Please tell me I am not hallucinating about BP and MAP...

[CharleyVCU1988]

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(Note: word choice/diction may be an issue for this post. I can clarify if need be. Details of case may be slightly fuzzy.)

I remember from medical school, to emphasize mean arterial pressure when it comes to helping determine adequate perfusion. Someone can have low systolic/diastolic BPs and still have a good MAP.

That being said, here is a case I encountered a couple of days ago, and I'm wondering whether I made the right decision.

Background - 50-yo AA man undergoing ileostomy reversal. No prior anesthetic complication history. History of Crohns (stopped immunosuppressors approx 1 week ago) as well as ankylosing spondylitis affecting cervical and lumbar spine. Chronic pain patient on long acting morphine and breakthrough oxycodone (?) METS < 4. Asthmatic, uses inhaler daily, but states he is SOB chronically. Claims he smokes cigarrettes and cannabis intermittently. Denies MI, CHF, arrhythmia treatment, no prior CVA/TIA history. States his normal systolic BP runs between 70-90s, has never encountered pre-syncopal/syncopal sx, angina, dyspnea. All labs WNL except for elevated Cr, past hx of CKD. Regional team that placed epidural encountering aforementioned low BP. I am unsure when at what point during the procedure they encountered the apparent hypotension but it seemed to resolve with a 500 cc bolus. Pre-op vitals 80/60s, tachycardic 110, NPO for at least 12 hours.

background of attending - my point of view - likes desflurane. Not a big fan of opioids - no one has gotten away with using opioids on his cases without him giving us an earful. Not a fan of pressor agents (phenylephrine, ephedrine) either, or perhaps their excessive use (in his view). Loves using the BIS monitor and is the only one that swears by its use outside of an emergent case.

Induction goes off smoothly and I have him at 1.0 MAC sevo. Several blood pressures appear after incision showing systolics around 75, 77, but good MAPs around 60. I don't do anything - this is the patient's baseline after all. Then more of these same BPs appear, but with MAPs in the low to mid 50s. Epidural pump containing 0.0625% bupivicaine not delivered at this time. Tidal volumes at 6 cc/kg IBW to try and maximize venous return, no PEEP added. I back off the sevo to about 0.7 MAC, but 5 minutes later the MAP is still pretty low, hovering in the 50s, systolics in 70s-80s. Reach for 80 mcg of phenylephrine, which brings the BP right back up to 90s-100s systolic, MAP back above 60. Attending is not happy.

Otherwise, no other issues with the case. BP remained in the 90s-100s systolic, even after the epidural was turned on. No other vasoactive medications given.

So what should I have done in this case? Should I have waited to let the lowered sevo concentration take its effect on the vasculature to let the BP come back up on its own? Should I have done nothing in the light of the BP, which is apparently around the patient's baseline? Did I waste a pressor?

Your thoughts are greatly appreciated.

 

[BLADEMDA]

The overall blood pressure as measured in the brachial artery is maintained by the cardiac output and the total peripheral resistance (TPR) to flow. The mean arterial pressure (MAP) is calculated by the formula:

where DBP and SBP are diastolic and systolic blood pressure, respectively. Mean arterial pressure is a useful concept because it can be used to calculate overall blood flow, and thus delivery of nutrients to the various organs. It is a good indicator of perfusion pressure (ΔP).

Blood flow is defined by Poiseuille's law:

where Q is the blood flow, ΔP is the pressure gradient, r is the radius of the vessel, N is the blood viscosity, and L is the length of the vessel. This formula is commonly restated in a more clinically useful expression:

Here CO is the cardiac output in liters/minute and is the clinical equivalent of blood flow (Q). MAP (in mm Hg) is used to approximate the pressure gradient (ΔP). TPR is the resistance to flow in dynes · sec · cm−5 and clinically represents 8 NL/πr4 The conversion factor 80 appears in the formula simply to allow use of more conventional units.

Example 1: BP of 120/80 and normal cardiac output of 5 L/min:

 

[BLADEMDA]

(Note: word choice/diction may be an issue for this post. I can clarify if need be. Details of case may be slightly fuzzy.)

I remember from medical school, to emphasize mean arterial pressure when it comes to helping determine adequate perfusion. Someone can have low systolic/diastolic BPs and still have a good MAP.

That being said, here is a case I encountered a couple of days ago, and I'm wondering whether I made the right decision.

Background - 50-yo AA man undergoing ileostomy reversal. No prior anesthetic complication history. History of Crohns (stopped immunosuppressors approx 1 week ago) as well as ankylosing spondylitis affecting cervical and lumbar spine. Chronic pain patient on long acting morphine and breakthrough oxycodone (?) METS < 4. Asthmatic, uses inhaler daily, but states he is SOB chronically. Claims he smokes cigarrettes and cannabis intermittently. Denies MI, CHF, arrhythmia treatment, no prior CVA/TIA history. States his normal systolic BP runs between 70-90s, has never encountered pre-syncopal/syncopal sx, angina, dyspnea. All labs WNL except for elevated Cr, past hx of CKD. Regional team that placed epidural encountering aforementioned low BP. I am unsure when at what point during the procedure they encountered the apparent hypotension but it seemed to resolve with a 500 cc bolus. Pre-op vitals 80/60s, tachycardic 110, NPO for at least 12 hours.

background of attending - my point of view - likes desflurane. Not a big fan of opioids - no one has gotten away with using opioids on his cases without him giving us an earful. Not a fan of pressor agents (phenylephrine, ephedrine) either, or perhaps their excessive use (in his view). Loves using the BIS monitor and is the only one that swears by its use outside of an emergent case.

Induction goes off smoothly and I have him at 1.0 MAC sevo. Several blood pressures appear after incision showing systolics around 75, 77, but good MAPs around 60. I don't do anything - this is the patient's baseline after all. Then more of these same BPs appear, but with MAPs in the low to mid 50s. Epidural pump containing 0.0625% bupivicaine not delivered at this time. Tidal volumes at 6 cc/kg IBW to try and maximize venous return, no PEEP added. I back off the sevo to about 0.7 MAC, but 5 minutes later the MAP is still pretty low, hovering in the 50s, systolics in 70s-80s. Reach for 80 mcg of phenylephrine, which brings the BP right back up to 90s-100s systolic, MAP back above 60. Attending is not happy.

Otherwise, no other issues with the case. BP remained in the 90s-100s systolic, even after the epidural was turned on. No other vasoactive medications given.

So what should I have done in this case? Should I have waited to let the lowered sevo concentration take its effect on the vasculature to let the BP come back up on its own? Should I have done nothing in the light of the BP, which is apparently around the patient's baseline? Did I waste a pressor?

Your thoughts are greatly appreciated.

Circulatory pressure is derived from the ejection of blood from the left ventricle.
Ventricular acceleration of blood into a normal arterial system results in elastic distention
of the vessel walls. Potential energy is generated by this elasticity and subsequent
recoil, in a normal arterial system, resulting in continuous pressured flow of blood,
even during diastole.9 Blood pressure is measured traditionally as a systolic number,
the highest pressure occurring as a result of left ventricular contraction, over a diastolic
number, which is the result of continuous forward flow during the period of cardiac
filling and rest. The MAP is not an arithmetic mean, and instead is derived to represent
the proportion of time in systole and diastole.10
The vascular circuit maintains blood pressure with the cardiac function acting as
pump, and the blood vessels serving as conduit. The circuit is composed of arteries,
capillaries, and veins. The pulmonary circuit is similarly composed, but is not discussed
here. The flow through these conduits at rest is near 5 to 8 L/min. The flow
is dependent on the pressure gradient between both ends of the circuit, and the resistance
to flow within each conduit.
The MAP can be measured by invasive or noninvasive monitoring. Shapiro & Loiacono formula assumes a resting heart rate of 60 beats per minute. At this rate, diastole
occupies two thirds of duration of the cardiac cycle. In normal physiology, the heart
rate is unfixed and varies greatly during the septic state. Patients with heart rates
greater than 100 beats per minute may have diastole lasting for less than half the
cardiac cycle. MAP is then falsely elevated by this formula, and organ perfusion
may be ineffective despite a measured MAP within a target range. Additionally,
MAP is maintained at the aortic and arterial level, but as the intravascular volume progresses
toward arterioles and capillaries, a significant pressure gradient exists.9
Blood flow through the circuit can only occur if a pressure gradient exists. CVP is
0 to 4 mm Hg, whereas the aortic MAP is around 70 to 90 mm Hg. This difference
produces a pressure gradient from central arteries, dispersing the pressure through
every patent vascular network, down to the value of the CVP. The rate of flow is determined
by the degree of gradient between tissue beds, not by only the inflow and
outflow absolute value

 

[BLADEMDA]

When we are taking care of patients in the O.R. many of us tend to be very conservative. We tend to overtreat a bit as to ensure the patient's organs have a nice buffer zone. While your attending may have settled for a MAP of 50-55 I would not. I would have insisted you maintain MAP above 60, preferably 65 for the case.
Again, without measuring blood gases for acidosis or lactate levels (or even urine output) it would be difficult to know if an MAP of 50 was adequate; but, was it optimum for this patient under GA? We know that Mechanical Ventilation and Inhalational agents can alter perfusion to vitals organs. So, I would advise caution in keeping the MAP only 50 in this case. Of course, others may disagree, as did your Attending but being cautious is wise and prudent the longer you do this job.

 

[urge]

You should ask your attending about the thinking behind his decision making.

I would have run some phenylephrine drip. I don't know what your attending has against it.

I would not cut on the inhaled agent if your are using little opioids. The pt will start jumping off the bed soon, or if paralyzed maybe have awareness. Most likely that's why he insists on the BIS.

 

[BLADEMDA]

Anesth Analg. 2012 Jun;114(6):1297-300. doi: 10.1213/ANE.0b013e31823aca2b. Epub 2011 Nov 10.
Spinal cord ischemia occurring in association with induced hypotension for colonic surgery.
Drummond JC1, Lee RR, Owens EL.
Author information

Abstract
A 19-year-old woman underwent an ileoanal pull-through. Intraoperatively, deepening of anesthesia was associated with reduced bleeding. Therefore, induced hypotension, mean arterial blood pressure 50 to 55 mm Hg, was maintained for 2.5 hours. Postoperatively, the patient was paraplegic with spinal cord infarction on magnetic resonance imaging from T9 to the tip of the conus medullaris. The collateralization of the anterior spinal artery is very variable and it seems likely that in this individual induced hypotension was associated with inadequate blood flow in the distribution of the artery of Adamkiewic

 

[BLADEMDA]

You should ask your attending about the thinking behind his decision making.

I would have run some phenylephrine drip. I don't know what your attending has against it.

I would not cut on the inhaled agent if your are using little opioids. The pt will start jumping off the bed soon, or if paralyzed maybe have awareness. Most likely that's why he insists on the BIS.

Without any Opioids on Board and LOW Inhalational Agents you will need that BIS and watch it like a hawk. Why not low dose Ketamine for some analgesia?
I assume your attending hates Nitrous Oxide as well?

As a resident you get to learn and do things with certain attendings that you would never do on your own or again for that matter. Please try to take it all in stride.

 

[deleted171991]

The guy's preop MAP seems to have been around 65. Now also remember that 65 is the minimal MAP considered to ensure a decent organ perfusion in most patients. Meaning that I would not let that patient's MAP drop too far under 65 before I treat it, unless I really have a good explanation in court (and, sorry, the 20-25% within baseline MAP does not apply here). You did the right thing (for the patient), don't worry.

You also have to wonder why the guy was tachycardic. Was he anemic? If yes, that would explain his lower BP, and also give you yet another reason why to watch his BP like a hawk.

 

[pgg]

Hard to know why your attending has the preferences he does. You did fine, subject to the weird limits in place. Just be careful backing off volatile agent like that. You spend enough time well below a MAC of gas without other agents on board and sooner or later you're going to run into an outlier ... BIS or no BIS.

Learn what you can from his approach but don't take it as gospel.

 

[CharleyVCU1988]

Wow, you guys are fast! I will address some of your inquiries here first, I also remembered another issue with this case involving his paralytics, but I don't want to derail this thread.

"I would have run a phenylephrine drip" - well, he half-teased me, half-mocked me, wondering if I was actually going to do that. Sheepishly said no.

"I would not cut on the inhaled agent if your are using little opioids. The pt will start jumping off the bed soon, or if paralyzed maybe have awareness. Most likely that's why he insists on the BIS."

The surgeons were reporting that he was "tensing up" before they made the incision - surgical team pressing on abdomen. Had already given 8 mg nimbex about 20 mins before. 0.7 MAC at the time. Yes, a risky move, but I didn't feel like I had another option at least with this attending. His state entropy at the time of the volatile cutback was around 40s. I later got him down to 1.0 MAC without much incident with his BP. sometimes it waffled to 1.1 MAC. Then I get queried by my attending "why is he that deep?" *headdesk.

Ketamine sounds like a good thought. never really used it much but I'll try and incorporate it into more cases now (I am a CA-1)

Whoever guessed that my attending on that case hates Nitrous Oxide is correct, he absolutely hates it for the n/v risk. I'm actually coming around to it to help me wake up faster whenever I can. One of the CA-3s who is doing a cardiac fellowship next year times things so perfectly that the tube is pulled right as the dressings are on/patient unbound/gowned.

"You also have to wonder why the guy was tachycardic. Was he anemic? If yes, that would explain his lower BP, and also give you yet another reason why to watch his BP like a hawk."

I suspected anemia of chronic disease with him given his Crohns. He denied any acute changes in cardiopulmonary status over the past several months. Surprisingly, he wasn't anemic and he didn't appear hemoconcentrated. He never mentioned anything about high ileostomy output and none of the colorectal notes mention anything like that. He wasn't given any sort of bowel prep either. In the end I attributed the tachycardia to his NPO status.

 

[nap$ter]

Without any Opioids on Board and LOW Inhalational Agents you will need that BIS and watch it like a hawk. Why not low dose Ketamine for some analgesia?
I assume your attending hates Nitrous Oxide as well?

As a resident you get to learn and do things with certain attendings that you would never do on your own or again for that matter. Please try to take it all in stride.

i don't want to start a BIS debate here but am curious -

what do you believe the MAC for recall to be? do you believe chronic opiates change that number?

i routinely run elderly patients on 0.6-0.8 MAC of sevo or iso with epidurals running during large abdominal cases (paralyzed) on phenylephrine drips. 50ug of fentanyl IV at the start, 50ug at the end (i use plain bupi 1/8% in the tep during the case).

i never use a BIS.

my partners do the same.

i trained with many attendings who did the same.

i also trained with attendings like the OP's - i do not practice like that.

that being said - a chronic pain patient gets more opioid during/after the case. i write for plain local in the epidural with an opiate PCA and replacement opioid postop. ketamine is great for this population.

 

[Gassed Prowler]

The reason for the focus on maintaining a MAP of 65 or greater is that the cerebral auto-regulation of blood flow occurs between a cerebral perfusion pressure range of 60-160mmHg. CPP less than 60 results in decreased blood flow to the noggin in a linear manor. CPP is measured by MAP-ICP or MAP-CVP. If we use our MAP value of 65 and a CVP value of 5 our cerebral perfusion pressure is 60 and still within the auto-regulation curve. If however we use a MAP of 55 and CVP of 5, the CPP becomes 50 and is well below the lower lateral limit of the auto-regulation cure, resulting in decreased flow to the noggin. Whats good for the noggin must be good for the other organs too.

Another new resident here so tell me if my reasoning is off base.

 

[Stank811]

As a CA-1 you are doing the correct thing and asking questions.

What have you found regarding nitrous in regards to post op N/V, post op cardiac complications, homocysteine levels, B12, bowel distention?

What have you found regarding phenylephrine in regards to mechanism on arteries, does it change pulmonary vascular resistance, what does a phenylephrine gtt do to cardiac output? In what pathological states should you use phenylephrine vs other pressers such as NE and vasopressin and why? What pathological states should you avoid phenylephrine and choose NE or vaso?

You will find arguments in the literature that could be used to spin both sides of the phenylephrine and nitrous argument. Once you understand the data well you will be able to formulate your own arguments and transition to a consultant anesthesiologist.

Continue to ask questions and always try to keep your curiosity it will only make you better. And have fun doing it you have chosen a great subspecialty of medicine.

 

[Brookstacular]

The reason for the focus on maintaining a MAP of 65 or greater is that the cerebral auto-regulation of blood flow occurs between a cerebral perfusion pressure range of 60-160mmHg. CPP less than 60 results in decreased blood flow to the noggin in a linear manor. CPP is measured by MAP-ICP or MAP-CVP. If we use our MAP value of 65 and a CVP value of 5 our cerebral perfusion pressure is 60 and still within the auto-regulation curve. If however we use a MAP of 55 and CVP of 5, the CPP becomes 50 and is well below the lower lateral limit of the auto-regulation cure, resulting in decreased flow to the noggin. Whats good for the noggin must be good for the other organs too.

Another new resident here so tell me if my reasoning is off base.

This is certainly the traditional dogma although it's quite oversimplified when you consider how little good data we have on the issue. Chronic hypertensives likely require a greater MAP as a result of shift of the autoregulatory curve and the magic number for a patient with lower MAPs is very likely below 60. It is unfortunately guesswork on our part as to whether the brain is perfused adequately. Even the most recent work on beach chair patients suggests no difference in markers of cerebral ischemia between aggressive and conservative BP management. It ultimately comes down to risk/benefits of aggressive pressor use versus "permissive hypotension."

 

[BLADEMDA]

This is certainly the traditional dogma although it's quite oversimplified when you consider how little good data we have on the issue. Chronic hypertensives likely require a greater MAP as a result of shift of the autoregulatory curve and the magic number for a patient with lower MAPs is very likely below 60. It is unfortunately guesswork on our part as to whether the brain is perfused adequately. Even the most recent work on beach chair patients suggests no difference in markers of cerebral ischemia between aggressive and conservative BP management. It ultimately comes down to risk/benefits of aggressive pressor use versus "permissive hypotension."

When something adverse occurs postoperatively and your anesthetic gets reviewed showing a MAP of 50 you will get to find out what the experts say about the dogma.

Scientifically I agree with your post but practicing in the real world there is no way I will allow MAP of 50 on a patient.

 

[drmwvr]

This is certainly the traditional dogma although it's quite oversimplified when you consider how little good data we have on the issue. Chronic hypertensives likely require a greater MAP as a result of shift of the autoregulatory curve and the magic number for a patient with lower MAPs is very likely below 60. It is unfortunately guesswork on our part as to whether the brain is perfused adequately. Even the most recent work on beach chair patients suggests no difference in markers of cerebral ischemia between aggressive and conservative BP management. It ultimately comes down to risk/benefits of aggressive pressor use versus "permissive hypotension."

You're spot on about the guesswork, especially given that we have not a clue what oxygenated blood reaches end organ tissue beds and what does not. Which is why a dismissive tone regarding 'traditional dogma' is puzzling. Not to sound cliché, but no two patients are alike and it's not an either aggressive or permissive question.

There is no such thing as a low or high CO, this is true... knowing who is who is not always possible. A MAP less than 65 for most all adults for prolonged periods is unwise.

 

[Orin]

Not a huge fan of this paper, but as we're being academic, we should probably discuss it:

Anesthesiology. 2013 Sep;119(3):507-15. doi: 10.1097/ALN.0b013e3182a10e26.
Relationship between intraoperative mean arterial pressure and clinical outcomes after noncardiac surgery: toward an empirical definition of hypotension.
Walsh M1, Devereaux PJ, Garg AX, Kurz A, Turan A, Rodseth RN, Cywinski J, Thabane L, Sessler DI.
Abstract
BACKGROUND:
Intraoperative hypotension may contribute to postoperative acute kidney injury (AKI) and myocardial injury, but what blood pressures are unsafe is unclear. The authors evaluated the association between the intraoperative mean arterial pressure (MAP) and the risk of AKI and myocardial injury.

METHODS:
The authors obtained perioperative data for 33,330 noncardiac surgeries at the Cleveland Clinic, Ohio. The authors evaluated the association between intraoperative MAP from less than 55 to 75 mmHg and postoperative AKI and myocardial injury to determine the threshold of MAP where risk is increased. The authors then evaluated the association between the duration below this threshold and their outcomes adjusting for potential confounding variables.

RESULTS:
AKI and myocardial injury developed in 2,478 (7.4%) and 770 (2.3%) surgeries, respectively. The MAP threshold where the risk for both outcomes increased was less than 55 mmHg. Compared with never developing a MAP less than 55 mmHg, those with a MAP less than 55 mmHg for 1-5, 6-10, 11-20, and more than 20 min had graded increases in their risk of the two outcomes (AKI: 1.18 [95% CI, 1.06-1.31], 1.19 [1.03-1.39], 1.32 [1.11-1.56], and 1.51 [1.24-1.84], respectively; myocardial injury 1.30 [1.06-1.5], 1.47 [1.13-1.93], 1.79 [1.33-2.39], and 1.82 [1.31-2.55], respectively].

CONCLUSIONS:
Even short durations of an intraoperative MAP less than 55 mmHg are associated with AKI and myocardial injury. Randomized trials are required to determine whether outcomes improve with interventions that maintain an intraoperative MAP of at least 55 mmHg.

The risk for AKI and MI increase with the amount of time spent at low MAPs. Things really take off less than 55 mmHg, but the risk increase starts @ the 65 cut off.

This is the probability for AKI and MI depending on the lowest MAP during a case. Things really take off at 55 mmHg, but the plateau is again @ ~65 mm Hg

 

[BLADEMDA]

Bottom line is that a MAP of 50 is low for most/many patients; this means a MAP of 60-65 is the threshold number for most cases (higher if history of HTN, CVA, CV risk factors, Beach Chair, etc) in the supine position. Again, I would not allow any of my midlevels to purposely run a MAP below 60 even though my guess is a few of them are less attentive to hypotension than I would prefer for the case.

The general consensus these days is a MAP no lower than 65. Please read what Dr. Drummond has to say on the matter:


Dr. John C. Drummond, professor and former chair of the Department of Anesthesiology at the University of California at San Diego, started his lecture by showing erroneous representations of the lower limit of autoregulation in neuroanesthesia chapters in textbooks of anesthesia—some of which he admittedly authored. He presented an overview of studies of autoregulation and showed the wide range in reported lower limits of autoregulation (30-110 mmHg, Anesthesiology 1997). Dr. Drummond believes that the available evidence favors a lower limit of 70 mmHg in the heathy and normotensive adult in the supine position, rather than the conventional or classic limit of 50 mmHg. Dr. Drummond commented that his most recent chapter in Miller has been modified to reflect this change in interpretation of available studies. He also emphasized that over 45% of the population has an incomplete circle of Willis, which may decrease the autoregulatory capacity.

 

[BLADEMDA]

“I have seen many, many cases in which neurologic injuries have struck seemingly out of the blue, where it seemed to me that the prevailing blood pressure practices had probably been” too low.

John C. Drummond

 

[deleted171991]

“I have seen many, many cases in which neurologic injuries have struck seemingly out of the blue, where it seemed to me that the prevailing blood pressure practices had probably been” too low.

John C. Drummond

Meaning many cases where he was paid to testify about that?

 

[BLADEMDA]

https://books.google.com/books?id=L2ckBQAAQBAJ&pg=PA387&lpg=PA387&dq=john drummond of minimum blood pressure&source=bl&ots=j9JPajbmLJ&sig=I0Ew6_9Qi7p1m84veFdHLsGbw4s&hl=en&sa=X&ei=6B7FVPu-K4emNvWGguAI&ved=0CDMQ6AEwBDgK#v=onepage&q=john drummond of minimum blood pressure&f=false

Miller Texbook of Anesthesia: 65-150 mm hg for cerebral autoregulation (please note the change from 50-150 stated in older text books)

 

[BLADEMDA]

Meaning many cases where he was paid to testify about that?

Correct. If there is an adverse event and your anesthesia record shows MAP of 50-55 then Dr. Drummond's testimony will likely cost your malpractice carrier a lot of money.

 

[deleted171991]

Correct. If there is an adverse event and your anesthesia record shows MAP of 50-55 then Dr. Drummond's testimony will likely cost your malpractice carrier a lot of money.

How nice! Another leech.

 

[drmwvr]

He also emphasized that over 45% of the population has an incomplete circle of Willis, which may decrease the autoregulatory capacity.

If 45% of the population had an incomplete circle of Willis to any clinical significance, no one would do a CEA without a shunt. I'm easily into 4 figures for CEA anesthetics and can say with confidence that not even 5% of those shunted patients had poor back flow.

Heard that claim often. Don't buy it. If cerebral auto regulation is impaired, it'll be for reasons discoverable on PE and hx.

 

[BLADEMDA]

If 45% of the population had an incomplete circle of Willis to any clinical significance, no one would do a CEA without a shunt. I'm easily into 4 figures for CEA anesthetics and can say with confidence that not even 5% of those shunted patients had poor back flow.

Heard that claim often. Don't buy it. If cerebral auto regulation is impaired, it'll be for reasons discoverable on PE and hx.

I agree with you; there is no way that figure is 45%. That said, I do think 3% or so is quite realistic and that is still a lot of patients. We know from doing lots of anesthetics that the complication rate is very low. But, in this medico-legal climate why in the world would anyone allow a MAP less than 60 for prolonged periods of time? It's simply bad practice which may eventually lead to bad outcome; or, as you will find out bad outcome leads to a review of the anesthetic record with all the "proof" the attorney needs to win the case against you and win big.

 

[drmwvr]

I agree with you; there is no way that figure is 45%. That said, I do think 3% or so is quite realistic and that is still a lot of patients. We know from doing lots of anesthetics that the complication rate is very low. But, in this medico-legal climate why in the world would anyone allow a MAP less than 60 for prolonged periods of time? It's simply bad practice which may eventually lead to bad outcome; or, as you will find out bad outcome leads to a review of the anesthetic record with all the "proof" the attorney needs to win the case against you and win big.

Agree with him on MAP (see my former post)... just saw the need to call out the often repeated C of W notion.

 

[fakin' the funk]

background of attending - my point of view - likes desflurane. Not a big fan of opioids - no one has gotten away with using opioids on his cases without him giving us an earful. Not a fan of pressor agents (phenylephrine, ephedrine) either, or perhaps their excessive use (in his view). Loves using the BIS monitor and is the only one that swears by its use outside of an emergent case.

This attending has a lot of weird rules that really paint you into a corner.

 

[fakin' the funk]

States his normal systolic BP runs between 70-90s, has never encountered pre-syncopal/syncopal sx, angina, dyspnea. All labs WNL except for elevated Cr, past hx of CKD. Regional team that placed epidural encountering aforementioned low BP. I am unsure when at what point during the procedure they encountered the apparent hypotension but it seemed to resolve with a 500 cc bolus. Pre-op vitals 80/60s, tachycardic 110, NPO for at least 12 hours.

Patient's physiology is interesting. You can see this "chronically low SVR" state in the chronically inflamed/infected pt, ESRDer, spinal cord injury pt, or adrenally insufficient. I am attributing this to low SVR unless you have some interesting TTE results to share. (And yes, I would require a TTE preop in this patient).

I would be pretty aggressive with fluid and intra-op vasopressor drip in this patient, and aim for MAP > 55.

If you really wanted to know if a MAP of 55 (or 60, or 65) was "enough" for your patient, how would you assess that?

Postop care for this patient will be interesting, and for that reason I also would not be too gung-ho about an epidural in this pt. A systolic of 70-90 is going to freak out most nurses, and if the patient has ANY symptoms of hypoperfusion postop or just persistently low BPs, guess what the first interventon will be? D/c the epidural.

 

[BLADEMDA]

Patient's physiology is interesting. You can see this "chronically low SVR" state in the chronically inflamed/infected pt, ESRDer, spinal cord injury pt, or adrenally insufficient. I am attributing this to low SVR unless you have some interesting TTE results to share. (And yes, I would require a TTE preop in this patient).

I would be pretty aggressive with fluid and intra-op vasopressor drip in this patient, and aim for MAP > 55.

If you really wanted to know if a MAP of 55 (or 60, or 65) was "enough" for your patient, how would you assess that?

Postop care for this patient will be interesting, and for that reason I also would not be too gung-ho about an epidural in this pt. A systolic of 70-90 is going to freak out most nurses, and if the patient has ANY symptoms of hypoperfusion postop or just persistently low BPs, guess what the first interventon will be? D/c the epidural.

Bilateral Tap block is my choice for postop pain management here.