Determining critical thresholds of tissue perfusion using indocyanine green in reconstructive surgery

The success or failure of a reconstruction is largely related to the
vascularization of the operated area. Especially in the presence of
non-vascularized material such as an implant or osteosynthesis material or a
need for adjuvant radiotherapy, adequate perfusion is of crucial importance.
Various techniques are used in reconstructive surgery to deliver
well-vascularized tissue, including local transpositions, pedicled skin / bone
/ muscle flaps or a so-called free flap, in which a tissue flap based on a
donor vessel is detached and anastomosed elsewhere on an acceptor vessel.
Nowadays we mainly focus on clinical signs such as capillary refill,
temperature, color and bleeding of the wound edges to access the vitality of
tissue. Alternatives include optical coherence imaging, laser Doppler,
saturation measurements and infrared thermography. A previous review in our
institute showed that the Doppler or fluorescence research has the most
potential to quantify perfusion. A doppler measurement (invasive or not)
provides local information about the patency of a vessel or anastomosis, but
this does not provide information about the exact blood flow in the different
regions in an operating area.
Near infrared fluorescence (also near infrared fluorescence angiography, NIR
FA) with ICG administration is an innovative technique to quantify tissue
perfusion. ICG was introduced by Fox et al. in 1957. and is widely implemented
in the medical field today. ICG is used for diagnostic purposes only. It has
been used successfully in vascular surgery, oncologic surgery and colorectal
surgery. Use of ICG to measure bone perfusion has been used less often, but has
been published in animal and cadaver models and even in patients. Based on the
results obtained in other subspecialties, NIR fluorescence appears to be a
promising way to quantify tissue perfusion in reconstructive surgery.

Our primary objective is to determine critical values of tissue perfusion for
reconstructive surgery be quantification using near-infrared fluorescence. The
fluorescence signal will be derived from a signal to noise ratio. The primary
outcome measures include the maximum and relative perfusion intensity.

The ultimate clinical goal is to prevent complications including partial lap
failure, wound dehiscence, wound infections and osseous non - union and these
parameters are being collected as secondary objectives.

This is an umbrella protocol that can be used for several prospective cohorts
with a similar study design. The cohorts will be included at the Amsterdam UMC,
location AMC and VUMC. We will include patients undergoing surgical debridement
(1) after trauma or radionecrosis and / or reconstructive surgery (2). As soon
as the patient is scheduled for surgery, we will provide the patient
information by mail. Our goal is to inform the patients at least one week in
advance and bring it to the attention again upon admission. There will rarely
be a patient who cannot give informed consent prior to the planned operation
because of major trauma in which the patient is operated immediately.

It's a very minor effort for the patient and the only risk lies in an allergic
response for which the risk is very low.