hg

Others

Ward

Common Calls

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