Key Points
- Controlled hypotension is an intentional reduction of mean arterial pressure (MAP) to decrease surgical blood loss and improve visualization, typically targeting a MAP of 50–65 mm Hg or a 20–30% reduction from baseline.1,2
- Autoregulatory limits vary by patient, and individuals with chronic hypertension require higher perfusion pressures to maintain organ blood flow.2
- Pharmacologic strategies include inhaled anesthetics, propofol, vasodilators, beta-blockers, calcium channel blockers, and alpha-2 agonists; nonpharmacologic strategies include positioning, regional anesthesia, and ventilation adjustments.2,3
- Complications include cerebral and myocardial hypoperfusion, acute kidney injury, and, in some cases, delayed emergence related to anesthetic depth or specific pharmacologic agents.4-7
Definition
- Controlled hypotension is the intentional lowering of systemic arterial pressure to reduce bleeding and improve visualization of the surgical field.1,2
- It is usually defined as either:1,2
- MAP 50–65 mm Hg, or
- A 20–30% reduction from the patient’s baseline MAP.
- Although historically referred to as controlled hypotension, the technique is more accurately understood as controlled blood pressure reduction, as the goal is to lower MAP while preserving adequate organ perfusion rather than producing true hypotension.
- Specific blood pressure targets should be individualized according to:2,4,5,7
- Patient comorbidities
- Cerebral perfusion thresholds
- Coronary perfusion thresholds
- Presence of chronic hypertension
Physiology
- MAP equals the product of cardiac output (CO) and systemic vascular resistance (SVR).
- Pharmacologic agents induce hypotension by lowering SVR, CO, or both.2,3
- Because the clinical objective is to maintain organ perfusion while reducing MAP, the term “controlled hypotension” can be physiologically misleading; the technique is intended to achieve a controlled MAP reduction that remains within each patient’s autoregulatory limits.
- Organ blood flow is normally maintained within autoregulatory limits; in chronic hypertension, the autoregulatory curve shifts to the right so that a higher MAP is needed to preserve cerebral and renal perfusion.2,4,5,7
- When MAP drops below the lower limit of autoregulation, blood flow becomes pressure-dependent, and the risks of hypoperfusion and ischemic injury increase.4,5,7
- Lowering MAP reduces arterial inflow and venous back-bleeding, with the greatest advantage in vascular surgical fields such as functional endoscopic sinus surgery, spine surgery, and orthognathic or maxillofacial operations.1,2,8
Figure 1. Autoregulation of organ blood flow and effects of chronic hypertension. Autoregulation allows relatively constant organ blood flow across a range of mean arterial pressures (MAP). In patients with chronic hypertension, the autoregulatory curve shifts to the right, so lower MAPs may be poorly tolerated and increase the risk of ischemia at “normal” hypotensive targets.
Indications
- Controlled hypotension can be used to reduce surgical bleeding and enhance visualization during procedures such as endoscopic sinus surgery, orthognathic and maxillofacial surgery, spine surgery, middle ear surgery, and total hip arthroplasty or other major orthopedic reconstructions.1,2,8,9
- It may also be employed in selected neurosurgical cases where a drier operative field is needed to permit precise dissection.2
Techniques
- Adequate monitoring is essential and typically includes continuous electrocardiography, pulse oximetry, capnography, and frequent noninvasive or invasive arterial blood pressure measurements.2,3,5,7,9
- Pharmacologic strategies for controlled hypotension include:2,3,6,8
- Inhaled anesthetics and propofol infusions to deepen anesthesia
- Vasodilators such as nitroprusside or nitroglycerin to decrease SVR
- Beta-blockers (for example, esmolol) to reduce heart rate and myocardial oxygen consumption.2
- Calcium channel blockers
- Alpha-2 agonists such as dexmedetomidine
- Nonpharmacologic strategies include:1,2,8,9
- Head-up or reverse Trendelenburg positioning during sinus and maxillofacial surgery
- Regional and neuraxial techniques that reduce SVR via sympathetic blockade
- Careful ventilation management, including mild hyperventilation in selected neurosurgical patients
- Tourniquet use for extremity orthopedic procedures
- Optimization of pneumoperitoneum pressures during laparoscopic surgery
Figure 2. Common techniques for achieving controlled hypotension. Techniques for controlled hypotension include adjustment of inhaled or intravenous anesthetics, vasodilators, beta-blockers, alpha-2 agonists, regional or neuraxial anesthesia, and patient positioning. Choice of method depends on patient comorbidities, surgical requirements, and institutional practice. The techniques presented in Figure 2 were ranked by the authors according to how frequently they are described and emphasized in the controlled hypotension literature, rather than on formal utilization data.1,2,8,9
Risks and Complications
- Potential complications of controlled hypotension include cerebral hypoperfusion and perioperative stroke.4,7
- These complications generally occur when MAP is reduced beyond the patient’s autoregulatory capacity, resulting in true hypotension rather than a controlled MAP reduction.
- Other major risks are:
- Myocardial ischemia from reduced coronary perfusion pressure.7,9,10
- Acute kidney injury due to decreased renal blood flow.5,7
- Cerebral hypoperfusion from excessive hypotension may contribute to postoperative neurocognitive dysfunction in susceptible patients.4,7
- Rarely, visual loss has been reported after spine surgery, although this complication is multifactorial and not solely attributable to hypotension.
- Excessive anesthetic depth can delay emergence, and some hypotensive agents may have effects that outlast their intended clinical window, resulting in prolonged postprocedural hypotension.2,3,6,7
Special Populations
- Pediatric patients usually tolerate lower MAPs because of strong autoregulatory mechanisms, but extra caution is needed in those with congenital heart disease, anemia, or when procedures carry a risk of venous air embolism.8
- In chronic hypertension, the rightward shift of the autoregulatory curve necessitates higher MAP targets, typically 65–75 mmHg, to prevent cerebral or renal hypoperfusion.2,4,5,7
- Elderly patients are more prone to hypoperfusion, renal injury, and postoperative neurocognitive disorders, so they need more conservative blood pressure goals and closer monitoring.4,5,7,10
- For patients with significant cardiac disease, agents that reduce SVR without major negative inotropy are generally preferred, and continuous ST-segment monitoring is recommended.3,7,10
Figure 3. Suggested intraoperative mean arterial pressure targets for common patient populations. Suggested MAP ranges vary by population and must be individualized. Healthy adults typically tolerate MAPs of 65–70 mm Hg, whereas patients with chronic hypertension, older adults, and those with significant cardiac disease may require higher MAPs (e.g., 70–80 mm Hg) to reduce the risk of myocardial, cerebral, or renal ischemia.
References
- Zhang L, Yu Y, Xue J, et al. Effect of deliberate hypotension on regional cerebral oxygen saturation during functional endoscopic sinus surgery: A randomized controlled trial. Frontiers in Surgery. 2021; 8:681471. Link
- Degoute CS. Controlled hypotension. Drugs. 2007;67(7):1053-76. PubMed
- Aronson S, Dyke CM, Stierer KA, et al. The ECLIPSE Trials: Comparative studies of clevidipine to nitroglycerin, sodium nitroprusside, and nicardipine for acute hypertension treatment in cardiac surgery patients. Anesth Analg. 2008;107(4):1110-21. PubMed
- Bijker Jilles B, Persoon S, Peelen Linda M, et al. Intraoperative hypotension and perioperative ischemic stroke after general surgery. Anesthesiology. 2012;116(3):658-64. PubMed
- Sun LY, Wijeysundera DN, Tait GA, Beattie WS. Association of intraoperative hypotension with acute kidney injury after elective noncardiac surgery. Anesthesiology. 2015;123(3):515-23. PubMed
- Ebert TJ, Hall JE, Barney JA, et al. The effects of increasing plasma concentrations of dexmedetomidine in humans. Anesthesiology. 2000;93(2):382-94. PubMed
- Sessler DI, Meyhoff CS, Zimmerman NM, et al. 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;128(2):317-27. PubMed
- Tobias JD. Controlled hypotension in children. Pediatric Drugs. 2002;4(7):439-53. PubMed
- Sneha K, Mandal S, Saha KK, et al. Effect of perioperative hypotension on long-term orthopaedic surgery recovery: A review. Bioinformation. 2025;21(4):768-73. PubMed
- Landoni G, Greco T, Biondi-Zoccai G, et al. Anaesthetic drugs and survival: a Bayesian network meta-analysis of randomized trials in cardiac surgery. British Journal of Anaesthesia. 2013;111(6):886-96. PubMed
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