Vasopressor Use and Free Flap Survival
Vasopressors do not adversely affect free flap survival and may actually improve outcomes—their use should be encouraged when hemodynamically indicated during free tissue transfer procedures. 1, 2
Evidence Supporting Vasopressor Safety
The traditional avoidance of vasopressors in microsurgery stems from theoretical concerns about pedicle vasospasm, but this fear is not supported by clinical evidence:
A 2023 systematic review and meta-analysis of 8,427 flaps demonstrated that vasopressor use actually reduced the relative risk of free flap failure (RR: 0.70; 95% CI: 0.50-0.97; p = 0.03) without increasing other adverse events. 2
A 2019 meta-analysis of 8,653 cases found vasopressors were associated with less total flap failure overall (OR: 0.71, p = 0.05) and specifically less pedicle thrombosis in head and neck reconstruction (OR: 0.58, p = 0.02). 1
Flap complication rates were similar across defect types (OR: 0.97, p = 0.81), though breast reconstruction showed a slight increase (OR: 1.46, p = 0.01). 1
Site-Specific Evidence
Head and Neck Reconstruction
A prospective randomized trial comparing goal-directed vasopressor-based protocols versus traditional volume-based support found no difference in flap failure (3% vs 7%, p = 0.63) or flap-related complications (32% vs 44%, p = 0.36). 3
Overall flap survival was 95% across both groups, with bony flaps showing lower complication rates in the vasopressor group (27% vs 55%). 3
Breast Reconstruction (DIEP Flaps)
In a large single-center series of 1,729 DIEP flaps, 79.7% of patients received intraoperative phenylephrine, ephedrine, or both with no significant difference in overall complications, microvascular events, takebacks, or flap loss. 4
Critically, the vasopressor group received significantly lower intraoperative fluid volumes, and multivariate analysis found excessive fluids (OR 2.03, p = 0.03)—not vasopressor use (OR 0.79, p = 0.7)—were associated with increased complications. 4
Extremity Reconstruction
A retrospective review of 47 consecutive free tissue transfers for head, neck, and extremity reconstruction found 53.2% received intraoperative vasopressors with 97% flap survival. 5
No significant difference existed in total or partial flap necrosis, arterial or venous thrombosis, or postoperative complications between vasopressor and non-vasopressor groups. 5
Clinical Algorithm for Vasopressor Use
When to use vasopressors during free flap surgery:
Initiate vasopressors when hypotension occurs despite adequate fluid resuscitation rather than administering excessive crystalloid volumes. 4
Vasopressor type, dose, and timing of administration do not appear to affect outcomes negatively. 1, 4, 5
Phenylephrine and ephedrine are the most commonly studied agents and appear safe for use. 4
Mechanism of Benefit
The protective effect of vasopressors likely relates to:
Optimizing hemodynamic stability and maintaining adequate perfusion pressure to the flap. 1
Avoiding iatrogenic fluid overload, which independently increases complications. 4
Maintaining systemic blood pressure ensures adequate driving pressure through the microvascular anastomosis. 2
Common Pitfalls to Avoid
Do not withhold vasopressors based on outdated theoretical concerns about vasoconstriction—this leads to excessive fluid administration which demonstrably increases complications. 4
Avoid permissive hypotension during free flap surgery; adequate perfusion pressure is essential for flap survival. 1
The majority of studies (14 studies representing 8,653 cases) found no negative effects regardless of dose, timing, or delivery method. 1