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Human simulator helps test automated CPR device

By Sharon Gray

The Faculty of Medicine’s human patient simulator is being used to test a new automated CPR device of interest to police, firemen and paramedics.

The physiology of STAN (standardized man) allows him to be a research subject as well as a teacher. “When Medical Enhancement Systems Inc. was looking for a patient to try its automated CPR Device, STAN was a good choice as a patient model,” said Ed Evelly, manager of Medical Education Support Services. “The Faculty of Medicine agreed to use its STAN as the test patient for the automated CPR device and STAN has been able to re-create a unique research environment for this emerging technology.”

Dr. Michael Hinchey of Memorial’s Mechanical Engineering division has been working with local inventor Paul Morrissey to bring an automated CPR device to reality. Rapid progress was made last summer when work term student Jonathan Smith worked on the project.

“CPR might seem effortless to someone who has never done it,” explained Dr. Hinchey. “However, to do it on a normal person, around 100 pounds of force must be applied to the chest. It is a very demanding task, and the person applying it quickly becomes exhausted.”

The automated CPR device uses a pneumatic piston or air pump to generate the 100 pounds of force needed. “The CPR pumping action is controlled by a small battery powered computer or controller which sends an electric signal to a solenoid flow control valve,” he said. “The device can also be controlled manually using a push button valve. A pressure regulator is used to adjust the amount of force generated. Presently, the maximum is around 115 pounds and the minimum is zero pounds.”

The idea for the CPR mechanical device came to Mr. Morrissey several years ago when he witnessed ambulance and fire department personnel administer CPR on a critically injured victim on a west end street in St. John’s. “Within five minutes of driving away I could mentally see a much easier way of performing such a laborious task.”

Dr. Hinchey said that all the pneumatic components used in the CPR device are off the shelf. “We are presently using components manufactured by the German company FESTO. These are very high quality and are designed to be used in factories on a continuous or non stop basis. Use of these components makes our device very reliable.”

A small SCUBA air tank and its regulator are used to supply the compressed air needed to operate the device. “The tank lasts about 10 minutes,” said Dr. Hinchey. “It is lightweight and spares can be easily carried. This makes our unit highly portable. In an ambulance or hospital, one could switch over to a much larger bottle.”

Parts of the device are currently attached to an aluminum horseshoe-shaped frame that slides under the patient. The plan is to make this frame out of plastic. Dr. Hinchey said the frames are made by Technical Services in the Faculty of Engineering at Memorial. “The bits are cut out using its water jet cutter and then welded together. We are also developing a version of the device that resembles a flak jacket. This has a chest plate and a back plate, both made from aluminum. The air pump is attached to the chest plate. Straps are used to tighten the plates onto the patient.”

A drawback of the jacket device is the patient must sit up to put it on. The horseshoe device can slide under a patient and be operational in around 30 seconds. “We have tried to make the device as simple as possible and require little or no assembly,” said Dr. Hinchey. “Obviously, when someone is having a heart attack, time is of the essence. There is no time for assembly or reading instructions. It has to be obvious how the device works. Presently, all one needs to do, after sliding the device under the patient, is turn on the air supply and press a button to start the controller. The controller has a knob for controlling the number of pumps or beats per minute.”

Mr. Morrissey has a patent pending on the device and has agreed to give Memorial 25 per cent of profits from sale of the device when it goes to market later in 2009. He anticipates an enormous commercial market for the device for use in hospitals, ambulances, airports, sports arenas and even in home residences. He expects it will sell for below $5,000 per unit and will be manufactured locally.