FREE FLAP MONITORING

Equipment required:  

• Suction with Yanker tip
• Gauze swabs
• Gloves
• Tongue depressors
• Light source (non LED)
• Hand held Doppler

 
Preparation: 

• Ensure good and reproducible lighting every time
• Suck out secretions and blood
• Dry and clean the flap with the gauze 
• A colleague to assist if required

Examination:  

• Colour
• Skin turgor- normal, flaccid or swollen
• Temperature- normal or cold 
• Capillary refill- should be < 2 seconds
• Hand held doppler if available
• Pin prick (registrar only- do not hit pedicle)
• Ensure no external compression- tracheostomy tapes, head in neutral position
• Repeat

Management of potential flap failure:

• Alert senior who may request you to contact theatre staff
• Evaluate and correct systemic factors (hypovolemia, hypotension) or mechanical factors (head positioning, external compression)
• Heparin +/- thrombectomy and thrombolytics
• Revise anastamosis
• Leech therapy

Buried flaps:

• Clinical assessment is not possible
• Some authors suggest a bone scan at 4 days post op

 
Important Notes:

• Venous failure is more common than arterial
• Reproducibility is the key to successful monitoring
• Avoid vasopressors during operation and postoperatively
• Micro dialysis is the gold standard but is labour intensive and expensive
• Free flap failure rates have decreased to generally less than 4% (includes successful salvage of flaps).
• The overall flap complication rate has been reported as 28-36%, with a flap takeback rate of 5-25%.
• The most critical factor in flap salvage is early detection
• Success of free tissue transfer is 95-98%
• Most failures are due to venous or arterial thrombosis
• Arterial thrombosis is responsible for 20% of failures and generally occurs within 24 hours
• Venous thrombosis is responsible for 50% of failures and generally occurs within 24-48 hours
• 80% of thrombi necessitating return to theatre occur in first 48 hours
• The probability of success of surgical salvage is low after the first 48 hours.
• Arterial problems generally present before venous

Causes of flap failure:

• Anastamotic failure- venous more common than arterial
• External compression- haematoma in neck, neck ties

Factors that may potentially affect success:

• Vein graft use
• Comorbidities (BMI, preop Hg, ASA/KFI, previous surgery, XRT, chemoXRT, smoking, diabetes)
• Previous radiotherapy
• Previous chemotherapy
• Type of anastomosis (end to end, end to side)
• Pedicle characteristics/ kinks
• Vessel selection
• Running vs. interrupted vs. anastomotic coupler
• Surgery time
• Loupes vs microscope (no evidence for this)
• Type of intraoperative fluid used
• Hypotension and vasopressor use (controversial)
• Patient age
• Osseous flaps
• Presence of infection
• Hypothermia