Preventing delirium A set of ICU interventions helps avoid brain injury by Bonnie Darves
Published in the July 2011 issue of Today's Hospitalist
WHILE THE CONVENTIONAL WISDOM has held that ICU patients fare better if they're kept immobile, a growing body of evidence indicates that critically ill patients do much worse with too much sedation. It's become clear that ICU patients kept immobile and sedated run a much higher risk of developing delirium, which in turn can lead to permanent cognitive disabilities.
Physicians at Vanderbilt University in Nashville are taking an aggressive approach to preventing delirium. Even the sickest ICU patients are now being helped out of bed, taken off a ventilator, actively
"Patients don't need as much sedation as we thought."
–Eduard Vasilevskis, MD Vanderbilt University
monitored for delirium and having their intake of sedatives drastically cut.
"The bundle of interventions is focused on brain function and ties into a lot of things that put patients at risk for delirium," says Eduard Vasilevskis, MD, an assistant professor of medicine in Vanderbilt's hospital medicine section, a researcher with the VA Tennessee Valley Geriatric Research Education and Clinical Centers (GRECC), and a member of the team that helped develop the model. "The interventions have also been shown to improve muscle strength and mortality."
In fact, the benefits are so pronounced that Dr. Vasilevskis thinks that hospitalists should lead the charge to adopt the bundle in their hospitals, given the substantial role they play in ICU care. Even if hospitalists don't treat critically ill patients, he adds, they care for patients who enter and leave the ICU frequently.
"When hospitalists are on board," he says, "they'll be much more aware of cognitive impairment downturns, and more attuned to avoiding benzodiazepines." And by championing the bundle in their facilities, Dr. Vasilevskis adds, hospitalists may substantially reduce patients' length of stay and readmission rates.
A multipronged approach
Dubbed the ABCDE (Awakening and Breathing coordination, Choice of drug, Delirium monitoring and Exercise/ early mobility) model, the bundle targets deficiencies in what Dr. Vasilevskis calls the "back end" of critical care. While advances in the field have significantly improved patients' chances of surviving a life-threatening illness, up to 80% of mechanically ventilated ICU patients develop delirium.
"Those cases often go undiagnosed," he points out. That in turn gives patients a twofold greater risk of long-term cognitive impairment and functional disability after hospital discharge. The Vanderbilt bundle, Dr. Vasilevskis says, seeks to reduce or prevent the brain injury that leads to those poor outcomes.
He and his colleagues described the bundle in the November 2010 issue of CHEST and a December 2010 supplement to Critical Care Medicine. ICU patients who pass the initial safety screen—those with intracranial injury or a recent myocardial infarction are excluded—undergo daily spontaneous awakening and breathing trials.
Patients who pass the spontaneous awakening trial by "waking up" within four hours of a break in sedation (with- out becoming agitated or experiencing a respiratory-rate hike) proceed directly to the spontaneous breathing trial, where they're allowed to breathe on their own.
Whether patients pass or fail that trial, those who can safely tolerate activity are mobilized with the help of physical therapists, nurses and respiratory therapists. The bundle also has patients being monitored daily for delirium using the Richmond Agitation-Sedation Scale or the confusion assessment method (CAM)-ICU.
Cutting back on sedation
The most aggressive bundle component, Dr. Vasilevskis notes, is the dramatic reduction in sedation and the avoidance of benzodiazepines.
If patients pass their spontaneous awakening trial, their sedatives are discontinued completely. If, however, they fail the trial, sedation is restarted—but at only 50% of patients' previous dose. "The goal is to reduce sedation levels by 50% every time a patient fails a trial," Dr. Vasilevskis explains.
That's a significant departure from the status quo, he notes. Most ICU patients remain heavily sedated throughout their stay because of fears they'll pull out their lines or experience psychological trauma. But data don't support those concerns.
"We've found that patients don't need as much sedation as we thought, that they can be comfortable with less and will have fewer long-term side effects," says Dr. Vasilevskis. It's sedation, he adds, that is one of the strongest predictors of both delirium and prolonged time on the ventilator.
In the Vanderbilt studies, reducing patients' exposure to sedatives and analgesics resulted in no increase in post-traumatic stress disorder, pain memory or psychological disease.
"If anything, these psychiatric components were slightly better in the group that received less drugs," says E. Wesley Ely, MD, MPH, a pulmonary and critical care researcher for Vanderbilt and VA-GRECC who has pioneered research in ICU delirium and collaborated with Dr. Vasilevskis on the bundle. "Often, with pain management alone, you will achieve adequate sedation."
Reducing length of stay
Studies have shown that early mobility can reduce ICU or total-hospital stays by at least two days, while using both spontaneous awakening and breathing trials can cut patients' length of stay by up to four days.
According to Dr. Vasilevskis, adding early mobilization and delirium monitoring to the spontaneous trials also produced significant gains in physical function at discharge. More than 60% of those who received the bundled interventions were able to independently walk and move from a bed to a chair, compared to just over 40% of the control group.
He notes that physicians don't know if outcomes would improve even more by continuing the delirium monitoring and mobility therapy outside the ICU. "But it would be reasonable to say that both would improve LOS and outcomes," he points out. "Anything that reduces brain problems will probably reduce readmissions."
While the payoff may be big, Dr. Vasilevskis admits that implementing the ABCDE bundle is no small feat. It requires a team approach, heavy lifting in the most literal sense, and coordination of staff—nurses and therapists, in particular—to conduct both the spontaneous trials and to mobilize patients early.
And in most institutions, "selling" an approach clinicians might consider risky may require a culture change. That's one of the reasons Dr. Ely believes that hospitalists should be the ones championing bundle implementation in their hospitals.
"Intensivists are often, understandably, focused on pulmonary issues," Dr. Ely says. "Hospitalists have a more longitudinal view of getting patients from being very sick to being ready for discharge, and are more attuned to underlying medical issues that can confound recovery."
On the plus side, Dr. Vasilevskis reports, the new model, while resource intensive, typically doesn't require additional staff. It's more a matter of "organizing staffing in a different way," he says, and making sure that staff have the right training and tools. For example, using newer and simpler neurological tools—such as the intensive care delirium screening checklist, the nursing delirium screening scale and the CAM-ICU—instead of older, more laborious ones frees up nursing time.
Based on Vanderbilt's experience, the best approach is to start small. Dr. Vasilevskis recommends beginning with delirium monitoring, then moving to spontaneous awakening and breathing trials, alone or in combination, and finally to early mobility.
"If you're not used to doing early mobility, you probably won't want to implement this all at one time," he says. "But there's no reason you can't do these things separately."
Bonnie Darves is a freelance health care writer based in Seattle.