Brief Report
A flexible pressure sensor could correctly measure the depth of chest compression on a mattress

https://doi.org/10.1016/j.ajem.2016.02.052Get rights and content

Abstract

Background

Feedback devices are used to improve the quality of chest compression (CC). However, reports have noted that accelerometers substantially overestimate depth when cardiopulmonary resuscitation (CPR) is performed on a soft surface. Here, we determined whether a flexible pressure sensor could correctly evaluate the depth CC performed on a mannequin placed on a mattress.

Methods

Chest compression was performed 100 times/min by a compression machine on the floor or a mattress, and the depth of CC was monitored using a flexible pressure sensor (Shinnosukekun) and CPRmeter. The depth of machine-performed CC was consistently 5 cm. We compared data from the feedback sensor with the true depth of CC using dual real-time auto feedback system that incorporated an infrared camera (CPR evolution).

Results

On the floor, the true depth of CC was 5.0 ± 0.0 cm (n = 100), or identical to the depth of CC performed by the machine. The Shinnosukekun measured a mean (± SD) CC depth of 5.0 ± 0.1 cm (n = 100), and the CPRmeter measured a depth of 5.0 ± 0.2 cm (n = 100). On the mattress, the true depth of CC was 4.4 ± 0.0 cm (n = 100). The Shinnosukekun measured a mean CC depth of 4.4 ± 0.0 cm (n = 100), and the CPRmeter measured a depth of 4.7 ± 0.1 cm (n = 100). The data of CPRmeter were overestimated (P < .0001 between the true depth and the CPRmeter-measured depth).

Conclusion

The Shinnosukekun could correctly measure the depth of CC on a mattress. According to our present results, the flexible pressure sensor could be a useful feedback system for CC performed on a soft surface.

Introduction

Feedback devices are used to improve the quality of chest compression (CC) [1], [2], [3], [4]. However, several studies have shown that feedback devices are not sufficiently reliable to ensure an adequate CC depth on soft surfaces, such as mattresses. According to the 2010 American Heart Association guidelines, real-time CC-sensing and feedback/prompt technology (eg, visual and auditory prompting devices) might be useful adjuncts during resuscitation efforts. However, rescuers should be aware of the potential for overestimation of CC depth when the victim is on a soft surface [5] . Previous reports noted that a sternum-only accelerometer (CPRmeter) substantially overestimated the depth when performing cardiopulmonary resuscitation (CPR) on a soft surface [6], [7]. To date, several reports have shown improvements in the overestimation of depth during CC on a mattress [8], [9], [10]. However, ideal methods have not yet been reported.

We recently developed a flexible pressure sensor, Shinnosukekun, that is capable of displaying the compressed points and providing instruction regarding the points to be compressed during CPR [11] . We can therefore measure the direct pressure applied by CC using a flexible pressure sensor.

Here, we determined whether a flexible pressure sensor could correctly evaluate the depth of CC performed on a mannequin on a mattress. Moreover, we study whether CPRmeter overestimates the compression depth when used with a mannequin on a mattress.

Section snippets

Compression machine and devices

A Little Anne mannequin (Laerdal, Stavanger, Norway) was used for CPR training. Chest compression was performed by a compression machine (electric servo test system BCH304; Saginomiya Seisakusho, Inc, Nakano-ku, Tokyo, Japan), and the depth of CC was monitored using a flexible pressure sensor (Shinnosukekun; Sumitomo Riko Co, Ltd., Komaki-shi, Aichi, Japan), CPRmeter (Laerdal), and dual real-time auto feedback system for CC, which incorporated an infrared camera (CPR evolution; Kissei

Results

On the floor, the true depth of CC was 5.0 ± 0.0 cm (n = 100), identical to the depth of CC administered by the machine. The flexible pressure sensor (Shinnosukekun) measured a mean (± SD) CC depth of 5.0 ± 0.1 cm (n = 100), and the CPRmeter measured a depth of 5.0 ± 0.2 cm (n = 100). There was no difference between the data obtained by flexible pressure sensor and those obtained by the CPRmeter ( Fig. 3A ; P > .05 between the true depth and the CPRmeter-measured depth, the CPRmeter-measured depth and the

Discussion

The flexible pressure sensor, Shinnosukekun, could correctly measure the depth of CC on both the floor and the mattress. Although CPRmeter correctly measured the depth of CC on the floor, it overestimated the depth of CC on the mattress. To date, acceleration sensors such as the CPRmeter have been reported to overestimate the depth of CC. Our results were consistent with those earlier results [9] . In contrast, a flexible pressure sensor can directly measure the force applied to the

Conclusions

The flexible pressure sensor could correctly measure the depth of CC performed on a mattress. Our results suggest the potential usefulness of a flexible pressure sensor as a feedback system when performing CC on a nonstiff surface such as a mattress.

Conflict of interest statement

Kouichiro Minami, Ichinosuke Maeda, and Shingo Hibino were involved in the development of the Shinnosukekun. This invention is patent pending, and thus, there is a conflict of interest.

Yota Kokubo has no conflicts of interest.

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