Pneumatic Chest Compression Device for CPR Kyra Ceceris, Daniel Metzinger, Tina Mornak University of Pittsburgh Senior Design – BioE 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 recommendations 1 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 compressions 1 ”

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 minute 3 Chest must be compressed to a depth of 1.5 to 2 inches 3 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 techniques 5 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 TrialCompression rate (compressions/min)

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 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?

Works Cited 1.Abella BS, Sandbo N, et al. Chest compression rates during cardiopulmonary resuscitation are suboptimal: a prospective study during in-hospital cardiac arrest. Circulation. 2005; 111: 428– A novel, manual sternal compression--Thoracic constraint device for cardiopulmonary resuscitation (LifeBelt paper) 5.Halperin, H.R., et al. A Preliminary Study of Cardiopulmonary Resuscitation by Circumferential Compression of the Chest with Use of a Pneumatic Vest. New England Journal of Medicine. 1993; 329: