Is Surgery a Risk Factor for Cognitive Dysfunction?
Post operative cognitive decline (POCD) is a real condition and probably as many as 15% of patients 60 and older will experience some memory or problem-solving declines within 3 months of surgery. Or maybe not.
Anesthesiologist and dementia researcher Kirk Hogan, MD, director of the Hogan Laboratory at the University of Wisconsin, is convinced that POCD is a real and present danger. And he said it's time for surgeons to stop ignoring the evidence and begin developing a thorough and reasonable informed consent process to address these risks.
Hogan addressed the issue in a presentation at the annual meeting of the American Society of Anesthesiology in San Diego,
Stanley Stead, MD, the ASA's vice president for professional affairs and an anesthesiologist in Encino, Calif., is not so sure.
"Do I think it's of concern? Yes. Do I think we need to look at it? Yes. But the reality is the data are not there yet. It's not everybody over age 60 who's at risk," he said, explaining that the research doesn't show what those risks really are.
"The risk of you having cognitive dysfunction is sort of like the risk that you're going to have alcoholic encephalopathy after a really busy weekend in Napa and Sonoma," he said.
Defining a Condition
And that is the crux of a problem that both unites and separates anesthesiologists and surgeons.
Attention is needed, Hogan said, and there is evidence to back that position, including a pair of studies reported earlier this year: the first by Brendan Silbert, MB, in Anesthesiology and the second by Miles Berger, MD, in Anesthesiology Clinics. Both studies, Hogan said, provide ample evidence that surgery-related cognitive dysfunction can no longer be overlooked.
The Silbert paper especially, is "the bail of hay that broke the camel's back" in providing evidence of POCD in patients 60 and older undergoing hip replacement, Hogan told MedPage Today. "It's the thing I wave under peoples' noses who tell me they don't believe this stuff," he said.
In those studies about two-thirds of patients who experienced cognitive decline after their procedures did eventually return to baseline cognition, Hogan said.
But he cautioned that some patients don't bounce back. "Five years later, you see, they've retired earlier, they consume more social services, and they appear to have an earlier mortality" compared to people with similar health conditions who did not undergo surgery.
Among the unanswered questions, he said, is whether some patients have a higher risk than others.
Right now, many surgeons are skeptical about the syndrome, but generally there is greater recognition among cardiac surgeons, who have dealt for years with the possibility that cardio-pulmonary bypass machines used during heart surgery may be associated with post-op cognitive problems. That debate prompted several studies comparing on-pump and off-pump coronary artery bypass graft (CABG) procedures, but the findings from those CABG trials have been inconclusive.
Outside of the cardiac surgery world, many surgeons "have no idea [about post-surgery cognitive impairment]. They say they've never heard of this," Hogan said.
"Have you ever tried to get a cat to look at its face in the mirror?" he asked rhetorically. "They won't look. We're looking away from informed consent. It's risk management, it's our hospitals, it's our boards, its resources. No one has wanted to start talking about it because it's such a can of worms in terms of what we say, who says it, and when we say it. All these things are up in the air."
Specialists don't even agree on what to call the syndrome, Hogan said. "Our nomenclature is fuzzy, "with some suggesting terms such as post-operative neurocognitive disorder -- mild to major," or "post-operative decline or dysfunction."
Generally speaking, Hogan said, surgeries susceptible to POCD involve patients under anesthesia for at least an hour, "but a lot of folks who are active in this field, some of the best investigators, think (shorter procedures like) colonoscopies, glaucoma surgeries, have effects too."
"It's not just the anesthesia," he emphasized, but the body's response to an invasive procedure involving cuts. "If you pull a few polyps off, you get inflammation," he said. That could have an impact on the brain.
How Can It Be Studied?
No matter the cause, surgical professions need to start researching the issue, he said.
Some of this needed research is already underway in a new effort from the American Society of Anesthesiology's Brain Health Initiative, which hopes to raise awareness for patients and their families to look for changes they may see after surgical discharge, said Lee Fleisher, MD, the initiative's chairman and an anesthesiologist at the University of Pennsylvania School of Medicine.
At first, the initiative is focusing on delirium symptoms, but it will be urging families to look for less severe cognitive changes that might affect recovery as well, Fleisher said.
"The (surgical physician) community is becoming aware of this, and how to message it," Fleisher said. It's tough, "because if you can't do anything about it except maybe say (to the patient) you shouldn't undergo surgery ..." that could be worse for some patients than any cognitive change they experience, Fleisher said.
Moreover, it is essential for patients and their caregivers to be made more aware that cognition might not completely return to normal after discharge, especially in an age of rapid discharge after surgery, Fleisher explained.
Efforts aimed at quantifying the frequency, extent, and duration of POCD have yielded little in the way of useful results because researchers have generally used different tests, different thresholds for defining POCD, and the timing for measurements of cognitive function pre- and post-op have varied, Hogan said.
Moreover, solving these issues via the standard route of randomized controlled trials presents unique -- and possibly insurmountable -- challenges: recruiting older patients and randomizing them to surgery or medical treatment and using the same mental acuity measurements at the same time points.
Nonetheless, Hogan is convinced the condition is real and worthy of further study, although he concedes that severity ranges from patients who complain they "don't feel as quick," to those who experience measurable memory deficits.
Berger, whose 2012 paper Hogan cited, agreed.
"The Silbert paper, amongst many others that have come out over the last 20 years, have made clear that postoperative cognitive dysfunction and postoperative delirium are important clinical problems faced by a large number of patients over the age of 60 after anesthesia and surgery," Berger said. "We clearly need more research to better understand what causes these conditions and how to prevent them."
"We need to advocate for publication guidelines, so the major journals in our specialty should say, if you want to call something POCD, you have to have this, and use these terms, and refer to these papers, and use these statistics and thresholds," Hogan said.
"You have to step back and think," Hogan said, "that this is an amazing thing that we do; we make the brain insensate and then traumatize the body. And for 200 years of this we thought this didn't have any repercussions. We didn't have the tools to find them yet, but now we do."
Fully Informed Consent
Another concern may be more immediate: if POCD risk is real, who will tell the patient?
Hogan acknowledged that as anesthesiologists and surgeons start working closer in bundled payment arrangements and perioperative surgical home collaborations, "we might have some conversations with patients with some validated safety steps of our own. But there's no question that legally, the safety step is on the surgeon's back; anesthesiologists don't schedule surgery, and rarely if ever cancel a case."
During his lecture, he emphasized that anesthesiologists can't be the ones doing the consent most of the time. "In the 3 minutes before surgery, on the way to the OR, with the patient in pajamas, we can't do it. It's too late."
But Claudette Lajam, MD, an orthopedic surgeon at NYU Langone who spoke on behalf of the American Academy of Orthopedic Surgeons, vehemently disagreed that getting a patient's informed consent about cognitive decline is the surgeon's job.
"It's the anesthesiologists who should be the ones to tell patients about these risks and get informed consent, not the surgeon," insisted Lajam, After all, the risks have been defined in anesthesiology journals, not the bone and joint surgery publications she reads.
Lajam continued that surgeons tells patients about risks of other more easily identifiable complications such as infections or blood clots.
Stead, the ASA vice-president, said that including the risk of cognitive dysfunction in a patient's informed consent process is "premature."
Richard Kline, PhD, MA, a neuroscientist at New York University School of Medicine who has done research on surgery and brain atrophy in older patients, said there is enough evidence of risk to start informing patients now. Doctors who say there isn't yet enough research on the issue have to answer the question, "why not?"
"Why don't they have an answer? It's not like they have to build a spaceship and land on mars. They could start doing pretty simple studies with cognitive tests on people before and after, and compare different types of surgical anesthetics. We already have indications that some are riskier than others."
"There's enough evidence to worry about it so maybe we should put something on the consent forms," he said.
Hogan sums it up this way: "There is simply no denial any more that normal healthy brains have this incidence three months after non cardiac surgery."