General anesthesia pharmacology - Medications for induction, maintenance, & emergence

what's up everybody my name is max feinstein and  i'm an anesthesia resident at the mount sinai   hospital in new york city. in this video i'm  going to be showing you all of the medications   that are included in a basic general anesthetic.  if you find this video interesting or helpful i'd   really appreciate it if you liked it and  subscribed to the channel. let's dive in! the first place to start in this video  is discussing what is general anesthesia,   and the most straightforward definition is: enough  anesthesia that a patient is not going to move at   all when there is a painful stimulus, specifically  when there's surgery going on. an anesthetic   plan will typically involve several components  including analgesia, which means pain control;   amnesia, meaning a patient's not going to remember  anything; areflexia, meaning a patient's not   moving at all; and unconsciousness. so all of the  medications here are going to help me strike that   right balance and be able to have the patient  wake up and feel comfortable once the surgery   is all done. it's really important to point out  that while this may represent a sort of generic   anesthesia plan, that anesthesia is absolutely not  a one-size-fits-all endeavor. i have to take into   consideration all different types of factors  including what type of surgery is going on,   does the patient need to be paralyzed or not  in order to optimize the surgical conditions,   how long is the surgery going on for, what  sorts of fluid shifts and hemodynamic changes   do i expect during surgery, and then other  factors relating to the patient such as what   sort of co-morbidities do they have, how old  are they, how much do they weigh. the way that   i conceptualize an anesthesia plan is broken  down into three fundamental parts. the first   is the "induction" meaning we're starting  our anesthetic. the second is "maintenance"   meaning we're continuing our anesthetic. and  then finally is "emergence" meaning we're   ending our anesthetic. before we get too far  in this video i do need to make the obligatory   disclaimer that this video is not intended to  be medical advice and it does not represent   the official views of mount sinai hospital. taking  all of these different factors into consideration,   when i go to make my anesthesia plan and  i'm picking drugs out of my anesthesia cart,   i feel kind of like a chef putting together the  perfect combination of ingredients that is going   to be suited for the patient who's in front of me  right now. for induction of anesthesia often the   first medication that i administer which i'll  do as soon as we get into the operating room   and connect all my monitors is a benzodiazepine  called midazolam. midazolam is a short-acting   benzodiazepine so for the patient one of the  greatest benefits is that it's an anxiolytic,   meaning it's going to put them at ease right away.  it also has the added benefit of being amnestic   which means for a lot of patients, their memory is  going to get really fuzzy once they get midazolam,   or they might not remember anything after that.  and then while the patient's still awake and i'm   getting ready to induce anesthesia, another  medication that i'll administer is fentanyl.   fentanyl is in the opioid class of medication.  fentanyl can be really helpful from an anesthetic   perspective because it does a number of really  important things for my emergence. one is that   it's going to decrease the amount of sympathetic  drive that a patient has particularly when i'm   doing what's called direct laryngoscopy. and then  another major benefit that i get is that i reduce   the amount of sympathetic response from surgical  stimulus that happens shortly after i start my   anesthetic. and then another important feature  that we get from using opioids intraoperatively   is that it reduces the amount of other anesthetics  that i need to administer in order to keep the   patient under general anesthesia. i often  like to inject a medication called lidocaine   which is a local anesthetic that when inject  intravascularly can reduce the amount of pain   that comes from a propofol injection. lidocaine  actually has a lot of additional benefits. when   injected intravascularly as part of an anesthesia  plan it can also reduce the amount of anesthetics   that i need to administer. it can also reduce  post-operative pain; it can reduce post-operative   ileus; so it's something that i do like to  include. next up is a medication that many of you   have heard of called propofol. propofol is very  commonly used both as an induction and maintenance   medication in general anesthesia, and it can also  be used pretty much by itself as the anesthetic   during monitored anesthesia care or "twilight  anesthesia" as you may have heard before.   like most anesthetics it's a vasodilator which  will often drop a patient's blood pressure so   this is something that we have to be very mindful  of when we're inducing anesthesia and so for that   reason i also have a couple of pressors that i  keep with me at all times so this is phenylephrine and this is ephedrine. both phenylephrine  and ephedrine are very helpful fast-acting   vasopressors that i can use, and typically when  i do use them it's on induction of anesthesia   to prop up blood pressure a little bit in  order to counteract the vasodilatory effects   mostly of propofol. once i've induced anesthesia,  if my plan is to intubate the patient - which is   common but not always necessary for  general anesthesia - then i need to   consider how am i going to optimize my intubating  conditions. in order to get a patient relaxed,   one of the very commonly used methods that we  have is to use a paralytic, and there are a lot   of different paralytics that are available  but i'll show you the most commonly used.   so the first is succinylcholine. succinylcholine  is in the depolarizing class of neuromuscular   blockers and will typically exert its effect  for five minutes, give or take. one of the   other options that i have is a medication called  rocuronium and i use this very often as well.   rocuronium is a non-depolarizing neuromuscular  blocker and it has a much longer effect time than   succinylcholine. the last agent that i like to  group into my induction medications is a steroid   called dexamethasone. the reason that i typically  give dexamethasone is that it's an excellent   anti-emetic meaning it's going to be helpful in  preventing nausea and vomiting after surgery. maintenance of anesthesia can be  accomplished in many different   ways. in front of me i have a bottle of  volatile anesthetic called sevoflurane.   so in this can sevoflurane is a liquid but then it  becomes vaporized and is inhaled by the patient.   as i mentioned before propofol can also be  used for a maintenance of general anesthesia.   some of the other volatile gases that are  commonly used include isoflurane and desflurane.   i'll typically reach for sevoflurane in a case  that isn't going to be that long but if a case   is going to last a long time i do like to use  isoflurane- it does have some additional cardiac   benefits and the one thing to keep in mind about  isoflurane though is it can take a while for that   medication to come off, so as i'm planning  for emergence i have to be mindful of which   maintenance anesthetic i'm using and how long  it's going to take for that medication to wear   off. other medications that i include as part of  my maintenance of anesthesia include analgesics,   so i'll commonly redose fentanyl and i'll  also re-dose paralytic if the case is going   to continue on for a long time and the surgeon  needs the patient to be paralyzed during surgery. the final part of an anesthesia plan is the  emergence meaning waking a patient up from general   anesthesia. the medications that are specific to  emergence include thinking about reversing any   sort of paralysis that's on board. and so when it  comes to reversal there are a couple of different   options that are very commonly used. the first  option is a medication that's called sugammadex sugammadex is actually one of the newest  medications that's used in anesthesia   and it's specifically designed to  reverse the aminosteroid paralytics,   and specifically in this case that would be  rocuronium. one of the things to keep in mind   is that it can cause an allergic reaction  one of the other things to keep in mind when   using sugammadex is that it can actually  render hormonal birth control ineffective   for up to a week. one of the other medications  that's commonly used for reverse and paralysis   is neostigmine. neostigmine is a cholinergic  medication, which if you're in medical school or   you've already graduated, you know that there are  a lot of cholinergic effects that can come from   a medication like neostigmine and so in order to  counteract those side effects, neostigmine is very   commonly administered alongside glycopyrrolate.  an important consideration to have when you're   administering neostigmine and glycopyrrolate  is that the order in which you administer   those medications is really important because  if you administer a large bolus of neostigmine,   it can cause really significant bradycardia  which can be really problematic for your patient.   so that's why it's important when you're  administering both neostigmine and glycopyrrolate   together that you administer the glycopyrrolate  first so that you don't end up with dangerous   bradycardia. the other thing to keep in mind is  that if you have a patient very deeply paralyzed   it's actually not safe to administer neostigmine  - you need to wait until the patient is not quite   as paralyzed so that you can reliably reverse  them with neostigmine. and so because of the   side effect profile, the relatively delayed onset  of action, and some of the limitations around how   deep a patient can or can't be paralyzed when  using neostigmine, a lot of anesthesiologists   do have a preference for sugammadex but have to  consider the unique side effect profile for that   too. so ultimately making the choice between  reversing with neostigmine and glycopyrrolate   versus sugammadex is going to be context dependent  based on what's going on with the specific   patient. the last medication that i commonly  include in my emergence plan is ondansetron.   ondansetron is an anti-emetic and it has a  peak effect time of about a half an hour,   so when i'm giving this medication i try to time  it so that it's approximately a half an hour   before the patient is emerged from anesthesia so  they wake up feeling quite comfortable. this does   have a side effect profile as well like pretty  much anything that we give, and specifically   ondansetron can be a QT prolonging medication, so  if you've got a patient who has a prolonged QTc   this is probably not something that's going  to be safe to administer so again you just   need to take into consideration what is going  to be important for this particular patient. well that wraps up this video, and if you  found it interesting you might want to check   out another one of my videos that i'll link  to right here in which i talk about how i make   sure that patients are fully unconscious during  general anesthesia. if you have any feedback i'd   love to read it in the comments below. thanks  very much for watching i'll see you next time

Channel: Max Feinstein

Views: 582,784

Keywords: Anesthesia, Anesthesiology, Surgery, Residency, Resident, Mount Sinai, Mt. Sinai, New York City, Surgeon, Medical school, Med school, Med student, Medical student, Premed, MCAT, USMLE, PGY1, PGY2, Doctor, Physician, Medicine, CRNA, Critical care, ICU, Ventilator, Intubation, Preoperative, IV, Intravenous, vital signs, blood pressure, electrocardiogram, monitoring, propofol, rocuronium, general anesthesia, zofran, ondansetron, sugammadex, neostigmine, glycopyrrolate, fentanyl, midazolam, versed, induction, maintenance

Id: hQiHj22VcFI

Length: 10min 19sec (619 seconds)

Published: Sat May 29 2021