to CPR performance based on that information, the device is not actually measuring what the rescuer is doing. For example, metronomes use an audible tone to prompt the rescuer to perform chest compressions at a predetermined rate, but cannot measure if the rescuer is actually performing synchronized compressions.

Intuitively, it is reasonable to expect feedbacks devices to outperform prompt devices. However, all feedback devices may not have the same impact on performance. In this study, only one of the feedback devices significantly outperformed the prompt device. Incidentally, that feedback device even outperformed standard non-device assisted CPR.

Generally, CPR training utilizing a real time feedback component results in improved student performance. Use of the TrueCPR™ device during CPR training improved compression rate and depth performance on a manikin by a group of in-hospital healthcare providers [3]. In a randomized controlled trial involving trained rescuers, one type of feedback device utilizing pressure sensing technology (CPR-Ezy™) significantly improved compression depth while a different device utilizing an accelerometer (Q-CPR™) resulted in worsening depths [4]. Researchers at the Medical University of Vienna found improved CPR measures when medical students received feedback during training, but performance measures associated with a mechanical device were no better or no worse than those associated with feedback from a trained human instructor [5].

However, the impact of this improved training on clinical outcomes is less clear. Early studies could find no significant improvement in outcome variables associated with the use of a feedback device in either the in-hospital [6] or out-of-hospital environments [7]. More recently, a multi-center study of in-hospital cardiac arrest could not demonstrate any survival advantages associated with the addition of feedback devices to a standard resuscitation attempt [8].

In contrast, secondary analysis of data collected during an investigation of CPR quality related to the use of one specific real-time audio-visual feedback device during an out-of-hospital resuscitation attempt transported by a helicopter demonstrated that use of the device resulted in increased survival to emergency department arrival, but not increased survival for an additional 24-hours or increased survival to hospital discharge [9]. Similarly, use of the Cardio First Angel™ CPR device instead of manual CPR with no feedback device in ICU patients resulted in improved ROSC and reduced rib fractures in ICU patients [10].  In contrast, the odds of surviving neurologically intact following an out-of-hospital cardiac arrest were reduced by about 50 percent when rescuers used the Q-CPR feedback device during the resuscitation [11].

In the largest trial to date to address this issue, researchers with the Resuscitation Outcomes Consortium could find no survival advantages provided by the use of a feedback device during resuscitation from out-of-hospital cardiac arrest [12]. The most recent meta-analysis of clinical trials using audio-visual feedback devices during resuscitation could find no evidence the devices improve clinical outcomes [13].

In a before and after observational study, the addition of real-time audiovisual feedback along with a targeted CPR quality training curriculum improved clinical CPR quality metrics, which resulted in an increased likelihood of both survival to hospital discharge and favorable function outcome [14]. However, because of the nature of this study no one can be sure whether the improved outcome measures resulted from the real-time feedback, the increased focus on quality CPR training, or some other unmeasured variable.

There are a number of possible reasons why no study has ever been able to clearly demonstrate clinical improvement with the use of any of these devices. First, survival following out-of-hospital cardiac arrest is time dependent. Patients generally have more favorable outcomes when ROSC occurs sooner rather than later. To increase the chances of survival, the first three links in the chain of survival should occur before EMS personnel arrive on the scene. If they do not, the chances of survival significantly decrease. By the time EMS arrives on the scene to begin using a feedback device, it is possible the window of opportunity for many of the early variables known to improve survival has already closed.

Although simulation data shows the use of feedback or prompt devices does improve CPR metrics, it is possible the improvements do not represent meaningful or useful data for real patients. Performing CPR on a manikin during a training situation is different than performing CPR on a human being in the ICU or ED, which is different still from performing CPR in the out-of-hospital environment.

The 2015 American Heart Association Guidelines Update for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care recommends the use of feedback devices as an adjunct to CPR training [15]. If feedback devices are not available, instructors should substitute prompt devices during CPR training.

Feedback and prompt devices appear to improve CPR quality metrics obtained during the simulated management of cardiac arrest. However, not all of the devices perform equally. EMS agencies considering the addition of feedback devices to the management of out-of-hospital cardiac arrest should investigate all options before choosing a particular technology.

The author has no financial interest, arrangement, or direct affiliation with any corporation that has a direct interest in the subject matter of this presentation, including manufacturer(s) of any products or provider(s) of services mentioned.


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