Cardiovascular diseases are by far the most frequent cause of death in industrial countries. In Germany alone, around 100,000 people per year suffer from sudden cardiac arrest, which frequently occurs as a result of cardiac infarction, serious injuries following an accident or electric shock. The job of first aiders is often impeded by the fact that it is difficult to correctly diagnose the disorder. A new “first-aid sensor” is now able to quickly provide information about the cardiovascular state of the injured person.
The device, which was developed by scientists from the Institute of Biomedical Engineering at the KIT (Karlsruhe Institute of Technology) is the size of a walnut and fits on any bunch of keys. Applied to the patient's neck, the device autonomously analyses the pulse and breathing in order to provide first aiders with reliable information as to whether the patient's respiration or cardiovascular system is not functioning normally or has stopped and reanimation is required.
"We had the idea of developing such a device knowing that unconscious people stand a far greater chance of survival if laypeople are able to quickly assess the existence of a life-threatening state and effectively treat the injured person," said Dr. Marc Jäger from the Institute of Biomedical Engineering who is coordinating the project. "Besides being a scientist, I am also an active firefighter. I have seen that first aiders need more help in their effort to treat the injured. That is why I initiated the project three years ago."
The probability of survival decreases by ten percent every minute that passes without heart-lung reanimation. There is usually no chance of survival ten minutes after suffering a cardiac arrest if no effort to reanimate the victim has been made.
"In Germany, it is mandatory to take a first-aid course in order to obtain a driving licence. However, over the years most people gradually forget what they have learnt. According to statistical data, only 14 percent of all people that happen to be present in emergencies where the victims have suffered a cardiac arrest have the confidence to attempt reanimation," said Jäger. Of these first aiders, only about 50% are able to correctly palpate the pulse. The result is that less than one out of 10 people suffering from life-threatening respiration or cardiac arrest can be correctly reanimated by passers-by. The new sensor system provides first aiders with reliable information about the victim's condition within the first few crucial minutes after the accident thus considerably increasing the victim's chance of survival.
Just ten seconds after applying the sensor to the victim's neck, the new system tells the first aiders whether reanimation is recommended or not necessary. The technology is based on novel non-linear methods which enable the device to simultaneously register pulse and respiration on a small area of the neck. The lifting and lowering of the ribcage or abdomen during breathing and the circulating blood leads to periodical mechanical changes on the body surface. The concept of signal acquisition is based on the idea of detecting the smallest alterations in the body layers nearest to the surface.
In contrast to commercial systems, the new device has decisive advantages. For example, the AED (automatic external defibrillator) measures the electrical signal (ECG), but information as to whether the blood is actually reaching the brain is not available. The average cost of an AED is around 2000 euros, making it quite expensive. The pulse oximeter sensor only detects breathing arrest very slowly (several minutes) and erroneous results are obtained in shock situations when the extremities are insufficiently supplied with blood.
Marc Jäger's research group has developed the "first-aid sensor" with the idea that it is both mobile and cheap. "It will only cost a few euros," said the scientist further explaining the researchers' intention to produce something that can be used anywhere and everywhere, and can be kept in a first-aid box or on a bunch of keys.
At present, the system correctly recognises the state of a person in about nine out of ten cases. The scientists at the Institute of Biomedical Engineering are working hard to further improve this rate of detection. The German Federal Ministry of Economics and Technology is supporting the project with funds from the "EXIST" research transfer programme which has been set up to support outstanding, research-based start-up concepts that are associated with complex and high-risk development work.