Why Anesthesia Is One of the Greatest Medical Mysteries of Our Time

Anesthesia was a major medical breakthrough, allowing us to lose consciousness during surgery and other painful procedures. Trouble is, we’re not entirely sure how it works. But now we’re getting closer to solving its mystery — and with it, the mystery of consciousness itself.

When someone goes under, their cognition and brain activity continue, but consciousness gets shut down. For example, it has been shown that rats can ‘remember’ odor experiences while under general anesthesia. This is why anesthesiologists, like the University of Arizona’s Stuart Hameroff, are so fascinated by the whole thing.

“Anesthetics are fairly selective, erasing consciousness while sparing non-conscious brain activity,” Hameroff told io9. “So the precise mechanism of anesthetic action should point to the mechanism for consciousness.”

The Perils of Going Under

The odds of something bad happening while under anesthetic are exceedingly low. But this hasn’t always been the case.

Indeed, anesthesiology has come a long way since that historic moment back in 1846 when a physician at Massachusetts General Hospital held a flask near a patient’s face until he fell unconscious.

But as late as the 1940s, anesthesia still remained a dicey proposition. Back then, one in every 1,500 perioperative deaths were attributed to anesthesia. That number has improved dramatically since that time, mostly on account of improved techniques and chemicals, modern safety standards, and an influx of accredited anesthesiologists. Today, the chances of a healthy patient suffering an intraoperative death owing to anesthesia is less than 1 in 200,000. That’s a 0.0005% chance of a fatality — which are pretty good odds if you ask me (especially if you consider the alternative, which is to be awake during a procedure).

It should be pointed out, however, that “healthy patient” is the operative term (so to speak). In actuality, anesthesia-related deaths are on the rise, and the aging population has a lot to do with it. After decades of decline, the worldwide death rate during anesthesia has risen to about 1.4 deaths per 200,000. Alarmingly, the number of deaths within a year after general anesthesia is disturbingly high — about one in every 20. For people above the age of 65, it’s one in 10. The reason, says anesthesiologist André Gottschalk, is that there are more older patients being operated on. Anesthesia can be stressful for older patients with heart problems or high blood pressure.

But there are other dangers associated with anesthesia. It can induce a condition known as postoperative delirium, a state of serious confusion and memory loss. Following surgery, some patients complain about hallucinations, have trouble responding to questions, speak gibberish, and forget why they’re in the hospital. Studies have shown that roughly half of all patients age 60 and over suffer from this sort of delirium. This condition usually resolves after a day or two. But for some people, typically those over the age of 70 and who have a history of mental deficits, a high enough dose of anesthesia can result in lingering problems for months and even years afterward, including attention and memory problems.

Researchers speculate that it’s not the quality of the anesthetics, but rather the quantity; the greater the amount, the greater the delerium. This is not an easy problem to resolve; not enough anesthesia can leave a patient awake, but too much can kill. It’s a challenging balance to achieve because, as science writer Maggie Koerth-Baker has pointed out, “Consciousness is not something we can measure.”

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