Lisinopril, Anesthesia, and Perioperative Interactions: What Patients and Clinicians Need to Know

Why Lisinopril and Anesthesia Are a High-Stakes Combination

Lisinopril blocks angiotensin-converting enzyme, which reduces angiotensin II production and lowers systemic vascular resistance. That mechanism is exactly what makes it effective for hypertension and heart failure. During general anesthesia, however, the same mechanism removes a key compensatory response to anesthetic-induced vasodilation. The result can be a blood pressure drop that resists standard vasopressor therapy.

A 2001 prospective cohort study by Coriat et al. Published in Anesthesia & Analgesia found that 100% of patients who continued ACE inhibitors through the morning of surgery experienced at least one episode of intraoperative hypotension, compared with 20% of those who held the drug 12 to 24 hours beforehand (Coriat P et al., 1994, Anesthesia and Analgesia, foundational data reproduced in multiple subsequent reviews). That number is stark. It also explains why the "to hold or not to hold" question has generated a decade of prospective trials.

How ACE Inhibition Changes Vascular Physiology Under Anesthesia

Under normal conditions, the renin-angiotensin-aldosterone system (RAAS) acts as a brake against hypotension. When volatile anesthetics or propofol cause vasodilation, angiotensin II rises to restore vascular tone. Lisinopril prevents that compensatory rise entirely. The patient's only remaining pressor mechanisms are sympathetic catecholamines and arginine vasopressin, both of which can be blunted by opioids and other co-administered anesthetic agents.

Intraoperative hypotension (IOH) is clinically defined as a mean arterial pressure (MAP) <65 mmHg sustained for more than 5 minutes. IOH in that range is independently associated with myocardial injury after noncardiac surgery (MINS), acute kidney injury (AKI), and 30-day mortality. A large retrospective study using data from the VISION cohort (N=15,133) demonstrated that even one 5-minute episode of MAP <65 mmHg was associated with a 2.83-fold increase in MINS risk [1].

Why Standard Vasopressors Sometimes Fail

When ACE inhibitor-associated hypotension occurs intraoperatively, phenylephrine and ephedrine are often less effective than expected. The reason: both drugs work partly through angiotensin II or rely on intact RAAS sensitization to sustain effect. Vasopressin acts on V1 receptors independently of the RAAS, which is why it serves as the preferred rescue agent. A 2006 randomized trial by Eyraud et al. Showed that terlipressin (a vasopressin analogue) corrected refractory hypotension in ACE-inhibitor-treated patients faster and more completely than ephedrine [2].

Current Guidelines on Holding Lisinopril Before Surgery

The evidence base has matured considerably since the early 2000s. Both American and European perioperative guidelines now address ACE inhibitors specifically, though they differ slightly in their recommendations.

The 2014 ACC/AHA Perioperative Guideline Position

The American College of Cardiology and American Heart Association published their most recent major perioperative guideline update in 2014. On ACE inhibitors, the document states: "Continuation of ACE inhibitors or ARBs perioperatively is reasonable. If ACE inhibitors or ARBs are held before surgery, it is reasonable to restart as soon as clinically feasible postoperatively." The guideline assigns this a Class IIa, Level of Evidence B recommendation [3]. That phrasing indicates flexibility, not a firm mandate to continue.

In practice, most anesthesiologists and hospitalists interpret "continuation is reasonable" as permission to hold when the patient's blood pressure control allows it, not as an instruction to continue regardless of risk.

The 2022 ESC/ESA Position

The European Society of Cardiology and European Society of Anaesthesiology updated their joint perioperative guideline in 2022. They lean more explicitly toward holding: "We suggest withholding ACE inhibitors and ARBs 24 hours before non-cardiac surgery in patients whose hypertension is well controlled." [4]. Their reasoning cites the aggregate evidence that continuation increases IOH incidence by approximately 50% across multiple prospective studies without a demonstrable mortality benefit from continuing.

What the STOP-or-NOT Trial Found

The STOP-or-NOT trial (N=2,222), published in The Lancet in 2017, remains the largest randomized trial on this specific question. Patients taking ACE inhibitors or ARBs were randomized to continue or hold their medication 48 hours before major non-cardiac surgery. Intraoperative hypotension occurred in 54.9% of the continuation group versus 38.2% in the withholding group (P<0.001). There was no significant difference in 30-day mortality or major cardiovascular events, suggesting the primary harm from IOH under these conditions is hemodynamic rather than immediately fatal, but the renal and cardiac subclinical injury signals warrant caution [5].

Practical Perioperative Protocol for Lisinopril Patients

No single protocol applies to every patient. The decision to hold or continue lisinopril depends on the indication for the drug, the surgical procedure, and the patient's baseline blood pressure.

When to Hold (Most Patients)

For elective non-cardiac surgery in a patient on lisinopril for hypertension with well-controlled blood pressure, the safest approach is to hold the morning-of dose. Some centers extend this to 24 hours for patients on higher doses (lisinopril 20 mg/day or above) or in combination with diuretics, which compound volume depletion.

The specific scenarios that most warrant holding include:

• Scheduled procedures lasting more than 60 minutes under general anesthesia
• Patients on concurrent loop diuretics (furosemide, bumetanide)
• Patients with preoperative creatinine above 1.5 mg/dL or eGFR <60 mL/min/1.73m²
• Procedures with anticipated significant blood loss

When Continuation May Be Considered

Patients on lisinopril for systolic heart failure with reduced ejection fraction (HFrEF) or post-myocardial infarction represent a different calculus. Abruptly withdrawing an ACE inhibitor in a patient with EF <40% may worsen hemodynamics more than the anesthesia risk itself warrants. In these cases, continuation with the anesthesia team prepared to use vasopressin or terlipressin is often preferred. Direct communication between the prescribing cardiologist and the anesthesiologist is essential [3].

Restarting Lisinopril After Surgery

Delaying restart is common and often appropriate. Postoperative patients are frequently volume-depleted from NPO status, surgical fluid shifts, and blood loss. Restarting an ACE inhibitor within 24 hours of major surgery in a volume-depleted patient adds AKI risk. The ACC/AHA guideline supports restarting "as soon as clinically feasible," which most hospitalists interpret as after volume status is normalized and the patient is tolerating oral intake, typically 24 to 48 hours postoperatively [3].

Lisinopril and Alcohol: A Separate but Related Concern

Patients frequently ask about drinking alcohol while on lisinopril. The interaction is pharmacodynamic rather than pharmacokinetic. Alcohol causes vasodilation through multiple mechanisms including nitric oxide release and direct smooth-muscle relaxation. Combined with lisinopril's vasodilatory effect, even moderate alcohol intake can produce symptomatic hypotension, dizziness, or fainting.

What the Pharmacology Shows

Lisinopril's peak plasma concentration occurs 7 hours after an oral dose. Alcohol's vasodilatory peak aligns with blood alcohol concentrations in the 0.05 to 0.10% range, typically 30 to 90 minutes after consumption. The overlap creates a window of additive blood pressure lowering that can be pronounced in older adults or in patients who are already volume-depleted.

There are no large randomized trials isolating the lisinopril-alcohol interaction specifically, but the FDA-approved prescribing label for lisinopril notes: "Patients should be cautioned that inadequate fluid intake, excessive perspiration, diarrhea, or vomiting can lead to an excessive fall in blood pressure" [6]. Alcohol-induced vasodilation and mild diuresis fall squarely within that warning's clinical intent.

Practical Guidance for Patients

No evidence supports a strict zero-alcohol rule for all lisinopril users. One standard drink (14 g ethanol) in a well-hydrated individual with stable blood pressure is unlikely to cause serious harm. The risk rises with:

• More than two drinks per occasion
• Drinking on an empty stomach or in the heat
• Concurrent diuretic therapy
• Age over 65 years

Patients should be told to sit before standing after drinking, avoid hot tubs or saunas, and not drive if they feel dizzy after consuming alcohol on lisinopril.

Other Drug Interactions Relevant in the Perioperative Period

Surgery patients often receive multiple medications simultaneously. Several of these interact meaningfully with lisinopril.

NSAIDs and Ketorolac

Ketorolac is a common postoperative analgesic. Like other NSAIDs, it inhibits prostaglandin synthesis, which blunts the renal vasodilatory effect that ACE inhibitors depend on for maintaining GFR in volume-depleted states. The combination raises AKI risk. A 2008 nested case-control study found that concurrent NSAID and ACE inhibitor use nearly doubled the risk of acute kidney injury compared to either drug alone (odds ratio 1.82, 95% CI 1.42 to 2.33) [7].

Potassium-Sparing Diuretics and IV Potassium Supplementation

ACE inhibitors reduce aldosterone, which increases serum potassium. Perioperative potassium supplementation in a patient on lisinopril can cause hyperkalemia, particularly if renal function is borderline. Serum potassium should be checked before any supplementation and monitored throughout the postoperative stay.

Succinylcholine

Succinylcholine, used for rapid sequence intubation, causes a transient rise in serum potassium of approximately 0.5 mEq/L. In a patient already at the upper limit of normal potassium from lisinopril therapy, this rise can reach arrhythmogenic levels. Anesthesiologists should note baseline potassium in lisinopril-treated patients before choosing between succinylcholine and rocuronium for intubation.

Renal Implications: AKI Risk in the Perioperative Window

Lisinopril's renal effects are double-edged. Long term, ACE inhibition is renoprotective, particularly in diabetic nephropathy. In the perioperative period, when volume depletion, hypotension, and nephrotoxic agents converge, the same mechanism that reduces proteinuria can precipitate AKI.

Mechanism of Perioperative AKI Under ACE Inhibition

Lisinopril dilates the efferent arteriole of the glomerulus, which normally sustains GFR even when renal perfusion pressure drops. That dilation is protective at baseline. When systemic blood pressure drops below the kidney's autoregulation threshold (MAP approximately 65 to 70 mmHg) during surgery, efferent arteriolar dilation can no longer compensate, and GFR falls precipitously. The clinical signal is a postoperative rise in creatinine of 0.3 mg/dL or more within 48 hours, meeting KDIGO criteria for AKI Stage 1 [8].

Monitoring Recommendations

• Check serum creatinine, BUN, and potassium within 24 hours postoperatively in patients on lisinopril who experienced IOH
• If creatinine rises more than 25% above baseline, delay reinitiation of lisinopril
• Ensure adequate IV fluid resuscitation before restarting the medication

Special Populations: Cardiac Surgery and High-Risk Procedures

The calculus changes for cardiac surgery. Cardiopulmonary bypass (CPB) itself causes significant RAAS activation, and some evidence suggests that preoperative ACE inhibitor use in cardiac surgery patients is associated with lower vasopressor requirements post-bypass, not higher. A meta-analysis published in JAMA in 2005 covering 11 trials found no increase in postoperative hypotension requiring vasopressors in patients continuing ACE inhibitors through cardiac surgery [9].

Individual institutional protocols vary, and the operative team's judgment takes precedence. The key distinction is that on-pump cardiac surgery maintains perfusion pressure mechanically during bypass, reducing the uncorrected hypotension window that characterizes off-pump or non-cardiac procedures.

The HealthRX Perioperative ACE Inhibitor Decision Framework, reviewed by our medical team, categorizes lisinopril patients into three tiers before elective surgery:

Tier 1 (Hold morning dose, restart at 48 h): Hypertension only, BP well controlled, eGFR >60, no diuretics, procedure under general anesthesia lasting >60 min.

Tier 2 (Hold 24 h, restart when euvolemic): Hypertension plus diuretic, eGFR 30 to 60, anticipated blood loss >500 mL, or patient age >70.

Tier 3 (Continue with anesthesia team briefed): HFrEF with EF <40%, post-MI within 90 days, or patient whose BP is uncontrolled and stopping creates acute hypertensive risk. Vasopressin should be available at induction.

What Patients Should Tell Their Surgical Team

Patients on lisinopril should disclose their full medication list, including dose and timing of the last dose, during the pre-anesthesia assessment. Specifically:

• The exact dose (lisinopril 5 mg, 10 mg, 20 mg, 40 mg daily)
• Whether they also take a diuretic, an ARB, or a direct renin inhibitor (aliskiren)
• Recent blood pressure readings and whether control is stable
• Any history of dizziness on standing, prior anesthesia complications, or kidney disease

Patients should not self-discontinue lisinopril without instruction from their prescribing provider. Abrupt discontinuation in a patient with poorly controlled hypertension can cause rebound blood pressure elevation, particularly in patients on doses above 20 mg/day.