Free Flap Monitoring and Salvage

 return to: Microvascular Surgery Protocols; see Leech Therapy - Anticoagulation Protocols 

Concepts

1. Free flap failure rates have decreased to generally less than 4%.
   1. This includes successful salvage of flaps. The overall flap complication rate has been reported as 28-36%, with a flap takeback rate of 5-25%.
2. The most critical factor in flap salvage is early detection
3. Factors which predict vascular compromise:

Does Matter	May Matter	Does Not Matter
Vein graft use	patient factors and comorbidities (BMI, preop Hg, ASA/KFI, previous surgery, XRT, chemoXRT, smoking, diabetes)	Type of anastomosis (end to end, end to side)
Pedicle characteristics/ kinks	Vessel selection	Running vs. interrupted vs. anastomotic coupler
Surgery time	Location of defect – skull base/midface	Loupes vs microscope
Tight closure (vessels, skin)	Intraop fluid >7L, Crystalloid >6 mL/kg/h	Hypotension and vasopressor use (controversial)(ref 1)
Age	Osseous flaps
Presence of infection	Hypothermia

1. Significant variation exists in flap monitoring and management protocols
   1. Monitoring frequencies
      1. In survey of academic otolaryngology programs, range from simple protocol of Q2h x 72h to complex protocol of Q1hx 48h, Q2h x48h, Q4h x48h, Q8h (ref 2)
   2. Monitoring methods
      1. Visual exam - color, capillary refill, turgor, temperature
      2. Pin prick – assess flow and color
      3. Doppler signal
      4. Devices – implantable Doppler, contrast Doppler, laser Doppler, Autoflow, surface temperature, photopletysmography, electrical impedance plethysmography, microdialysis, tissue pH
   3. Anticoagulation regimens

Agent	Mechanism	Protocols used at Iowa	Prevalence of use in survey (ref 2)
Heparin	Binds antithrombin III, inactivate Xa and thrombin. May also reduce platelet aggregation.	-  start at end of flap harvest, then bid -  start at beginning of case, then bid-tid depending on pt size	27%
ASA	Irreversible COX inhibitor	- 81mg x 14days - 325mg until d/c home	77%
Dextran	Prevent fibrin stabilization of thrombi, platelet adhesion? Risk pulmonary edema, renal failure.	- 12h on, 12h off x 5 days	35%

 

Iowa post-operative flap protocol

1. Best head position is indicated on a written order, no pillows
   1. Avoid kinks on vascular pedicle
2. No trach ties, no elastic cords
   1. Avoid external compression
3. Monitoring
   1. Resident
      1. The on-call resident is called to the operating room at the end of the case to become familiar with the appearance of the patient's flap. Resident checks are q3h for the first 24 hours, then bid.
      2. Visual assessment, pinprick, Doppler signal
   2. Nursing
      1. Doppler signal and color
      2. Q1h  for 48h, then q4h for 72h, then q8h 

Findings in select post-operative complications

1. Hematoma
   1. Subtle flap fullness
   2. Bruising of neck skin
   3. Dark blood on pinprick
2. Venous congestion:
   1. Swollen and tense with dark blue congestion
   2. Immediate, dark blood on pinprick
   3. More common than arterial insufficiency
3. Arterial insufficiency
   1. Pale, cold, no palpable turgor
   2. Does not bleed when pricked
   3. No Doppler pulse

Flap salvage

1. Direct exploration
   1. Alert OR staff
   2. While waiting, evaluate and correct systemic factors (hypovolemia, hypotension) or mechanical factors (head positioning, external compression) if present, and consider incising the flap as a temporizing measure if congested
   3. If thrombosis found:
      1. Heparin +/- thrombectomy and thrombolytics (see Anticoagulation Protocol)
      2. Revise anastamosis
2. Leech therapy (see Leech Therapy Protocol ) 
   1. For venous congestion
   2. Consider if patient who cannot safely return to the operating room, possibility of successfully revising flap is very small (this is determined by the operating surgeon), only a portion of the flap is affected

References

1. Monroe MM, McClelland J, Swide C, Wax MK. Vasopressor use in free tissue transfer surgery. OHNS, (2010) 142, 169-173
2. Spiegal JH, Polat JK. Microvascular flap reconstruction by otolaryngologists: prevalence, postoperative care, and monitoring techniques. Laryngoscope 117:485--490, 2007