Since intensive care units (ICU) were created in hospitals more than a half a century ago, there has been a steady decline in death rates for individuals who are critically ill and require life support. That’s significant and meaningful progress, and it’s thanks to the pioneering work of many doctors, nurses and researchers who have discovered better ways to liberate patients from life support so that they can leave the hospital breathing and functioning on their own.

But as a neurologist who practices medicine in the intensive care unit, I’ve come to recognize that we now need to focus the same attention on the neurological health of patients leaving the ICU.  New studies are shedding light on the high rates of acute brain dysfunction – or delirium — for patients who have undergone treatment in hospital intensive care units.

Depending on the study, the rate of acquiring delirium as a result of treatment in ICU ranges from 30 to 80 percent – staggering numbers by any measure.  What does delirium look like?  Delirium is characterized by a fluctuating level of consciousness – when someone drifts in and out of awareness — poor attention and disorganized thinking.

What we see ranges from a patient lying in bed completely inattentive and disengaged from their environment to patients that are agitated and combative.  Delirium can be excruciating for family members to watch.

On our bedside rounds, families often ask, “How is it that my mom was admitted three days ago with pneumonia and now she just stares at me blankly like she’s never seen me before?” That’s hospital-acquired delirium.

Questions like these are difficult to answer, mostly because we simply don’t know.

When a patient becomes critically ill, whether it be due to a heart attack, severe infection or trauma, they can require assistance with breathing, and may be connected to a ventilator for life support.  Individuals are also frequently treated with medications for pain and anxiety.

Despite the fact that we treat our patients on life support to the best of our ability in the ICU, the brain may begin to function abnormally.

At medical conferences, we have sessions on “The pathophysiology (aka cause) of delirium,” at which speakers present beautiful and elaborate line drawings, with interconnected arrows leading from one box to another.  However, in my relatively early career in academic medicine, I’m learning that the more complex the schematic diagram, the less we know about the underlying topic. It’s particularly true of hospital-acquired delirium.

Delirium is a common problem where the cause is not known, but we do know that older age and pre-existing dementia are significant risk factors.

We are slowly chipping away at the problem.  As a medical community, we are implementing guidelines about sedation practices, we try to promote sleep and we encourage early mobilization and physiotherapy.  My colleagues and I are starting a multi-centre study designed to ask whether poor oxygen delivery to the brain contributes to the risk of delirium.

The consequences of delirium can be deadly.  Those that experience it during ICU stays are more likely to spend more time on life support, die in the ICU or die in the hospital.

And for survivors, ICU delirium is a risk factor for long-term cognitive impairment. This newly acquired frailty post-ICU is more than just occasionally forgetting where you lost your keys.  The BRAIN-ICU study from Vanderbilt University suggests that 40 per cent of ICU survivors who developed delirium in the hospital function at the level of someone with moderate traumatic brain injury and 26 per cent at the level of someone with mild Alzheimer’s disease.

So what can be done?

Physicians and medical administrators can engage families in patient care.  We know that simple things like abandoning “visiting hours” can reduce delirium rates.  Government agencies should recognize that ICU survivorship needs to be a research priority, something our patients have known for a while.  When asked, healthy seniors have told us that long-term brain function should be the number one outcome examined in critical care studies.

On our path towards finding strategies to prevent and treat delirium, we ask the families of our patients to help too.  Please, come to visit your loved one.  Talk to them and bring familiar items that can help keep them grounded.  It is these small gestures that can sometimes matter most.

J. Gordon Boyd is a neurologist and critical care physician. He is a network investigator, Canadian Frailty Network, and a contributor EvidenceNetwork.ca.

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