This is the first part of unraveling the mystery of what exactly we anesthesiologists are doing while our patients are asleep. Everyone who has had general anesthesia knows the experience. You go into the room and you may vaguely recall seeing the inside of the OR, getting onto the OR table and lying down, and then...you're done. What happens in between? The answer to that question is more complex than meets the eye. Some of our tasks are obvious; some are less so. Either way, a lot of things that happen in an awake person without them even thinking about it don't happen at all under anesthesia. That is where the anesthesiologist takes over. Literally.
ABC. This is the most obvious and yet far-reaching task of the anesthesiologist, and it stands for Airway-Breathing-Circulation. In an awake person, the airway is maintained by muscle tone in the mouth and throat, muscle tone which decreases dramatically under anesthesia. Airway refers to giving the patient a means by which to exchange oxygen with the outside world. That can be a lot of things; usually it is a breathing tube placed in the mouth and windpipe, called, unsurprisingly, an endotracheal tube. There are several other airway devices placed in the mouth that can also be used for this purpose, or even a mask hooked up to tubing and an anesthesia machine will do. Of the members of the anesthesiologist's mighty triumvirate of ABC, A (airway) is king. Without it, nothing else matters.
Breathing. Duh. Of course we need to breathe, right? Yes , and we do so just fine while awake; the problem is that general anesthesia, and most sedatives for that matter, decrease the body's desire to breathe, and some drugs stop breathing completely. In my first post on this blog, I mentioned that each general anesthetic literally involves giving enough drugs to kill a person. It put off a few people who read it, but I'll explain myself here. Any drug that slows down breathing can be extremely dangerous, because it requires vigilance to administer it. If you were to give someone drugs to slow or stop their breathing and then just walk away, you'd kill them. But that's not the case at all in anesthesia. A trained anesthesia professional is sitting right there, using a mask to help the patient breathe, or more commonly, hooking their breathing tube up to an anesthesia machine that breathes for them.
Circulation. Almost all of the drugs used in general anesthesia also decrease the blood pressure, some more than others, but the important thing is that the anesthesiologist maintains the blood pressure. It has to be high enough that vital organs like the brain, heart, kidneys, etc. get enough blood to function well, but low enough that the patient doesn't bleed too much or suffer a stroke. This all has to be done against the backdrop of some interloper (oh, those surgeons!) performing painful and intentional trauma on the body, which understandably causes a great deal of stress on the body and a strong adrenaline rush. That's why we give anesthesia in the first place. It is a balancing act often determined by many things, including the patient's health and the kind of surgery being performed. Ultimately, circulation, namely blood pressure, tells us how we're doing. Too much anesthesia and the patient's blood pressure is dangerously low. Too little, and it's high. And the patient moves. And...the patient remembers. Which leads me to my next point...
Make sure the patient doesn't remember. This seems obvious, right? But in older times, it was not unheard of to use the anesthetic technique of giving only a small amount of anesthesia combined with a muscle relaxant to keep the patient from moving. So the patients were immobile for the surgery, but if the anesthetist underestimated how much drug to give by even a little, well, that's where the nightmare stories on news shows came about, with patients hearing their surgeons talking during their operation or feeling pain but unable to tell anyone. Part of any general anesthetic is to ensure complete amnesia of everything that happens during the surgery.
Make sure the patient doesn't move. This is another painfully obvious job here, but it bears repeating. it is unreasonable to ask any surgeon to have to hit a moving target with their scalpels or sutures.
Protect the nerves. What do I mean here? When you're asleep, you're immobile, of course, during the duration of the surgery. Though it's necessary for the surgeons, it is not normal in real life, and that presents its own set of problems. When you you go to bed at night, you don't stay in the same position. You start on your back, switch to one side, maybe switch again to the other side, even go to your stomach. You have to, or you'll get numb from lying in the same position for hours. That's where the anesthesia problem lies. There are certain parts on the body where nerves are very superficial to the skin, and those parts are especially susceptible to being injured when placed in the same position for too long.
First among these is that spot on the inside of your elbow, the funny bone, known in medical terms as the ulnar groove. If that is pressed on too vigorously while the patient is lying still for their surgery, it can cause injury to the 4th and 5th fingers on that hand - numbness, tingling, and even permanent weakness. It's the anesthesiolgist's job to make sure that doesn't happen. Vulnerable spots like the funny bone are padded heavily while under anesthesia, to ensure too much pressure isn't placed on them. Other key places to protect and pad during anesthesia are the back of the forearm (radial nerve) and the outside of the knee (peroneal nerve).
Protect the eyes. An awake person has many ways to protect their eyes. Cover them with their hand, maybe, or even just close the eyes tightly. If a small speck gets in the eye, it reflexively starts making tears to wash the offending thing out. Under anesthesia, all such defenses are gone, so the anesthesiologist must again take over. They will often put a mild lubricant in the eye, some sort of artificial tears, to make sure the eye stays moist. Then, the eyes are taped closed, to make sure they don't accidentally open and expose the eyeball. Some people even put plastic shields over the taped eyes, like a pair of wraparound sunglasses, to make sure the eyes aren't harmed. The eyes, so valuable and vulnerable, are
watched VERY carefully during surgery.
These are some of the high points. There are more, but you get the idea. The bottom line is that the patient, while under anesthesia, is as defenseless as a little baby, and regardless of what kind of operation is being done, needs to be protected in even basic ways. That is the task of your anesthesiologist.
No comments:
Post a Comment