Authors: Kong H et al.
Anesthesiology 144(2): 301–313, February 2026, 10.1097/ALN.0000000000005778
This single-center, randomized, double-blind, placebo-controlled trial evaluated whether preemptive magnesium sulfate infusion improves intraoperative hemodynamic stability during pheochromocytoma and paraganglioma (PPGL) resection.
Hemodynamic instability during PPGL surgery remains a major perioperative challenge due to catecholamine surges during tumor manipulation and vasoplegia after tumor removal. Although magnesium has been used empirically to blunt catecholamine effects and stabilize blood pressure, robust randomized data have been limited.
In this study, 92 patients scheduled for PPGL resection were randomized to receive either magnesium sulfate (50 mg/kg loading dose followed by 15 mg/kg/h infusion) or placebo. Infusions began 30 minutes before surgery and were discontinued after tumor removal. Eighty-eight patients were included in the modified intention-to-treat analysis.
The primary outcome was a composite measure of intraoperative hemodynamic instability, defined as cumulative time outside prespecified targets (systolic arterial pressure >160 mmHg, mean arterial pressure <60 mmHg, heart rate >100 beats/min), expressed as a percentage of total anesthesia duration.
Results showed:
• Cumulative instability time was significantly lower in the magnesium group: 4.3% versus 8.3% in placebo (P = 0.003).
• Maximum intraoperative systolic pressure was lower with magnesium (median 185 mmHg vs 196 mmHg; P < 0.001).
• Fewer patients required phentolamine (66% vs 89%; P = 0.011).
• Total phentolamine dose was lower (3 mg vs 9 mg; P = 0.011).
• Peak magnesium concentration after loading was 1.82 mmol/L.
• No significant differences in safety outcomes were observed.
Importantly, magnesium reduced both hypertensive surges and overall instability duration without increasing adverse events.
Mechanistically, magnesium acts via calcium channel antagonism, sympatholytic effects, and attenuation of catecholamine release, which makes physiologic sense in PPGL physiology.
What You Should Know
PPGL resection remains one of the highest-risk procedures for dramatic intraoperative hemodynamic fluctuations despite preoperative alpha-blockade. This trial provides prospective randomized evidence supporting routine preemptive magnesium infusion in this setting.
The magnitude of effect is clinically meaningful. Reducing cumulative instability time by approximately half may translate into fewer end-organ stress episodes, although longer-term outcome data were not evaluated here.
For anesthesiologists managing complex endocrine cases, this regimen appears:
• Effective in reducing blood pressure excursions
• Associated with lower vasodilator requirements
• Not linked to increased safety concerns
Given that magnesium is inexpensive and widely available, this protocol may reasonably be incorporated into PPGL management pathways pending institutional review.
Key Points
• Randomized, double-blind trial in PPGL surgery patients.
• Preemptive magnesium significantly reduced cumulative intraoperative instability.
• Lower peak systolic pressures and reduced phentolamine use were observed.
• No increase in adverse safety outcomes.
• Provides high-quality data supporting magnesium use in PPGL resections.
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