Non-invasive measurement of tissue oxygenation through Near-Infrared Spectroscopy
The problem
When it comes to chronic wound management, acute wounds in reconstructive surgery, or limb preservation, tissue oxygenation refers to oxygen saturation which is a measure of the percentage of dissolved oxygen in tissue. Tissue oxygenation takes place when oxygen molecules enter the tissues of humans when blood is oxygenated in the lungs through the oxygen molecules traveling from the air and into the blood.
Tissue viability and healing capacity are directly impacted by common conditions including:
Peripheral sensation (neuropathy)
Metabolic status (diabetes)
Vascular supply (peripheral arterial disease)
Common surgical procedures are all at risk of higher complication rates when patients have compromised vascular status and comorbidities including:
Total hip and knee arthroplasty
Oncologic surgeries (i.e., post-mastectomy breast reconstruction)
Current Assessment Methods
There is a gap in the medical system for fast, accurate, repeatable technology that is cost-effective and efficient. The current gold standard approach of clinical monitoring in wound care is:
Visual inspection
Physical measurements with a paper ruler
Vascular assessments to determine oxygenation
Existing systems for monitoring tissue oxygenation are limited by the need for wired connections, the inability to provide real-time data, the extensive training, and specialization that is required for use, or the operation is restricted to surface tissues only. Most assessment methods also require contact with the patient, whether that is pressure cuffs wrapped around a patient’s limbs or electrodes attached to the patient’s skin.
Available conventional tests for vascular assessment of blood and tissue perfusion include Ankle-Brachial Index (ABI), Toe-Brachial Index (TBI), and Transcutaneous Oxygen Pressure (TcPO2). These older methods each have major disadvantages compared to near-infrared spectroscopy (NIRS) imaging.
Ankle-brachial index assessment (Chaudru 2016)
Transcutaneous oximetry (López-Moral 2023)
An innovative solution
As an alternative to direct O2-sensing approaches, near-infrared spectroscopy (NIRS) has demonstrated the ability to accurately quantify tissue oxygen saturation levels with zero patient contact. NIRS is an optical method consisting of illuminating chemical compounds that absorb, reflect, and scatter light directed at that compound. Faster detection of critical changes in tissue oxygenation could enable earlier and more successful intervention when tissue complications arise. NIR light is very useful in detecting oxygenated and deoxygenated blood, which conveys a comprehensive picture of tissue health and the healing capacity of acute and chronic wounds.
SnapshotNIR, by Kent Imaging, is a near-infrared (NIR), reflectance-based technology that measures tissue oxygen saturation in superficial tissue at the critical macrovascular level. Using multiple wavelengths of NIR light, SnapshotNIR measures the relative amounts of oxygenated and deoxygenated hemoglobin in the areas where oxygen exchange is happening. SnapshotNIR provides users with a tissue oxygenation map that can be used for medical decision-making, such as tracking and trending oxygenation, and to evaluate tissue viability.
SnapshotNIR being used with a patient with a chronic ankle wound.
Kent Imaging has developed a cost-effective and easy-to-use point-of-care imaging device that is completely non-invasive, removing the need for patient contact or injected dyes. Snapshot NIR captures the availability of oxygenated blood in tissue in a matter of seconds, helping to provide diagnostic insight for improved decision-making throughout the continuum of care. The tracked and documented oxygenation data allows patients to be assessed for appropriate advanced wound care modalities, to monitor the therapeutic benefit, and share that information with the patient and between healthcare providers all in one handheld, portable device.
Changing your clinical practice with SnapshotNIR
Clinicians can view oxyhemoglobin and deoxyhemoglobin trends which can support assessment of underlying conditions or tissue healing capacity.
StO2 ranges can support clinical decision-making when StO2 is <39%, between 40-69% or >70%
Low oxyhemoglobin and high deoxyhemoglobin may indicate underlying venous disease or other vascular compromise hindering the wound’s ability to heal
Physicians can use the visual data from SnapshotNIR to:
Communicate more effectively with their colleagues for expedited referrals
Document wound status for patient monitoring and insurance reimbursement
Support clinical decision-making for interventions
Educate their patients on their prognosis and healing capacity
References
Chaudru S, De Müllenheim PY, Le Faucheur A, Kaladji A, Jaquinandi V, Mahé G. Training to perform ankle-brachial index: systematic review and perspectives to improve teaching and learning. European Journal of Vascular and Endovascular Surgery. 2016 Feb 1;51(2):240-7.
López-Moral M, García-Madrid M, Molines-Barroso RJ, García-Álvarez Y, Tardáguila-García A, Lázaro-Martínez JL. Analyses of transcutaneous oxygen pressure values stratified for foot angiosomes to predict diabetic foot ulcer healing. Journal of Tissue Viability. 2023 Nov 1;32(4):480-6.
https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/tissue-oxygenation
https://www.nature.com/articles/s41587-021-00866-y
https://annalsofintensivecare.springeropen.com/articles/10.1186/2110-5820-2-11
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2704021/
https://pubmed.ncbi.nlm.nih.gov/24900919/
To speak to a product expert about Kent’s imaging technologies, contact us here.
To learn more about the applications of Kent Imaging’s SnapshotNIR, click here.