Name: Author Spotlight: Enhancing Vascular Function and Physical Capacity in Cardiovascular Disease Through Novel Interventions and NIRS Technology
Uploaded: 2024-03-22T14:20:00
Description: Read this Scientific Article Protocol about Author Spotlight: Enhancing Vascular Function and Physical Capacity in Cardiovascular Disease Through Novel Interventions and NIRS Technology at JoVE.com

The authors would like to acknowledge Dr A. Meneses, whose previous work contributed to the refinement of the protocol described herein. Additionally, the authors would like to thank all of the research participants who have donated their time to enable protocols such as this to be developed in order to further clinical and scientific understanding.

All methods described here have been approved by the human research ethics committee of the University of the Sunshine Coast. Furthermore, all participants gave their written informed consent to participate in the measurements outlined in this protocol. Please note, vascular occlusion testing in the lower limb is contra-indicated in individuals who have previously had a revascularization procedure involving a vascular graft or stenting of the femoral or popliteal arteries. After preparing the equipment, the participant i...

Optimizing NIRS for Assessing Lower Limb Vascular Function

<ol>
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This article outlines standardized procedures for the assessment of lower limb reactive hyperemia using CW-NIRS TSI to evaluate microvascular function. This protocol has been refined by examination of cuff occlusion duration on response magnitude, NIRS test-retest reliability during reactive hyperemia, as well as the level of agreement between NIRS and other methods of microvascular evaluation such as contrast-enhanced ultrasound23,24. A longer cuff-occlusion dur...

Cardiovascular disease (CVD) is the leading contributor to global mortality1. While myocardial infarction and stroke are the most common manifestations of CVD, vascular diseases of the lower limbs, such as peripheral arterial disease (PAD) and diabetic foot disease, contribute substantially to the personal, social, and healthcare burden of CVD2,3,4. Importantly, these disease states are characterized by microvascular and macrovascular dysfunction5 that contribute to symptoms (e.g., intermittent claudication), functional impairment, poor mobility as well as social isolation and reduced quality of life6. Historically, upper-limb vascular assessment techniques have been used as a measure of systemic vascular function and associated cardiovascular risk; however, these methods are potentially not sensitive to local impairments in lower limb vascular function7,8. While there is currently a range of techniques used to assess vascular function in the lower limb, such as flow-mediated dilatation (FMD) and contrast-enhanced ultrasound, each method has disadvantages and limitations, such as equipment cost, operator skill, or the need for invasive venous access. For these reasons, there is a need for standardized and effective techniques to evaluate lower limb vascular (dys)function that can be more readily implemented in research and clinical settings.
Continuous wave near-infrared spectroscopy (CW-NIRS) is a non-invasive, low-cost, and portable method that quantifies the relative changes in hemoglobin oxygenation in vivo. As the NIRS oxygenated and deoxygenated hemoglobin signals are derived from the small (&#60;1 mm in diameter) vessels, local skeletal muscle metabolism and microvascular function are able to be evaluated9. Specifically, the tissue saturation index (TSI) [TSI = oxygenated hemoglobin/ (oxygenated hemoglobin + deoxygenated hemoglobin) x 100], provides a quantitative measure of tissue oxygenation9. When measured before, during, and after occlusion and reactive hyperemia, the changes in TSI indicate &#39;end-organ&#39; vascular responsiveness, relative to the pre-occlusion baseline. Importantly, this method is sensitive to alterations in muscle microvascular responsiveness and perfusion associated with ageing10, disease progression11, and clinical interventions (e.g., revascularization surgery12,13 or exercise rehabilitation14,15,16,17) in individuals with, or at risk of microvascular dysfunction.
The availability of NIRS systems has led to a rapid rise in the number of research studies reporting microvascular function18. However, differences in reactive hyperemia&#160;testing protocols, omission of detailed, repeatable NIRS methods, as well as a lack of uniformity in the description, presentation, and analysis of NIRS response parameters make comparisons across individual trials challenging. This limits the collation of data for meta-analysis and the formulation of clinical assessment recommendations9,15.
Therefore, in this article, we describe our laboratory&#39;s standardized NIRS and vascular occlusion testing protocols for the assessment of lower limb reactive hyperemia. By disseminating these methods, we aim to contribute to the improved standardization and repeatability of data collection procedures and harmonized reporting.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Cuff Inflator Air Source</td>
			<td>Hokanson&#160;</td>
			<td>AG101 AIR SOURCE</td>
			<td></td>
		</tr>
		<tr>
			<td>Elastic Cohesive Bandage</td>
			<td>MaxoWrap</td>
			<td>18228-BL</td>
			<td>For blocking out ambient light</td>
		</tr>
		<tr>
			<td>OxySoft</td>
			<td>Artinis</td>
			<td>3.3.341 x64</td>
			<td></td>
		</tr>
		<tr>
			<td>PortaLite (NIRS)</td>
			<td>Artinis</td>
			<td>0302-00019-00</td>
			<td></td>
		</tr>
		<tr>
			<td>PortaSync MKII (Remote)</td>
			<td>Artinis</td>
			<td>0702-00860-00</td>
			<td>For Marking milestones during measurement</td>
		</tr>
		<tr>
			<td>Rapid Cuff Inflator</td>
			<td>Hokanson&#160;</td>
			<td>E20 RAPID CUFF INFLATOR</td>
			<td></td>
		</tr>
		<tr>
			<td>Thigh Cuff</td>
			<td>Hokanson&#160;</td>
			<td>CC17</td>
			<td></td>
		</tr>
		<tr>
			<td>Transpore Surgical Tape</td>
			<td>3M</td>
			<td>1527-1</td>
			<td>For fixing probe to skin</td>
		</tr>
	</tbody>
</table>

near-infrared spectroscopy during reactive hyperemia for the assessment of lower limb vascular function 

Vascular diseases of the lower limb contribute substantially to the&#160;global burden of cardiovascular disease and comorbidities such as diabetes. Importantly, microvascular dysfunction can occur prior to, or alongside, macrovascular pathology, and both potentially contribute to patient symptoms and disease burden. Here, we describe a non-invasive approach using near-infrared spectroscopy (NIRS) during reactive hyperemia, which provides a standardized assessment of lower limb vascular (dys)function and a potential method to evaluate the efficacy of therapeutic interventions. Unlike alternative methods, such as contrast-enhanced ultrasound, this approach does not require venous access or sophisticated image analysis, and it is inexpensive and less operator-dependent. This description of the NIRS method includes representative results and standard terminology alongside the discussion of measurement considerations, limitations, and alternative methods. Future application of this work will improve standardization of vascular research design, data collection procedures, and harmonized reporting, thereby enhancing translational research outcomes in the areas of lower limb vascular (dys)function, disease, and treatment.

Author Spotlight: Enhancing Vascular Function and Physical Capacity in Cardiovascular Disease Through Novel Interventions and NIRS Technology

Near-Infrared Spectroscopy During Reactive Hyperemia for the Assessment of Lower Limb Vascular Function 

Our research is focused on understanding how impairments in vascular function and blood flow contribute to the decline in physical function with age and age-related cardiovascular conditions. We also aim to develop novel therapies and exercise interventions that target vascular function and enhance physical capacity in quality of life in people living with cardiovascular disease. Differences in testing protocols, omission of detailed, repeatable NIRS methods, and a lack of uniformity in the description, presentation, and analysis of NIRS response parameters makes comparisons across individual trials challenging.This limits the collation of data for meta-analysis and the formulation of clinical assessment recommendations. Compared to plethysmography, NRS has high temporal resolution and directly evaluates changes in microvasculature. Compared to ultrasound, NIRS does not require sophisticated image analysis or intravenous contrast agents.The relative ease and affordability of NIRS means that users can be trained rapidly, enabling multicenter investigations with minimal inter operator variability. We're focused on improving skeletal muscle microvascular function through interventions like ischemic preconditioning and blood flow restriction exercise training. We're currently testing the effect of neuromuscular electrical stimulation as a therapy to promote vascular function and to enhance walking capacity in people with peripheral artery disease.

Near-infrared spectroscopy 
Continuous wave near-infrared spectroscopy devices measure relative changes in oxygenated (O2Hb) and deoxygenated (HHb) hemoglobin, which reflect local O2 delivery and utilization via light-emitting sources and photodetectors, set&#160;specific distances apart. Wavelengths of light between ~700 nm and 850 nm are emitted, corresponding with the peak absorbency of O2Hb and HHb. Once near-infrared light has penetrated skeletal muscle...

Read this Scientific Article Protocol about Author Spotlight: Enhancing Vascular Function and Physical Capacity in Cardiovascular Disease Through Novel Interventions and NIRS Technology at JoVE.com

Here, we describe a non-invasive approach using near-infrared spectroscopy to assess reactive hyperemia in the lower limb. This protocol provides a standardized assessment of vascular and microvascular responsiveness that may be used to determine the presence of vascular dysfunction as well as the efficacy of therapeutic interventions.

Vascular diseases of the lower limb contribute substantially to the&#160;global burden of cardiovascular disease and comorbidities such as diabetes. ...

near-infrared-spectroscopy-during-reactive-hyperemia-for-assessment

Research

JoVE Journal

Biology

NIRS-Based Reactive Hyperemia Assessment in Lower Limb Vascular Studies

To begin, ask the participant to lie in a supine position on an examination plinth or bed. Place a cuff around the thigh, proximal to the knee, ensuring that the tubes do not come into contact with the calf. Elevate the leg with the foot and ankle on foam support, leaving the lower leg stable and accessible For measurements.Turn on the rapid cuff inflator module. Activate the cuff inflator air source. Verify air passage through the hose and connect the hose to the thigh cuff.Fix the near infrared spectroscopy or NIRS transmitter receiver probe on the skin overlying the measurement sites. Cover the probe with black kinesiology tape to block ambient light, preserving NIRS signal integrity. Instruct the participant to maintain a relaxed posture, avoid talking, and keep their legs still throughout the data collection period.Using the computer interface, start the NIRS device and acquire the data for a minimum of two minutes before starting the measurement. Monitor the computer screen to ensure data signal integrity and physiologically plausible values. If no fluctuations in the NIRS signal are noted, push the corresponding button on the software to set the NIRS data baseline.Collect at least one minute of baseline data ensuring no signal fluctuations or movement artifacts in recording. Set the cuff pressure to 200 millimeters of mercury on the rapid cuff inflator. before selecting the cuff mode.Inform the participant about potential sensations during the cuff's inflation to 200 millimeters of mercury for five minutes and subsequent total cuff deflation. When ready to initiate cuff inflation, mark the end of the baseline period in the recording. Inflate the thigh cuff to a supra systolic pressure of 200 millimeters of mercury.Monitor the computer or screen to ensure data integrity during the occlusion period. Just before the end of the five minute occlusion, remind the participant to keep their legs still, and refrain from talking for approximately three minutes after cuff deflation. After five minutes, rapidly deflate the thigh cuff to zero millimeters of mercury, and simultaneously mark the end of the occlusive period in the recording.After a three minute post-occlusion or after the NIRS data has returned to baseline, mark the end of the recovery period and stop the measurement. Finally, export the NIRS results and save the data treatment and analysis. NIRS distinguishes microvascular responsiveness between healthy individuals and those with peripheral arterial disease during reactive hyperemia testing.