Definition & Overview
Flap and graft surgeries are common medical procedures used in plastic and reconstructive surgery. They are similar in a sense that they both involve skin transplantation. The difference is, in flap surgery, the tissue from the donor site needs to be transplanted with an adequate blood supply, which isn’t the case in graft surgery. Nevertheless, blood flow at the donor site needs to be adequate in order to ensure the success of either procedure.
One of the ways surgeons use to test a prospective donor site for adequate blood flow is to inject an agent, such as fluorescein, into the blood stream. As the agent is visible through the skin using a UV light, doctors can gauge if blood flow to the area is sufficient.
To appreciate the importance of injecting an agent to test blood flow, it is important to understand the different types of graft and flap surgeries.
There are two types of graft surgeries — full thickness and partial skin graft. In a full thickness skin graft, the donor site is made up of both the upper and lower layers of skin, otherwise known as the epidermis and dermis. In a partial skin graft, only the epidermis and a small portion of the dermis are harvested for transplantation.
Flap surgeries are a bit more complex since they have different classifications. They can be classified by their composition, location, or vascular pattern.
However, regardless of the classification, every type of flap surgical procedure requires the same component: a healthy blood supply. This means that the donor site may have a different composition or come from different locations, but the site needs to have an adequate supply of blood. This is why a flap surgery also involves harvesting arteries and veins from the donor site.
Who Should Undergo & Expected Results
Graft or flap surgeries are recommended for people who have lost a significant amount of skin and tissue at certain body parts. The loss could be due to an injury, disease, or medical treatment, such as mastectomy or amputation.
The diameter and condition of the receiving site will determine whether the surgical procedure would be a skin graft or flap surgery.
In some cases, the reconstruction surgical procedure is performed right after the medical treatment procedure. For instance, a flap surgery may be performed immediately after a mastectomy.
Regardless of when the flap or graft surgical is performed, doctors want to ensure that the procedures have the highest chances of success. Doctors will recommend a graft procedure if the receiving site has an adequate blood supply. If not, the doctor may recommend a flap surgery instead because this would mean that the donated tissue would come with its own blood supply.
How Does the Procedure Work?
Prior to a graft or flap surgery, the doctor will gauge the chances of success by measuring the flow of blood at the donor site. This can be done by injecting a dye (agent) into the bloodstream. The spread of the agent through the blood stream can be tracked via an ultraviolet light.
One of the common agents used in the procedure is fluorescein. Various studies suggest that fluorescein is reliable and that the results are consistent. Moreover, a fluorescein test is safe and researchers have only noticed a few minor bad reactions.
If the test predicts a high survivability rate of a flap or graft, the surgeon will proceed with the procedure.
Skin graft surgeries are usually scheduled weeks in advance so patients have sufficient time to prepare themselves.
In most cases, patients will be able to return home after the procedure. However, if a general anaesthetic is used, they may need time to recover in the hospital for at least a couple of hours before they are allowed to travel.
For the procedure, the surgeon will perform a fluorescein test on the donor site to ensure that it has sufficient blood supply. If so, the surgeon will proceed to harvest the graft according to the chosen method (full or partial thickness). The graft will then be placed over the receiving site and stitched into place.
A flap surgery is similar, but with the addition of microsurgery to connect the blood vessels at the receiving site.
After performing a successful fluorescein test, the doctor will proceed to remove the donor tissue and transplant it into the receiving site. However, the procedure will take a bit longer because the surgeon will need to connect the blood vessels through microsurgery.
It can take months for a flap surgery to heal. During this time, the doctor will monitor the progress of the flap. This is done to ensure that it has survived the procedure and is accepted by the recipient site.
Possible Risks and Complications
All medical procedures have risks and a possibility for complications. In a skin graft or flap surgery, there is a risk that the procedure may not be successful. The graft or flap may not survive even if different tests have predicted a good chance of survivability.
Moreover, the donor site may be affected as well. Especially if the tissue removed contains muscles. Patients can expect a certain degree of pain at both the recipient and donor sites while recovering. Therefore, it is important that they have access to pain medications.
There is also a risk of developing an infection at the affected areas. Should an infection occur, it would need to be managed promptly to prevent it from spreading and affecting the newly transplanted tissue.
In addition to the risk and possible complications of the procedure itself, there are also risks associated with a fluorescein test. However, they are usually minor. Some patients have reported nausea and increased blood pressure over 10% of the pre-procedure reading.
Burnam JA, “Intravenous Fluorescein Vascularity Studies of a new Technique: The Subcutaneous Pedicled Extension Flap”: http://www.ncbi.nlm.nih.gov/pubmed/17431986
McGrath MH, Adelberg D, Finseth F; “The intravenous fluorescein test: use in timing of groin flap division”; http://www.ncbi.nlm.nih.gov/pubmed/365930
Morykwas MJ, Hills H, Argenta L.C.; “The safety of intravenous fluorescein administration”; http://www.ncbi.nlm.nih.gov/pubmed/1883161
**What is Intravenous Injection of an Agent to Test Vascular Flow in Flap or Graft?**
Intravenous injection of an agent to test vascular flow in a flap or graft, also known as **fluorescein angiography**, is a medical procedure used to assess the blood flow in a surgical flap or transplanted tissue graft. It involves the injection of a fluorescent agent, typically fluorescein sodium, intravenously, followed by observation and imaging of the injected area to assess the vascularity of the tissue.
* **Visualization of blood flow:** Fluorescein angiography allows real-time visualization of blood flow in the flap or graft, enabling surgeons to evaluate the adequacy of vascularization.
* **Early detection of vascular compromise:** The procedure can detect early signs of vascular compromise, such as thrombosis or ischemia, allowing prompt intervention to prevent tissue loss.
* **Guidance for flap positioning and dissection:** By identifying areas of good and poor perfusion, fluorescein angiography can guide surgeons in selecting the optimal flap anatomy and dissection planes during reconstructive surgery.
* **Monitoring of graft survival:** In the case of tissue grafts, fluorescein angiography can be used to monitor graft survival and assess the revascularization process over time.
After intravenous injection of the fluorescent agent, the flap or graft should exhibit a uniform distribution of fluorescence, indicating adequate blood flow. Any areas of absent or diminished fluorescence suggest vascular impairment or compromise.
Intravenous injection of an agent to test vascular flow in a flap or graft is typically performed in the following steps:
* A small amount of fluorescein sodium is injected into a peripheral vein.
* The area of interest is illuminated with a specific wavelength of light (e.g., blue or green) that excites the fluorescein.
* A camera or imaging device captures images of the fluorescence, which can be viewed on a monitor or recorded for further analysis.
Intravenous injection of an agent to test vascular flow in a flap or graft is a valuable tool in the armamentarium of surgeons performing flap and grafting procedures. It provides real-time assessment of blood flow, early detection of vascular problems, and guidance for surgical decision-making. By enhancing the visualization of vascularity, fluorescein angiography helps optimize surgical outcomes and prevent tissue complications.