An April 29, 2020 Nature Journal article titled “Olfactory sniffing signals consciousness in unresponsive patients with brain injuries” found that nasal response to odors (sniffing) by 43 severely brain-injured patients predicted the likelihood of recovery and long-term survival.
According to Noam Sobel, PhD, of the Weizmann Institute of Science in Rehovot, Israel, one of the authors of the article and speaking to MedpageToday:
“If you sniff at an odorant, then it’s 100% you will regain consciousness to at least a minimal level, and you will likely live for years,” he told MedPage Today. “If you don’t sniff at an odorant, that is a bad sign, but not all hope is lost.” (Emphasis added)
Amazingly, he said that 37.5% of the unresponsive patients who didn’t sniff did eventually regain consciousness.
Dr. Giacino, PhD of Harvard Medical School who helped write the 2018 American Academy of Neurology guidance on disorders of consciousness told Medpage that this study is “a cleverly and carefully designed study that adds another much-needed tool to the consciousness-detection toolbox” even though “Between 30% and 60% of patients who sustain severe TBI (traumatic brain injury) have diminished or complete loss of smell due to the mechanics of the injury.”)
He also noted that, based on available evidence, about four in 10 patients who are deemed unconscious on bedside examination actually retain conscious awareness and that “A significant portion of these patients have covert consciousness — preserved cognitive function that cannot be expressed through speech or movement.” (Emphasis added)
WHY IS THIS STUDY SO IMPORTANT?
As Dr. Giacino said in the Medpage article:
“Published evidence from Canada in a large cohort of ICU patients with traumatic brain injury [TBI] found that approximately 70% of the deaths were due to withdrawal of treatment and in about 60% of cases, the decision to stop treatment was made within 72 hours,” he said. “It’s possible that a positive sniff test might delay this decision, which is important since we know that about 20% of TBI patients who survive what appears to be catastrophic injury recover to a functionally-independent level by 5 years post-injury.” (Emphasis added)
As we have seen over the past decades, whether or not a severely brain-injured person is or can become conscious has become a life and death matter. We have seen this in the cases of Nancy Cruzan, Terri Schiavo and Zach Dunlap even though, as I wrote in my August 18, 2018 blog, “Medical Experts Now Agree that Severely Brain-injured Patients are Often Misdiagnosed and May Recover”.
THIS ISSUE HAS BEEN CLOSE TO MY HEART FOR DECADES.
Just before Drs. Jennet and Plum invented the term “persistent vegetative state” in 1972, I started working with many comatose patients as a young ICU nurse. Despite the skepticism of my colleagues, I talked to these patients as if they were awake because I believed it was worth doing, especially if it is true that hearing is the last sense to go. And why not do it to respect the patient as a person?
Then one day a 17 year old young man I will call “Mike” was admitted to our ICU in a coma and on a ventilator after a horrific car accident. The neurosurgeon who examined him predicted he would be dead by morning or become a “vegetable.” The doctor recommended that he not be resuscitated if his heart stopped.
But “Mike” didn’t die and almost 2 years later returned to our ICU fully recovered and told us that he would only respond to me at first and refused to respond to the doctor because he was angry when heard the doctor call him a “vegetable” when the doctor assumed ‘Mike” was comatose!
After that, every nurse was told to treat all our coma patients as if they were fully awake. We were rewarded when several other coma patients later woke up.
Over the years, I’ve written about several other patients like “Jack”, “Katie” and “Chris” in comas or “persistent vegetative states” who regained full or some consciousness with verbal and physical stimulation. I have also recommended Jane Hoyt’s wonderful 1994 pamphlet “A Gentle Approach-Interacting with a Person who is Semi-Conscious or Presumed in Coma” to help families and others stimulate consciousness. Personally, I have only seen one person who did not improve from the so-called “vegetative” state during the approximately two years I saw him.
But I never even thought to give any of my patients a sniff test. What a simple test for medical professionals to do!
And even though this study is small and needs to be replicated and validated, I believe it is further evidence that we need to reevaluate our current medical ethics and laws that allow life-sustaining treatment to be withdrawn from people with severe brain injuries on the premise that such brain-injured people have no “quality of life” and that such injuries are routinely hopeless.
And I hope that the sniff test can become a standard part of all medical evaluations of people with severe brain injuries.