How anesthesia "knocked" you out.

When it comes to the experience of undergoing anesthesia, there are various colloquial expressions like "knocked out," "going under," "sedated," and "put to sleep." But what's the actual mechanism by which anesthesia induces unconsciousness? Anesthesia is one of the most frequently performed medical procedures, with over 60,000 people in the U.S. alone undergoing anesthesia each day. Despite its widespread use, we still don't have a comprehensive understanding of how anesthesia precisely operates in the human body to induce unconsciousness, but we do know that it is effective.

The term "anesthesia" itself means the "loss of sensation." Millions of Americans receive anesthesia annually to prevent them from feeling pain and to keep them immobile and unresponsive, allowing doctors to safely perform life-saving surgeries that would be exceedingly challenging and painful for a conscious patient. Although we don't fully grasp the intricacies of how anesthesia works, it remains a remarkable medical advancement.

Before the late 1800s, medical procedures involved little to no pain relief beyond substances like alcohol, opium, and even hemlock—methods far from foolproof. For centuries, surgeries such as tooth extractions and bone repairs were conducted with minimal pain relief for patients. However, in the 1840s, scientists discovered that certain gases, like sulfuric ether and chloroform, had sedative properties. This marked the birth of anesthesia and revolutionized medical treatment, making it significantly less painful and traumatic.

Modern anesthesia methods are considerably safer and more reliable than those early gases, yet the precise mechanisms remain elusive. Anesthesia can be categorized into four types: local, regional, sedation, and general anesthesia. Local anesthesia involves injecting a small amount of the drug into a specific area, commonly used for dental procedures and minor surgeries. Regional anesthesia targets a broader section of the body, numbing it more substantially, often used in procedures like epidural injections for labor pain relief.

Both local and regional anesthesia leave patients fully conscious; they don't induce unconsciousness. For that purpose, general anesthesia is employed. General anesthesia affects the entire body in four ways: it immobilizes the body to prevent movement during surgery, acts as an analgesic to eliminate pain perception, sedates the patient to an unconscious state, and induces amnesia, ensuring the patient has no memory of the procedure. In essence, being under general anesthesia is akin to a drug-induced coma, although it's a reversible one.

While under general anesthesia, an electroencephalogram (EEG) shows a significant decrease in brain activity, akin to levels seen in cases of brainstem death. The popular phrase "put to sleep" might sound less intimidating than describing it as a coma.

So, what is it like to be under general anesthesia? Donna Penner's story offers a glimpse into this enigmatic experience and serves as a cautionary tale of how things can occasionally go horribly wrong. Donna, a 45-year-old mother from Manitoba, Canada, underwent exploratory abdominal surgery to investigate her mysterious symptoms. Despite her nerves, Donna met with her anesthesiologist, who reassured her that the procedure should go smoothly, given her lack of risk factors.

Donna was prepped for surgery and administered a combination of drugs by her anesthesiologist. Unexpectedly, Donna woke up just before the surgeon's first incision. She was fully conscious but immobilized and unable to communicate her awareness. She endured the agony of the surgery, feeling every cut and movement. She was unable to move or cry out, and she believed she was going to die.

Remarkably, Donna survived this ordeal, but her recovery was arduous. The traumatic experience left her with severe Post Traumatic Stress Disorder (PTSD), anxiety, and panic attacks for years. To this day, Donna cannot tolerate wearing tight clothing around her neck due to the sensation of breathlessness it evokes, reminiscent of her traumatic experience in the operating room.

The reason why Donna woke up during surgery remains unclear, but it's estimated that as many as 1 in 1,000 patients may experience a similar situation. Recent studies suggest the number could be even higher. Fortunately, such cases are rare, and for most patients under general anesthesia, the procedure proceeds smoothly without awareness of the surgery. When patients wake up, usually about an hour after the anesthesiologist stops administering the drugs, they have no recollection of the experience.

Coming out of anesthesia, patients may feel disoriented, emotional, or lightheaded, with slurred speech. Common side effects include vomiting, dizziness, headaches, sore throats, or chest infections due to the use of a breathing tube. Some may experience confusion and memory loss, which usually resolve quickly. In extremely rare instances, serious side effects can occur, such as nerve damage, severe allergic reactions, awareness during surgery, or even death.

Despite our limited understanding of how anesthesia operates, it remains a vital tool in modern medicine. Researchers are striving to improve our comprehension of anesthesia and develop more sophisticated techniques to enhance its effectiveness and precision. Researchers envision a future where anesthesia becomes a more delicate and targeted tool, minimizing side effects while ensuring patient safety.