This text is part of the special Research section
The probability of recovery of a patient in a coma or in a vegetative state is crucial information for doctors and relatives. But it can be very difficult to establish. Two Montreal researchers have created a tool to predict the recovery of patients using an anesthetic product known for fifty years.
Propofol has been an essential hospital supply since the 1970s. But this anesthetic product was used until now to put patients in a state of unconsciousness and not to predict their probability of coming out of it. Until Stefanie Blain-Moraes, professor at the School of Physical Therapy and Occupational Therapy at McGill University, decided to examine the effects of this anesthetic on the brains of people with impaired consciousness.
The effects of propofol on the brain of a healthy person were already known. “When administered to a healthy subject, the electroencephalogram (EEG) shows a change in functional connectivity which is characterized by an inversion of information transfer. On an awake person, the transfer goes from front to back, but after the administration of propofol, it becomes neutral or from back to front”, explains Catherine Duclos, assistant professor-researcher at the faculty of Medicine from the University of Montreal.
As part of her post-doctorate at McGill University, she measured with Stefanie Blain-Moraes the effects of propofol on patients in a coma, in a vegetative state or in minimal consciousness (able to wake up, but not or little aware of themselves or their surroundings). These conditions can be caused by brain trauma or any injury that deprives the brain of oxygen, such as a stroke or an overdose.
A new prognostic index
In January 2022, Catherine Duclos and Stefanie Blain-Moraes published with a team of researchers the results of a preliminary study in theAmerican Journal of Respiratory and Critical Care Medicine. “Our study included 12 patients in the acute (in the first weeks following their brain injury) and chronic phase,” explains Catherine Duclos.
The team, led by McGill University, quantified changes in patients’ brain functional connectivity before, during and after propofol administration, using a 128-lead EEG. “We examined the functional connectivity and the information circuits converging or starting from the electrodes placed on their skull”, explains Catherine Duclos.
Critical decisions are made in the first weeks following a brain injury, when patients are hospitalized in intensive care
These “connectors” can be compared to a motorway network. “In a healthy awake subject, these places are located at the back of the brain, but when propofol is administered, it is the frontal regions that become the information transfer highways”, describes the researcher.
100% reliable predictions
Based on the changes observed, the research team then calculated a “functional reconfiguration index” which they compared with the clinical evolution of the patients studied. The more the observed reconfiguration was pronounced, approaching that of a healthy person, the higher the index.
“The three people who recovered consciousness within three months had a much higher index than the others, whose index was very low,” noted Catherine Duclos, for whom these high responses revealed residual or potential consciousness in these patients.
Catherine Duclos and Stefanie Blain-Moraes are continuing their research to find the ideal combination of electrodes in order to translate their index with a clinical EEG system of around twenty electrodes and to validate their index on a larger pool of patients in the acute phase. A crucial moment for healthcare teams and families.
“Critical decisions are made in the first weeks after a brain injury, when patients are hospitalized in intensive care. Our index could help anticipate whether the patient will wake up within three months, thus facilitating decision-making and the treatment plan,” she says.
An easily accessible tool
The functional reconfiguration index developed by the research team has the advantage of being simple to implement (the material can easily be brought into the rooms) and of not relying on the ability or desire to respond patients. “The patient in a minimally conscious state may be exhausted or simply unable to understand or perform a requested task, but propofol will have the same effect on his brain, regardless of his state at the time of the evaluation”, underlines Catherine Duclos .
The work of his research team could lead to an innovative and safe use of propofol, which has put millions of people to sleep for fifty years.
“It’s like water in intensive care! launches Catherine Duclos. The majority of patients who stay there receive it. It is a molecule familiar to clinicians, who are not afraid to introduce it, because patients have often already received it without reacting. Our approach is both innovative and promising for the future! »