Orthostatic leg blood volume changes assessed by near‐infrared spectroscopy

Truijen, Jasper; Kim, Y. S.; Krediet, C. T. Paul; Stok, Wim J.; Kölgen, R. S.; Colier, Willy N.J.M.; Secher, Niels H.; Lieshout, Johannes J. van

doi:10.1113/expphysiol.2011.061051

Cited by 33 publications

(44 citation statements)

References 34 publications

(48 reference statements)

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“…Further, the ICC's are consistent with those previously reported where the relative change in tHb has been measured using cw-NIRS at the soleus (29).…”

Section: Discussionsupporting

confidence: 79%

“…A novel finding is the indication that, despite the assumptions made by cw-NIRS when determining absolute haemoglobin concentrations using SRS (20,27), cw-NIRS and fd-NIRS derived measures of leg blood volume (tHb) were not different during head-up tilt. Typically, cw-NIRS has been used to determine relative change in haemoglobin concentrations during orthostatic stress (18,29,32). This is due to the inherent limitation of cw-NIRS; its inability to measure the scattering of NIRlight (μs) as it travels through tissue.…”

Section: Discussionmentioning

confidence: 99%

“…The re-distribution of blood during orthostatic stress can be assessed by using NIRS to determine changes in total haemoglobin concentration (tHb) (18,29,32). This technique relies on the relative transparency of tissue to infrared light and oxygen-dependent absorption characteristics of haemoglobin to determine concentrations of oxy-haemoglobin (O2Hb) and deoxy-haemoglobin (HHb), the sum of which is tHb (14,22).…”

Section: Introductionmentioning

confidence: 99%

“…Previously, orthostatic stress-induced blood volume shifts have been assessed in the soleus (29) because this muscle consists predominantly of type I muscle fibres and is highly vascularized (11). While assessments of the soleus demonstrate good between-day reliability (29), it can be difficult to locate, particularly in physically inactive individuals. Also, most of the soleus muscle mass lies beneath the gastrocnemius, which may be beyond the depth penetration of NIR light.…”

Section: Introductionmentioning

confidence: 99%

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The validity and reliability of continuous-wave near-infrared spectroscopy for the assessment of leg blood volume during an orthostatic challenge

et al. 2016

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DisclaimerThe University of Gloucestershire has obtained warranties from all depositors as to their title in the material deposited and as to their right to deposit such material.The University of Gloucestershire makes no representation or warranties of commercial utility, title, or fitness for a particular purpose or any other warranty, express or implied in respect of any material deposited.The University of Gloucestershire makes no representation that the use of the materials will not infringe any patent, copyright, trademark or other property or proprietary rights.The University of Gloucestershire accepts no liability for any infringement of intellectual property rights in any material deposited but will remove such material from public view pending investigation in the event of an allegation of any such infringement. PLEASE SCROLL DOWN FOR TEXT. ABSTRACTNear-infrared spectroscopy (NIRS) can potentially be used to assess the cardiovascular autonomic system by monitoring orthostatic challenge-induced shifts in lower limb blood volume. However, in order to be of clinical utility the test must be valid, reliable, and relatively simple to conduct. reliability. This orthostatic test may present a relatively simple and inexpensive approach for assessing the cardiovascular autonomic nervous system. Abstract word count: 248

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“…Further, the ICC's are consistent with those previously reported where the relative change in tHb has been measured using cw-NIRS at the soleus (29).…”

Section: Discussionsupporting

confidence: 79%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The validity and reliability of continuous-wave near-infrared spectroscopy for the assessment of leg blood volume during an orthostatic challenge

et al. 2016

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“…However, to our knowledge, no attention has been given to the lower extremities. The lower limbs exhibit large fluctuations in blood flow throughout the day due to periods of sitting, standing, and walking (32,36,47), and importantly, skeletal muscle contractions performed in this region are our primary means of locomotion. There are also known differences in resistance vessel function between the upper and lower extremities (31, 35), making extrapolation of findings from the arm to the leg difficult.…”

mentioning

confidence: 99%

Characterizing rapid-onset vasodilation to single muscle contractions in the human leg

Credeur

Holwerda

Restaino

et al. 2015

Journal of Applied Physiology

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Credeur DP, Holwerda SW, Restaino RM, King PM, Crutcher KL, Laughlin MH, Padilla J, Fadel PJ. Characterizing rapid-onset vasodilation to single muscle contractions in the human leg. J Appl Physiol 118: 455-464, 2015. First published December 24, 2014 doi:10.1152/japplphysiol.00785.2014 following single muscle contractions has been examined in the forearm of humans, but has not yet been characterized in the leg. Given known vascular differences between the arm and leg, we sought to characterize ROV following single muscle contractions in the leg. Sixteen healthy men performed random ordered single contractions at 5, 10, 20, 40, and 60% of their maximum voluntary contraction (MVC) using isometric knee extension made with the leg above and below heart level, and these were compared with single isometric contractions of the forearm (handgrip). Single thigh cuff compressions (300 mmHg) were utilized to estimate the mechanical contribution to leg ROV. Continuous blood flow was determined by duplex-Doppler ultrasound and blood pressure via finger photoplethysmography (Finometer). Single isometric knee extensor contractions produced intensity-dependent increases in peak leg vascular conductance that were significantly greater than the forearm in both the above-and belowheart level positions (e.g., above heart level: leg 20% MVC, ϩ138 Ϯ 28% vs. arm 20% MVC, ϩ89 Ϯ 17%; P Ͻ 0.05). Thigh cuff compressions also produced a significant hyperemic response, but these were brief and smaller in magnitude compared with single isometric contractions in the leg. Collectively, these data demonstrate the presence of a rapid and robust vasodilation to single muscle contractions in the leg that is largely independent of mechanical factors, thus establishing the leg as a viable model to study ROV in humans. vascular conductance; hyperemia; exercise onset; blood flow AT THE ONSET of dynamic exercise, skeletal muscle blood flow responses are characterized by an initial rapid increase, followed by a slower rise to steady state (20,39,44). In an effort to focus on the rapidity of the blood flow responses to exercise, studies have been performed to assess the vasodilation following single 1-s isometric muscle contractions. This initial response following a single muscle contraction, termed rapidonset vasodilation (ROV), is proportional to the intensity of contraction and peaks within five cardiac cycles postcontraction (8,11,30,48,51). ROV is considered to be an important initiating event to exercise hyperemia (8, 9). Previous investigations into ROV in humans have focused on the forearm as a model of study (2,6,12,48). However, to our knowledge, no attention has been given to the lower extremities. The lower limbs exhibit large fluctuations in blood flow throughout the day due to periods of sitting, standing, and walking (32,36,47), and importantly, skeletal muscle contractions performed in this region are our primary means of locomotion. There are also known differences in resistance vessel function between the upper and lower extremities (...

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Suspension syndrome: a potentially fatal vagally mediated circulatory collapse—an experimental randomized crossover trial

et al. 2019

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Purpose Suspension syndrome describes a potentially life-threatening event during passive suspension on a rope. The pathophysiological mechanism is not fully understood and optimal treatment unknown. We aimed to elucidate the pathophysiology and to give treatment recommendations. Methods In this experimental, randomized crossover trial, 20 healthy volunteers were suspended in a sit harness for a maximum of 60 min, with and without prior climbing. Venous pooling was assessed by measuring the diameter of the superficial femoral vein (SFV), lower leg tissue oxygenation (StO 2 ) and by determining localized bioelectrical impedance. Hemodynamic response was assessed by measuring heart rate, blood pressure, stroke volume, and left ventricular diameters. Signs and symptoms of pre-syncope were recorded. Results Twelve (30%) out of 40 tests were prematurely terminated due to pre-syncopal symptoms (mean 44.7 min, minimum 13.4, maximum 59.7). SFV diameter increased, StO 2 and the capacitive resistance of the cells decreased indicating venous pooling. Heart rate and blood pressure did not change in participants without pre-syncope. In contrast, in participants experiencing pre-syncope, heart rate and blood pressure dropped immediately before the event. All symptoms dissolved and values returned to normal within 5 min with participants in a supine position. Conclusions Sudden pre-syncope during passive suspension in a harness was observed in 30% of the tests. Blood pools in the veins of the lower legs; however, a vagal mechanism finally leads to loss of consciousness. Time to pre-syncope is unpredictable and persons suspended on a rope should be rescued and put into a supine position as soon as possible. Electronic supplementary material The online version of this article (10.1007/s00421-019-04126-5) contains supplementary material, which is available to authorized users.

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Orthostatic leg blood volume changes assessed by near‐infrared spectroscopy

Cited by 33 publications

References 34 publications

The validity and reliability of continuous-wave near-infrared spectroscopy for the assessment of leg blood volume during an orthostatic challenge

The validity and reliability of continuous-wave near-infrared spectroscopy for the assessment of leg blood volume during an orthostatic challenge

Characterizing rapid-onset vasodilation to single muscle contractions in the human leg

Suspension syndrome: a potentially fatal vagally mediated circulatory collapse—an experimental randomized crossover trial

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