Free Flap Surgery
Last modified: 10 February 2022, 5:33:46 PM AEDT
Gems1 / 6
- Priority = flap survival
- Breast reconstruction
- Implant-based
- Autologous flap
- Flap perfusion
- Q = (π x ΔP x r4) / (8 x μ x L)
- r = vessel radius
- L = length
- μ = blood viscosity
Contraindications2 / 6
- Hypercoagulable states = ⬆risk anastomotic thrombosis
- sickle cell anaemia
- polycythaemia
Technique / description3 / 6
- Gold standard = deep inferior epigastric perforator free flap
- Types
- Pedicled
- Latissimus dorsi
- Free flap
- requires microsurgery
- harvest ellipse of lower abdominal tissue and transfer to chest
- TRAM = transverse rectus abdominis myocutaneous
- DIEP = deep inferior epigastric perforator
- spares rectus abdominis M = preserves abdominal strength, ⬇risk hernia
- Pedicled
- Microvascular anastomosis to internal mammary A and V in chest
- Insetting of flap and shaping of transferred tissue
Complications4 / 6
- Primary ischaemia
- during flap transfer
- anaerobic cellular metabolism
- proportional to duration of ischaemia
- TRAM flaps (which contain M) are more sensitive to ischaemia
- Reperfusion
- begins with vessel declamping after completion of microvascular anastomosis
- Flap perfusion
- denervated = loses intrinsic E tone
- feeding A/V still response to physical (temperature), circulating catecholamines, drugs
- priorities = avoidance of
- hypovolaemia
- hypothermia
- vasoconstriction
- Interstitial oedema
- absence of intact lymphatics
- Flap failure
- incidence DIEP = 0.9%
Anaesthetic considerations5 / 6
-
Pre-op
-
Appropriate patient selection is predictor of good clinical outcome in microsurgery
- Advanced age
- co-morbidities
- Smoking = 4 weeks cessation
- Obesity = Weight loss
-
Intra-op
-
Optimise flap perfusion
- C = Provision of full, hyperdynamic circulation
- normovolaemia
- caution fluid overload
- internal mammary A = close to heart = excellent perfusion pressure
- C = maintain MAP
- ephedrine / phenylephrine appears safe
- E = Maintain normal body temperature
- Underbody warming
- adequate ambient temperature
- C = adequate Hct
- optimal balance between viscosity, BQ, adequate O2-carrying capacity = 30-35%
- careful haemodilution / normovolaemia
- F = careful fluid management
- goal-directed therapy
- H = DVT prophylaxis
- TEDS + calf compressors
- C = Provision of full, hyperdynamic circulation
-
Long surgery > 8 hr
- D = VA (Des / Sevo / Iso)
- Sevo = may attenuate ischaemic-reperfusion injury
- Iso = maintains microcirculatory flow
- TIVA = emergence can be prolonged
- D = Remifentanil
- excellent intraop analgesia
- rapid control of arterial BP
- marked vasoD
- negates use of NMBA
- D = Careful positioning
- D = VA (Des / Sevo / Iso)
-
Emergence
-
reduce coughing = ⬆venous pressure, ⬇flap blow
-
techniques
- remifentanil
- deep extubation
- exchange ETT for LMA
-
Post-op