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
Guideline
2019
British journal of anaesthesia
Mean arterial pressures below 60-70 mmHg are associated with myocardial injury,
Meta-analysis
2018
British journal of anaesthesia
Organ injury is reported after 10 minutes or more below a mean arterial pressure of
Randomised trial
2018
Anesthesiology
Hypotension on the four days after surgery carried a far stronger association with
Cohort
2025
British journal of anaesthesia
Cumulative intraoperative norepinephrine dose is independently associated with
Randomised trial
2021
Journal of the American College of
Targeting a MAP of at least 75 mmHg instead of 60 mmHg cut time spent below 65 mmHg
Cohort
2018
Anesthesia and analgesia
A maximum intraoperative heart rate above 100 bpm together with a minimum systolic
6 resolved citations behind this deck; every point above traces to one of them.
WHERE THE GUIDANCE SITS
What the guidelines and pooled evidence say
2 findings, each on the slide that follows.
British journal of anaesthesia 2019
Mean arterial pressures below 60-70 mmHg are associated with myocardial injury,
Mean arterial pressures below 60-70 mmHg are associated with myocardial injury, acute kidney injury and death
British journal of anaesthesia 2018
Organ injury is reported after 10 minutes or more below a mean arterial pressure of
Organ injury is reported after 10 minutes or more below a mean arterial pressure of 80 mmHg, after shorter periods below 70 mmHg
WHERE THE GUIDANCE SITS
Mean arterial pressures below 60-70 mmHg are associated with myocardial injury,
Guideline · British journal of anaesthesia
Mean arterial pressures below 60-70 mmHg are associated with myocardial injury, acute kidney injury and death, and the injury is a function of both how far the pressure falls and how long it stays there.
Perioperative Quality Initiative Consensus Statement on Intraoperative Blood Pressure, Risk and Outcomes for Elective Surgery, British journal of anaesthesia 2019 · PMID 30916004
WHERE THE GUIDANCE SITS
Organ injury is reported after 10 minutes or more below a mean arterial pressure of
Meta-analysis · British journal of anaesthesia
Organ injury is 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 55-50 mmHg.
Intraoperative Hypotension and the Risk of Postoperative Adverse Outcomes: A Systematic Review, British journal of anaesthesia 2018 · PMID 30236233
WHAT THE TRIALS FOUND
Where randomised evidence moved the question
2 findings, each on the slide that follows.
Anesthesiology 2018
Hypotension on the four days after surgery carried a far stronger association with
Hypotension on the four days after surgery carried a far stronger association with myocardial infarction and death (odds ratio 2.83) than each extra…
Journal of the American College of Cardiology 2021
Targeting a MAP of at least 75 mmHg instead of 60 mmHg cut time spent below 65 mmHg
Targeting a MAP of at least 75 mmHg instead of 60 mmHg cut time spent below 65 mmHg by roughly 60% but did not reduce acute myocardial injury or…
WHAT THE TRIALS FOUND
Hypotension on the four days after surgery carried a far stronger association with
Randomised trial · Anesthesiology
Hypotension on the four days after surgery carried a far stronger association with myocardial infarction and death (odds ratio 2.83) than each extra 10 minutes of intraoperative hypotension (odds ratio 1.08).
Period-Dependent Associations Between Hypotension During and for Four Days After Noncardiac Surgery and a Composite of Myocardial Infarction and Death: A Substudy of the POISE-2 Trial, Anesthesiology 2018 · PMID 29189290
THE NUMBERS
Postoperative hypotension carries the stronger association
Odds of the 30-day composite of myocardial infarction and death, POISE-2 substudy.
Hypotension on the ward carried an odds ratio of 2.83 against 1.08 per 10 intraoperative minutes — the danger does not end when the case does.
Period-Dependent Associations Between Hypotension During and for Four Days After Noncardiac Surgery and a Composite of Myocardial Infarction and Death: A Substudy of the POISE-2 Trial, Anesthesiology 2018 · PMID 29189290
WHAT THE TRIALS FOUND
Targeting a MAP of at least 75 mmHg instead of 60 mmHg cut time spent below 65 mmHg
Randomised trial · Journal of the American College of
Targeting a MAP of at least 75 mmHg instead of 60 mmHg cut time spent below 65 mmHg by roughly 60% but did not reduce acute myocardial injury or 30-day major cardiac events and acute kidney injury.
Targeting Higher Intraoperative Blood Pressures Does Not Reduce Adverse Cardiovascular Events Following Noncardiac Surgery, Journal of the American College of Cardiology 2021 · PMID 34711333
THE NUMBERS
Targeting a higher MAP cut hypotension without changing outcomes
Time below MAP 65 fell by 60%. The composite outcome did not move.
Halving hypotension exposure did not reduce myocardial injury or 30-day major cardiac events — the association is not straightforwardly causal.
Targeting Higher Intraoperative Blood Pressures Does Not Reduce Adverse Cardiovascular Events Following Noncardiac Surgery, Journal of the American College of Cardiology 2021 · PMID 34711333
IN PRACTICE
What the cohorts and reviews add
2 findings, each on the slide that follows.
British journal of anaesthesia 2025
Cumulative intraoperative norepinephrine dose is independently associated with
Cumulative intraoperative norepinephrine dose is independently associated with postoperative acute kidney injury, so escalating vasopressor to chase…
Anesthesia and analgesia 2018
A maximum intraoperative heart rate above 100 bpm together with a minimum systolic
A maximum intraoperative heart rate above 100 bpm together with a minimum systolic pressure below 100 mmHg is more strongly associated with…
IN PRACTICE
Cumulative intraoperative norepinephrine dose is independently associated with
Cohort · British journal of anaesthesia
Cumulative intraoperative norepinephrine dose is independently associated with postoperative acute kidney injury, so escalating vasopressor to chase a pressure target is not a risk-free trade.
Association of Intraoperative Hypotension and Cumulative Norepinephrine Dose With Postoperative Acute Kidney Injury in Patients Having Noncardiac Surgery: A Retrospective Cohort Analysis, British journal of anaesthesia 2025 · PMID 39672776
THE NUMBERS
Chasing the pressure with vasopressor is not free
Both exposures were independently associated with acute kidney injury in 38,338 patients.
Both exposures were independently associated with kidney injury in a retrospective cohort. Whether the norepinephrine contributed or merely marked sicker patients is untested.
Association of Intraoperative Hypotension and Cumulative Norepinephrine Dose With Postoperative Acute Kidney Injury in Patients Having Noncardiac Surgery: A Retrospective Cohort Analysis, British journal of anaesthesia 2025 · PMID 39672776
IN PRACTICE
A maximum intraoperative heart rate above 100 bpm together with a minimum systolic
Cohort · Anesthesia and analgesia
A maximum intraoperative heart rate above 100 bpm together with a minimum systolic pressure below 100 mmHg is more strongly associated with myocardial injury than low systolic pressure alone.
A Prospective International Multicentre Cohort Study of Intraoperative Heart Rate and Systolic Blood Pressure and Myocardial Injury After Noncardiac Surgery: Results of the VISION Study, Anesthesia and analgesia 2018 · PMID 29077608
THE NUMBERS
Tachycardia and hypotension together beat either alone
Odds of myocardial injury after noncardiac surgery, VISION study.
Watch the heart rate as well as the pressure — the combination is more strongly associated with myocardial injury than low pressure by itself.
A Prospective International Multicentre Cohort Study of Intraoperative Heart Rate and Systolic Blood Pressure and Myocardial Injury After Noncardiac Surgery: Results of the VISION Study, Anesthesia and analgesia 2018 · PMID 29077608
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
Mean arterial pressures below 60-70 mmHg are associated with myocardial injury, acute kidney injury and death, and the injury is a function of both how far the pressure falls and how long it stays there.
2
2
Organ injury is 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 55-50 mmHg.
3
3
Hypotension on the four days after surgery carried a far stronger association with myocardial infarction and death (odds ratio 2.83) than each extra 10 minutes of intraoperative hypotension (odds ratio 1.08).
4
4
Targeting a MAP of at least 75 mmHg instead of 60 mmHg cut time spent below 65 mmHg by roughly 60% but did not reduce acute myocardial injury or 30-day major cardiac events and acute kidney injury.
5
5
Cumulative intraoperative norepinephrine dose is independently associated with postoperative acute kidney injury, so escalating vasopressor to chase a pressure target is not a risk-free trade.
The oral-boards stem on the next slide puts these into one scenario.
KEY TAKEAWAYS
What to carry into the next case
Mean arterial pressures below 60-70 mmHg are associated with myocardial injury,
British journal of anaesthesia 2019
Organ injury is reported after 10 minutes or more below a mean arterial pressure of
British journal of anaesthesia 2018
Hypotension on the four days after surgery carried a far stronger association with
Anesthesiology 2018
Cumulative intraoperative norepinephrine dose is independently associated with
British journal of anaesthesia 2025
Mean arterial pressures below 60-70 mmHg are associated with myocardial injury,
Questions I'll ask you in the room
How does your plan change if the patient is not optimised?
What is the physiology behind what we just did?
Talk me through the trade-off you made there.
What would make you abandon this plan and do something else?
Oral boards stem
A 74-year-old with treated hypertension is 90 minutes into an open hemicolectomy. The MAP has sat between 58 and 63 mmHg for the last 20 minutes on a low-dose phenylephrine infusion, and the surgeon is asking you to keep the field dry.
Board questions
1. Summarise the mean arterial pressure thresholds and exposure durations at which organ injury has been reported in the systematic review literature on intraoperative hypotension: what is reported below a MAP of 80 mmHg, below 70 mmHg, and below 55-50 mmHg?
Show answer
Organ injury is reported after 10 minutes or more below a MAP of 80 mmHg, after shorter periods below 70 mmHg, and at any exposure below 55-50 mmHg.
There is no single hypotension number - the lower the pressure, the shorter the exposure that has been linked to injury.
Intraoperative Hypotension and the Risk of Postoperative Adverse Outcomes: A Systematic Review, British journal of anaesthesia 2018 · PMID 30236233
2. You are escalating a norepinephrine infusion to hold a MAP target during noncardiac surgery. State what a retrospective cohort analysis found about cumulative intraoperative norepinephrine dose and postoperative acute kidney injury, and what that implies about the trade-off you are making.
Show answer
Cumulative intraoperative norepinephrine dose was independently associated with postoperative acute kidney injury in that retrospective cohort. It is an association rather than proven causation, but it means escalating vasopressor to chase a pressure target is not a risk-free trade.
Both sides of the equation carry risk - the low pressure you are treating and the drug you are treating it with.
Association of Intraoperative Hypotension and Cumulative Norepinephrine Dose With Postoperative Acute Kidney Injury in Patients Having Noncardiac Surgery: A Retrospective Cohort Analysis, British journal of anaesthesia 2025 · PMID 39672776
3. In a prospective international multicentre cohort study of noncardiac surgery, which combination of intraoperative vital-sign extremes showed a stronger association with myocardial injury than low systolic pressure alone? Name both components with their thresholds.
Show answer
A maximum intraoperative heart rate above 100 bpm together with a minimum systolic pressure below 100 mmHg. That combination was more strongly associated with myocardial injury than low systolic pressure alone - an association reported from a prospective cohort.
Read the heart rate next to the pressure - tachycardia with a low systolic carried a stronger association with myocardial injury than the low pressure by itself.
A Prospective International Multicentre Cohort Study of Intraoperative Heart Rate and Systolic Blood Pressure and Myocardial Injury After Noncardiac Surgery: Results of the VISION Study, Anesthesia and analgesia 2018 · PMID 29077608
4. Patients were randomised to an intraoperative MAP target of at least 75 mmHg versus 60 mmHg. Describe what the higher target achieved in terms of hypotension exposure and what it did not achieve in terms of clinical outcomes, then say what this implies about treating time-below-threshold as a surrogate endpoint.
Show answer
The higher target cut time spent below 65 mmHg by roughly 60%, but did not reduce acute myocardial injury or 30-day major cardiac events and acute kidney injury. Reducing the hypotension exposure did not carry the clinical outcomes with it, so time-below-threshold behaved as a surrogate that moved on its own.
You can successfully move the number you are targeting and still not move the outcome you actually care about.
Targeting Higher Intraoperative Blood Pressures Does Not Reduce Adverse Cardiovascular Events Following Noncardiac Surgery, Journal of the American College of Cardiology 2021 · PMID 34711333
The bottom lineMean arterial pressures below 60-70 mmHg are associated with myocardial injury,
Sources
[1] Perioperative Quality Initiative Consensus Statement on Intraoperative Blood Pressure, Risk and Outcomes for Elective Surgery, British journal of anaesthesia 2019 · PMID 30916004 open
[2] Intraoperative Hypotension and the Risk of Postoperative Adverse Outcomes: A Systematic Review, British journal of anaesthesia 2018 · PMID 30236233 open
[3] Period-Dependent Associations Between Hypotension During and for Four Days After Noncardiac Surgery and a Composite of Myocardial Infarction and Death: A Substudy of the POISE-2 Trial, Anesthesiology 2018 · PMID 29189290 open
[4] Association of Intraoperative Hypotension and Cumulative Norepinephrine Dose With Postoperative Acute Kidney Injury in Patients Having Noncardiac Surgery: A Retrospective Cohort Analysis, British journal of anaesthesia 2025 · PMID 39672776 open
[5] Targeting Higher Intraoperative Blood Pressures Does Not Reduce Adverse Cardiovascular Events Following Noncardiac Surgery, Journal of the American College of Cardiology 2021 · PMID 34711333 open
[6] A Prospective International Multicentre Cohort Study of Intraoperative Heart Rate and Systolic Blood Pressure and Myocardial Injury After Noncardiac Surgery: Results of the VISION Study, Anesthesia and analgesia 2018 · PMID 29077608 open