ANAESTHESIA FOR FREE FLAP SURGERY: WHAT DO ANAESTHESIOLOGISTS THINK?

BACKGROUND

Microvascular free flap surgery is currently the main technique to ensure head and neck cancer reconstruction, improving survival and functional outcomes.1 Success rate of this surgery has raised mainly due to advancements in the knowledge of the physiology underlining flap survival. Few scientific evidence exists concerning the best anaesthetic practice for this type of surgery.
The aim of this study was to characterize current anaesthetic management for free flap head and neck surgery.

METHODS

A literature review was performed using the terms free flap, anaesthesia, head and neck  and microvascular free tissue. Posteriorly, we applied a survey sent by e-mail to Portuguese Anaesthesiology Services, between May and December 2017. Results were analysed using Microsoft Excel 2016®.

RESULTS

We obtained 29 responses. Responders’ characteristics are described in graphics 1 and 2.
In response to a clinical scenario in which anaesthesiologists were asked what would be their first line strategy to raise arterial pressure when surgically needed, 36% answered they would reduce remifentanil, 22% would use crystalloids and 18% would use colloids. Regarding the use of vasopressors, 86% responded they avoid its use whenever possible and only 10% considered the use of vasopressors safe in this type of surgery.
The majority (69%) responded they reached a neutral to 2L positive fluid balance at the end of surgery, against 31% who reached a final 2-5L positive fluid balance. Concerning the use of colloids, 50% stated that the most adequate type to use is a hydroxyethyl starch. 89% of the responders limits the use of colloids to a maximum of 2L. 
On the matter of fluid management, 41% considered measuring serum lactate the most useful parameter and 32% considered instead the urinary output.
Regarding monitoring, 86% use central temperature monitoring. Although 93% use invasive blood pressure, only 10% use cardiac output monitoring. 

DISCUSSION AND CONCLUSIONS

The majority of anaesthesiologists (55%) stated that they anesthetize for this type of surgery on an irregular basis, which is surprising since free flap surgery is usually performed on reference centres, where a more regular practice would be expected.
In order to expand plasma volume and raise arterial pressure, most of the responders still prefers the use of crystalloids rather than colloids, even if scientific evidence favors the use of colloids in this context. Another unexpected topic is that only 10% of anaesthesiologists considered vasopressors safe to use in this type of surgery, even if recent evidence suggests that its use is safe, contrarily to what has been published in the past.
Anaesthetic management for free flap surgery is controversial. More studies are needed to establish the best evidence-based anaesthetic strategy.

12 / Anaesthesia for free flap surgery: what do anaesthesiologists think?