Elsevier

Resuscitation

Volume 69, Issue 2, May 2006, Pages 295-301
Resuscitation

EXPERIMENTAL PAPER
A new device producing manual sternal compression with thoracic constraint for cardiopulmonary resuscitation,☆☆

https://doi.org/10.1016/j.resuscitation.2005.07.025Get rights and content

Summary

Objective

Blood flow during conventional cardiopulmonary resuscitation (CPR) is usually less than adequate to sustain vital organ perfusion. A new chest compression device (LifeBelt™) which compresses both the sternum and the lateral thoraces (compression and thoracic constraint) has been developed. The device is light weight, portable, manually powered and mechanically advantaged to minimize user fatigue. The purpose of this study was to evaluate the mechanism of blood flow with the device, determine the optimal compression force and compare the device to standard manual CPR in a swine arrest model.

Methods

Following anesthesia and instrumentation, intravascular contrast injections were performed in four animals and the performance characteristics of the device were evaluated in eight animals. In a comparative outcome study, 42 anesthetized and instrumented swine were randomized to receive LifeBelt™ or manual CPR. Ventricular fibrillation (VF) was induced electrically and was untreated for 7.5 min. After 7.5 min, countershocks were administered and chest compressions initiated. Pulseless electrical activity (PEA) was observed after one to three shocks in all animals. CPR was continued until restoration of spontaneous circulation (ROSC) or for 10 min after the first shock. If ROSC had not occurred within 5 min of beginning CPR, 0.01 mg/kg of epinephrine (adrenaline) was administered. During CPR, peak systolic aortic pressure (Ao), diastolic coronary perfusion pressure (CPP-diastolic aortic minus diastolic right pressure) and end-tidal CO2 were measured.

Results

Angiographic studies demonstrated cardiac compression as the mechanism of blood flow. Optimal performance, determined by coronary perfusion pressure, was observed at a sternal force of 100–130 lb (45–59 kg). In the comparative trial, significant differences in the measured CPP were observed between LifeBelt™ and manual CPR both at 1 min (15 ± 8 mmHg versus 10 ± 6 mmHg, p < 0.05) and 5 min (17 ± 4 mmHg versus 13 ± 7 mmHg, p < 0.02) of chest compression. A greater (p < 0.05) ETCO2, a marker of cardiac output and systemic perfusion, was observed with LifeBelt™ CPR (20 ± 7 mmHg) than with manual CPR (15 ± 5 mmHg) at 1 min. Peak Ao pressures were not different between methods. With the device, 86% of animals were resuscitated compared to 76% in the manual group.

Conclusions

Blood flow with the LifeBelt™ device is primarily the result of cardiac compression. At a sternal force of 100–130 lb (45–59 kg), the device produces greater CPP than well-performed manual CPR during resuscitation from prolonged VF.

Introduction

Only 2–5% of the 350,000 annual victims of sudden cardiac death (SCD) or out-of-hospital cardiac arrest due to sudden cardiac death survive to be discharged from the hospital.1 Of those that do survive, the vast majority suffer from the complications of anoxic encephalopathy, many are comatose or vegetative, and, of those who survive for more than a 6 months, few return to their pre-arrest normal daily activities.2, 3, 4 This poor outcome has been shown to be multi-factorial in origin. However, the two most important determinants of outcome are time to defibrillation (if ventricular fibrillation [VF] is the etiology of arrest) and the early administration of effective cardiopulmonary resuscitation (CPR).5 Early CPR is most commonly provided by trained citizens. Yet the public's reluctance to perform CPR and its declining effectiveness over time as currently practiced may limit its use and curtail dissemination of a potentially life saving intervention.6, 7, 8

A three-phase time-sensitive model for resuscitation after cardiac arrest has been described.9 The model emphasizes defibrillation in the first phase and artificial circulation, i.e., chest compressions, in the second phase. However, an increasing number of reports document the declining incidence of VF as the initially encountered cardiac arrest rhythm disturbance, even among instances of advanced rescuer witnessed cardiopulmonary collapse.10, 11, 12, 13 Patients with cardiac arrest not due to a ventricular arrhythmia now make the majority of victims of out-of-hospital cardiac arrest. The dismal outcome accompanying the appearance of post-countershock non-perfusing spontaneous cardiac rhythms (so-called pulseless electrical activity [PEA]) has been demonstrated and emphasized14, 15 and providing CPR and cardiac perfusion prior to electrical defibrillation has been shown to improve the outcome of VF arrest.16, 17 The latter two observations further emphasize the importance of effective CPR in life saving efforts. The use of effective CPR, the cornerstone of second phase, therefore assumes the role of the primary intervention in most victims.

The Post-resuscitative and initial Utility of Life Saving Efforts (PULSE) Conference, convened in 2000, represented a multi-agency initiative which defined five domains of resuscitation science, including translational studies and bioengineering.18 Mechanisms of generating greater blood flows during CPR and new mechanical devices and methods for securing maximal forward flow during cardiac arrest were included among high priority objectives.

A simple mechanical CPR device that can be applied rapidly and used easily by the lay person and advanced rescuers has obvious benefit in maximizing the likelihood of successful cardiac resuscitation. A simple device, manually operated and producing minimal user fatigue, may provide a means with which to overcome the lay public's demonstrated reluctance to perform CPR and improve the management of both ventricular fibrillation and other cardiac arrest rhythms.

Section snippets

The device

The LifeBelt™ CPR product is a simple mechanical device designed to provide a combination of circumferential thoracic and sternal compression force to generate blood flow during cardiac arrest (Figure 1). The device was designed primarily for use in the out-of-hospital environment by lay rescuers, emergency medical technicians, and paramedics. The initial specifications of the device include a three to one mechanical advantage for the operator, such that 40 lb of force will result in the

Angiographic studies

Contrast injections into the LV during VF produced opacity in the LV and left atrium, indicating mitral regurgitation (Figure 2a). During sternal depression (Figure 2b), the heart moved abruptly dorsally, the lower two-thirds of the LV cavity appeared to decrease in size on the lateral projection, and the aortic valve opened approximately 250 ms after maximal antero-posterior displacement of heart. Complete washout of the radiopaque medium was typically achieved after two or three sternal

Discussion

These preliminary studies demonstrated a primary mechanism for blood flow with the LifeBelt™ CPR device during cardiac arrest, defined optimal performance parameters for the device, and demonstrated efficacy for resuscitation from prolonged cardiac arrest and short-term survival.

Findings on ventriculography and aortography suggest that the LifeBelt™ functions largely as a “cardiac pump”. The circumferential thoracic strap incorporated into the device appears to function as a “thoracic

Acknowledgement

This study was supported, in part, by a grant from the National Institutes of Health, 1 R41 HL071378-01 A1.

References (25)

Cited by (9)

  • Systematic review of the mechanisms driving effective blood flow during adult CPR

    2014, Resuscitation
    Citation Excerpt :

    Specifically, a wide adjustable belt wraps around the patient's chest, allowing for downward compression of the sternum as well as lateral chest wall compression, thus spreading the force of compressions over a larger surface area of the chest. In an animal study 50, a significant increase in coronary perfusion pressure at 1- and 5-minute intervals and a greater level of end-tidal carbon dioxide at 1 min was reported with this device. However, in another study, the authors did not detect significant differences in neurologically intact survival between LifeBelt CPR and manual CPR 51.

  • Evolution and new perspective of chest compression mechanical devices

    2008, American Journal of Emergency Medicine
    Citation Excerpt :

    Moreover, it was designed to lessen user fatigue [25,58]. Niemann et al [58], in an angiographic study of pigs (15 used LifeBelt and 14 S-CPR), reported that, with the use of the LifeBelt, there were significantly greater levels of CPP compared to S-CPR at 1 minute (15 ± 8 vs 10 ± 6 mm Hg, P < .05) and 5 minutes (17 ± 4 vs 13 ± 7 mm Hg, P < .02) of chest compression. Similarly, there were significantly greater levels of ETCO2 with LifeBelt compared to S-CPR (20 ± 7 vs 15 ± 75 mm Hg, respectively; P < .05) at 1 minute.

  • Cardiac arrest with continuous mechanical chest compression during percutaneous coronary intervention. A report on the use of the LUCAS device

    2007, Resuscitation
    Citation Excerpt :

    Ballooning of the right ventricle is associated with compression of the interventricular septum during asystole and requires ongoing chest compression to empty the ventricle for effective defibrillation to occur.10 Diastolic aortic minus diastolic right atrial pressure is improved in experimental studies using mechanical devices such as the LifeBelt™.11 This may be explained by compression of the heart as demonstrated by angiography.

  • In this issue

    2006, Resuscitation
View all citing articles on Scopus

Presented, in part, at the American Heart Association Resuscitation Science Symposium, November 5–6, 2004, New Orleans, LA.

☆☆

A Spanish translated version of the summary and keywords of this article appears as Appendix in the online version at 10.1016/j.resuscitation.2005.07.025.

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