Can noradrenaline (norepinephrine) be used to maintain blood pressure in patients undergoing free muscle flap surgery?

Can Noradrenaline Be Used for Free Muscle Flap Surgery Patients to Maintain Blood Pressure?

Yes, noradrenaline can be used to maintain blood pressure in free muscle flap surgery patients, but it should be used judiciously after optimizing intravascular volume, and caution is warranted in patients with multiple vascular comorbidities.

Key Principles for Vasopressor Use in Free Flap Surgery

Optimize Volume Status First

• Volume optimization must precede vasopressor initiation to ensure adequate tissue perfusion and avoid unnecessary vasoconstriction 1.
• Goal-directed hemodynamic therapy using stroke volume monitoring should guide fluid resuscitation before commencing vasopressors 1.
• Bedside transthoracic echocardiography can assess cardiac contractility and guide appropriate use of inotropes versus vasopressors once optimal intravascular volume is achieved 1.

Blood Pressure Targets During Surgery

• Maintain mean arterial pressure (MAP) ≥60-65 mmHg during surgery to prevent end-organ injury including acute kidney injury and myocardial injury 1.
• A MAP target of 60-65 mmHg individualized to the patient should be maintained using appropriate vasopressors as needed 1.
• Intraoperative hypotension (MAP <65 mmHg or systolic blood pressure <90 mmHg) for approximately 15 minutes is associated with postoperative organ injury 1.

Noradrenaline as First-Line Vasopressor

• Noradrenaline is the first vasopressor of choice for maintaining adequate blood pressure once volume status is optimized 1.
• Noradrenaline provides both vasoconstrictor effects and beta-agonism to support cardiac contractility 1.
• Low doses of noradrenaline or phenylephrine are strongly recommended to maintain adequate gut and tissue perfusion when hypotension persists despite fluid optimization 1.

Evidence Specific to Free Flap Surgery

Safety Profile in Free Flap Patients

• Perioperative noradrenaline use does not adversely affect free flap survival in patients undergoing microvascular reconstructive surgeries 2.
• In a retrospective analysis of 120 free flap patients, those receiving noradrenaline had no significant difference in flap outcome compared to controls (0% poor outcome vs 3.92% in controls) 2.
• Experimental studies in pigs showed that moderate normovolemic hypotension or noradrenaline use for correcting hypotension did not affect flap perfusion as assessed by microdialysis 3.

Critical Caveat: Vascular Comorbidities

• Patients with two or more vascular comorbidities who receive vasopressors have significantly higher risk of partial flap necrosis (OR: 3.882,95% CI: 1.266-14.752) 4.
• In patients with multiple vascular comorbidities (hypertension, diabetes, peripheral vascular disease), vasopressor use should be minimized or limited 4.
• The re-exploration rate may be marginally increased with noradrenaline use, though final flap outcome remains unaffected in patients without multiple comorbidities 2.

Avoid Hypovolemia

• Extradural anesthesia combined with even mild hypovolemia (10% blood loss) causes significant decreases in cardiac output (31%), MAP (24%), and flap microcirculatory blood flow (20-22%) 5.
• During phenylephrine infusion in normovolemic conditions, MAP increases while microcirculatory blood flow in flaps remains stable 5.
• This underscores the critical importance of maintaining normovolemia before and during vasopressor administration 5.

Practical Algorithm for Vasopressor Use

Step 1: Assess Volume Status

• Use goal-directed hemodynamic monitoring with stroke volume assessment 1.
• Ensure adequate intravascular volume before considering vasopressors 1.
• Consider arterial line placement for continuous blood pressure monitoring 1.

Step 2: Identify Patient Risk Factors

• Document number of vascular comorbidities (hypertension, diabetes, peripheral vascular disease, coronary artery disease) 4.
• Patients with ≥2 vascular comorbidities require heightened caution with vasopressor use 4.

Step 3: Initiate Vasopressor if Needed

• If MAP remains <60-65 mmHg despite adequate volume resuscitation, start noradrenaline infusion 1.
• Begin with low doses and titrate to maintain MAP ≥60-65 mmHg 1.
• Noradrenaline can be safely started via large peripheral vein until central access is established 1.

Step 4: Monitor Flap Perfusion

• Maintain normothermia as hypothermia is associated with worse outcomes 2.
• Avoid excessive crystalloid administration which may cause tissue edema 6.
• Minimize red blood cell transfusions as they may increase postoperative complications (though this relationship is not definitive) 6.

Common Pitfalls to Avoid

• Do not use vasopressors as first-line treatment for hypotension without ensuring adequate volume status 1.
• Do not avoid vasopressors entirely when hypotension persists despite adequate volume, as prolonged hypotension causes organ injury 1.
• Do not use aggressive vasopressor dosing in patients with multiple vascular comorbidities without careful risk-benefit assessment 4.
• Do not combine epidural anesthesia with hypovolemia, as this significantly impairs flap perfusion 5.