Each year, millions of Americans undergo surgery with anesthesia safely, with little risk and few negative side effects. Whether for an invasive medical procedure or routine dental work, anesthesia is administered regularly to patients across a broad age spectrum. However, questions are now being raised about the effects anesthesia may have on the human brain, particularly in older patients.
Earlier this fall, health care professionals specializing in Anesthesiology and Critical Care, along with colleagues from professional societies, government agencies and nonprofit organizations, gathered in Washington, D.C. for the American Society of Anesthesiologists’ Brain Health Summit. The group discussed and sought solutions on some very important points related to the impact of anesthesia and surgery on the brain, including: determining whether the postoperative risks of delirium and delayed cognitive recovery are significant enough to include in preoperative consent and patient education materials; developing a strategy for disseminating best practices to reduce the risk; creating an advocacy strategy to elicit funding for more research on postoperative delirium and delayed cognitive recovery.
“After an older adult undergoes anesthesia, they can often experience postoperative delirium, which is a state of serious confusion, disorientation and inattention,” said Lee A. Fleisher, MD, chair of Anesthesiology and Critical Care at Penn. “Patients in this state may hallucinate, they may forget why they are in the hospital, or have difficulty communicating or understanding what is going on around them. A significant aspect of my career, and that of other anesthesiologists, centers on determining why postoperative delirium occurs, who will or will not experience it, and what steps can be taken to minimize the effects.”
One of the biggest questions that has been asked is whether this state of bewilderment is caused by the anesthesia itself or the stress of the surgical procedure.
An important aspect is this basic question is “how does general anesthesia work?”
In more invasive surgeries, when general anesthesia is used, it renders patients unconscious, leaving them with no memory of the surgery – a proverbial black box. Anesthesia also inhibits some of the body’s physiological responses to the surgery including keeping a patient’s blood pressure, stress and heart rate under control.
In describing anesthetics, an article from Scientific American says, “The most commonly used general anesthetic agents are administered by breathing and are thus termed inhalational or volatile anesthetics…Their primary site of action is in the central nervous system, where they inhibit nerve transmission by a mechanism distinct from that of local anesthetics. The general anesthetics cause a reduction in nerve transmission at synapses, the sites at which neurotransmitters are released and exert their initial action in the body. But precisely how inhalational anesthetics inhibit synaptic neurotransmission is not yet fully understood. It is clear, however, that volatile anesthetics, which are more soluble in lipids than in water, primarily affect the function of ion channel and neurotransmitter receptor proteins in the membranes of nerve cells, which are lipid environments.”
Fleisher elaborated on this adding, “Once inhaled or administered, general anesthesia reduces the patient’s consciousness and response to pain at the most basic level. But, there is still some degree of uncertainty around how exactly anesthetics work, particularly from one patient to the next. This is one of the reasons why there is a constant need to monitor anesthesia levels and the patient’s responses during surgery.”
Today, the most common form of anesthesia involves a mixture of gases, which are measured to a very specific amount to suit each individual patient. The mixture is monitored and adjusted by an Anesthesiologist throughout the procedure.
Now that there is a better sense of what anesthesia does – albeit there are still many questions about how and why it works – and about lingering effects, specifically regarding postoperative delirium, experts wonder if the cognitive impairment be traced to a specific mixture of anesthetics. Or rather, are certain patients more susceptible to experiencing it?
In a 2015 Scientific American article, Roderic G. Eckenhoff, MD, vice-chair for Research and the Austin Lamont Professor of Anesthesiology and Critical Care, said, “No particular anesthetic has been exonerated in patients. But we can't say yet that there is an anesthetic that patients should not get.”
Fleisher added, “There is limited research around the correlation between postoperative delirium and specific patient populations or certain kinds of anesthetics. It remains largely unknown as to who exactly will experience these side effects.”
That said, after much discussion at the Brain Health Summit, leaders in the field came to the following conclusions, which will set the wheels in motion for additional research and educational initiatives:
- The general public needs to be informed about the risks and effects of postoperative delirium in order to help them make an informed preoperative decision, and to hopefully assist in improving outcomes of elderly patients. A patient awareness campaign should be created, and a “toolbox” given to clinicians to aid in the discussion of cognitive dysfunction, delirium and postoperative cognitive impairment with patients, their families, and caregivers.
- Similar educational initiatives should be geared toward health care providers in order to narrow the gaps in knowledge about how to handle postoperative delirium, as well as to create unified best practices for how to identify preexisting impairments, and how to care for patients who experience cognitive decline after surgery.
- Materials should be created to inform and educate prospective funders about the research being done in the area of postoperative delirium in order to refocus funding to aid this work.
While the Summit provided some direction and tactics for industry leaders to act upon, there are still other options that can be explored and implemented to advance learning, protect patients, and uncover the uncertainties around anesthesia and postoperative delirium.
“Encouraging patients to follow a balanced diet and exercise regularly in the lead up to surgery, allowing patients to bring mementos and family photos to their hospital room after surgery, even asking families and caregivers to keep a close eye on small declines in patients’ cognitive function preoperatively – simple things like the patient not being as sharp as he or she once were – may help clinicians properly prepare for patient care, and may help patients readjust after surgery and avoid postoperative delirium,” Fleisher said. “While these have not been scientifically proven to help, we think that even the smallest measures may make a difference for patients who are coming out of anesthesia.”