字幕列表 影片播放 列印英文字幕 If you've ever landed on the surgeon's slab, you're probably really grateful that you won't remember or feel the operation. Anesthesia is there to get you through it. But what exactly happens when you go under? Tens of thousands of people undergo anesthesia every day in the United States. But here's the not so pleasant thought: surgery predates anesthetic drugs by thousands of years. Before the mid-1800s, surgeons turned to alcohol, narcotics, and even smacking their patients upside in the head to induce unconsciousness. That is not awesome bedside manner, so surgeries were often done when patients were totally awake. Some historians believe that before the advent of anesthetics, about half of patients in surgery died of shock. That's why, in 1846, the first public demonstration of a surgery performed with general anesthesia took the medical world by storm. Doctors at Massachusetts General Hospital in Boston administered the first-ever anesthetic: diethyl ether. In fact, the theater where the surgery took place received this totally awesome name: the Ether Dome. The landmark event was heralded in the press as the “end of pain.” But anesthetics don't just address pain; they also temporarily paralyze the body and induce amnesia. Fortunately for you, that means you have no memories of the procedure. Today, doctors usually give their patients combinations of different drugs to ensure a balance of these effects throughout a procedure. These include inhaled substances like sevoflurane and nitrous oxide, as well as intravenous drugs like propofol and ketamine. Scientists know that anesthesia works, but they haven't worked out all the details of how it works, or even more broadly, how consciousness itself works. The current thinking goes that these drugs work to create the perfect operating conditions by influencing neurotransmitters: those are the chemical messengers that transmit signals between nerve cells. Specifically, many anesthetics are thought to cut off access to receptors of a neurotransmitter called gamma-Aminobutyric acid—or GABA. GABA is involved in sending signals for responsiveness from the cerebral cortex that's the part of the brain responsible for our emotions and higher-level thinking. When this path is blocked by anesthetics, the connections for arousal signals are lost and its sleepytime. But as you might imagine, bringing the brain down to such a low level of activity can be a little dangerous. Too much and the drugs could slow down activity not only in the consciousness-controlling cortex but in the brainstem itself--which could stop a patient's heart and cause serious brain damage or even death. But too little drug and the patient could wake up. Avoiding all that is where anesthesiologists and nurse anesthetists come in. These medical professionals monitor a patient's breathing, heart rate, and other vital signs to make sure they're delivering just the right amounts of anesthetic drugs in real time. That way you won't feel a thing as a skilled surgeon removes your funny bone for four hundred dollars. Although, maybe next time you'll want to spring for doctors who don't use children as assistants or, you know, drip cigarette ash on your face. But maybe that's just me.