| 1. |
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| 2. |
- Andersson, Roger, et al.
(författare)
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Non-invasive monitoring of haemodynamic changes in haemodialysis patients using photoplethysmography (PPG)
- 2002
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Presently there is no simple non-invasive method to monitor haemodynamic changes during haemodialysis but such a method is highly needed. This study aims at investigating the possibility to monitor such changes during a single haemodialysis session using a photoplethysmography method (PPG). This non-invasive method illuminates a proportion of the patients skin and the received PPG-signal reflects local blood flow. The haemodialysis sessions were performed as in normal routine with more frequently performed blood pressure measurements by an oscillometric method or with continuous intra arterial blood pressure measurements. The obtained PPG-signals are linked to the blood pressure changes and are affected by the ultrafiltration rate and drugs administrated during the session. The relation between the blood pressure changes and the changes in the different PPG components seems however to be complex and need to be investigate further. The PPG-method shows promises, which is emphasised by the strong need of a non-invasive monitoring method.
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| 3. |
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| 4. |
- Fridolin, Ivo, et al.
(författare)
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Measurement of solutes in dialysate using UV absorption
- 2001
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Ingår i: Proceedings of SPIE, the International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 4263, s. 40-47
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this work was to describe a new method for optical monitoring of solutes in a spent dialysate. The method utilizes UV light absorption employing a commercially available spectrophotometer. Measurements were performed both on collected dialysate samples and on-line. The concentration of several removed solutes and electrolytes in the serum and in the dialysate was determined simultaneously using standard laboratory techniques. During on-line monitoring the spectrophotometer was connected to the fluid outlet of the dialysis machine. On-line measurements during a single hemodialysis session demonstrated a possibility to monitor deviations in the dialysator performance (e.g. dialysator in bypass). The experimental results indicated a good correlation between UV absorption and several removed solutes (urea, creatinine) in the spent dialysate. The correlation coefficient for urea and creatinine concentrations in the dialysate was very high for every individual treatment. The UV absorbance correlates well to the concentrations of several solutes thought to be uremic toxins. The results indicate that the technique can be used as a continuous, on-line method for monitoring deviations in the dialysator performance and may estimate the removal of the overall toxins. In the future, the new method will be used to evaluate parameters describing delivery of the prescribed treatment dose such as KT/V and Urea Reduction Rate (URR).
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| 5. |
- Fridolin, Ivo, et al.
(författare)
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On-line monitoring of solutes in dialysate using adsorption of ultraviolet radiation : technical description
- 2002
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Ingår i: International Journal of Artificial Organs. - 0391-3988 .- 1724-6040. ; 25:8, s. 748-761
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE:The aim of this work was to describe a new optical method for monitoring solutes in a spent dialysate using absorption of UV radiation.METHOD:The method utilises UV-absorbance determined in the spent dialysate using a spectrophotometrical set-up. Measurements were performed both on collected dialysate samples and on-line. During on-line monitoring, a spectrophotometer was connected to the fluid outlet of the dialysis machine, with all spent dialysate passing through a specially-designed cuvette for optical single-wavelength measurements. The concentrations of several substances of various molecular sizes, electrical charge, transport mechanism, etc. were determined in the dialysate and in the blood using standard laboratory techniques. The correlation coefficient between UV-absorbance of the spent dialysate and concentration of the substances in the spent dialysate and in the blood was calculated from data based on the collected samples.RESULTS:The obtained on-line UV-absorbance curve demonstrates the possibility to follow a single hemodialysis session continuously and to monitor deviations in the dialysator performance using UV-absorbance. The experimental results indicate a very good correlation between UV-absorbance and several small waste solutes removed such as urea, creatinine and uric acid in the spent dialysate and in the blood for every individual treatment at a fixed wavelength of 285 nm. Moreover, a good correlation between the UV-absorbance and substances like potassium, phosphate and beta2-microglobulin was obtained. The lowest correlation was achieved for sodium, calcium, glucose, vitamin B12 and albumin.CONCLUSIONS:A technique for on-line monitoring of solutes in the spent dialysate utilising the UV-absorbance was developed. On-line monitoring during a single hemodialysis session exploiting UV-absorbance represents a possibility to follow a single hemodialysis session continuously and monitor deviations in dialysis efficiency (e.g. changes in blood flow and clearance). The UV-absorbance correlates well to the concentration of several solutes known to accumulate in dialysis patients indicating that the technique can be used to estimate the removal of retained substances.
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| 6. |
- Fridolin, Ivo, 1971-, et al.
(författare)
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On-line monitoring of solutes in dialysate using wavelength-dependent absorption of ultraviolet radiation
- 2003
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Ingår i: Medical and Biological Engineering and Computing. - 0140-0118 .- 1741-0444. ; 41:3, s. 263-270
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the study was to assess the wavelength dependence of the UV absorbance during monitoring of different compounds in the dialysate. UV absorbance was determined by using a double-beam spectrophotometer on dialysate samples taken at pre-determined times during dialysis, over a wavelength range of 180–380 nm. Concentrations of several removed substances, such as urea, creatinine, uric acid, phosphate and β 2-microglobulin, were determined in the blood and in the spent dialysate samples using standard laboratory techniques. Millimolar extinction coefficients, for urea, creatinine, monosodium phosphate and uric acid were determined during laboratory bench experiments. The correlation between UV absorbance and substances both in the dialysate and in the blood was calculated at all wavelengths. A time-dependent UV absorbance was determined on the collected dialysate samples from a single dialysis session over a wavelength range of 200–330 nm. The highest contribution from observed compounds relative to the mean value of the absorbance was found around 300 nm and was approximately 70%. The main contribution to the total absorbance from uric acid was confirmed at this wavelength. The highest correlation for uric acid, creatinine and urea was obtained at wavelengths from 280 nm to 320 nm, both in the spent dialysate and in the blood. The wavelength region with the highest correlation for phosphate and β 2-microglobulin, with a suitable UV-absorbance dynamic range, was from 300 to 330 nm. In the wavelength range of 220–270 nm the highest absorbance sensitivity for the observed substances was obtained. A suitable wavelength range for instrumental design seems tobe around 290–330 nm. The relatively high correlation between UV absorbance and the substances in the spent dialysate and in the blood indicates that the UV-absorbance technique can estimate the removal of several retained solutes known to accumulate in dialysis patients.
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| 7. |
- Fridolin, Ivo, et al.
(författare)
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Optical non-invasive technique for vessel imaging : I. Experimental results
- 2000
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Ingår i: Physics in Medicine and Biology. - : IOP Publishing. - 0031-9155 .- 1361-6560. ; 45:12, s. 3765-3778
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates some prerequisites for vessel imaging based on diffuse reflectance measurements in order to develop an optical non-invasive method for the imaging and monitoring of vessels.The method utilizes near-infrared (NIR) radiation (890 nm) from a light emitting diode. The light is guided into the tissue via an optical fibre (diameter 1.0 mm). The backscattered light is collected by an optical fibre of the same type and detected by an optical power meter. The fibres are moved over the skin in two directions with the aid of two motors operated by a microcomputer. Spatially resolved reflectance at the skin surface could be presented as a vessel-map in a colour-coded form on a computer screen.Experimental results indicate that the vessel imaging facility depends upon source-detector separation, relative position and vessel depth, and does not depend essentially on the radiant power from the light source. It is shown that, by a proper choice of probe parameters, one can improve the vessel identification ability.After vessel imaging the technique can potentially be used to monitor several physiological parameters on a selected vascular bed or to distinguish between injured and healthy tissue by monitoring local blood flow, oxygen saturation and the recirculation, pre- and post-operatively.
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| 8. |
- Fridolin, Ivo, 1971-, et al.
(författare)
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Optical non-invasive technique for vessel imaging : II. A simplified photon diffusion analysis
- 2000
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Ingår i: Physics in Medicine and Biology. - : Institute of Physics (IOP). - 0031-9155 .- 1361-6560. ; 45:12, s. 3779-3792
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this paper is to explain theoretically the origin of previously presented experimental results by an optical non-invasive method using NIR for imaging blood vessels based on a specific combination of several physical parameters. The theoretical model is based on the diffusion approximation derived from the transport theory deep in a bulk tissue. An analytical solution was obtained describing photon behaviour under certain conditions during vessel identification. The modelled results indicate that the vessel identification facility depends upon source-detector separation and vessel depth, and does not depend essentially on the radiant power from the light source. The solution offers a relatively simple theoretical explanation of the experimental results and can be applied to several other clinical applications using similar technical solutions.
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| 9. |
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| 10. |
- Jönsson, Björn, 1951-, et al.
(författare)
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Is oscillometric ankle pressure reliable in leg vascular disease?
- 2001
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Ingår i: Clinical Physiology and Functional Imaging. - : Wiley. - 1475-0961 .- 1475-097X. ; 21:2, s. 155-163
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Tidskriftsartikel (refereegranskat)abstract
- The objective of the study was to evaluate the validity of oscillometric systolic ankle pressure in symptomatic leg arterial occlusive disease. Ankle pressure measurements using oscillometric curves obtained using a standard 12-cm cuff with a specially designed device for signal processing were validated against the continuous wave (CW) Doppler technique. Thirty-four subjects without signs or symptoms of peripheral vascular disease (68 legs) and 47 patients with leg ischaemia (85 legs) varying from moderate claudication to critical ischaemia were examined. The oscillometric curves were analysed using several algorithms reported in the literature, based on the assumption that maximum oscillations are recorded near mean arterial pressure. In normals, reasonable agreement between CW Doppler and oscillometric methods was seen. When an algorithm that determined the lowest cuff pressure at which maximum oscillations occurred, and a characteristic ratio for systolic pressure of 0·52 was used, the mean difference between CW Doppler and oscillometry was 1·7 mmHg [range −19 to +27, limits of agreement (2 SD) 21·1 mmHg]. In ischaemic legs, oscillometry overestimated systolic ankle pressure by a mean of 28·8 mmHg [range –126 to +65, limits of agreement 82·8 mmHg]. The difference was more pronounced among patients with critical ischaemia compared with claudicants, and also more evident among diabetics. The error of oscillometric pressure determination in subjects with leg arterial disease inversely increased with CW Doppler ankle pressure. In 39% of the recordings in legs with a CW Doppler systolic pressure below 100 mmHg, the oscillometric mean arterial pressure was higher than the recorded CW Doppler systolic pressure. In conclusion, the oscillometric method to determine systolic ankle pressure, based on the concept of maximum cuff oscillations occurring near mean arterial pressure, is not reliable in leg arterial disease, usually overestimating ankle pressure.
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| 11. |
- Laurent, Claes, 1958-, et al.
(författare)
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Non-invasive monitoring of systolic blood preassure on arm utilizing photoplethysmography (PPG)
- 2000
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Ingår i: World Congress of Medical Physics and Biomedical Engineering,2000. - : Springer-Verlag. ; , s. 131-135
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Konferensbidrag (refereegranskat)abstract
- Photoplethysmography (PPG) can be used to measure systolic blood pressure at the brachial artery. With a specially designed probe, positioned in the most distal position beneath a pressure cuff on the upper arm, this is possible. The distance between the light source (880 nm) and the photodetector was 20 mm. A test was performed on neuro-intensive care patients by determining blood pressure from the PPG curves, and, when it was compared with systolic blood pressure obtained from inserted indwelling arterial catheters, a correlation factor of r=0.95 was achieved. The difference between blood pressure obtained using PPG and invasive blood pressure measurement was 3.9±9.1 mmHg (mean±SD), n=19. The depth to the brachial artery was 13.9±4.1 mm (mean±SD), n=18. A digital PPG system utilising pulsating light was also developed.
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| 12. |
- Laurent, Claes, 1958-, et al.
(författare)
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Noninvasive monitoring of systolic blood pressure on the arm utilizing photoplethysmography (PPG) : clinical report
- 2004
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Ingår i: <em>Proc. SPIE</em> 5318, Advanced Biomedical and Clinical Diagnostic Systems II. - Bellingham WA, USA : SPIE. ; , s. 99-
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Konferensbidrag (refereegranskat)abstract
- A soft (silicone) probe, containing six light emitting diodes (880 nm) and three photo detectors, utilizes photoplethysmography (PPG) to monitor pulsations from the brachialis artery under an occluding cuff during deflation. When the arterial pulse returns, measured by PPG, the corresponding pressure in the cuff is determined. This pressure is assumed to equal the systolic pressure. An assessment trial was performed on 21 patients (9 women and 12 men, aged 27-69) at the Neuro-Intensive care unit. Since the patients were already provided with arterial needles, invasive blood pressure could be used as the reference. By choosing a threshold, for detecting pulses, as a fraction (4%) of the maximum amplitude, the systolic blood pressure was underestimated (-0.57 mmHg, SD 12.1). The range of systolic pressure for the patients was 95.5 - 199.0 mmHg, n=14. The method is promising, but improvements still have to be made in order to improve the technique.
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| 13. |
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| 14. |
- Lindberg, Anette, 1973-
(författare)
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Viruses as a Model System for Studies of Eukaryotic mRNA Processing
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Viruses depend on their hosts for the production and spread of new virus particles. For efficient virus replication, the viral genes have adapted the strategy of being recognized and processed by the cellular biosynthetic machineries. Viruses therefore provide an important tool to study the cellular machinery regulating gene expression. In this thesis, we have used two model DNA viruses; herpes simplex virus (HSV) and adenovirus, to study RNA processing at the level of pre-mRNA splicing in mammalian cells. During a lytic infection, HSV cause an almost complete shut-off of host cell gene expression. Importantly, HSV infection cause inhibition of pre-mRNA splicing which is possibly advantageous to the virus, as only four HSV genes contain introns. The HSV immediate early protein, ICP27, has been shown to modulate several post-transcriptional processes such as polyadenylation and pre-mRNA splicing. We have studied the role of ICP27 as an inhibitor of pre-mRNA splicing.We show that ICP27 inhibits pre-mRNA splicing in vitro in the absence of other HSV proteins. We further show that ICP27 inhibits splicing at the level of spliceosome assembly. Importantly, ICP27 induced inhibition of splicing can be reversed, either by the addition of purified SR proteins or by the addition of an SR protein specific kinase, SRPK1. We propose that SR proteins are prime candidates as mediators of the inhibitory effect of ICP27 on pre-mRNA splicing. In order to learn more about how splicing is organized in the cell nucleus in vivo, we investigated how cellular splicing factors are recruited to sites of transcription and splicing in adenovirus infected cells using confocal microscopy. Our results showed that the SR proteins, ASF/SF2 and SC35, are efficiently recruited to sites in the nucleus where adenovirus genes are transcribed and the resulting pre-mRNAs are processed. Our results demonstrate that only one of the two RNA recognition motifs (RRMs) present in the ASF/SF2 protein is required for its recruitment to active sites of splicing. The arginine/serine rich (RS) domain in ASF/SF2 is redundant and insufficient for the translocation of the protein to active viral polymerase II genes in adenovirus infected cells.
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| 15. |
- Lindberg, Per Olov, et al.
(författare)
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Homothetic functions revisited
- 2002
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Ingår i: Economic Theory. ; 19:2, s. 417-427
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Tidskriftsartikel (refereegranskat)
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| 16. |
- Sandberg, Margareta, et al.
(författare)
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Effects of acupuncture on skin and muscle blood flow in healthy subjects
- 2003
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 90:1-2, s. 114-119
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Tidskriftsartikel (refereegranskat)abstract
- In 14 healthy female subjects, the effects of needle stimulation (acupuncture) on skin and muscle blood flow were investigated using a non-invasive custom-designed probe and photoplethysmography (PPG). In randomised order, 2–7 days apart, three modes of needle stimulation were performed on the anterior aspect of the tibia: superficial insertion (SF), insertion into the anterior tibial muscle (Mu), and insertion into the muscle including manipulation of the needle in order to elicit a distinct sensation of distension, heaviness or numbness (DeQi). Before intervention, the subjects rested for 30 min. After the intervention, the needle was left in situ for 20 min. Blood flow recordings were performed intermittently from 10 min prior to the intervention to the end of the trial. In a fourth session, serving as control, corresponding measurements were performed without any needle stimulation. Area under curve was calculated for 5-min periods prior to and after stimulation, respectively, and for the remaining 15-min period after stimulation. Compared to the control situation, muscle blood flow increased following both Mu and DeQi for 20 min, with the latter being more pronounced for the initial 5 min. Skin blood flow increased for 5 min following DeQi. However, no increase was found following SF. The DeQi stimulation was preceded by higher visual analogue scale ratings of anxiety prior to stimulation, which might have influenced skin blood flow to some extent. The results indicate that the intensity of the needling is of importance, the DeQi stimulation resulting in the most pronounced increase in both skin and muscle blood flow.
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| 17. |
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| 18. |
- Sandberg, Margareta, et al.
(författare)
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Peripheral effects of needle stimulation (acupuncture) on skin and muscle blood flow in fibromyalgia
- 2004
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Ingår i: European Journal of Pain. - 1090-3801. ; 8:2, s. 163-171
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Tidskriftsartikel (refereegranskat)abstract
- Acupuncture has become a widely used treatment modality in various musculoskeletal pain conditions. Acupuncture is also shown to enhance blood flow and recovery in surgical flaps. The mechanisms behind the effect on blood flow were suggested to rely on vasoactive substances, such as calcitonin gene-related peptide, released from nociceptors by the needle stimulation. In a previous study on healthy subjects, one needle stimulation into the anterior tibial muscle was shown to increase both skin and muscle blood flow. The aim of this study was to examine the effect of needle stimulation on local blood flow in the anterior tibial muscle and overlying skin in patients suffering from a widespread chronic pain condition. Fifteen patients with fibromyalgia (FM) participated in the study. Two modes of needling, deep muscle stimulation and subcutaneous needle insertion were performed at the upper anterior aspect of the tibia, i.e., in an area without focal pathology or ongoing pain in these patients. Blood flow changes were assessed non-invasively by photoplethysmography (PPG). The results of the present study were partly similar to those earlier found at a corresponding site in healthy female subjects, i.e., deep muscle stimulation resulted in larger increase in skin blood flow (mean (SE)): 62.4% (13.0) and muscle blood flow: 93.1% (18.6), compared to baseline, than did subcutaneous insertion (mean (SE) skin blood flow increase: 26.4% (6.2); muscle blood flow increase: 46.1% (10.2)). However, in FM patients subcutaneous needle insertion was followed by a significant increase in both skin and muscle blood flow, in contrast to findings in healthy subjects where no significant blood flow increase was found following the subcutaneous needling. The different results of subcutaneous needling between the groups (skin blood flow: p=0.008; muscle blood flow: p=0.027) may be related to a greater sensitivity to pain and other somatosensory input in FM.
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| 19. |
- Uhlin, Fredrik, et al.
(författare)
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Estimation of delivered dialysis dose by on-line monitoring of the ultraviolet absorbance in the spent dialysate
- 2003
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Ingår i: American Journal of Kidney Diseases. - 0272-6386 .- 1523-6838. ; 41:5, s. 1026-1036
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Tidskriftsartikel (refereegranskat)abstract
- Background:Several methods are available to determine Kt/V, from predialysis and postdialysis blood samples to using on-line dialysate urea monitors or to ionic dialysance using a conductivity method. The aim of this study is to compare Kt/V calculated from the slope of the logarithmic on-line ultraviolet (UV) absorbance measurements, blood urea Kt/V, dialysate urea Kt/V, and Kt/V from the Urea Monitor 1000 (UM; Baxter Healthcare Corp, Deerfield, IL).Methods:Thirteen uremic patients on chronic thrice-weekly hemodialysis therapy were included in the study. The method uses absorption of UV radiation by means of a spectrophotometric set-up. Measurements were performed on-line with the spectrophotometer connected to the fluid outlet of the dialysis machine; all spent dialysate passed through a specially designed cuvette for optical single-wavelength measurements. UV absorbance measurements were compared with those calculated using blood urea and dialysate urea, and, in a subset of treatments, the UM.Results:Equilibrated Kt/V (eKt/V) obtained with UV absorbance (eKt/Va) was 1.19 ± 0.23; blood urea (eKt/Vb), 1.30 ± 0.20, and dialysate urea (eKt/Vd), 1.26 ± 0.21, and Kt/V in a subset measured by the UM (UM Kt/V) was 1.24 ± 0.18. The difference between eKt/Vb and eKt/Va was 0.10 ± 0.11, showing a variation similar to the difference between eKt/Vb and eKt/Vd (0.03 ± 0.10) and in a subset between eKt/Vb and UM Kt/V (−0.02 ± 0.11).Conclusion:The study suggests that urea Kt/V can be estimated by on-line measurement of UV absorption in the spent dialysate.
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| 20. |
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| 21. |
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| 22. |
- Zhang, Q, et al.
(författare)
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A non-invasive measure of changes in blood flow in the human anterior tibial muscle
- 2001
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 84:5, s. 448-452
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Tidskriftsartikel (refereegranskat)abstract
- We used photoplethysmography (PPG) to monitor blood flow changes in the human anterior tibial muscle during arterial occlusion and during isometric and concentric contractions. Single-fibre laser-Doppler flowmetry (LDF) was used as a reference in 12 healthy subjects (5 men, 7 women, mean age 24 years). Post-exercise hyperaemic muscle blood flow (MBF) was measured immediately after isometric dorsiflexion of the ankle joint at maximal contraction for 1 min and full range-of-motion dorsiflexion and plantar flexion of the ankle joint for 1 min. A thigh tourniquet was applied for the evaluation of post-occlusive reactive hyperaemia. The MBF (baseline=100%) was [mean (SD)] 150 (31)% (P = 0.003) by PPG (880 nm) and 182 (66)% (P = 0.012) by LDF. After 1 min of maximal isometric contraction, MBF increased to 150 (51)% (P = 0.003) by PPG (880 nm) and to 169 (43)% (P = 0.005) by LDF. After 1 min of maximal concentric contractions, MBF increased to 158 (59)% (P = 0.003) by PPG (880 nm) and to 170 (99)% (P = 0.008) by LDF. Skin blood flow, PPG (560 nm), did not change significantly after isometric or concentric contractions. The results indicate that reactive hyperaemia after exercise and arterial occlusion can be assessed in the human anterior tibial muscle using PPG.
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| 23. |
- Zhang, QX, et al.
(författare)
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Effects of limb elevation and increased intramuscular pressure on human tibialis anterior muscle blood flow
- 2001
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 85:6, s. 567-571
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Tidskriftsartikel (refereegranskat)abstract
- The effects of limb elevation and increased intramuscular pressure (IMP) on blood flow in the tibialis anterior muscle and leg neuromuscular function were studied in eight healthy subjects. Muscle blood flow (MBF) was measured by photoplethysmography using a custom-designed probe. IMP was elevated bilaterally by vein obstruction (60-65 mmHg) lasting 30 min induced by a thigh tourniquet of casted legs. Skin sensibility of the feet and the amplitude and area of the compound muscle action potentials from the extensor digitorum brevis muscle were evaluated. The subject kept one leg elevated 32 cm above heart level and the contralateral leg at heart level. All recordings were made before, during and after vein obstruction. IMP increased to 40 mmHg in the vein-obstructed casted legs. Perfusion pressure decreased from [mean (SD)] 42 (5.8) mmHg to 17 (6.4) mmHg in the elevated leg and from 65 (9.9) mmHg to 43 (8.4) mmHg in the non-elevated leg. MBF decreased by 50% in the elevated leg and by 42% in the non-elevated leg. Subjects experienced sensory dysfunction and muscular weakness in the elevated leg. In conclusion, increased IMP, induced by venous obstruction of a casted leg, reduced perfusion pressure and MBF, and resulted in a diminished amplitude and area of the compound muscle action potentials. Limb elevation above heart level combined with venous stasis of a casted leg further reduced perfusion pressure and MBF, and induced sensory dysfunction and muscular weakness.
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| 24. |
- Zhang, Qiuxia, 1960, et al.
(författare)
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Muscle blood flow in response to concentric muscular activity vs passive venous compression
- 2004
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Ingår i: Acta Physiol Scand. - : Wiley. - 0001-6772 .- 1365-201X. ; 180:1, s. 57-62
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Tidskriftsartikel (refereegranskat)abstract
- AIM: To measure muscle blood flow (MBF) using photoplethysmography (PPG) following concentric muscular activity of the leg (active treatment) or passive venous compression (passive treatment) with or without venous obstruction. METHODS: In study A, blood flow in the anterior tibial muscle was measured in 15 healthy subjects with a mean age of 30 years. In study B, blood flow in the gastrocnemius muscle was measured in nine healthy subjects with a mean age of 34 years. Subjects performed concentric muscular activity in one leg. Passive venous compression by a venous foot pump was applied in the contralateral leg. RESULTS: MBF increased significantly following concentric muscular activity, but not following passive venous compression. MBF decreased in both legs when venous obstruction, induced by a thigh tourniquet, was applied. However, MBF was significantly higher following concentric muscular activity than passive venous compression. CONCLUSION: We conclude that concentric muscular activity produces higher MBF values than passive venous compression.
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