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Postoperative flap monitoring and selected early patient discharge

Authors: Ahmad Makki MD, Thomas Givskov Sørense and Magnus Balslev Avnstorp MD


Here you will learn about post-operative observation of microsurgical flaps, which is very important and often maintained by experienced nurses or resident surgeons in night shifts. Furthermore, you will learn about that carefully selected free flap patients may be discharged early after surgery without increasing the rates of postoperative complications or readmissions.

Post-operative observation of patients with microsurgical flaps

Postoperative care should be maintained by healthcare professionals, experienced with flap monitoring and general care for patients who have undergone microsurgery.

Pain should be relieved while adequate fluid administrated and body temperature should be maintained. In case of head and neck reconstruction, the tracheostomia tube should be cleaned and maintained.

Flap Observation

Disruption of perfusion to a flap can result in partial or complete tissue loss (necrosis). Changes in flap tissue perfusion need to be recognized quickly. Therefore strict validated observation methods are used.

Circulatory disturbances can be divided into arterial insufficiency and venous insufficiency.

Clinical evaluation by an experienced microsurgeon is the gold standard for perfusion assessment. Important signs in circulatory disturbances include changes in:

  • Skin flap color
  • Capillary refilling
  • Tissue tugor
  • Stab incision by needle or a cut edge will ultimately show color of blood (dark = non oxygenated, bright red = well oxygenated) and how fast it bleeds

Arterial circulatory disturbances usually include a pale looking flap with lack of capillary refill (capillary response). Muscle flaps can be particularly difficult to judge – color change with loss of a beefy red appearance is most common.

Venous disturbances are usually caused by a clot or kink of the vessel preventing the blood from leaving the flap. The flap becomes congested and bluish in color while the capillary refill is referred to as brisk (Fast refill in 1 second in bluish color) (1).  The normal venous refill should be around 3 seconds.


  • A pale, cool flap without capillary refill implies an arterial inflow problem
  • A rigid, blue flap with rapid refill implies venous insufficiency (Brisk refill) 
  • A pink color with 1-to-2-second refill is consistent with good perfusion
  • Stabbing with a needle or the tip of a scalpel should cause bright red bleeding. If no bleeding is noted, arterial occlusion is implied. If brisk, dark bleeding occurs, venous insufficiency with congestion should be considered. The stab should be away from the base of the free flap, avoid a lesion of the perforator

Devices for flap monitoring

Surface or pencil Doppler: Small hand-held probe attached to a control box and speaker. The probe is applied to the skin overlying the blood vessel and the presence or absence of a vascular signal is determined by sound. A clear pulse sound is a safe sign.

Implantable anastomotic flow coupler: The probe is placed on the anastomosis of the draining vein from the free flap. Monitors venous flow. A continuous flow sound is a safe sign.

Pulse oximetry: The device records the pulsation of the vascular bed and the oxygen saturation. If a pulse is absent as in an arterial occlusion, or oxygen saturation is decreased as in venous occlusion, an alarm sounds.

Microdialysis: An implantable catheter in the flap that drains the interstitial fluid. The fluid is objectively measured for the metabolites glucosis, lactate and pyruvate, which is sensitive to ischemia. A stabile glucosis, a low lactate and a stabile lactate/pyruvate-ratio (L/P-ratio) is a good sign. In cases of ischemia the glucoses will decrease, while the lactate and L/P-ratio will increase.


The patients should remain in hospital for 3-14 days depending on location of surgery and drains that have been placed during surgery and the general condition and mobility of the patient


  1. Brian A Janz, Jorge I de la Torre. Principles of Microsurgery. Medscape, clinical procedures. https://emedicine.medscape.com/article/1284724-overview.

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