Pneumatic Chest Compression Device for CPR

Kyra Ceceris, Daniel Metzinger, Tina Mornak

University of PittsburghSenior Design – BioE 1160-1161

Mentor: Dr. J. Menegazzi

Overview

• More than 300,000 Americans die of cardiac arrest each year, and more than 95% of cardiac arrest victims die before reaching the hospital 3

• More than 11.4 million people a year are taught CPR; almost half are paramedics or other health workers 3

• CPR can double chance of survival 3

Overview cont’d.

• In a study published by the AHA, in-hospital chest compression rates were found to be below resuscitation recommendations1

• As EMS workers become tired, • chest compressions become slower and

weaker • conventional methods

of CPR become less

effective over long

periods of time

Solution

• There is a need for a mechanical device that can provide chest compressions reliably

• “Devices have the potential to generate better hemodynamic characteristics than manual chest compressions1”

Project Objectives

• Design a CPR device to:• Deliver more effective chest compressions

• Reduce fatigue in emergency workers

• Device components:• Foot pump

• Chest cuff

• Hose connecting foot pump to chest cuff

Device Requirements

• Device must compress chest at a rate of 100 compressions per minute3

• Chest must be compressed to a depth of 1.5 to 2 inches3

• Device must provide a sternal force of 100 to 130 lbs.4

• Device must meet CPR guidelines

CPR Guidelines

• Conventional method of 30:2 compression-ventilation ratio established by American Heart Assoc.

• A recent study found survival rates of cardiac arrest are twice as high if not given rescue breaths

• New recommendations:• Continuous compressions for 4 minutes • Followed by a rate of 100:2 compression-

ventilation ratio

Customer

• The device could be purchased for every ambulance and emergency room

• Client Requirements:• Transportable• Functionality equivalent or better to manual CPR• Moderately priced• Easily attached and removed from patient• Compact and easy to store

Market Size

• Every medical environment that is equipped with a defibrillator is a target buyer for this device

• Around 35,000 ambulances in the U.S.2

• Over 80% are equipped with a defibrillator

• Thousands of hospitals in the US

• Each with multiple crash carts

• Fire fighter first responders

equipped with AEDs

Competitive Analysis

• Current devices have remained unpopular in the clinical arena because they are cumbersome and expensive

• Patented Devices:

• Pressurized fluid chest compressor

• Constricting belts

• Inflatable vest

Competitors

• LifeBelt• Manually

operated• Circumferential

compressions• No ECG• Constricting

belts

• AutoPulse• Battery operated

• Circumferential compressions

• Built-in ECG

• LUCAS• Battery

operated

• Sternal compressions

• Built-in ECG

Strengths and Weaknesses

• Strengths• Circumferential • Size/Weight• No “outside” power

source required• Less tiring than

manual• Easy to manufacture

(compared to others)• Cost• Easy to place on

patient (no backboards)

• Weaknesses• Not automatic

(requires effort and control from operator)

• Still has to be carried (vs. nothing with manual)

• No built in ECG

Design Alternatives

• Plastic material over chest cuff

• Direct chest cuff force downward only

• Pressurized fluid instead of air● Greater pressure on chest● Fluid would make the device a lot heavier

Our Design - Rationale

• Circumferential compressions are more effective than traditional CPR techniques5

• Due to geometric advantages, it is more efficient at reducing the volume of the thorax than manual CPR

• Less risk of generating trauma because of reduce deformation of individual portions of thoracic wall

Prototypes

• Alpha Foot Pump• Poor sealing of

port to make closed loop system

• Cyclic frequency of first pump was slow spring compression force needed to be increased

Prototypes

• Alpha Chest Cuff• Blood pressure

bladders would not inflate enough or at the correct frequency

• Systematic Plumbing• Tube diameters and

wall thickness very important, had to be redesigned

Device Description

• Three main pieces to the device. • Foot powered air pump• Chest Cuff with Velcro Fastening system• Network of tubing important to function

• Operator uses large muscle groups like the quadriceps to pump air from a foot pump to inflate 1L bladders in the chest cuff.

• Weight: 4.5 lbs foot pump• Dimensions:

• 12in diameter foot pump• Cuff currently fits average male torso

Device Description

• Foot powered air pump

• Chest Cuff

• Systematic Tubing

Future Prototypes

• Custom-made foot-pump

• Larger volume

• Stronger springs

• Custom-made chest cuff

• Larger volume

• Inflating on chest of patient only

Experimental Design

• Measured volume of air displacement of foot pump• Experimentally measured

volume of water displaced to graduated cylinder

• Average of manufactures claimed volume, experimental volume and expected geometric volume was 1.9 L

Experimental Design

• Performed compressions for 1 minute

• Achieved average rate of ~57 compressions/minute

• Previous prototype performed with a cyclic frequency of 15 compressions/minute

Trial Compression rate (compressions/min)

1 56

2 57

3 57

Quality System Considerations

• Failure Mode:• Materials Failure

• Control – choose strong material, such as hard plastics resistant to cracking

• Mechanical Failure• Control – stress and fatigue testing, as well

as max. and min. pressures

• Operator Error• Control – proper training and

labeling/instructions

Regulatory

• Sec. 870.5200 External cardiac compressor.

• (a) Identification. An external cardiac compressor is an external device that is electrically, pneumatically, or manually powered and is used to compress the chest periodically in the region of the heart to provide blood flow during cardiac arrest.

• (b) Classification. Class III (premarket approval).

Project Management

Acknowledgements

• Sources of funding:• Generous gift of Drs. Hal Wrigley and Linda

Baker• Department of Bioengineering

• Dr. J. Menegazzi• Jonathan Lever

Questions?