Monitoring Free Tissue Transfer Hemodynamics Using NIRS

Advanced Optical Monitoring of Free Tissue Transfer Hemodynamics

Free tissue transfer (FTT) is a surgical procedure for repairing cancer resection wounds. Free tissue transfer usually involves taking skin from one area of the body (e.g. leg) and transplanting it to the surgically created wound (e.g. neck wound). Due to problems with anastomosis, the transplanted skin can die. If the poor blood supply can be detected early, transplanted skin can be saved by taking patients back to the operating room. The investigators propose to improve the design and test a novel, non-invasive monitoring system specifically for head and neck surgeries for early detection of poor blood supply to the transplanted tissue after FTT surgery.

Study Overview

• Status: Enrolling by invitation
• Conditions: Oxygen Supply Absent
• Intervention / Treatment: Device: Free Flap NIRS

Detailed Description

PURPOSE: To improve the design and evaluation of a novel spatially resolved near-infrared spectroscopy (NIRS) system customized for continuous postoperative free tissue transfer (FTT) monitoring and to make this system commercially available.

HYPOTHESIS: The novel NIRS device is capable of monitoring FTT reconstruction continuously for 72 hours after surgery with minimal interference to patient care, minimal discomfort to the patient, and minimal interference with clinical assessment.

JUSTIFICATION FOR THE STUDY: FTT consists of transplanting skin, muscle or bone along with its feeding blood vessels from one body site to reconstruct a defect created by removing cancerous tumours or traumatic injury at a separate site. The key to the survival of the transplanted tissue is the meticulously created microvascular anastomosis between the blood vessels of the transplanted tissue and the blood vessels of the recipient site. Microsurgical techniques have been refined over time to maintain the patency of the anastomosed blood vessels. Nevertheless, the current FTT failure rate is between 1 and 10%.

When FTT failure occurs, it is a devastating experience for the patient and the surgical team. The patient has to be urgently brought to the operating room for an attempted salvage of the microvascular anastomosis. In the event of unsuccessful salvage, the patient has to undergo multiple surgeries that compound the associated morbidity, prolong hospital stay, and increase health care costs. Early detection of vascular compromise is essential for increasing the odds of successful salvage. Thus, the methods used to monitor the FTT vascular status are critical and have received much attention in the literature. Clinical examination remains the gold standard and the most popular method of monitoring FTT viability. The two downsides of clinical examinations are the requirement for personnel trained and experienced in FTT monitoring and the inability to provide reliable continuous monitoring. Therefore recognition of FTT compromise is often delayed significantly compromising successful surgical salvage attempts.

Recently, NIRS has been recognized as the technology with the most potential to address the problems seen with FTT clinical monitoring. NIRS is a non-invasive technique that passes near-infrared light (600-1000 nm) through the tissues at a depth of 10 to 20 mm. Calculating the amount of absorbed light allows real-time measurements of oxygenated, deoxygenated, and total hemoglobin concentrations. Therefore, an abnormality of tissue perfusion and oxygenation can then be detected instantaneously and confirmed clinically. Reducing the time from detection of vascular compromise to the attempted FTT rescue in the operating room decreases the ischemia time and increases the FTT salvage rate.

A recent meta-analysis concluded that NIRS is "a reliable monitoring technique that is non-invasive, objective, and easy to use". However, there are currently no NIRS systems available that can monitor FTT used in head and neck surgery. This is largely due to the difficulty in creating NIRS sensors that are small enough to be used in the head and neck region. Developing and evaluating a novel, customized NIRS system with a miniaturized sensor suitable for a variety of FTT options is needed, presenting an attractive clinical opportunity.

The proposed study's principal investigator (D.W.A.) is the pioneer of head and neck FTT in British Columbia, with FTT experience spanning over 35 years. He will use his expertise to consult with Dr. Shadgan, a clinical biophotonics research scientist, to provide clinical and technical specifications required for the construction of the NIRS prototype. Currently, they successfully built and tested the miniaturized NIRS sensor on 3 patients, and they were able to obtain promising results. To establish our method and refine the design of the sensor to be compatible with a wide variety of FTT surgeries, The investigators plan to conduct this pilot study.

OBJECTIVES

1. Develop a novel NIRS system with miniaturized sensors suitable for various FTT reconstruction options.
2. Conduct a pilot study on up to 60 patients to determine perfusion thresholds indicative of vascular compromise for a variety of FTT reconstructive options, and to improve the design and application of sensors to the variety of FTT.

RESEARCH DESIGN

The NIRS prototype will be tested intra- and post-operatively on a single patient undergoing FTT reconstruction. Intra-operative NIRS measurements simulating FTT compromise will be collected during a single FTT operation.

Post-operatively the NIRS probe will be placed and fixed over the FTT for 72 hours and its measurements will be recorded. In addition, experienced nurses not involved in the proposed study will monitor the FTT vascular status with the conventional clinical methods currently employed at VGH and Surrey Memorial Hospital. The clinical assessment will be documented in the standardized table and correlated to the NIRS recordings. Finally, at the end of the 72-hours, both the patient and the clinicians will complete questionnaires to evaluate their experience with the NIRS system.

STATISTICAL ANALYSIS

The collected intra-operative and post-operative NIRS measurements will be used to establish a threshold for low perfusion alarm on the NIRS monitor for different types of tissues.

The data that will be collected through patients' and doctors' questionnaires will go through descriptive statistical analysis.

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Canada
  • British Columbia
    • Surrey, British Columbia, Canada, V3V 1Z2
      • Surrey Memorial Hospital
    • Vancouver, British Columbia, Canada, V5Z 1M9
      • Vancouver General Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• 60 patients undergoing a variety of free tissue transfer for head and neck cancer. The result of the reconstruction should be easily visible to the clinicians.
• Age of 18 years old or older

Exclusion Criteria:

• Serious medical condition or other disease which occurs at the same time
• Metastatic disease
• Pregnant or nursing

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Participants; Data collection from Participants and evaluate their feedback by filling a questioner	Device: Free Flap NIRS; Monitoring of tissue oxygenation after Free Tissue Transfer (FTT) surgeries.
Active Comparator: Care providers; Care providers will provide their feedback via questioner	Device: Free Flap NIRS; Monitoring of tissue oxygenation after Free Tissue Transfer (FTT) surgeries.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Establish a baseline Total Oxygenation Index (TOI) to measure NIRS on FTT cases	The total oxygenation index (TOI) measurements will be used to establish a TOI baseline for Free Tissue Transfer (FTT) and to calibrate and tune the FTT-system	Up to 36 months
Enhance the design and accuracy of the FTT- NIRS sensor based on patient and clinicians feedback	The data collected will be used to enhance the design and accuracy of the next generation of NIRS sensors based on the feedback provided by the patient and clinician	24 months

Collaborators and Investigators

• Sponsor: University of British Columbia
• Collaborators: Vancouver General Hospital; Surrey Memorial Hospital (SMH)

Study record dates

Study Major Dates

• Study Start (Actual): April 20, 2025
• Primary Completion (Estimated): December 29, 2026
• Study Completion (Estimated): September 1, 2027

Study Registration Dates

• First Submitted: May 2, 2024
• First Submitted That Met QC Criteria: October 25, 2024
• First Posted (Actual): October 28, 2024

Study Record Updates

• Last Update Posted (Actual): May 1, 2026
• Last Update Submitted That Met QC Criteria: April 27, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Tissue Oxygenation; NIRS Sensor; Free Tissue Transfer (FTT)
• Additional Relevant MeSH Terms: Signs and Symptoms, Respiratory; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Hypoxia
• Other Study ID Numbers: H22-03706

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No