Flap Monitoring Instructions

Evaluation of a Flap for Clinicians

Every flap, whether a pedicle flap such as a TRAM flap or a free flap such as a DIEP flap has arterial inflow and venous drainage. When the inflow or drainage is compromised the flap is at risk of dying and becoming necrotic. Early recognition of vascular compromise may allow for flap salvage by taking the patient back to the operating room for either repair of the microvascular anastomosis, adding another venous anastomosis to increase drainage, or perhaps just repositioning of the pedicle. Success in flap salvage is very dependent upon keeping this compromised time to a minimum. Therefore early diagnosis is imperative.

Arterial compromise of a flap is less harmful to the flap than venous compromise. With venous compromise blood is continuously pounding the flap from the arterial side with no drainage. The flap becomes engorged with blood and may take on a bluish hue and later a frank purplish color. The flap will become hard and distended i.e. swollen. The flap may try to decompress itself by bleeding from the edges with a resultant hematoma. Pinprick to this flap will give rapid, dark, bleeding. Eventually, the artery will secondarily thrombose. When this happens the situation is almost always unsalvageable. Venous problems are more common than arterial problems.

With arterial compromise, the flap will have a white appearance. There is no capillary refill. Pinprick will not give any spontaneous bleeding. Unless blood flow is restored to this flap, it will go on to die.

Clinical evaluation of a flap should include evaluation of how soft the flap is, the color of the flap, and capillary refill. Clinical evaluation is a necessary and required part of any flap evaluation. Capillary refill is easiest to see when a round device such as the handle from a clamp is utilized. Capillary refill should be between 1.5 and 2.5 seconds. Rapid capillary refill may represent venous compromise. Capillary refill can sometimes be hard to see. This would occur in the patient of color, with a low hematocrit, or in a patient where the arterial side is in spasm or constricted. If capillary refill is not visible, the next step in the evaluation would include pinprick to the flap. Spontaneous bleeding should occur within 20 - 30 seconds. Pinprick is done by utilizing a 25 gauge needle that is barely inserted into the dermis and then brought upwards to make a small tear in the skin surface. If one spot does not bleed, a second attempt should be performed. With a low hematocrit, there is often constriction of the vessels, bleeding on pin prick can take 30 seconds, and capillary refill may be impossible to see. Consideration for transfusing this patient should be given and close continued observation performed.

Temperature was not included in flap evaluation because it is unreliable. For example, if the flap was used to reconstruct a breast then most of it was buried beneath the patient's skin and the breast is sitting under the covers. One would expect this flap to be warm whether it was being perfused or not.

A flap that has been previously compromised and salvaged in the operating room is particularly difficult to evaluate. The flap that has been venous compromised may have a bluish tinge. Serial examinations are especially important in this situation. If this flap is becoming bluer, if the flap is becoming more swollen, then this would indicate ongoing venous insufficiency. This situation requires intervention to prevent flap loss. The person leaving and the person coming on duty should evaluate this flap together so that a baseline for the new observer is established.

If you have the responsibility of evaluating a flap, never accept anything but certainty that the flap is healthy. If this requires calling a second observer or the attending, then that should be done. A resident should call his senior resident first, a nurse should call either a more senior nurse or a resident for the second evaluation. If you do not believe what the second observer has told you or are still unclear about the status of the flap, then the attending should be notified. Your responsibility does not end until you are certain that the flap is healthy or the attending is called. Remember, with a vascularly compromised flap, time is of the essence.

A previously venous compromised flap that has been salvaged but still has a bluish appearance will eventually go on to become a pink and healthy flap.

In addition to the clinical observation, we are fortunate to have the availability of the ViOptix monitor. This is a monitor that sits on the surface of the skin and continuously measures tissue oxygenation. This is different than the pulse oximeter which measures oxygenation in the blood. A fall in tissue oxygenation can mean a flap that is vascularly compromised. As the normal value of tissue oxygen varies from patient to patient and flap to flap, familiarity with this equipment is necessary for interpretation of the data. This monitor may indicate that a flap is compromised before that conclusion is made clinically.

Supplemental nasal oxygen raises the tissue oxygen saturation in a flap and may offer some protection by extending the time available to salvage a compromised flap.

The position of the patient, i.e. upright or supine can also change the appearance of a flap and the tissue saturation. Any flap that you suspect is compromised when it is evaluated in an upright position should be reevaluated with the patient in a supine position and with nasal oxygen in place.


  • A hematoma in the recipient area where a flap has been placed does not require any action if the flap appears healthy. T/F
  • Every flap should be pricked as part of its evaluation. T/F
  • The patient has a hematocrit of 25 and no visible capillary refill. The very next step in flap evaluation is ___________.
  • Pinprick flap evaluation is done by barely scratching the surface of the skin with a small gauge needle. T/F
  • A high tissue oxygen saturation reading on the ViOptix monitor makes clinical evaluation of the flap unnecessary. T/F
  • A warm flap is always a healthy flap. T/F
  • A flap that bleeds spontaneously not on the first, but on the second pinprick after 20 seconds is healthy. T/F
  • If a flap has capillary refill of 2 seconds and is pink, no further clinical flap evaluation is necessary at that time. T/F
  • Capillary refill of 1 second may mean _______________.
  • If a flap has been evaluated and is thought to be compromised, the correct action is _____________.


  • F
  • F
  • Pinprick the flap to evaluate bleeding
  • T
  • F
  • F
  • T
  • T
  • Venous compromise
  • To call the attending