What should be the target heart rate and blood pressure for a post-operative patient at rest who is being treated with noradrenaline (norepinephrine)?

Target Heart Rate and Blood Pressure for Post-Operative Patients on Noradrenaline

For post-operative patients at rest receiving noradrenaline, maintain mean arterial pressure (MAP) ≥60-65 mmHg or systolic blood pressure (SBP) ≥90 mmHg, with heart rate targets of 60-70 beats per minute when beta-blockade is used, though specific heart rate targets for noradrenaline alone are not established in guidelines. 1

Blood Pressure Targets

Minimum Thresholds to Prevent Organ Injury

• Maintain MAP ≥60-65 mmHg as the absolute minimum threshold to reduce risk of myocardial injury, acute kidney injury, and mortality 1
• Keep SBP ≥90 mmHg as hypotension below this level for ≥15 minutes is associated with increased death, myocardial injury, stroke, and renal complications 1
• Avoid MAP <65 mmHg for sustained periods, as harm from hypotension accrues during brief periods of profoundly low pressures rather than prolonged moderate hypotension 1

Individualized Targets Based on Baseline

• For patients with normal preoperative blood pressure: maintain SBP 90-160 mmHg (or 70-140% of baseline) 2
• For patients with preoperative hypertension: target SBP >70% of preoperative baseline as these patients have higher thresholds for harm than the standard 90 mmHg cutoff 1, 2
• Calculate trigger values as <75% of baseline for hypotension requiring immediate bedside assessment 3, 2

Upper Limits for Hypertension

• Treat postoperative hypertension when SBP >180 mmHg or diastolic BP >110 mmHg to reduce risk of myocardial ischemia/infarction, acute decompensated heart failure, cerebral ischemia, and bleeding 1
• Resume chronic antihypertensive medications as soon as clinically reasonable to prevent complications from rebound hypertension, as delaying resumption of ACE inhibitors/ARBs increases 30-day mortality 1

Heart Rate Considerations

When Beta-Blockade is Co-Administered

• Target resting heart rate of 60-70 beats per minute when beta-blockers are used perioperatively with systolic blood pressure maintained >100 mmHg 1

Monitoring for Complications

• Recognize that tachycardia (HR ≥110 bpm) is associated with subsequent serious adverse events and occurred in 16% of patients before complications versus 3.9% in patients without complications 4
• Monitor for phenylephrine-induced reflex bradycardia if pure alpha-agonists are used instead of noradrenaline, as this can decrease cardiac output 1

Advantages of Noradrenaline Over Pure Vasopressors

• Noradrenaline (combined α1- and β1-adrenergic agonist) maintains or improves cardiac output while increasing arterial pressure, potentially improving organ perfusion compared to pure vasopressors like phenylephrine 1
• Pure vasopressors such as phenylephrine may simultaneously increase arterial pressure and reduce organ perfusion despite raising blood pressure numbers 1

Monitoring Intensity Requirements

Frequency of Assessment

• Increase monitoring frequency beyond routine 4-6 hour intervals for patients requiring vasopressor support or with trending blood pressure changes 2
• Conventional 4-hour vital sign checks miss 54% of MAP episodes <65 mmHg sustained >15 minutes and 68% of bradycardia episodes 5
• Implement continuous monitoring when possible as it detects nearly twice as much hypotension as intermittent oscillometric monitoring at 2-5 minute intervals 3

Critical Periods

• Postoperative hypotension may be more important than intraoperative hypotension because it is often prolonged and unrecognized 3
• Each 10-minute episode of hypotension on postoperative day 0 increases risk of MI and death by 3%, and any hypotension on postoperative days 1-4 nearly doubles the risk 1
• Vital signs typically deteriorate 6-12 hours before cardiac and respiratory arrests, emphasizing need for close monitoring 1

Common Pitfalls to Avoid

• Do not tolerate prolonged hypotension during sleep assuming it is physiologic without documentation of the patient's home baseline blood pressure, as circadian variations exist but may not justify accepting low pressures 1, 2
• Do not assume normal blood pressure readings exclude hypotensive episodes when using intermittent monitoring, as continuous monitoring detects substantially more events 3
• Do not delay treatment of MAP <60-65 mmHg or SBP <90 mmHg, as prolonged hypotension increases mortality and organ injury 2
• Avoid drops >30% below baseline, as this threshold is associated with end-organ injury 2