So in the last entry, I got into what exactly happens in the time between leaving the preoperative area holding room and the time you go to sleep, with the monitors and oxygen being applied, but usually not remembered by the patient due to the amnesia properties of midazolam...
It is at this point that general anesthesia begins. I get asked all the time, not unreasonably, about what kinds of drugs I will use. Being that most patients don't know or care much about pharmacology, I don't bore the crap out of them with details. Most want to know if I will give them "gas." Most are surprised by my reply, which is that the actual drug that initially puts them to sleep is given through the IV. That drug, which is used in 98 to 99 percent of anesthetics in the United States, is propofol, which has unfortunately gained quite a notorious reputation due to its link to the death of Michael Jackson.
Propofol, in the right hands, i.e. those of a trained and skilled anesthesiologist or nurse anesthetist, is a very safe drug. It has been used millions of times in operating rooms in the last twenty years and has a great track record of success. But it does two important things. It makes the blood pressure go down significantly, and when given in the quantities needed to induce general anesthesia, it slows and even stops breathing. Now these are the qualities that can make it dangerous when not given in the proper setting. That's why the monitors are put on the patient before they go to sleep, so that if the blood pressure goes down and/or the breathing stops, we can do something about it right away.
Fortunately, when I give propofol to a patient to put them to sleep for anesthesia, I'm not walking out of the room or standing in another room while other people give it. I, like every other anesthesiologist who does the same thing, am right there, standing at the head of the patient's bed, waiting for them to fall asleep. Once they are asleep, I use the mask, which is attached to an anesthesia machine, to help them breathe.
Propofol also hurts when it's injected. We try to give a little bit of local anesthetic through the IV with the propofol, to try to diminish that discomfort. Usually it works; sometimes it doesn't. Fortunately, because of the midazolam the patient has received before, they don't remember the displeasure of that experience.
Once the propofol has been given to put the patient initially to sleep, then that is the point where we turn on the anesthetic gas, and that keeps the patient asleep during the duration of the surgery. The problem is that we need a way to give that gas, and if the initial medicine has made the patient stop breathing, then we need to breathe for them. So some sort of tube is inserted into the patient's mouth and is hooked up to a breathing machine from there.
Often, especially in shorter surgeries, the tube that is placed in the patient's mouth is a soft, plastic or rubber tube called a laryngeal mask airway, or LMA. The LMA has a large, teardrop shaped cuff at one end, which when placed correctly, sits on top of the opening to the esophagus and vocal cords. It's usually fairly straightforward to put in; the patient's mouth is opened and the LMA is just gently inserted. It's the other kind of tube that is put in, an endotracheal tube, that is what most people associate when they think of a "breathing tube."
An intubation, as it is called, is the process of placing one of these endotracheal tubes into the patient's mouth and through their vocal cords, where the tip of the tube sits inside the trachea. From this point, the other end of the tube can be attached to an anesthesia machine, and the anesthetic gases that keep the patient asleep can be given.
An intubation, to a layperson who has never seen one before, is kind of a wild procedure. It always amazes me when I'm intubating a patient and can see out of the corner of my eye, some medical student or nursing student and the shocked look on their face. They're fascinated and horrified at the same time.
I remember the first time I saw an intubation as a medical student. The anesthesiologist tilted the patient's head back a little bit, opened the mouth, and stuck this...big, metal thing...into the patient's mouth, and then after some maneuvering, grabbed the breathing tube and shoved it into the patient's mouth for what seemed like forever. I thought he would shove it in so far that it'd get lost. And as he pushed the tube in, I could see the patient's Adam's apple sort of bounce up. I swallowed hard, and I think I felt a little twinge of sympathy pain in my own throat at that point.
I found later on that the big metal thing was a laryngoscope, a metal flashlight of sorts with a straight, dull metal blade attached to it. When held in the right position, a little light shines down the length of the blade. The blade is placed into the patient's mouth to move the tongue out of the way and visualize the epiglottis and vocal cords. Once the vocal cords are in view, it is just a matter of guiding, gently, the tube through them. It's not nearly as violent a procedure as I witnessed that day, but it can be a challenging one that takes some getting used to. But again, as general anesthesia slows or even stops the patient's breathing, it is up to the anesthesiologist to maintain an airway and use that airway to breathe for the patient during the duration of the surgery. That's where the intubation comes in. There is method to the madness...
Thursday, December 1, 2011
Wheeling on back
So you're having surgery...you get to the operating room area, where the nurses greet you, ask you to take off all of your clothes and put on this skimpy little gown, and ask you a bunch of questions. Then a couple more people ask you all of the same questions, and you're thinking, Didn't any of you guys read my chart? And that's where your anesthesiologist comes in, promising you amnesia and the absence of pain, hopefully reassuring you that all will be OK.
The role of the anesthesiologist before the operation starts is one of reassurance. Once they have checked over your medical records and history and determine that it is indeed safe for you to receive anesthesia, they want to ease whatever (understandable) anxiety you might have about the surgery. Of course, a large part of that is done through verbal reassurance, but, yes, drugs do play a major part in the process.
Somewhere between the holding area where you get dressed for surgery and the actual operating room, the anesthesiologist slips you a little medication through your IV. There are a few ones that can be used, but these days, by far the most common drug used for this purpose is midazolam, also known by the trade name of Versed. For those who want to know, it is a class of drug known as a benzodiazepine, which potentiates an inhibitory neurotransmitter in the nervous system known as GABA. The great thing about midazolam in the context of preparing patients for surgery is that it causes amnesia. It probably doesn't take longer than 30 seconds to work, and it only lasts about 30 minutes, but in that time, it's enough for people to forget completely about the entire process of leaving the surgery holding area and going into the operating room.
So most of the time, by the time the patient gets to the operating room, they have had midazolam, and though they may look and act normally to the casual observer, they in fact will have amnesia of the events in question. Patients move themselves onto the operating table and make small talk with the OR staff and the anesthesiologist, and usually don't remember a second of it. Midazolam can make some people a little bit disinhibited as well, so occasionally we'll get the patient who suddenly gets into confessional mode when the drugs are on board. I actually know people who worked in the OR with me who, when they needed elective surgery, decided to have it done somewhere else because they were so afraid of what they might say when they were given midazolam.
The good thing, though, is that midazolam calms the anxious patient and that is good for everyone. Once the patient is in the room, they are monitored with several things, just like in the holding area - a blood pressure cuff, EKG pads for the heart, and a small probe on the finger. This is a pulse oximeter, which measures a value known as the oxygen saturation, a measure of how much oxygen is in the blood. It also makes a distinctive high-pitched beeping sound in concert with the patient's heartbeat and is a useful tool in that regard.
Usually, while the anesthesiologist is placing these monitors, the OR nurses, and whoever else may be in the room (surgeons, medical students, etc.) are doing other stuff to the patient. One particularly important thing is the placement of these funny compression devices around the legs - they make the legs look like they're wrapped in large white inflatable tortillas. They inflate and deflate periodically during the surgery, squeezing the legs in the process. This device is called an SCD, or Sequential Compression Device. It is important because the leg squeezing that it does promotes the continuous flow of blood in the legs.
During anesthesia, and especially during the beginning of anesthesia, the blood in the patient's legs tends to slow down as sleep sets in and the blood pressure goes down. The problem with slowed blood is that it increases the risk of forming a blood clot in the leg, which can then travel up to the lung. When this happens, it is called a pulmonary embolism, and it can be fatal. These squeezing devices, funny though they look, are very effective and have greatly decreased the incidence of what used to be a rare but all-too-common complication of even routine general anesthetics.
But I digress. Once all of these monitors and sequential devices are placed, the patient is then ready to go off to sleep. But it's not as simple as slapping a gas mask on them or slamming drugs through the IV. First, the patient is given oxygen to breathe through a mask. Often, when people are not sedated until they actually come into the room, this is the last thing they remember, lying on the bed, looking up at the ceiling, with a mask on top of their nose and mouth.
As a medical student, I never understood, watching the anesthesiologists put patients to sleep, why in the world they did this. Why didn't they just go right to the gas? What's the point? Well, the normal air we breathe is about 21% oxygen; most of the rest of it is nitrogen. Right before going to sleep, when the patient breathes 100% oxygen, it fills their lungs with oxygen and removes the nitrogen. Nitrogen is nice, but it doesn't help human cells metabolize and thrive like oxygen does. All that oxygen serves as a safety net of sorts; if for some reason the breathing slows or stops as the patient goes to sleep, there is enough oxygen in the blood that a few seconds of not breathing won't be a disaster. So the oxygen mask is a nice thing to do for patients, allowing them to relax with the deep breaths we ask them to take, but it serves this safety purpose as well.
So at this point, with the monitors on and the oxygen in place being breathed by the patient, the induction of anesthesia - the "going to sleep" part - can begin...
The role of the anesthesiologist before the operation starts is one of reassurance. Once they have checked over your medical records and history and determine that it is indeed safe for you to receive anesthesia, they want to ease whatever (understandable) anxiety you might have about the surgery. Of course, a large part of that is done through verbal reassurance, but, yes, drugs do play a major part in the process.
Somewhere between the holding area where you get dressed for surgery and the actual operating room, the anesthesiologist slips you a little medication through your IV. There are a few ones that can be used, but these days, by far the most common drug used for this purpose is midazolam, also known by the trade name of Versed. For those who want to know, it is a class of drug known as a benzodiazepine, which potentiates an inhibitory neurotransmitter in the nervous system known as GABA. The great thing about midazolam in the context of preparing patients for surgery is that it causes amnesia. It probably doesn't take longer than 30 seconds to work, and it only lasts about 30 minutes, but in that time, it's enough for people to forget completely about the entire process of leaving the surgery holding area and going into the operating room.
So most of the time, by the time the patient gets to the operating room, they have had midazolam, and though they may look and act normally to the casual observer, they in fact will have amnesia of the events in question. Patients move themselves onto the operating table and make small talk with the OR staff and the anesthesiologist, and usually don't remember a second of it. Midazolam can make some people a little bit disinhibited as well, so occasionally we'll get the patient who suddenly gets into confessional mode when the drugs are on board. I actually know people who worked in the OR with me who, when they needed elective surgery, decided to have it done somewhere else because they were so afraid of what they might say when they were given midazolam.
The good thing, though, is that midazolam calms the anxious patient and that is good for everyone. Once the patient is in the room, they are monitored with several things, just like in the holding area - a blood pressure cuff, EKG pads for the heart, and a small probe on the finger. This is a pulse oximeter, which measures a value known as the oxygen saturation, a measure of how much oxygen is in the blood. It also makes a distinctive high-pitched beeping sound in concert with the patient's heartbeat and is a useful tool in that regard.
Usually, while the anesthesiologist is placing these monitors, the OR nurses, and whoever else may be in the room (surgeons, medical students, etc.) are doing other stuff to the patient. One particularly important thing is the placement of these funny compression devices around the legs - they make the legs look like they're wrapped in large white inflatable tortillas. They inflate and deflate periodically during the surgery, squeezing the legs in the process. This device is called an SCD, or Sequential Compression Device. It is important because the leg squeezing that it does promotes the continuous flow of blood in the legs.
During anesthesia, and especially during the beginning of anesthesia, the blood in the patient's legs tends to slow down as sleep sets in and the blood pressure goes down. The problem with slowed blood is that it increases the risk of forming a blood clot in the leg, which can then travel up to the lung. When this happens, it is called a pulmonary embolism, and it can be fatal. These squeezing devices, funny though they look, are very effective and have greatly decreased the incidence of what used to be a rare but all-too-common complication of even routine general anesthetics.
But I digress. Once all of these monitors and sequential devices are placed, the patient is then ready to go off to sleep. But it's not as simple as slapping a gas mask on them or slamming drugs through the IV. First, the patient is given oxygen to breathe through a mask. Often, when people are not sedated until they actually come into the room, this is the last thing they remember, lying on the bed, looking up at the ceiling, with a mask on top of their nose and mouth.
As a medical student, I never understood, watching the anesthesiologists put patients to sleep, why in the world they did this. Why didn't they just go right to the gas? What's the point? Well, the normal air we breathe is about 21% oxygen; most of the rest of it is nitrogen. Right before going to sleep, when the patient breathes 100% oxygen, it fills their lungs with oxygen and removes the nitrogen. Nitrogen is nice, but it doesn't help human cells metabolize and thrive like oxygen does. All that oxygen serves as a safety net of sorts; if for some reason the breathing slows or stops as the patient goes to sleep, there is enough oxygen in the blood that a few seconds of not breathing won't be a disaster. So the oxygen mask is a nice thing to do for patients, allowing them to relax with the deep breaths we ask them to take, but it serves this safety purpose as well.
So at this point, with the monitors on and the oxygen in place being breathed by the patient, the induction of anesthesia - the "going to sleep" part - can begin...
Monday, October 31, 2011
What just happened?
I had my wisdom teeth taken out in an oral surgeon's office when I was 19 and that is the only time I have ever had general anesthesia. Here's what I remember. First, I lay down and the nurses put monitors on me. I started hearing beeping noises and was reassured that that was merely my own heartbeat. Then they started an IV, put a mask over my nose, and...
Then I was lying sideways on a cart in the recovery room, groggy, with my sister imploring me to get up so that she could drive me home. Apparently surgery was done, which was very confusing to me, because I had last remembered the monitors and the mask, with a few people milling around me. Later that evening, she also informed me that I had been given a whole litany of postoperative instructions during that time in the recovery room, none of which I remembered. Strangely, at least to me, the nurse gave those instructions knowing I wouldn't remember them, but told them to me anyway. Thank goodness for my sister.
With maybe a few changes in syntax, that is what the vast majority of people experience when they get a general anesthetic. It is a wonderful thing that we are able to do by managing the various drugs at our disposal. A surgical operation, be it 10 minutes or 10 hours, always feels to the patient as though it took 10 seconds. But what happens in between? That is what a log of this blog is intending to look at, and in the next few entries, I just want to go through, step by step, just exactly what is happening from the anesthesiologist's perspective while you are asleep in surgery.
Then I was lying sideways on a cart in the recovery room, groggy, with my sister imploring me to get up so that she could drive me home. Apparently surgery was done, which was very confusing to me, because I had last remembered the monitors and the mask, with a few people milling around me. Later that evening, she also informed me that I had been given a whole litany of postoperative instructions during that time in the recovery room, none of which I remembered. Strangely, at least to me, the nurse gave those instructions knowing I wouldn't remember them, but told them to me anyway. Thank goodness for my sister.
With maybe a few changes in syntax, that is what the vast majority of people experience when they get a general anesthetic. It is a wonderful thing that we are able to do by managing the various drugs at our disposal. A surgical operation, be it 10 minutes or 10 hours, always feels to the patient as though it took 10 seconds. But what happens in between? That is what a log of this blog is intending to look at, and in the next few entries, I just want to go through, step by step, just exactly what is happening from the anesthesiologist's perspective while you are asleep in surgery.
Sunday, September 18, 2011
Awareness in surgery: a view from an anesthesiologist
During general anesthesia, a surgical patient needs to be given a combination of drugs that ensures four basic things: 1) immobility 2) muscle relaxation 3) hypnosis, and 4) amnesia. The first two are the chief concerns of the surgeon, but the most pressing one for the patient is the last one. I get asked by patients about it almost every day. "I'm not gonna remember, am I?" My answer is always the same - not if I can help it.
I have been an anesthesiologist for a decade now, and I have yet to have an incident of intraoperative awareness that I know of. However, it is a well documented phenomenon, and one that is a big problem for people who have experienced it. I have interviewed a few patients who remembered being awake during surgery, and though a few were nonchalant about it, most were absolutely horrified by the experience, and for good reason. Imagine it - you're having surgery, you can't move, and you are (supposedly) unconscious. Yet you remember incidents during your operation, including being cut open, or people talking about you. Worse yet, you feel pain but can't do anything about it. Just thinking about it is nauseating, and I wouldn't wish it on my worst enemy.
There are a few things I want to discuss regarding this phenomenon. First, how often does it happen? Second, when does it happen? Third, how (in the world?!?!) could any anesthesiologist let it happen?
Incidence:
There have been numerous studies documenting how often recall under general anesthesia occurs, and they vary. Some cite an incidence of up to 0.9% - almost 1 in a hundred. That's a lot. There was a more recent study from the University of Illinois at Chicago that looked at almost 180,000 patients over a three year period that had undergone general anesthesia. They found an incidence of recall of about 0.006%, or 1 in about 14,500. That's not a lot - but try telling that to the one person out of that 14,500 who was awake during surgery. I'm more inclined to believe the more recent study, as anesthetic techniques have changed over the years and we have a wide range of drugs at our disposal to ensure amnesia.
When (and how) it happens:
Type of surgery
Not all general anesthetics are the same from the standpoint of recall. There are some cases where the risk of being aware during anesthesia is significantly higher than in others:
1. Cardiac surgery - A lot of the first documented widespread episodes of intraoperative awareness were during open heart surgery. I don't remember the statistics, but it's more than the 0.9% cited in previous studies on all general anesthetics.
2. C-sections under general anesthesia. General anesthesia presents a unique dilemma during a c-section. Of course, the woman in such a situation needs to be asleep to get her baby out. The problem is afterwards; the gases used in general anesthesia tend to relax the uterus. This may be a good thing when the obstetricians are trying to remove the baby, but afterwards, those relaxing properties prevent the uterus from contracting, and this can increase the risk of bleeding. So the anesthesiologist is limited in how much anesthetic gas they can use.
3. Trauma surgery - The problem here is the condition trauma patients are in when they arrive to the OR. They are unstable, with low blood pressures. Most of the anesthetic drugs we give tend to lower the blood pressure, so if a patient comes in with a blood pressure of 60 over 40, for example, the last thing we should do is make it even lower with anesthetic drugs.
4. Emergency surgery, of any kind. The same logic applies here as in trauma surgery. A person having emergent surgery is unstable and tolerates even a small amount of anesthesia very poorly.
Type of patient
Not everyone is at the same risk for remembering stuff during anesthesia. If you fit into one of these categories, be aware that your risk is greater:
1. Users of alcohol and drugs. This makes total sense, doesn't it? If someone drinks a lot of alcohol or uses drugs of any kind, they have a greater tolerance to anesthesia. This doesn't just apply to street drugs like heroin or cocaine. It applies to prescription pain meds (like Vicodin or Oxycontin) and prescription sedatives/anti-anxiety drugs (like Valium or Xanax). People who use these drugs are just a little different from the rest of us. For one, their livers are turbocharged and spit out anesthetic drugs quickly. For another, their brain cells have fewer receptors for anesthesia drugs, so it takes more drug to affect those brain cells.
2. People on antidepressants. See above. These drugs tend to make the liver metabolize drugs faster.
3. People who have had similar episodes before. Another intuitive one. If, for some reason a patient was aware during anesthesia even though everything sounded OK medically, there's probably something going on with that patient. We don't know exactly how these anesthetic gases work; as such, it's hard to predict how or why some people just aren't as affected by them as others.
4. People who have been told that they might be aware during anesthesia. No one is sure why that is; I suppose you could look at it as a self-fulfilling prophecy kind of thing.
5. Redheads. What?!?!? Seriously? It has always been a unwritten rule, especially among the older anesthesiologists, that redheads need more anesthesia for reasons no one knows. I always dismissed these old geezers as a bunch of idiots, but a study came out in one of our major journals in the last few years, and it backed it up. Granted, the study was very small, but it did show that redheads needed significantly more inhaled anesthetic gas (up to 20% more!) to maintain the same level of anesthesia as non-redheads. Believe what you may, I guess. I'm just putting it out there...
I have been an anesthesiologist for a decade now, and I have yet to have an incident of intraoperative awareness that I know of. However, it is a well documented phenomenon, and one that is a big problem for people who have experienced it. I have interviewed a few patients who remembered being awake during surgery, and though a few were nonchalant about it, most were absolutely horrified by the experience, and for good reason. Imagine it - you're having surgery, you can't move, and you are (supposedly) unconscious. Yet you remember incidents during your operation, including being cut open, or people talking about you. Worse yet, you feel pain but can't do anything about it. Just thinking about it is nauseating, and I wouldn't wish it on my worst enemy.
There are a few things I want to discuss regarding this phenomenon. First, how often does it happen? Second, when does it happen? Third, how (in the world?!?!) could any anesthesiologist let it happen?
Incidence:
There have been numerous studies documenting how often recall under general anesthesia occurs, and they vary. Some cite an incidence of up to 0.9% - almost 1 in a hundred. That's a lot. There was a more recent study from the University of Illinois at Chicago that looked at almost 180,000 patients over a three year period that had undergone general anesthesia. They found an incidence of recall of about 0.006%, or 1 in about 14,500. That's not a lot - but try telling that to the one person out of that 14,500 who was awake during surgery. I'm more inclined to believe the more recent study, as anesthetic techniques have changed over the years and we have a wide range of drugs at our disposal to ensure amnesia.
When (and how) it happens:
Type of surgery
Not all general anesthetics are the same from the standpoint of recall. There are some cases where the risk of being aware during anesthesia is significantly higher than in others:
1. Cardiac surgery - A lot of the first documented widespread episodes of intraoperative awareness were during open heart surgery. I don't remember the statistics, but it's more than the 0.9% cited in previous studies on all general anesthetics.
2. C-sections under general anesthesia. General anesthesia presents a unique dilemma during a c-section. Of course, the woman in such a situation needs to be asleep to get her baby out. The problem is afterwards; the gases used in general anesthesia tend to relax the uterus. This may be a good thing when the obstetricians are trying to remove the baby, but afterwards, those relaxing properties prevent the uterus from contracting, and this can increase the risk of bleeding. So the anesthesiologist is limited in how much anesthetic gas they can use.
3. Trauma surgery - The problem here is the condition trauma patients are in when they arrive to the OR. They are unstable, with low blood pressures. Most of the anesthetic drugs we give tend to lower the blood pressure, so if a patient comes in with a blood pressure of 60 over 40, for example, the last thing we should do is make it even lower with anesthetic drugs.
4. Emergency surgery, of any kind. The same logic applies here as in trauma surgery. A person having emergent surgery is unstable and tolerates even a small amount of anesthesia very poorly.
Type of patient
Not everyone is at the same risk for remembering stuff during anesthesia. If you fit into one of these categories, be aware that your risk is greater:
1. Users of alcohol and drugs. This makes total sense, doesn't it? If someone drinks a lot of alcohol or uses drugs of any kind, they have a greater tolerance to anesthesia. This doesn't just apply to street drugs like heroin or cocaine. It applies to prescription pain meds (like Vicodin or Oxycontin) and prescription sedatives/anti-anxiety drugs (like Valium or Xanax). People who use these drugs are just a little different from the rest of us. For one, their livers are turbocharged and spit out anesthetic drugs quickly. For another, their brain cells have fewer receptors for anesthesia drugs, so it takes more drug to affect those brain cells.
2. People on antidepressants. See above. These drugs tend to make the liver metabolize drugs faster.
3. People who have had similar episodes before. Another intuitive one. If, for some reason a patient was aware during anesthesia even though everything sounded OK medically, there's probably something going on with that patient. We don't know exactly how these anesthetic gases work; as such, it's hard to predict how or why some people just aren't as affected by them as others.
4. People who have been told that they might be aware during anesthesia. No one is sure why that is; I suppose you could look at it as a self-fulfilling prophecy kind of thing.
5. Redheads. What?!?!? Seriously? It has always been a unwritten rule, especially among the older anesthesiologists, that redheads need more anesthesia for reasons no one knows. I always dismissed these old geezers as a bunch of idiots, but a study came out in one of our major journals in the last few years, and it backed it up. Granted, the study was very small, but it did show that redheads needed significantly more inhaled anesthetic gas (up to 20% more!) to maintain the same level of anesthesia as non-redheads. Believe what you may, I guess. I'm just putting it out there...
Saturday, September 17, 2011
The White Stuff: An informal look at propofol
In 2009 Michael Jackson passed away under tragic and unfortunate circumstances. The reason? It was an overdose of the anesthetic drug propofol. For over 20 years, propofol has been one of the most commonly used anesthetic drugs on earth, and if you had surgery during that time, it was more than likely used to put you to sleep. But until that June day two years ago, nobody outside of medicine had ever heard of it, and pundits were all over the TV in the days following Michael Jackson's death, speculating on how it might have killed him. That is a story for another blog entry. What I do want to do, however, is give a little insight into this mysterious drug, which even now I am asked about at least once a week. It is important because like I said, it is the single most common induction drug used today in anesthesia, and a little information goes a long way in reassuring anyone about to undergo anesthesia.
First of all, what is propofol? It is different from all of the other sedative drugs used in anesthesia today. It is not a benzodiazepine, like the more familiar drugs Valium or Klonopin. Nor is it a barbiturate, like sodium thiopental (Pentothal). Both of these drugs have known mechanisms of action; they make certain inhibitory substances in the nervous system more potent. Propofol is in its own unique class of drugs; it is what is known as a "hindered phenol".
No, I don't really know what that means either. Nor are people in general completely sure of how propofol works. It is thought that like other sedatives, it potentiates the action of certain inhibitory substances, or neurotransmitters, in the central nervous system.
Enough about that. Propofol is a relatively new drug, having just come along in the last twenty-five years or so. Unlike most other drugs, which are mixed in saline or water, propofol is mixed in a lipid emulsion, with a substance, lecithin, that is similar to egg whites. As such, propofol has a unique place in the pantheon of drugs because of its snow-white color. It is often offhandedly referred to by non-anesthesiologist medical personnel as "milk of amnesia," a moniker I find annoying, albeit understandable. Propofol does a few things that make it so valuable and useful for anesthesiologists:
It acts for a short time and is metabolized quickly. Propofol is given in a large dose in the beginning of an anesthetic to put patients to sleep, and it causes almost immediate unconsciousness. Within five to ten minutes, though, that large dose has completely worn off and the patient will awaken unless they are given more anesthetic.
It can cause that unconsciousness, yet can wear off quickly without lingering side effects.In fact, propofol, when used for sedation (or misused, like MIchael Jackson's physician did), needs to be given through a pump, continuously. Shortly after the propofol stops, the patient wakes up and has little if any of the "hangover" feeling that characterized many sedative drugs before it. That is a great, and very useful quality to have in a drug.
Propofol, however, has a couple of properties that can make it extremely dangerous if not used correctly. First, it can cause blood pressure to drop significantly, especially in someone who is dehydrated - like a patient having surgery, who has been instructed not to eat or drink for at least 8 hours before their procedure. If that drop in blood pressure isn't treated in some way and is allowed to continue for any period of time, it can cause significant damage to vital organs. Elderly people are especially susceptible to this.
But the most significant - and now, the most notorious - property of propofol is that it decreases breathing, and can cause it to stop completely if given in large enough doses. If that sounds alarming, it can be. Propofol is a very safe drug in the hands of anesthesia providers who are trained in how to manage the airway and breathe for the patient who cannot do so on their own. But for someone not trained in airway management, propofol can be an extremely dangerous drug indeed. Almost all medical personnel are trained in basic or advanced life support, which does involve learning how to maintain an airway in a patient who is not breathing, but very few are trained with advanced airway management skills that are critical to know when such drugs as propofol are being given.
Doctors from specialties outside anesthesiology, like GI doctors and cardiologists, use mild sedation for a lot of their procedures, and have recently petitioned for the privilege of using propofol. All have been turned down by the governing society of anesthesia, the American Society of Anesthesiologists. They are certainly capable doctors in their area of expertise; they just don't necessarily have the skills in resuscitation and airway management to help a patient who stops breathing from an accidental overdose of propofol. That's not their fault; their training focuses on their particular area of expertise. Anesthesiologists do resuscitation and airway management for a living.
Again, it bears repeating that of the millions of surgeries performed in the United States each year under general anesthesia, propofol is used to put patients to sleep in, oh, 99.9% of them. Propofol is used, safely, in almost all of those as well, because it is given by an anesthesia provider who is vigilantly watching the patient with the help of multiple monitors, and has been trained for years in its proper use.
First of all, what is propofol? It is different from all of the other sedative drugs used in anesthesia today. It is not a benzodiazepine, like the more familiar drugs Valium or Klonopin. Nor is it a barbiturate, like sodium thiopental (Pentothal). Both of these drugs have known mechanisms of action; they make certain inhibitory substances in the nervous system more potent. Propofol is in its own unique class of drugs; it is what is known as a "hindered phenol".
No, I don't really know what that means either. Nor are people in general completely sure of how propofol works. It is thought that like other sedatives, it potentiates the action of certain inhibitory substances, or neurotransmitters, in the central nervous system.
Enough about that. Propofol is a relatively new drug, having just come along in the last twenty-five years or so. Unlike most other drugs, which are mixed in saline or water, propofol is mixed in a lipid emulsion, with a substance, lecithin, that is similar to egg whites. As such, propofol has a unique place in the pantheon of drugs because of its snow-white color. It is often offhandedly referred to by non-anesthesiologist medical personnel as "milk of amnesia," a moniker I find annoying, albeit understandable. Propofol does a few things that make it so valuable and useful for anesthesiologists:
It acts for a short time and is metabolized quickly. Propofol is given in a large dose in the beginning of an anesthetic to put patients to sleep, and it causes almost immediate unconsciousness. Within five to ten minutes, though, that large dose has completely worn off and the patient will awaken unless they are given more anesthetic.
It can cause that unconsciousness, yet can wear off quickly without lingering side effects.In fact, propofol, when used for sedation (or misused, like MIchael Jackson's physician did), needs to be given through a pump, continuously. Shortly after the propofol stops, the patient wakes up and has little if any of the "hangover" feeling that characterized many sedative drugs before it. That is a great, and very useful quality to have in a drug.
Propofol, however, has a couple of properties that can make it extremely dangerous if not used correctly. First, it can cause blood pressure to drop significantly, especially in someone who is dehydrated - like a patient having surgery, who has been instructed not to eat or drink for at least 8 hours before their procedure. If that drop in blood pressure isn't treated in some way and is allowed to continue for any period of time, it can cause significant damage to vital organs. Elderly people are especially susceptible to this.
But the most significant - and now, the most notorious - property of propofol is that it decreases breathing, and can cause it to stop completely if given in large enough doses. If that sounds alarming, it can be. Propofol is a very safe drug in the hands of anesthesia providers who are trained in how to manage the airway and breathe for the patient who cannot do so on their own. But for someone not trained in airway management, propofol can be an extremely dangerous drug indeed. Almost all medical personnel are trained in basic or advanced life support, which does involve learning how to maintain an airway in a patient who is not breathing, but very few are trained with advanced airway management skills that are critical to know when such drugs as propofol are being given.
Doctors from specialties outside anesthesiology, like GI doctors and cardiologists, use mild sedation for a lot of their procedures, and have recently petitioned for the privilege of using propofol. All have been turned down by the governing society of anesthesia, the American Society of Anesthesiologists. They are certainly capable doctors in their area of expertise; they just don't necessarily have the skills in resuscitation and airway management to help a patient who stops breathing from an accidental overdose of propofol. That's not their fault; their training focuses on their particular area of expertise. Anesthesiologists do resuscitation and airway management for a living.
Again, it bears repeating that of the millions of surgeries performed in the United States each year under general anesthesia, propofol is used to put patients to sleep in, oh, 99.9% of them. Propofol is used, safely, in almost all of those as well, because it is given by an anesthesia provider who is vigilantly watching the patient with the help of multiple monitors, and has been trained for years in its proper use.
Thursday, September 15, 2011
To-do list: the responsibilities of the anesthesiologist
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.
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.
Tuesday, September 6, 2011
To sleep or not to sleep, Part II
So, just as promised, I want to go over the pros and cons of conscious sedation, so that if given the choice, you as a patient can make an informed decision about whether not to go completely to sleep for your surgery. First, I just want to more clearly define what I mean by "conscious sedation."
Conscious sedation refers to a level of anesthesia that is more than being completely awake, but less than being completely asleep. It is often referred to as "twilight" anesthesia, and the technical term for it is Monitored Anesthesia Care, called MAC for short. When patients receive MAC anesthesia, their consciousness is depressed somewhat. They have amnesia and are sedated enough that they may respond to very strong noxious stimuli but not much if at all to weaker stimuli. As opposed to a general anesthetic where the patient's breathing is significantly slowed down and their blood pressure can also decrease quite a bit, conscious sedation depresses these functions only mildly, if at all.
With that in mind, let's go over the good and bad of having conscious sedation.
The Good:
1. You're more awake during the surgery. In most cases, the amount of sedation you receive for such a case is enough that you don't remember anything, but not so much that you're totally out of it. Patients will sometimes remember hearing voices and the beeping sounds of monitors, but will note that they didn't really care about them and weren't worried or concerned about hearing them.
2. You wake up faster afterwards. The most common sedative administered during conscious sedation is propofol. Yes, that's the same drug that was misused by Michael Jackson, but in the hands of trained anesthesia professionals, it is a very safe drug. One of its best qualities is that it only lasts a few minutes, so during sedation it is given continuously into the IV via a small pump. When the surgery is done, the pump is discontinued, and the patient wakes up within a few minutes. There is little or none of the groggy feeling that so often accompanies general anesthesia.
3. Less nausea and vomiting. The stuff that really causes nausea is the combination of narcotics and the inhaled anesthetic gases that are used to maintain general anesthesia. With conscious sedation, there is no inhaled gas and significantly less narcotic being given.
4. Receiving less drugs = fewer side effects . General anesthesia is strong stuff. Even a "routine" general anesthetic involves the administration of some pretty potent medicines, ones that can drastically lower all bodily functions, including blood pressure, heart rate, neurologic function, even immune function. A general anesthetic is much more stressful on the body than conscious sedation.
The Bad:
1. You're more awake during the surgery. Again, the likelihood of remembering much at all during conscious sedation is quite small, but it's much more likely to happen than in general anesthesia. If you're the kind of person who wants to be totally knocked out and doesn't want to know anything, well, conscious sedation is not an optimal choice for you.
2. You may end up getting general anesthesia anyway. Everyone deals with conscious sedation differently. Some people do great with just a little bit of IV sedative and some local anesthetic in their incision. Others get uncomfortable - real uncomfortable. It's uncommon but possible that if you get too uncomfortable during your sedation, the anesthesiologist may have to put you to sleep anyway, defeating the whole purpose of having sedation.
3. Sedative-induced confessions. Yeah, this is a rare sort of thing, but there are some people, when given a small amount of sedative, start confessing like a sentimental college kid on graduation night. People know their tendencies. I know OR personnel I work with who have chosen to have their surgeries at outside hospitals just because they feared what they might say once they had a little sedation.
4. It can actually be more dangerous. This is especially true if you have issues with snoring or sleep apnea. When you are under general anesthesia, you have a breathing tube in your mouth that the anesthesiologist uses to help with your breathing. With conscious sedation, you have small plastic prongs in your nose that give oxygen, but that's about it. When people get sleepy, it is easier for the tissues in their mouth and throat to collapse, blocking the flow of oxygen into the lungs and causing blood oxygen levels to decrease dangerously. The vigilant anesthesia provider, of course, can deal with this accordingly, but even small lapses in vigilance can cause big, big problems. This leads me to the next point...
5. The quality of your conscious sedation experience is very anesthesiologist dependent. If you have an anesthesiologist or nurse anesthetist who is experienced with conscious sedation, and is working with a surgeon who is well aware of the issues faced by the anesthesiologist, things usually go very smoothly. But the problem is with anesthesia providers, like residents, who fail to understand a lot of the complexities that come with giving conscious sedation. I remember being a resident and thinking these cases would be easy; if anything, they are harder than general anesthesics, just for the fact that the patient is partially awake. These conscious sedation cases require, in many ways, more vigilance than general anesthetics.
Ultimately, whether you get general anesthesia or conscious sedation for your surgery depends on several things, including the type of surgery, and the experience/comfort of both your anesthesiologist and surgeon. Most importantly, there needs to be a three-way dialogue, between patient, surgeon, and anesthesiologist in order to arrive at a consensus of the best way to proceed.
Conscious sedation refers to a level of anesthesia that is more than being completely awake, but less than being completely asleep. It is often referred to as "twilight" anesthesia, and the technical term for it is Monitored Anesthesia Care, called MAC for short. When patients receive MAC anesthesia, their consciousness is depressed somewhat. They have amnesia and are sedated enough that they may respond to very strong noxious stimuli but not much if at all to weaker stimuli. As opposed to a general anesthetic where the patient's breathing is significantly slowed down and their blood pressure can also decrease quite a bit, conscious sedation depresses these functions only mildly, if at all.
With that in mind, let's go over the good and bad of having conscious sedation.
The Good:
1. You're more awake during the surgery. In most cases, the amount of sedation you receive for such a case is enough that you don't remember anything, but not so much that you're totally out of it. Patients will sometimes remember hearing voices and the beeping sounds of monitors, but will note that they didn't really care about them and weren't worried or concerned about hearing them.
2. You wake up faster afterwards. The most common sedative administered during conscious sedation is propofol. Yes, that's the same drug that was misused by Michael Jackson, but in the hands of trained anesthesia professionals, it is a very safe drug. One of its best qualities is that it only lasts a few minutes, so during sedation it is given continuously into the IV via a small pump. When the surgery is done, the pump is discontinued, and the patient wakes up within a few minutes. There is little or none of the groggy feeling that so often accompanies general anesthesia.
3. Less nausea and vomiting. The stuff that really causes nausea is the combination of narcotics and the inhaled anesthetic gases that are used to maintain general anesthesia. With conscious sedation, there is no inhaled gas and significantly less narcotic being given.
4. Receiving less drugs = fewer side effects . General anesthesia is strong stuff. Even a "routine" general anesthetic involves the administration of some pretty potent medicines, ones that can drastically lower all bodily functions, including blood pressure, heart rate, neurologic function, even immune function. A general anesthetic is much more stressful on the body than conscious sedation.
The Bad:
1. You're more awake during the surgery. Again, the likelihood of remembering much at all during conscious sedation is quite small, but it's much more likely to happen than in general anesthesia. If you're the kind of person who wants to be totally knocked out and doesn't want to know anything, well, conscious sedation is not an optimal choice for you.
2. You may end up getting general anesthesia anyway. Everyone deals with conscious sedation differently. Some people do great with just a little bit of IV sedative and some local anesthetic in their incision. Others get uncomfortable - real uncomfortable. It's uncommon but possible that if you get too uncomfortable during your sedation, the anesthesiologist may have to put you to sleep anyway, defeating the whole purpose of having sedation.
3. Sedative-induced confessions. Yeah, this is a rare sort of thing, but there are some people, when given a small amount of sedative, start confessing like a sentimental college kid on graduation night. People know their tendencies. I know OR personnel I work with who have chosen to have their surgeries at outside hospitals just because they feared what they might say once they had a little sedation.
4. It can actually be more dangerous. This is especially true if you have issues with snoring or sleep apnea. When you are under general anesthesia, you have a breathing tube in your mouth that the anesthesiologist uses to help with your breathing. With conscious sedation, you have small plastic prongs in your nose that give oxygen, but that's about it. When people get sleepy, it is easier for the tissues in their mouth and throat to collapse, blocking the flow of oxygen into the lungs and causing blood oxygen levels to decrease dangerously. The vigilant anesthesia provider, of course, can deal with this accordingly, but even small lapses in vigilance can cause big, big problems. This leads me to the next point...
5. The quality of your conscious sedation experience is very anesthesiologist dependent. If you have an anesthesiologist or nurse anesthetist who is experienced with conscious sedation, and is working with a surgeon who is well aware of the issues faced by the anesthesiologist, things usually go very smoothly. But the problem is with anesthesia providers, like residents, who fail to understand a lot of the complexities that come with giving conscious sedation. I remember being a resident and thinking these cases would be easy; if anything, they are harder than general anesthesics, just for the fact that the patient is partially awake. These conscious sedation cases require, in many ways, more vigilance than general anesthetics.
Ultimately, whether you get general anesthesia or conscious sedation for your surgery depends on several things, including the type of surgery, and the experience/comfort of both your anesthesiologist and surgeon. Most importantly, there needs to be a three-way dialogue, between patient, surgeon, and anesthesiologist in order to arrive at a consensus of the best way to proceed.
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