inductions a few important patterns that will make any induction easy uh the aim of this is
really that there's you know really a select few critical general anaesthetic inductions
um and i want to give you something that's pretty practical and effective um with also specific
doses to think about and i think when i was going through my training you know everyone gets a bit
of propofol an opioid and a relaxant and then every other induction seems to be something that
resembles a cardiac induction but i guess i want to make mention that each of your cardiovascularly
relevant inductions will probably be something like a critical cardiac issue a hypovolemic shock
primary hypertension subarach or anything kind of cardiac lesion like a valve and each of these
have very different priorities and and they can be subtly different these can be easy enough to
talk about individually but let's say you get a situation where a patient has a couple of these
a couple of these different pathologies i think it's really useful to have this
framework because then you can talk about your ideal priorities and combine combined methods for
these inductions to talk about your case in a in a knowledgeable way let's imagine a patient who's
like a 60 kilo 70 year old gentleman who's got an ejection fraction of 20 so you know pretty bad
um due to some kind of ischemic cardiomyopathy what broadly speaking are your goals
and then just off the cuff just tell me what your induction doses would be and any extra monitoring
you'd have above an art line for these patients my main goals would be hemodynamic invasives
so i want to ensure that they have adequate free life prior to induction and sinus with them with a
normal control grade and that their contractility and arthritis maintain during my induction
so to facilitate that i would induce them for a general anesthetic utilizing a dose of propofol of
about zero well i'm just going to say one milligram per kilo yes actually if i gave you
the dose the weight of the patient i'll give you the weights for every one of these 60 kilo patient
yep okay i'd utilize a dose of profile of 50 milligrams uh i'd utilize fentanyl with a dose of
350 micrograms and i'm not the relaxer that i choose would be rocky rhonin
and i would give the dose to 0.6 milligrams per kilo so in this patient for this anesthetic i'll
give you two grams fantastic that's a very common cardio conduction if you haven't a lot of you will
already have done cardiac and you know it really is running a very small dose of profile giving a
big dose of fentanyl you know turn up the volatile and they often have a lot of middaz on board from
the from the lines you put in as well and then you slowly get the volatile up and put the tube in
at your leisure um but yeah again when you've tell me your goals the detail doesn't matter so much uh
it's a hypothalamic shock i used to think this was very similar but i want to make note that this is
a very different induction say this patient is a 20 year old motor vehicle accident so some kind of
intra abdominal laceration of a vessel let's say they've dropped three liters
and you rush them up to theater and you're you know they're they're tachycardic hypertensive
at maybe 70 millimeters mercury so you're running your little hypertensive resuscitation type plan
and you want to induce before a laparotomy so otherwise fit in well-known allergies
70 kilo 20 year old what do you want what are your goals and what are the actual drugs you give
i would make all reasonable attempts to uh ensure to adequately resuscitate this patient to achieve
a blood pressure that's to maintain adequate organ perfusion so bp of 90 systolic would be
preferable and my goals in this patient would be to maintain a sympathetic tone and to avoid any uh
and to minimize uh drugs that would reduce contractility uh and afterload essentially
and to this end i would choose an induction with ketamine uh one milligram per kilo iv and rock
uranium one milligram per kilo fantastic i'll do something very similar just another when i was
going through my training to me this was seemed to be very similar to the cardiac induction as
in i saw a lot of people just approaching it very similarly but just note that i really don't care
about contractility it's a young person often they have no problems with contractility and i
don't care about a rapid heart rate i want as much sympathetic tone in these patients as is
reasonable so you know just maintaining lots of volume and having aramine running is probably
the the biggest deal for me so yeah rsi ketamine midas sucks with metaramine ultimate10 vase
motor tone is what i do and again just to reiterate obviously i haven't given doses in
this situation every examiner i've ever spoken to they'll give you the scenario of a patient
make whatever assumptions about their weight and just give some reasonable doses you know round it
off because you know in real life you never say i'd give 88 milligrams of something you
round off to 100 or 50 and if it's relevant just round off to whatever number but give a number
uh next case pulmonary hypertension so imagine this patient is a let's say a 60 year old female
60 kilos with some kind of lung pathology which has caused pulmonary hypertension with them rsvp
pressures of um say above 90. so pretty serious um the main goals in a pulmonary hypertension
induction is to avoid large changes in pulmonary arterial pressure so avoiding acidosis
and hypercapnia and hypoxia so therefore i'll perform a technique that allows rapid facilitation
of those parameters and essentially perform a standard technique that might
ensure the airway doesn't become obstructed yeah sounds good and you're very right to assume that
the right heart is doing well so again my goals i i i think of two things i think of you know
right heart function and your after which is your pulmonary vascular function and i'll do something
very similar avoid pulmonary voting increase in palmitary pressure with those things you mentioned
i'd also maybe just make it make an attempt to make sure my ventilation pressures are low and
then maintain right hyperfusion and often this is if the right heart is bad this is like a critical
cardiac for the right heart plus my pulmonary artery pressures that's great uh and again this
would look very similar to the um critical cardiac induction in many in many cases if the right heart
is bad otherwise exactly what you said uh let's go through a subrag bleed case so imagine imagine
someone is like our previous patient say uh you know 60 year old female grade 3 subarach 60 kilos
and you're gonna do an induction in theater for clipping so my goal would be to avoid
any uh extremes of blood pressure to maintain um cerebral perfusion um
and to perform neuroprotective anesthesia um so i would use tea sort of protofollow remy tv
uh one milligram of keto a broth i think yeah sounds good so again i i like that you mentioned
hypertension so i i specifically mentioned rebleed because rebleed is the highest mortality event
in this in this patient having you know 50 or 70 percent if the patient does re-bleed and that can
be you know related back to having a hypertensive episode causing that increase in your transmutable
pressure gradient on induction so everything i do is to avoid that primarily and then secondarily
cerebral perfusion um so i mean and again you can do it you've said your goals you can do whatever
you want really profile remy fentanyl teva uh because i'm less experienced with titrating the
remy to that effect i just give bigger doses of alfentanol plus propofol in a decent dose
plus sucks and then i just add something else on about you know iv lignicain or asmolol if there's
a if there's a hypertensive episode uh but again setting your goals the the detail matters a lot
less tabling in your workbooks look when i first did this as a trainer i thought it was just really
useful like you know every single valve lesion plus hokam and tamponade has certain priorities
and it's great to see people talking in terms of preload rate rhythm contractility and afterload
i remember back in the day one of my consultants said this is the way i talk about you know cardiac
function and i just i just found it really useful so it's really great to hear that people are using
that way because it just communicates a lot to me personally priorities that i was you know told
as i was going through my training and probably similar to what a lot of you have gone through so
eric's gnosis you know slow sinus squeeze is what people talked about so full preload low normal
rate science rhythm is critical uh contractility is something to maintain and after height to
maintain chronic perfusion pressure and then the other ones are filled out in this way so
say your degree and micro regress full fast forward so full preload fast rate sinus rhythm
isn't particularly critical maintain contractility and low afterload these parameters all support
forward flow mitral stenosis a bit interesting it's unlike aortic stenosis where you have a
full preload and most of the case we we have a mitral stenosis if we have too much of an order
transfusion such as in the pregnancy cases they can go into apo so i think you know trying to
achieve that normal preload level is is obviously challenging but but an ideal low normal rate again
sinus rhythm would be ideal maintaining contractility and again a higher afterload
hockum is very similar to aortic stenosis however you know having a law having a low contractile
decreases that dynamic obstruction that can happen when you have this really thick musculature and
hypertrophy of the left ventricular outflow tract so full preload low normal heart rate to maintain
your diastolic perfusion time sinus rhythm is ideal low contractility and a high afterload to
maintain that perfusion of your thick myocardium with tampon i think of adrenaline so anything that
adrenaline does essentially is what i want for for tamponade so full preload fast rate is is
is what often occurs and is supportive of a cardiac output sinus rhythm would be ideal
high contractility is maintained and afterload is high again because you've got such a high
intra intraventricular pressure you really need to maintain the coronary perfusion
through that as well see in summary from that we've got the critical cardiac hyperlink shock
pumping hypertension subarachnoid bleed and valves and these are just a sample of some of the common
cardiovascularly relevant anesthesia inductions that you'll get and i found it really useful to
have the priorities very specifically outlined for each of these that allows me to tailor my drugs
towards those priorities but also if i get a really complex situation which is
unlikely but can happen in the viva if i do get something that um you know combines a critical
cardiac patient also having hyperventilating shock at least i know how to kind of talk through
or talk around the complexities of the potentially conflicting goals