Sunday, April 30, 2017

Return to: Microvascular Surgery Protocols

See also: Leech Therapy - Anticoagulation Protocols 

Concepts

  • Free flap failure rates have decreased to generally less than 4%.
    • 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%.
  • The most critical factor in flap salvage is early detection
  • Factors which predict vascular compromise:
Does MatterMay MatterDoes Not Matter
Pedicle characteristics/kinkspatient factors and comorbidities (BMI, preop Hg, ASA/KFI, previous surgery, XRT, chemoXRT, smoking, diabetes)Type of anastomosis (end to end, end to side)
Surgery timeVessel selectionRunning vs. interrupted vs. anastomotic coupler
Tight closure (vessels, skin)Location of defect – skull base/midfaceLoupes vs microscope
AgeIntraop fluid >7L, Crystalloid >6 mL/kg/hHypotension and vasopressor use (controversial) (Monroe et al. 2010)
Presence of infectionOsseous flaps 
Previous surgery/radiationHypothermia
 Vein graft use
 History of previous DVTs (deep venous thromboses)
 
  • Significant variation exists in flap monitoring and management protocols
    • Monitoring frequencies
      • 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 (Spiegal et al. 2007)
    • Monitoring methods
      • Visual exam - color, capillary refill, turgor, temperature
      • Pin prick – assess flow and color
      • Doppler signal
      • Devices – implantable Doppler, contrast Doppler, laser Doppler, Autoflow, surface temperature, photopletysmography, electrical impedance plethysmography, microdialysis, tissue pH
    • Anticoagulation regimens:
AgentMechanismProtocols used at IowaPrevalence of use in survey (Spiegal et al. 2007)
HeparinBinds 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 patient size

- may be used at therapeutic dosage of 500 units/hr

27%
ASAIrreversible COX inhibitor- 81mg x 14 days
- 325mg until discharge home
77%
DextranPrevent fibrin stabilization of thrombi, platelet adhesion? Risk pulmonary edema, renal failure.- 12h on, 12h off x 5 days35%
Toradol   
Lovenox   

Iowa Post-Operative Flap Protocol

  1. Best head position is indicated on a written order, no pillows
    • Avoid kinks on vascular pedicle
  2. No trach ties, no elastic cords
    • Avoid external compression
  3. Monitoring
    1. Resident
      • 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.
      • Exam
        • Visual assessment for color
        • Assess turgor
        • Capillary refill
        • Pinprick
        • Doppler signal
    2. Nursing
      • Doppler signal and color
      • Q1h  for 48h, then q4h for 72h, then q8h 

Findings in Select Post-Operative Complications

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

Flap Salvage

  1. Direct exploration
    • Alert OR staff
    • 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
    • If thrombosis found:
  2. Leech therapy (see Leech Therapy Protocol)
    • For venous congestion
    • 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

Monroe MM, McClelland J, Swide C, Wax MK. Vasopressor use in free tissue transfer surgery. OHNS, (2010) 142, 169-173

Spiegal JH, Polat JK. Microvascular flap reconstruction by otolaryngologists: prevalence, postoperative care, and monitoring techniques. Laryngoscope 117:485--490, 2007