I’m a certified registered nurse anesthetist (CRNA). Read my bio
for a quick run-down of my day job. One of my goals with this blog is to de-mystify anesthesia. For most people, it’s a mysterious process. The average person has surgery a handful of times in his or her life. I find that most people don’t truly understand what happened to them during their surgery. This is not because doctors and nurses try to be obtuse. It’s because these things are complicated. In addition, unless you already have some idea of what you’re looking for, it’s hard to find thorough, accurate information about anesthesia for free online. You need the education and experience of the profession to sift what you see. Most good anesthesia articles are written in the language of the profession. They’re difficult to understand if you don’t already know what they’re talking about.
So earlier this week I asked my twitter and facebook followers for questions about anesthesia. Here are the questions and my answers.
Disclaimer: I am not a doctor. Nothing I say constitutes medical advice.
Question: What are the the various kinds/types of anesthesia?
- General Anesthesia - usually involves gas and an airway - either an endotracheal tube (ETT) or a laryngeal mask airway (LMA)
- MAC – monitored anesthesia care, AKA sedation – typically only involves drugs given through the IV, no gas
- Local anesthesia /blocks – numbing medicine injected near or on a nerve. This does not affect the brain or make you sleepy, but it does make you numb. Epidurals and spinals (central neuraxial blocks) fall into this category, as do femoral nerve blocks, sciatic blocks, interscalene blocks, etc. for joint surgery. The optic nerve is sometimes blocked for eye surgery. You can do hand or finger blocks. Sometimes the surgeon does this, and sometimes the anesthesia provider does it. Dentists use local anesthetic without an anesthesia provider present.
- TIVA – total intravenous anesthesia – a rarely used hybrid of general and MAC, in which you introduce an airway, but do not use gas, keeping the patient asleep with IV medications instead. There are only a few situations where you would want to do this, usually because you need a controlled airway, but the patient has a severe reaction to gas.
Question: What chemicals do you use? Do you know how those chemicals are manufactured?
I personally prefer a nice cup of coffee to anything in my anesthesia cart. :D Just play’in. By “chemicals,” I’ll assume you mean medications that we give the patients. This question is really too broad, but I’ll try to answer. The goals of general anesthesia are:
amnesia (no memories)
akinesia (no movement)
analgesia (no pain)
To this end, we give halogenated anesthetic gases (sevoflurane, desflurane, isoflurane) and IV propofol or etomidate for sleep, versed and ketamine for amnesia, paralytics (succinylcholine, rocuronium, vecuronium, cisatracurium ) for akinesia, and opioids (fentanyl, morphine, remifentanyl, sufenta) and other medications (toradol, tylenol) for pain. We also give antiemetics (zofran, decadron), since anesthetic gases cause nausea. We give medications to control blood pressure, as anesthesia can make BP dangerously low, and surgical stimulus can make it dangerously high. We give agents to reverse our paralytics and other drugs to counteract the negative side-effects of that reversal. And there are plenty of options I haven’t listed. Providing a good anesthetic is like cooking. No two cooks are alike. It’s a cocktail with two customers – the patient and surgeon. The patient has to be comfortable and alive, and the surgeon has to be able to do his or her job. We facilitate this with a formidable arsenal of “chemicals.”
How these chemicals are manufactured is a question outside the scope of my practice (and, frankly, outside the scope of practice of everyone I work with). You’d need to ask an organic chemist. I could probably follow their explanation, but that’s about it.
Question: How is being anaesthetized different than being asleep?
The short is that when you’re asleep and someone cuts your belly open, you wake up. ;) There are 4 Stages of Anesthesia
. Adults typically sink down through stages 1 and 2 so fast that you don’t notice. Children, on the other hand, have a noticeable excitement phase (Stage 2). Surgical anesthesia is Stage 3. The 4th stage is essentially brain death or something close to it. You always keep the patient hovering above the abyss.
Question: Do people really hear what med staff says while under?
During stage 3 anesthesia: no. During stages 1 and 2: sometimes. True surgical awareness is very rare and usually happens when the patient’s blood pressure is so low that the anesthetist had to decrease their level of anesthesia in order to save the patient’s life. This happens most frequently in a trauma situation, such as a car accident victim, where the patient is bleeding out. Emergency c-section is also a high risk for awareness. This happens because medical staff are trying to save the life of the baby and mother. Sometimes very fragile patients simply cannot tolerate enough anesthesia to keep them unaware. However, this is extremely unusual. We have excellent amnesic drugs these days, such as versed, which can erase memories retroactively if given within a few moments of the event.
On the other hand, “general anesthesia” should not confused with a “MAC” (monitored anesthesia care) AKA “sedation.” If you’ve ever had a colonoscopy or endoscopy, it was probably done with a MAC. People can remember things from a sedation; no guarantee can be provided that they will not. In fact, some level of awareness is often desired, as the patient may need to follow instructions. However, I can tell you that, in practice, people hardly ever remember anything from a MAC, either.
Question: What is more dangerous, being under anesthesia, or having the actual surgery?
That depends on how sick the patient is and what kind of surgery he or she is having. Also most surgery is impossible without anesthesia. Aside from the fact that the patient would be a moving target (writhing in pain), abdominal muscles would make abdominal surgery difficult or impossible without paralysis, which is part of the anesthesia. In addition, it would be difficult for the surgeon to hear his iPod over the screaming, and surgeons get really cranky without their music. ;)
Seriously, anesthesia is a component of the “actual surgery.” You can’t tweeze them apart. However, if you’re asking who has more opportunities to kill you (the surgeon or the anesthetist), that’s easy. The anesthetist.
I think that's enough for one evening. If I haven't mispelled any of these drugs, it'll be a small miracle. I'll answer some more questions tomorrow.