Near-Infrared Imaging for Perfusion Assessment of Traumatic Soft Tissue and Skeletal Injuries

To date, intraoperative assessment of tissue and bone viability is predominantly subjective, depending on the clinical view of the surgeon, resulting in a variation in the thoroughness of debridement. Inadequate initial resection leads to multiple debridement interventions, leading to prolonged hospitalization or readmission with consequently high direct medical costs.

Near-Infrared Fluorescence (NIRF) imaging with Indocyanine Green (ICG) could potentially be a relevant contribution to adequately treating soft tissue and skeletal injuries by creating an improved distinction between viable and non-viable tissue, based on perfusion indices.

This study evaluates whether intraoperative perfusion assessment with ICG fluorescence imaging is a feasible and quantifiable technique for treating traumatic injuries.

Rationale: In 2020 71.623 Dutch patients were acutely admitted to hospitals due to sustained traumatic injuries. 7% of the injuries related to open wounds and 44% to fractures. The majority of traumatic musculoskeletal injuries needs to be diagnosed and treated as soon as possible to lower the risk of infections and to minimize adverse outcome, such as necrosis and/or osteomyelitis. To date, intraoperative assessment of tissue and bone viability is predominantly subjective, resulting in a variation in thoroughness of debridement. If not all necrotic tissue is removed, suboptimal healing occurs, which serves as a potential food source for bacteria. In addition, inadequate initial resection leads to multiple debridement interventions, leading to prolonged hospitalization or readmission with consequently high direct medical costs. Since tissue necrosis is an ongoing process, radical resection of avital tissue during the initial procedure is not always possible. The surgeon's visual estimation is not optimal to predict the final amount of debridement. After maximal debridement, antibiotic treatment and coverage of open wounds, the incidence of infection can rise to 27%. Compromised perfusion is at the centre of this problem. An adequate blood supply is crucial for tissue viability and infection clearance.

Near-Infrared Fluorescence (NIRF) imaging with Indocyanine Green (ICG) has already shown its potential in effective real-time assessment of intra-operative tissue perfusion and the early prediction of future necrosis in multiple studies. This technique could potentially be a relevant contribution in adequately treating soft tissue and skeletal injuries by creating an improved distinction between viable and non-viable tissue, based on perfusion indices. However to date, the feasibility to quantify this technique in posttraumatic tissue has not been successfully evaluated.

Objective: The primary objective of this study is to evaluate the feasibility of Near-infrared Fluorescence (NIRF) imaging with Indocyanine green (ICG) to assess and quantify tissue perfusion in post-traumatic soft tissue and/or skeletal injury.

Study design: The study is a prospective observational multicentre pilot study. All included patients will undergo a perfusion assessment using ICG NIR fluorescence imaging. Perfusion assessment will not affect treatment of patients.

Study population: Patients aged 18 years or older with traumatic soft tissue and/or skeletal injury. Injuries included in the study are: open deglovement; crush injuries of extremities; open fractures, non-unions of clavicula, tibia, humerus, rib and/or ulna fractures and fracture related infections.

Intervention: Patients will undergo an intra-operative perfusion assessment using ICG NIR fluorescence imaging. For patients undergoing additional debridement procedures, perfusion assessment with ICG will be repeated during every procedure.

Main study parameters/endpoints: The primary outcome of this study is a time-intensity curve with quantified perfusion parameters in traumatic soft tissue and/or skeletal injuries. Perfusion parameters included in the analyses are time till maximum intensity (Tmax), maximum intensity (Imax) the ingress rate, the normalized slope, the absolute slope and the area under the curve at 30, 60 and 120 seconds.

Eligibility Criteria:
Inclusion Criteria:

In order to be eligible to participate in this study, a subject must meet all the following criteria:

* Age ≥ 18 years
* Diagnosed with one or more of the following injuries:

  * Crush injury
  * Open deglovement
  * Open fracture(s) (Gustilo 3, -A, -B \& -C)
  * Non-union tibia/clavicula/ulna/humerus/rib
  * Fracture related infection
* Indication for surgical intervention

Exclusion Criteria:

A potential subject who meets any of the following criteria will be excluded from participation in this study:

* Hemodynamically unstable due to severe blood loss
* Allergic or hypersensitive to iodine/crustaceans/shellfish
* Diagnosed with endocrine thyroid disorders (hyperthyroidism)
* Pregnancy
* Diagnosed with impaired renal function eGFR \<30 L/min/1.73m2
* Diagnosed with severely disturbed hepatic enzymes/liver failure