Explain it before you treat it
There is no evidence-based number at which treatment must begin. The consensus statement records insufficient evidence to recommend a general upper limit of arterial pressure at which therapy should be initiated, while noting that pressures above 160 mmHg have been associated with myocardial injury and infarction sessler-2019-d6.
So the first move is not a drug. It is a cause.
The five reversible causes
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Pain. The commonest, and the one most likely to be under-treated in a patient who cannot yet say so. Treat the pain and re-measure.
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A full bladder. The guideline asks for assessment of urine output and voiding case by case for selected patients and procedures asa-pacu-2013-d6. Scan the bladder rather than guess. See the urinary retention material on Day 17.
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Hypercarbia. Hypoventilation from opioid or residual block raises carbon dioxide and drives the sympathetic response. Look at rate and depth, and at the capnograph if there is one.
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Hypoxemia. Check the saturation and treat it as an airway problem until proven otherwise.
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Withdrawal of a home antihypertensive. The clonidine label warns that sudden cessation has resulted in nervousness, agitation, headache and tremor accompanied or followed by a rapid rise in blood pressure and elevated plasma catecholamines, more likely at higher doses or with a beta-blocker, and instructs that the drug be continued to within four hours of surgery and resumed as soon as possible afterwards fda-clonidine-label-2022.
Shivering, anxiety, a distended stomach and a cold patient belong on the same list.
Where a threshold does exist
Local practice differs. after craniotomy, after carotid endarterectomy because of cerebral hyperperfusion, after aortic or cardiac surgery, and in preeclampsia, the surgical or obstetric service usually sets an explicit upper limit, and that limit is part of the order set rather than a finding. Find out what it is before the patient arrives. The absence of a general threshold is not the absence of any threshold.
Local practice differs. those limits are institutional; find out what they are before the patient arrives, not after.
If you do treat
The agents usually stocked for this have FDA labels, and two of them do not say what residents are commonly taught. Labetalol’s label gives an initial 20 mg by slow intravenous injection over 2 min, then further injections of 40 or 80 mg at 10-minute intervals until the pressure responds or a total of 300 mg has been given fda-labetalol-label-2020. Hydralazine’s usual injected dose is 20 to 40 mg, repeated as necessary, and its label warns that where intracranial pressure is raised, lowering the blood pressure may increase cerebral ischemia fda-hydralazine-label-2021. Nicardipine starts at 5 mg/hr and increases by 2.5 mg/hr every 15 min to a maximum of 15 mg/hr fda-nicardipine-label-2024. Clevidipine starts at 1 to 2 mg/hr, may be doubled at 90-second intervals early, usually works at 4 to 6 mg/hr, and is capped by its lipid load at no more than 1000 mL or an average of 21 mg/hr in 24 h fda-clevidipine-label-2022.
This card previously gave labetalol as 5 to 10 mg increments and hydralazine as 5 to 10 mg. Neither figure is in the labelling quoted above, where labetalol starts at 20 mg fda-labetalol-label-2020 and hydralazine is usually 20 to 40 mg fda-hydralazine-label-2021. If your unit uses the smaller increments, that is a local protocol.
Continue a beta blocker the patient already takes. The 2024 perioperative cardiovascular guideline makes that a Class 1 recommendation for patients on stable doses, and separately grades starting one on the day of surgery, in a patient with no immediate need, as harm thompson-2024-accaha. That wording was read from the journal’s own recommendation table, which renders as an untagged image and was transcribed by eye. The guideline carries a published correction that has not been read, so treat the wording as current pending that check.
Note what the guideline says about looking harder: the literature is insufficient to evaluate the impact of cardiovascular assessment and monitoring, or of routine electrocardiographic monitoring, on perioperative complications asa-pacu-2013-d6. Monitoring is not the treatment either.
Sources
[[sessler-2019-d6]] consensus statement 2019 n: NA open
Sessler DI, Bloomstone JA, Aronson S, et al. Perioperative Quality Initiative consensus statement on intraoperative blood pressure, risk and outcomes for elective surgery. Br J Anaesth. 2019 May;122(5):563-574.
Consensus statement 2, verbatim sense: for adult noncardiac surgical patients there is insufficient evidence to recommend a general upper limit of arterial pressure at which therapy should be initiated, although pressures above 160 mmHg have been associated with myocardial injury and infarction. This is the strongest available statement that the number itself is not the treatment target.
[[asa-pacu-2013-d6]] guideline 2013 n: NA open
American Society of Anesthesiologists Task Force on Postanesthetic Care. Practice Guidelines for Postanesthetic Care: an updated report. Anesthesiology. 2013 Feb;118(2):291-307.
States that the literature continues to be insufficient to evaluate the impact of cardiovascular assessment and monitoring, or of routine electrocardiographic monitoring, on perioperative complications. Also states that assessment of urine output and voiding should be done case by case, which is the bladder limb of this day's differential.
[[fda-clonidine-label-2022]] advisory 2022 n: NA open
Clonidine Hydrochloride Tablets, USP [prescribing information]. Solco Healthcare US / Major Pharmaceuticals. Revised 07/2022. DailyMed set ID 8171776a-dd14-4dcc-8860-3c27d8ea9504.
FDA label, WARNINGS (withdrawal): 'Sudden cessation of clonidine treatment has, in some cases, resulted in symptoms such as nervousness, agitation, headache, and tremor accompanied or followed by a rapid rise in blood pressure and elevated catecholamine concentrations in the plasma' (first 125 characters verbatim; remainder paraphrased in findings - re-quote from label); reactions more likely after higher doses or with beta-blockers; rare hypertensive encephalopathy, stroke, death; taper over 2-4 days. PRECAUTIONS (perioperative): continue to within four hours of surgery and resume as soon as possible thereafter.
[[fda-labetalol-label-2020]] advisory 2020 n: NA open
Labetalol Hydrochloride Injection, USP [prescribing information]. Hikma Pharmaceuticals USA Inc. Revised January 2020. DailyMed set ID 30f9fdef-8781-4327-9a8d-812cb31ff041. DailyMed updated 10 July 2024.
FDA label, DOSAGE AND ADMINISTRATION, Repeated Intravenous Injection, VERBATIM: 'Initially, labetalol HCl injection should be given in a 20 mg dose (which corresponds to 0.25 mg/kg for an 80 kg patient) by slow intravenous injection over a 2 minute period.' And: 'Immediately before the injection and at 5 and 10 minutes after injection, supine blood pressure should be measured to evaluate response. Additional injections of 40 or 80 mg can be given at 10 minute intervals until a desired supine blood pressure is achieved or a total of 300 mg of labetalol HCl injection has been injected. The maximum effect usually occurs within 5 minutes of each injection.' Slow Continuous Infusion, VERBATIM: 'The diluted solution should be administered at a rate of 2 mL/min to deliver 2 mg/min' and 'The effective intravenous dose is usually in the range of 50 to 200 mg. A total dose of up to 300 mg may be required in some patients.' No boxed warning on this label. NOTE FOR THE CARD: the label's 20 mg initial dose is larger than the 5 to 10 mg increments the hypertension card currently teaches; the card's figure has no label source.
[[fda-hydralazine-label-2021]] advisory 2021 n: NA open
Hydralazine Hydrochloride Injection, USP [prescribing information]. Akorn, Inc. Revision code HY00N Rev. 04/21. DailyMed set ID e31239e0-8c5a-4d10-9404-af32278484a3. DailyMed updated 12 September 2022.
FDA label, DOSAGE AND ADMINISTRATION, VERBATIM: 'When there is urgent need, therapy in the hospitalized patient may be initiated intramuscularly or as a rapid intravenous bolus injection directly into the vein. Hydralazine hydrochloride injection should be used only when the drug cannot be given orally. The usual dose is 20 to 40 mg, repeated as necessary.' And: 'Blood pressure should be checked frequently. It may begin to fall within a few minutes after injection, with the average maximal decrease occurring in 10 to 80 minutes. In cases where there has been increased intracranial pressure, lowering the blood pressure may increase cerebral ischemia.' No boxed warning on this label. NOTE FOR THE CARD: the label's usual dose is 20 to 40 mg, not the 5 to 10 mg the hypertension card currently teaches.
[[fda-nicardipine-label-2024]] advisory 2024 n: NA open
Nicardipine Hydrochloride Injection, USP, for intravenous use [prescribing information]. Hikma Pharmaceuticals USA Inc. Revised 8/2024. DailyMed set ID 18fb1c2b-0c1e-436c-a5b6-d4840b5da228. DailyMed updated 24 August 2024.
FDA label section 1.1, VERBATIM: 'Nicardipine hydrochloride injection, USP is indicated for the short-term treatment of hypertension when oral therapy is not feasible or desirable.' Dosing, VERBATIM: 'For a gradual reduction in blood pressure, initiate therapy at a rate of 5 mg/hr. If desired blood pressure reduction is not achieved at this dose, increase the infusion rate by 2.5 mg/hr every 15 minutes up to a maximum of 15 mg/hr, until desired blood pressure reduction is achieved. For more rapid blood pressure reduction, titrate every 5 minutes.' Section 2.1, VERBATIM: 'Administer Nicardipine Hydrochloride by slow continuous infusion by a central line or through a large peripheral vein. Change the infusion site every 12 hours if administered via peripheral vein.' Section 2.5, on hypotension or tachycardia, VERBATIM: 'discontinue infusion. When blood pressure and heart rate stabilize, restart infusion at low doses such as 30 mL/hr to 50 mL/hr (3 mg/hr to 5 mg/hr) and titrate to maintain desired blood pressure.' No boxed warning on this label.
[[fda-clevidipine-label-2022]] advisory 2022 n: NA open
CLEVIPREX (clevidipine) injectable emulsion [prescribing information]. Chiesi USA, Inc. Revised 9/2022. DailyMed set ID f9290625-b723-4eda-bab8-a97bef6041f6. DailyMed updated 6 November 2025.
FDA label section 2.2, VERBATIM: 'Initiate the intravenous infusion of Cleviprex at 1-2 mg/hour.' And: 'The dose may be doubled at short (90 second) intervals initially. As the blood pressure approaches goal, the increase in doses should be less than doubling and the time between dose adjustments should be lengthened to every 5-10 minutes. An approximately 1-2 mg/hour increase will generally produce an additional 2-4 mmHg decrease in systolic pressure.' And: 'The desired therapeutic response for most patients occurs at doses of 4-6 mg/hour. Patients with severe hypertension may require doses up to 32 mg/hour, but there is limited experience at this dose rate.' Lipid-load limit, VERBATIM: 'Because of lipid load restrictions, no more than 1000 mL or an average of 21 mg/hour of Cleviprex infusion is recommended per 24 hour period.' Section 2.1, VERBATIM: 'Patients who receive prolonged Cleviprex infusions and are not transitioned to other antihypertensive therapies should be monitored for the possibility of rebound hypertension for at least 8 hours after the infusion is stopped.' No boxed warning on this label. Note: the DailyMed product title prints the drug name as 'clevipidine', a typographical error in the label title.
[[thompson-2024-accaha]] guideline 2024 n: NA open
Thompson A, Fleischmann KE, Smilowitz NR, de Las Fuentes L, Mukherjee D, Aggarwal NR, Ahmad FS, Allen RB, Altin SE, Auerbach A, Berger JS, Chow B, Dakik HA, Eisenstein EL, Gerhard-Herman M, Ghadimi K, Kachulis B, Leclerc J, Lee CS, Macaulay TE, Mates G, Merli GJ, Parwani P, Poole JE, Rich MW, Ruetzler K, Stain SC, Sweitzer B, Talbot AW, Vallabhajosyula S, Whittle J, Williams KA. 2024 AHA/ACC/ACS/ASNC/HRS/SCA/SCCT/SCMR/SVM Guideline for Perioperative Cardiovascular Management for Noncardiac Surgery. Circulation. 2024;150(19):e351-e442.
ANSWERS THE DAY 6 / HYPERTENSION CARD BETA-BLOCKER QUESTION. Section 7.7 Perioperative Beta Blockers, COR 1, LOE B-NR, VERBATIM: 'In patients on stable doses of beta blockers undergoing NCS, beta blockers should be continued through the perioperative period as appropriate based on the clinical circumstances.' Adjacent, COR 2b LOE B-NR: 'In patients scheduled for elective NCS who have a new indication for beta blockade, beta blockers may be initiated far enough before surgery (optimally >7 days) to permit assessments of tolerability and drug titration if needed.' And COR 3 Harm, LOE B-R: 'In patients undergoing NCS and with no immediate need for beta blockers, beta blockers should not be initiated on the day of surgery due to increased risk for postoperative mortality.' ROUTE CAVEAT THAT MUST BE RESOLVED BEFORE THIS IS QUOTED AS VERBATIM FROM THE JOURNAL: the Circulation article page loaded and is marked Free Access, but its section 7.7 body text was truncated out of what the fetcher returned. The quoted text above was read from the AHA's own official slide set for this guideline on professional.heart.org, which reproduces the recommendation tables with COR and LOE. That is an AHA publication but it is not the journal article. One confirmatory read of Circulation page e399 is recommended.