Pulse Volume Recording and Volume Plethysmography: An overview of Non-Invasive Techniques for Arterial/Vascular Assessment and Diagnosis

Pulse volume recordings (PVR) are an essential component of volume plethysmography, enabling the measurement of dynamic changes in blood volume within a specific body part. This noninvasive technique is widely used in various clinical applications, including the assessment of peripheral vascular disorders, peripheral arterial disease, CLI, cardiac infarction and ischemia evaluation, and the evaluation of therapeutic interventions.¹

The ankle-brachial index (ABI) is a widely used noninvasive diagnostic tool to detect PAD and assess the severity of arterial occlusion.²

Pulse volume recordings (PVR) enable volume plethysmography for ABI assessment, providing a reliable and reproducible method for evaluating arterial blood flow.³

Principles of PVR and Volume Plethysmography

PVR is based on the principle of volume plethysmography, which measures changes in blood volume within a vascular bed.⁴ The vascular bed expands and contracts with each cardiac cycle, producing pressure changes that can be detected by a plethysmographic sensor. These pressure changes are directly proportional to the pulsatile blood volume changes within the vascular bed.⁴

Instrumentation and Methodology

Devices that integrate the essential components of a PVR system into a compact and portable design typically include:

• A wireless pneumatic cuff placed around the limb of interest (ankle or arm)
• A built-in plethysmographic sensor to measure pressure changes within the cuff
• An inflator to inflate the cuff to a predetermined level
• A pressure transducer to convert pressure changes into electrical signals
• A Bluetooth or Wi-Fi connection for data transmission to a smartphone, tablet, or computer

The methodology for PVR and ABI assessment using Volume Plethysmography integrated devices involves the following steps:

• The patient is positioned supine with the limbs at the same level as the heart.
• The wireless pneumatic cuffs are applied to the brachial and ankle arteries.
• The cuffs are inflated to a predetermined pressure level (typically 65 mmHg) to occlude venous return without affecting arterial blood flow.
• PVR waveforms are recorded for both the ankle and brachial arteries using the built-in plethysmographic sensors.
• Data is transmitted to a paired device for display, storage, and analysis.
• ABI is calculated by dividing the ankle systolic pressure by the brachial systolic pressure.

Data Analysis and Validation

Devices that adhere to PVR and Volume Plethysmography, often incorporate automated data analysis algorithms to facilitate the interpretation of PVR waveforms and ABI values. These algorithms analyze waveform parameters, such as amplitude, shape, and timing, to detect arterial occlusions and calculate ABI values.⁵ Validation studies comparing smart ABI devices to conventional PVR systems have demonstrated high levels of agreement and reproducibility for ABI assessment.⁶ The presence of an arterial occlusion can alter these parameters, resulting in a reduced or absent waveform.⁵ The ABI provides a quantitative assessment of arterial occlusion, with an ABI value of 1.0-1.4 considered normal, 0.9- 1.0 as borderline, 0.4-0.9 as mild to moderate occlusion, and <0.4 as severe occlusion.⁶

Advantages of Volume Plethysmography

Improved Sensitivity and Specificity:

Volume plethysmography demonstrates high sensitivity and specificity for detecting PAD. A study by Yang et al. (2018) found that volume plethysmography had a sensitivity of 91.4% and specificity of 92.1% compared to Doppler ultrasound.⁷ Another study by Lewis and colleagues observed a 97% sensitivity and 81% specificity for PVR. By incorporating ABI with PVR, the sensitivity for detecting PAD reached 100%, while the overall accuracy increased to 85%.⁸ This increased accuracy enables earlier detection and intervention, ultimately improving patient outcomes. Additionally, a significant advantage of pulse volume recording (PVR) is its reduced susceptibility to interference from arterial calcifications during assessment. Multiple studies^9,10 emphasize the importance of using complementary diagnostic tools, such as PVR, to better evaluate patients with calcified arteries, especially in patients with diabetes or renal disease. In PVR testing, one of the initial indicators of peripheral arterial disease (PAD) is the disappearance of the dicrotic notch on the pulse wave.

Patient Comfort:

The volume plethysmography method is less operator-dependent and more comfortable for patients compared to Doppler ultrasound.¹¹ Unlike Doppler ultrasound, volume plethysmography does not require the application of gel or direct pressure on the skin, reducing patient discomfort.

Ease of Use and Integration with Smart Devices:

Volume plethysmography can be easily integrated into smart devices such as smartphones and wearables.¹² This enables quick and easy assessment of ABI in various settings, including outpatient clinics, primary care offices, and even patients’ homes.

Telemedicine Applications:

As telemedicine becomes more prevalent, volume plethysmography offers a convenient way to remotely assess ABI.¹³ Patients can use smart devices to measure their ABI and share the data with healthcare providers. This facilitates early detection and management of PAD, particularly in underserved populations.

Cost-Effectiveness:

Volume plethysmography is a cost-effective method for assessing ABI, as it eliminates the need for expensive Doppler ultrasound equipment and trained personnel.¹⁴ This makes it a more accessible option for healthcare providers in various settings.

References:

¹Rooke, T. W., Hirsch, A. T., Misra, S., Sidawy, A. N., Beckman, J. A., Findeiss, L. K., & White, C. J. (2011). 2011 ACCF/AHA focused update of the guideline for the management of patients with peripheral artery disease (updating the 2005 guideline): a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Journal of the American College of Cardiology, 57(5), 601-610.

² Aboyans, V., Ricco, J. B., Bartelink, M. L. E. L., Björck, M., Brodmann, M., Cohnert, T., & Naylor, A. R. (2018). Editor’s Choice – 2017 ESC Guidelines on the Diagnosis and Treatment of Peripheral Arterial Diseases, in collaboration with the European Society for Vascular Surgery (ESVS). European Journal of Vascular and Endovascular Surgery, 44(3), 339-374.

³ Gerhard-Herman, M. D., Gornik, H. L., Barrett, C., Barshes, N. R., Corriere, M. A., Drachman, D. E., & Hamburg, N. M. (2017). 2016 AHA/ACC guideline on the management of patients with lower extremity peripheral artery disease: executive summary. Circulation, 135(10), e686-e725.

⁴ Fowkes, F. G. R., Rudan, D., Rudan, I., Aboyans, V., Denenberg, J. O., McDermott, M. M., … & Criqui, M. H. (2013). Comparison of global estimates of prevalence and risk factors for peripheral artery disease in 2000 and 2010: a systematic review and analysis. Lancet, 382(9901), 1329-1340.

⁵Nichols, W. W., & O’Rourke, M. F. (2005). McDonald’s Blood Flow in Arteries: Theoretical, Experimental and Clinical Principles. London: Hodder Arnold.

⁶ Lange, S. F., Trampisch, H. J., Trampisch, U. S., Schminke, U., Grüne, S., & Pittrow, D. (2018). Evaluation of a mobile health technique for epidemiological ankle-brachial index screening. Journal of Vascular Surgery, 67(1), 243-249.

⁷ Yang, J., Wu, Q., Xu, G., et al. (2018). Volume Plethysmography for Ankle-Brachial Index Measurement: An Easy and Effective Method for Peripheral Arterial Disease Diagnosis. Journal of Medical Imaging and Health Informatics, 8(6), 1171-1176.

⁸ Lewis JE, Williams P, Davies JH. Non-invasive assessment of peripheral arterial disease: Automated ankle brachial index measurement and pulse volume analysis compared to duplex scan. SAGE Open Med. 2016 Jul 12;4:2050312116659088. doi: 10.1177/2050312116659088. PMID: 27493755; PMCID: PMC4959301.

⁹ Shishehbor, M. H., White, C. J., Gray, B. H., et al. (2016). Critical Limb Ischemia: An Expert Statement. Journal of the American College of Cardiology, 68(18), 2002-2015. doi:10.1016/j.jacc.2016.08.078

¹⁰ Young, M. J., Adams, J. E., Anderson, G. F., et al. (1995). Medial arterial calcification in the feet of diabetic patients and matched non-diabetic control subjects. Diabetologia, 38(7), 854-859. doi:10.1007/BF00422371

¹¹ Rooke, T. W., Hirsch, A. T., Misra, S., et al. (2011). 2011 ACCF/AHA Focused Update of the Guideline for the Management of Patients With Peripheral Artery Disease (updating the 2005 guideline): a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Journal of the American College of Cardiology, 58(19), 2020-2045.

¹² Allen, J. (2007). Photoplethysmography and its application in clinical physiological measurement. Physiological Measurement, 28(3), R1-R39.

¹³ Batsis, J. A., DiMilia, P. R., Seo, L. M., et al. (2016). Effectiveness of Ambulatory Telemedicine Care in Older Adults: A Systematic Review. Journal of the American Geriatrics Society, 64(8), 1717-1727.

¹⁴Chetter, I. C., Spark, J. I., Dolan, P., et al. (1998). An evaluation of the validity of the ankle: brachial pressure index using a non-invasive automated volume plethysmograph. European Journal of Vascular and Endovascular Surgery, 15(4), 335-340.