The French National Institute for Health and Medical Research (Inserm) has recently published the results of a study that looked at 127 coma patients aged between 17 and 80 years old. The aim of the study was to determine the patients’ conscious state with the help of a simple audio test.
What did the test involve?
Inserm researchers analysed the difference in heart beats depending on a audio stimulation. This test consisted of making patients listen to repetitive audio sequences as well as some variations. Researchers studied whether during these variations, the rhythm of the patient’s heart beat changed. According to the researchers when a patient’s heart beat changed during audio variations it meant that the patient was conscious of sounds around them and that the prognosis of their conscious state is better.
A vegetative state is when a patient is awake but not conscious however a patient can have a minimal conscious state implying a certain degree of consciousness. This categorisation means that it is possible to establish a prognosis about how the patient will be once they are out of their coma. However the tools that are generally used to determine the conscious state of a patient are often complicated like electroencephalogram (EEG),an MRI or PET-scan. What’s more the analysis of results are sometimes complex.
This is why the test developed by the researchers at Inserm is so promising as it is simple to carry out. After having analysed the results of the 127 patients in a vegetative sate or with minimal consciousness, they agreed that only when the patient had a minimal conscious state was their cardio rhythm modified by an audio stimulation.
Other studies in the future
The researchers maintained that the results of the audio and heart beat tests were complementary to the results obtained by the electroencephalogram. These two tests together have improved the quality of the prognosis of a coma patients conscious state.
In the future, other studies are going to concentrate on the interaction of physiological signs in relation to conscious movements like breathing and dilated pupils. This new approach should help to better evaluate the conscious state of coma patients.