A growing number of animal and human studies have found troubling associations between general anesthesia in childhood and cognitive deficits later in life. On February 25, an
article in the New England Journal of Medicine (NEJM) underscored these concerns, calling for further research. The authors also urged physicians to disclose the possible risks to parents, a practice already
endorsed by several professional organizations, including the American Academy of Pediatrics and American Society of Anesthesiologists.
As a pediatric anesthesiologist and a researcher in this field, I feel physicians need to take an active role in helping parents weigh the potential risks and benefits of general anesthesia. When safe and feasible, we also need to offer alternatives. However, in my experience, relatively few anesthesia practices are openly addressing this important subject.
In today's post, I’ll describe the evidence around pediatric general anesthesia and why it justifies changes to our current clinical practice. In Part 2, I’ll share how our anesthesia group at Good Samaritan Hospital in San Jose, Calif., is working to educate parents and make anesthesia safer for kids.
Show Me the Evidence
General anesthesia is usually achieved through a cocktail of several drugs that puts the patient into a medically induced coma. In the 1990s, studies began to emerge suggesting that this cocktail caused cell death in the brains of immature animals. What's more, researchers found that these animals didn’t perform well on cognitive tasks in adulthood.
This of course raised a frightening question: could the same deficits be happening to human children?
It's a difficult question to answer, because with humans, we’re far more limited in what we can study experimentally. We can’t subject kids’ brains to risky procedures just to see what happens! We
can however compare the cognitive function of kids who have a history of general anesthesia to kids who don't.
So far, studies on the subject have yielded mixed results. In many cases, the findings can't be widely generalized because of the presence of confounding variables. In other words, it's feasible that another factor (prolonged hospitalization, serious illness) caused the observed cognitive deficits rather than the anesthetic.
Another common problem in the literature is the type of outcome studied. Many researchers chose to look for overt cognitive deficits like learning disabilities or speech-language issues. However, bearing in mind that we've been using anesthetics for about 150 years, common sense suggests that if anesthesia in childhood does have long-term effects, they're probably quite subtle. Otherwise, they'd have been noticed already.
A Firsthand Experience
In 2014, I led a research team that studied the relationship between general anesthesia in infancy and a memory process called recollection. This study yielded some of the
strongest evidence yet linking pediatric general anesthesia to later cognitive problems.
Research suggests general anesthesia might damage a part of the developing brain called the hippocampus that converts short-term memories into long-term ones. Memory retrieval involves two processes that operate simultaneously:
- Recollection. This is the ability to retrieve and use facts that have been memorized. For example, if you met an old classmate on the street, you might recollect that her name is Samantha Smith and that you sat next to her in high school Spanish.
- Familiarity. This is the sense that you know something without knowing the associated details. For example, you might be able to recognize someone on the street but not remember her name or where you met her.
Recollection deficits can be quite subtle, because the person (or animal) can often use familiarity to compensate. For example, if we teach a rat with recollection issues to run a maze, it might have trouble remembering the sequence of turns. But it might still be able to "feel" its way through by taking the path that seemed right.
So to truly test recollection, we have to remove familiarity from the equation. In the lab, this means creating a time delay (usually about 60 to 75 minutes) between the encoding of new information and its retrieval.
Our team tested recollection in 28 pairs of age-matched children (one who had undergone general anesthesia as a baby and one who had not). We also tested recollection in a randomized sample of rats, half of which underwent general anesthesia at seven days of age.
Among our findings:
- A history of general anesthesia in infancy was associated with significantly poorer recollection in both rats and humans.
- Because the rats in the study were healthy and randomized, we could be reasonably confident that the effect wasn't due to underlying disease.
So what does this mean? Well, the fact that the humans and rats experienced similar cognitive deficits — particularly after potentially confounding variables were controlled for — is compelling.
Of course, this was a relatively small study. Other teams are already at work to see whether or not our findings can be replicated. And it will take larger and longer-term studies to make a strong case for causation.
Questions remain, for sure. But speaking as a physician, researcher and parent, I'm convinced that we now have more than enough evidence to warrant caution.
Barriers to Disclosure
Unfortunately, many pediatric anesthesiologists remain reluctant to acknowledge the possible risks of general anesthesia in childhood — much less educate parents and offer alternatives. And I think that there are a number of reasons for this.
First, good clinical practice is guided by evidence, and the evidence has gaps. It may be years before we can say with confidence whether pediatric anesthesia is harmful, in what way, to whom and which alternatives are safer.
Second, I think the idea that our practices could be harmful is very difficult for physicians to accept. It's painful to think that our anesthesia care — which has saved and improved so many young lives — may also have had some lingering ill effects for our patients.
Nevertheless, a consensus is emerging that we can no longer remain silent on the subject. In my next post, I'll share how my own practice is tackling the issue, plus how we hope to make pediatric anesthesia care even safer in the future.
