Anesthesia

People have anesthesia all the time during the surgery. While being "submissive" is quite common, there are still many doctors who don't know it.

A better understanding of how anesthesia works could improve the medications used during the process.

This is what Bruno van Swinderen, PhD, an associate professor at the University of Queensland in Australia, set out to do in a recent study published in Cell Reports.

He said his team found that propofol, a drug commonly used in anesthesia, the one implicated in Michael Jackson's death, goes beyond just putting a person to sleep.

"Propofol anesthesia is extremely safe, as is most general anesthesia today," van Swinderen told Healthline. "However, knowing this alternative mechanism could help us understand why recovery from general anesthesia is slow and sometimes problematic. You can keep people on propofol safely for a long time, so I feel we have found a medicine that works quite well. " He noticed.

"Propofol is the preferred sedative to knock him out first. Usually other anesthetics are then given to keep him down," added van Swinderen.

How Does It Work?

What exactly does propofol do?

Van Swinderen's team looked at the impact of propofol on synaptic release in rats. Synaptic release is how neurons or nerve cells communicate with each other.

Doctors knew that propofol impacted the brain's sleep system similar to that of a sleeping pill, but van Swinderen said his team found that it disrupts presynaptic mechanisms as well.

It likely affects the communication between neurons throughout the brain in a different way than sleep.

"That way, it's very different from a sleeping pill," he said in a statement.

The researchers found that propofol restricted the movement of a key protein, syntaxin 1A, which is needed for synapses in all neurons. This reduces the communication between neurons in the brain.

This may explain why patients are often groggy after surgery, van Swinderen said.

"We think the widespread disruption of synaptic connectivity, the communication pathways of the brain, is what makes surgery possible, even though effective anesthetics like propofol will make you fall asleep earlier," she said.

The finding could explain why general anesthesia can be problematic for young and old patients, they said.

Difficulty Of Research

Van Swinderen said the challenge in studying the response to anesthesia is to discover how a myriad of small effects during the pre-synapse phase lead to large changes in brain function.

"It's difficult to study in humans," she said. "It is also difficult to align a super-resolution microscope on human brain cells."

There is great value in using animal models because the synaptic release infrastructure in animals and humans is nearly identical. Humans simply have more brain cells, she said.

A drug that provides better control over the immobilization (or remobilization) of syntaxin 1A in presynapses would give doctors better control over how and when to keep the brain numb, van Swinderen said. If such drugs are developed, they could be used in conjunction with conventional sedatives.

Complications and Dangers

Long-term damage or complications of anesthesia are not well understood or discussed in the field.

"General anesthesia is extremely safe, but we don't know if some of the complications [long-lasting cognitive deficits in some patients, for example] stem from this potentially brain effect," she said.

"Human brains have a trillion synapses," van Swinderen explained. “If the mobility of Syntaxin 1A is affected in all of them, you can imagine how this could lead to long-lasting changes. But this is still just a hypothesis that needs to be tested.

According to James Lozada, DO, a researcher in obstetric anesthesiology at Northwestern University Feinberg School of Medicine in Illinois, awakening during surgery, something called intraoperative awareness, is rare.

This happens in 1 or 2 out of about 1,000 procedures, according to the American Society of Anesthesiologists. Other reports indicate that 1 in 19,000 patients experience intraoperative awareness during a procedure.

Lozada said it may be more common in procedures when the patient is unstable, such as trauma-related surgeries, emergency cesarean sections, or those that require lower doses of medication to treat the patient safely.

A 2013 report found that better surveillance can help prevent the phenomenon.

As for the age-old question of why people should fast during anesthesia, Lozada said they should follow the advice of their doctors.

Fasting guidelines vary depending on the type of procedure and the patient, but patients generally cannot eat solid foods for six to eight hours. Many places have become more relaxed about allowing a small to moderate amount of clear fluids for up to two hours before the procedure, Lozada said.

"You can absolutely risk your health by not fasting," he explained.

Under anesthesia, the muscles of the stomach and throat relax, making it easier to vomit. Because the patient is asleep and unable to protect the airways, the vomit can enter the lungs and cause damage in a process called aspiration pneumonia.

Propofol

Research sheds light on the mechanisms behind how anesthetics work, although medical anesthesiologists generally understand this, Lozada said.

"The work shows that propofol disrupts some normal cellular functions, which the authors say could lead to general anesthesia," Lozada said. "It takes even more work to prove it definitively."

The choice of drugs to be used during surgery is made by doctors individually. Factors involved in selection include heart and lung function, vital signs, general health, history of anesthetic response, and allergies.

That said, once a patient uses propofol once, it doesn't necessarily mean he can get it back medically, she said.

"It's what anesthesiologists are trained to test and in their hands it's generally well tolerated," she said.

Van Swinderen doesn't want his study to alarm patients.

"People shouldn't worry about general anesthesia, it works very well. It is important to know how the drugs we use work and it is surprising that we are still confused about how this procedure works. It is extremely common and leaves us unconscious and numb." , she said she. "Knowing more will help us resolve side effects better."