Recognising and Treating Intraoperative Hypotension
CA-1 · intraoperative teaching CA-1 Bootcamp day 3. Authored from cited abstracts; every claim carries a PMID.
THE QUESTIONWhere the evidence disagrees
This topic was selected because an evidence synthesis beats a textbook on it: the trials disagree, or the guidance has moved recently.
THE EVIDENCE
What each source contributes, and how strong it is
Study design first — a cohort and a randomised trial do not carry the same weight.
Design
Year
Journal
What it found
Other
2014
World Journal of Cardiology
Cardiac output is the product of stroke volume and heart rate
Other
2019
British Journal of Anaesthesia
The Perioperative Quality Initiative consensus is that intraoperative mean art
Other
2022
BMC Anesthesiology
Reported definitions of intraoperative hypotension are wildly inconsistent acr
Other
2018
Anesthesia and Analgesia
In the VISION cohort a minimum systolic pressure below 100 mmHg together with
Other
2018
British Journal of Anaesthesia
Across 42 studies, organ injury was reported after 10 minutes or more below a
Other
2021
Journal of the American College of
Randomising cardiovascular-risk patients to a mean arterial pressure target of
6 resolved citations behind this deck; every point above traces to one of them.
IN PRACTICE
What the cohorts and reviews add
6 findings, each on the slide that follows.
World Journal of Cardiology 2014
Cardiac output is the product of stroke volume and heart rate
Cardiac output is the product of stroke volume and heart rate
British Journal of Anaesthesia 2019
The Perioperative Quality Initiative consensus is that intraoperative mean art
The Perioperative Quality Initiative consensus is that intraoperative mean arterial pressures below 60 to 70 mmHg are associated with myocardial…
BMC Anesthesiology 2022
Reported definitions of intraoperative hypotension are wildly inconsistent acr
Reported definitions of intraoperative hypotension are wildly inconsistent across the literature
Anesthesia and Analgesia 2018
In the VISION cohort a minimum systolic pressure below 100 mmHg together with
In the VISION cohort a minimum systolic pressure below 100 mmHg together with a maximum heart rate above 100 bpm was more strongly associated with…
IN PRACTICE
Cardiac output is the product of stroke volume and heart rate
Other · World Journal of Cardiology
Cardiac output is the product of stroke volume and heart rate, and it can only be altered through heart rate or rhythm, preload, contractility or afterload - which is the whole list you have to walk before you reach for a drug.
Mehta et al., World Journal of Cardiology 2014 · PMID 25276302
IN PRACTICE
The Perioperative Quality Initiative consensus is that intraoperative mean art
Other · British Journal of Anaesthesia
The Perioperative Quality Initiative consensus is that intraoperative mean arterial pressures below 60 to 70 mmHg are associated with myocardial injury, acute kidney injury and death, and that the injury is a function of both how far the pressure falls and how long it stays down.
Sessler et al., British Journal of Anaesthesia 2019 · PMID 30916004
IN PRACTICE
Reported definitions of intraoperative hypotension are wildly inconsistent acr
Other · BMC Anesthesiology
Reported definitions of intraoperative hypotension are wildly inconsistent across the literature, and the recommendation from that review is to use the Perioperative Quality Initiative absolute values - a mean arterial pressure below 60 to 70 mmHg or a systolic below 100 mmHg - and to report how long the patient spent there.
Weinberg et al., BMC Anesthesiology 2022 · PMID 35277122
IN PRACTICE
In the VISION cohort a minimum systolic pressure below 100 mmHg together with
Other · Anesthesia and Analgesia
In the VISION cohort a minimum systolic pressure below 100 mmHg together with a maximum heart rate above 100 bpm was more strongly associated with myocardial injury (odds ratio 1.42) than a systolic below 100 mmHg on its own (odds ratio 1.20), so the heart rate is part of the problem and not a bystander.
Abbott et al., Anesthesia and Analgesia 2018 · PMID 29077608
IN PRACTICE
Across 42 studies, organ injury was reported after 10 minutes or more below a
Other · British Journal of Anaesthesia
Across 42 studies, organ injury was reported after 10 minutes or more below a mean arterial pressure of 80 mmHg, after shorter periods below 70 mmHg, and at any exposure below 55 to 50 mmHg - depth and duration multiply rather than act separately.
Wesselink et al., British Journal of Anaesthesia 2018 · PMID 30236233
IN PRACTICE
Randomising cardiovascular-risk patients to a mean arterial pressure target of
Other · Journal of the American College of
Randomising cardiovascular-risk patients to a mean arterial pressure target of at least 75 mmHg instead of at least 60 mmHg cut time spent below 65 mmHg by about 60% but did not reduce acute myocardial injury or 30-day major cardiac and kidney events, so chasing a higher number is not automatically treatment.
Wanner et al., Journal of the American College of Cardiology 2021 · PMID 34711333
IN THE ROOM
What this changes about the next case
Colour is the strength of the evidence behind each step, not the urgency.
1
1
Cardiac output is the product of stroke volume and heart rate, and it can only be altered through heart rate or rhythm, preload, contractility or afterload - which is the whole list you have to walk before you reach for a drug.
2
2
The Perioperative Quality Initiative consensus is that intraoperative mean arterial pressures below 60 to 70 mmHg are associated with myocardial injury, acute kidney injury and death, and that the injury is a function of both how far the pressure falls and how long it stays down.
3
3
Reported definitions of intraoperative hypotension are wildly inconsistent across the literature, and the recommendation from that review is to use the Perioperative Quality Initiative absolute values - a mean arterial pressure below 60 to 70 mmHg or a systolic below 100 mmHg - and to report how long the patient spent there.
4
4
In the VISION cohort a minimum systolic pressure below 100 mmHg together with a maximum heart rate above 100 bpm was more strongly associated with myocardial injury (odds ratio 1.42) than a systolic below 100 mmHg on its own (odds ratio 1.20), so the heart rate is part of the problem and not a bystander.
5
5
Across 42 studies, organ injury was reported after 10 minutes or more below a mean arterial pressure of 80 mmHg, after shorter periods below 70 mmHg, and at any exposure below 55 to 50 mmHg - depth and duration multiply rather than act separately.
The oral-boards stem on the next slide puts these into one scenario.
KEY TAKEAWAYS
What to carry into the next case
Cardiac output is the product of stroke volume and heart rate
World Journal of Cardiology 2014
The Perioperative Quality Initiative consensus is that intraoperative mean art
British Journal of Anaesthesia 2019
Reported definitions of intraoperative hypotension are wildly inconsistent acr
BMC Anesthesiology 2022
In the VISION cohort a minimum systolic pressure below 100 mmHg together with
Anesthesia and Analgesia 2018
Cardiac output is stroke volume times heart rate, so walk the list - rate, rhythm, preload, afterload, contractility - and hold the adult to a mean arterial pressure above 65 and a systolic above 100 while you do it.
Questions I'll ask you in the room
Say the equation out loud - which of its terms has actually changed in this patient?
Is this rhythm sinus, and at this rate is the rhythm itself the problem?
How would you decide whether he needs volume rather than a pressor?
What is your mean arterial pressure target here, and where does that number come from?
Oral boards stem
You are at the head of the bed on your own for the first time. Forty minutes into a hemicolectomy in a 70-year-old, the cuff cycles and reads 72/38, mean 49. Your attending walks in, does not touch anything, and asks you to talk out loud through why the pressure is low before you treat it - naming the parts of the equation rather than naming a drug.
The bottom lineCardiac output is stroke volume times heart rate, so walk the list - rate, rhythm, preload, afterload, contractility - and hold the adult to a mean arterial pressure above 65 and a systolic above 100 while you do it.
Sources
[1] Mehta et al., World Journal of Cardiology 2014 · PMID 25276302 open
[2] Sessler et al., British Journal of Anaesthesia 2019 · PMID 30916004 open
[3] Weinberg et al., BMC Anesthesiology 2022 · PMID 35277122 open
[4] Abbott et al., Anesthesia and Analgesia 2018 · PMID 29077608 open
[5] Wesselink et al., British Journal of Anaesthesia 2018 · PMID 30236233 open
[6] Wanner et al., Journal of the American College of Cardiology 2021 · PMID 34711333 open