Effect of spaceflight on the subcutaneous venoarteriolar reflex in the human lower leg

2007 ◽  
Vol 103 (3) ◽  
pp. 959-962 ◽  
Author(s):  
Anders Gabrielsen ◽  
Peter Norsk
Keyword(s):  
Blood Flow ◽  
Knee Joint ◽  
Ankle Joint ◽  
Lower Leg ◽  
Statistical Significant Difference ◽  
Significant Difference ◽  
The Everyday ◽  
Decrease Blood Flow ◽  
Subcutaneous Blood Flow

Whenever the legs are lowered in humans, a venoarteriolar reflex is activated by the hydrostatic distension of the venules. Through local axon reflexes, the adjacent arterioles are contracted to decrease blood flow and prevent formation of edema. Because the venoarteriolar reflex is activated by gravity, we tested the hypothesis that long-term weightlessness would attenuate it. The reduction in subcutaneous blood flow was measured by the 133Xe washout technique just proximal to the ankle joint in dependent lower legs of eight supine astronauts, where the knee joint was passively bent by 90°. The measurements were conducted before spaceflight and 3–6 h on landing following 4–6.5 mo in space. Activation of the venoarteriolar reflex reduced subcutaneous blood flow by 37 ± 9% ( P = 0.016) before flight and by 64 ± 8% ( P < 0.001) following landing with no statistical significant difference between the two reductions ( P = 0.062). Therefore, our results show that the venoarteriolar reflex is not attenuated by weightlessness and therefore does not need the everyday stimulus of gravity to maintain efficiency.

Lack of effect of peripheral nervous blockade on nocturnal fluctuations in lower-leg subcutaneous blood flow in man

1993 ◽  
Vol 84 (3) ◽  
pp. 297-304 ◽  
Author(s):  
J. H. Sindrup ◽  
L. J. Petersen ◽  
J. Kastrup ◽  
H. Wroblewski ◽  
J. K. Kristensen
Keyword(s):  
Blood Flow ◽  
Data Storage ◽  
Human Subjects ◽  
Lower Leg ◽  
Tissue Blood Flow ◽  
Storage Unit ◽  
Significant Difference ◽  
Blood Flow Increase ◽  
Subcutaneous Blood Flow ◽  
The Right

1. The local subcutaneous adipose tissue blood flow was measured simultaneously in the right and left lower legs of 10 normal human subjects under outpatient nocturnal conditions. The 133Xe-wash-out technique, portable CdTe(Cl) detectors and a portable data-storage unit were used for the measurement of blood flow. 2. The purpose of the study was to unveil the possible role of centrally controlled nerve fibres to the measurement area as mediators of a previously described nocturnal subcutaneous hyperaemia of 2 h duration. Therefore, before the sleeping period, a local nervous blockade was applied immediately proximal to the isotope depot on the right lower leg by the injection of approximately 15 ml of bupivacaine (5 mg/ml) subcutaneously. 3. Control experiments revealed blockade of the baroreceptor vasoconstrictor reflex activity 4 h after application of the local nervous blockade in three subjects examined. 4. Identical nocturnal isotope-wash-out curves were recorded from the two legs. Subcutaneous blood flow was found to increase significantly (P <0.0001) after approximately 1 h of sleep and the hyperaemia persisted for 2 h. 5. A significant positive correlation was detected between the latency periods from going to bed until the onset of the hyperaemia in the right and left lower legs (P <0.001, r = 0.95). 6. No significant difference could be detected between the relative blood flow increase during the hyperaemic phase in the right and left lower legs (P = 0.83). 7. It is concluded that the present data seem to rule out a central nervous factor(s) as the eliciting mechanism of the nocturnal subcutaneous hyperaemia. A circulating humoral factor(s) might be involved, although modification by local metabolic factors cannot be excluded. The possible physiological significance of the nocturnal hyperaemia is discussed.

Native Arterio-Venous Fistula for Hemodialysis: What to Expect Early after Creation?

2003 ◽  
Vol 4 (2) ◽  
pp. 39-44 ◽  
Author(s):  
M. Leblanc ◽  
E. Saint-Sauveur ◽  
V. Pichette
Keyword(s):  
Blood Flow ◽  
Vascular Access ◽  
Complication Rates ◽  
Ultrasound Dilution ◽  
Flow Monitoring ◽  
Significant Difference ◽  
Lower Complication ◽  
Vascular Mapping ◽  
Venous Fistula

Native arterio-venous fistulas (AVFs) are preferred for hemodialysis vascular access over synthetic grafts and long-term catheters. However, prevalence rates of native AVFs are variable around the world and have increased only slightly in United States since the DOQI guidelines. To increase rates of native AVFs, pre-operative vascular mapping by ultrasound has been found of major help for appropriate selection of the vessels. The minimal desirable lumen diameter of the artery should be > 2 mm and > 2.5 to 3 mm for the vein at the anatomosis. Early failure can be reduced to less than 10% when the feeding artery is > 2 mm, even in diabetics. If sizes of the vessels are smaller than those targets at the wrist, moving to the upper arm should be considered. The interval between creation and first cannulation varies from 2 weeks to 4 months. There might not be much advantage to wait for more than 4 weeks; however, in large dialysis units, observing a delay of 4 to 6 weeks may be worthwhile to avoid initial problems such as infiltrations and lacerations. Access flow monitoring is essential since it is a reliable predictor of vascular access dysfunction, reducing associated morbidity and costs. Early monitoring of recently created native AVFs has shown that the increase in intra-access blood flow occurs very soon after construction and becomes maximal after a few weeks. A recent prospective study involving all new native AVFs monitored by ultrasound-dilution between weeks 6 and 10 after creation, and every 3 to 6 weeks over 4 months, showed no statistically significant difference in access blood flow between the initial and final measurements (respective values of 1132 ± 681 and 1097 ± 644 ml/min). Access flow was higher in males, and in brachio-cephalic compared to radio-cephalic AVFs. Over the long-term, AVFs are associated with longer patency and lower complication rates, and efforts should be directed at further increasing their prevalence.

scholarly journals Long-Term Outcomes of Digital Nerve Repair Accompanied by Digital Artery Injury in Flexor Zone 2

2019 ◽  
Vol 06 (01) ◽  
pp. e7-e9
Author(s):  
Gokce Yildiran ◽  
Mustafa Sutcu ◽  
Osman Akdag ◽  
Zekeriya Tosun
Keyword(s):  
Blood Flow ◽  
Blood Supply ◽  
Nerve Repair ◽  
Arterial Injury ◽  
Digital Artery ◽  
Digital Nerve ◽  
Significant Difference ◽  
Sensory Recovery

Abstract Objectives Better healing results of any tissue or area is closely linked with a well-blood supply in reconstructive surgery. Peripheric nerve healing is closely related to blood supply as well. We aimed to assess whether there was any difference between digital nerve healing with and without extrinsic blood supply. Methods We assessed 48 patients with unilateral digital nerve injury at zone 2. Twenty-four of them had unrepairable arterial injury and other 24 had no arterial injury. The 24 patients in the “unrepaired artery group” (UA) and 24 patients in the “intact artery group” (IA) were compared. Results Mean follow-up time was 17.7 months. The mean two-point discrimination (2PD) was 5.29 mm in IA group and 5.37 mm in UA group. One neuroma in IA group and two neuromas in UA group were determined. We found no statistically significant difference between these groups in terms of neuroma, 2PD, and cold intolerance. The results of British Medical Research Council sensory recovery clinical scale were comparable for these two groups. Conclusion Digital nerve healing is related to numerous factors. We hypothesized that blood flow may be one of these factors; however, at this zone digital artery repair is not the foremost determinant for digital nerve healing. Further researches should be done for upper injury levels. Despite this result, we argue not to leave the digital artery without repairment and we propose to repair both artery and nerve to achieve the normal anatomical integrity and to warrant finger blood flow in possible future injuries.

scholarly journals Effect of insulin treatment on pulsatility ratio and resistance index of the retinal artery in patients with type 2 diabetes

PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0254980
Author(s):  
Tsuneaki Omae ◽  
Youngseok Song ◽  
Takafumi Yoshioka ◽  
Tomofumi Tani ◽  
Akitoshi Yoshida
Keyword(s):  
Type 2 Diabetes ◽  
Blood Flow ◽  
Insulin Treatment ◽  
Diabetic Patients ◽  
Type 2 Diabetic Patients ◽  
Significant Difference ◽  
Retinal Artery ◽  
Type 2 Diabetic

This study aimed to evaluate whether long-term insulin treatment is associated with abnormalities in retinal circulation in type 2 diabetic patients. We evaluated 19 eyes of nondiabetic individuals and 68 eyes of type 2 diabetic patients. The eyes of diabetic patients were classified into two groups according to the presence or absence of long-term insulin therapy. We used a Doppler optical coherence tomography flowmeter to measure diameter, velocity, and blood flow in the major temporal retinal artery. The pulsatility ratio (PR) and resistance index (RI), indices of vascular rigidity, were calculated from the blood velocity profile. PR and RI were significantly elevated in type 2 diabetic patients compared with nondiabetic subjects (P < 0.05). In type 2 diabetes patients, PR and RI were significantly higher in patients receiving long-term insulin treatment than in those without (P < 0.01). There was a significant difference in velocity (P < 0.05), but not diameter and blood flow, between nondiabetic subjects and type 2 diabetes patients. No significant difference in diameter, velocity, or blood flow was observed between the groups with and without long-term insulin treatment. Long-term insulin treatment can affect PR and RI, which might be associated with vascular rigidity of the retinal artery in patients with type 2 diabetes.

Effects of Extensive Training on Female Teenage Gymnasts’ Active and Passive Ankle-Joint Position Sense

2002 ◽  
Vol 11 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Taner Aydin ◽  
Yavuz Yildiz ◽  
Cemil Yildiz ◽  
Tunç Alp Kalyon
Keyword(s):  
Ankle Joint ◽  
Position Sense ◽  
Joint Position Sense ◽  
Joint Position ◽  
Mean Values ◽  
Extensive Training ◽  
Significant Difference ◽  
Group 2 ◽  
Female Gymnasts

Objective:To compare the ankle-joint position-sense patterns of gymnasts and nongymnasts.Design:Proprioceptive ability was evaluated with active and passive angle-reproduction tests.Participants:40 subjects assigned to 2 groups: group 1 (n = 20), healthy subjects, and group 2 (n = 20), teenage female gymnasts.Measurements:Joint-position sense was actively measured with a Cybex NORM™ isokinetic dynamometer and passively with a proprioception-testing device.Results:A Mann-Whitney U test was used to compare the mean values of the gymnasts’ and controls’ ankles. Results revealed statistically significant differences (P < .05) between the 2 groups. No statistically significant difference between the dominant and nondominant ankles in the 2 groups was observed.Conclusions:The results suggest that extensive training might affect ankle-joint position sense, but genetics and natural selection could be the reason. It is thought that athletes are able to develop enhanced neurosensory pathways as a result of long-term training.

scholarly journals Comparison of tunnel expansion, isometric muscle strength and clinical condition after anterior cruciate ligament reconstruction with single- or dual-bundle

2017 ◽  
Vol 5 (2_suppl2) ◽  
pp. 2325967117S0004
Author(s):  
Salih Beyaz ◽  
Ümit Özgür Güler ◽  
Şenay Demir ◽  
Selcen Pehlivan ◽  
Bekir Murat Çınar ◽  
...  
Keyword(s):  
Knee Joint ◽  
Cruciate Ligament ◽  
Scoring Systems ◽  
Peak Torque ◽  
Double Bundle ◽  
Tunnel Widening ◽  
Single Bundle ◽  
Significant Difference ◽  
Anterior Cruciate

Thirty-one patients who suffered anterior cruciate ligament (ACL) injury and underwent ACL reconstruction (16 single-bundle, 15 double-bundle) with ENDOBUTTON between November 2007 and March 2008 were included in the study. Isokinetic and concentric strength measurements of the quadriceps and hamstring muscles at the 6th month and 8th year were made using a Biodex 3 device at angular velocities of 60°/sec, 120°/sec and 180°/sec. The peak torque and peak torque to body weight ratios were recorded. 3D-CT scans of the joints were performed on the 2nd, 3 rd and 6th month and 8th year. CT slices were divided into six equal parts marking the distance between the femoral and tibial tunnels with the most distant part of the knee joint as L1, and with the entry point on the knee joint as L6. The tunnel length was measured in millimeters and perpendicularly to the tibial axis in the sagittal and coronal planes. Tunnel cross-sectional areas were also measured in mm2 using the same device on axial reconstructions. Clinical evaluations on the 8th year were performed with the IKDC, Tegner and Lysholm knee scoring systems and laxity in the patients was evaluated with the anterior drawer test. Posterolateral tunnel widening was analyzed with the repeated measures ANOVA technique whereas two-way mixed ANOVA was employed in evaluating the anteromedial tunnel widening. Three-way ANOVA was used in assessing the Biodex results and comparison of the scoring systems results were done with the t-test. Results: No difference was found between the groups in terms of IKDC, Lysholm and Tegner scores and anterior drawer test results at the 8th year follow-up (p>0.05). Points where significant amounts of tunnel widening were observed are shown in Table 1 . On evaluation of the anteromedial bundles alone, it was observed that double-tunnel reconstruction led to greater widening. No significant difference was found between the groups in terms of muscle strength in the 8th year assessments, however, there was a statistically significant difference between the preoperative and 6th month results (p<0.05). Patients in both groups had better results at the 8th year follow-up when compared to their preoperative and 6th month results. The results of our study confirmed significant amounts of widening at parts of the femoral tunnel close to the knee joint in patients treated with single-bundle or double-bundle ACL reconstruction. However, there is no difference between the groups in terms of clinical results and isometric muscle strengths in the long term. [Table: see text] Discussion: It has been suggested that the tunnel widening will lead to failure of the reconstruction. It is hypothesized that, in double-bundle reconstruction, the tunnels will widen more and finally coalesce, which in turn, will result in failure of the reconstruction. In our study, we found no evidence pointing out to a coalescence of the tunnels in the long term. We believe the greater widening in the anteromedial bundle in the double-tunnel surgery vs. the single-tunnel method is due to the smaller diameter of the graft and its greater mobility

Nocturnal variations in subcutaneous blood flow rate in lower leg of normal human subjects

1991 ◽  
Vol 260 (2) ◽  
pp. H480-H485 ◽  
Author(s):  
J. H. Sindrup ◽  
J. Kastrup ◽  
B. Jorgensen ◽  
J. Bulow ◽  
N. A. Lassen
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Human Subjects ◽  
Blood Flow Rate ◽  
Lower Leg ◽  
Tissue Blood Flow ◽  
Subcutaneous Blood Flow ◽  
Normal Human ◽  
Night Period ◽  
133Xe Washout

Subcutaneous adipose tissue blood flow rate was measured in the lower leg of 22 normal human subjects over 12- to 20-h ambulatory conditions. The 133Xe washout technique, portable CdTe(Cl) detectors, and a portable data storage unit were used. The tracer depot was applied on the medial aspect of the right lower leg 10 cm proximal to the malleolar level by means of the epicutaneous, atraumatic labeling technique. The change from upright to supine position from day 1 in the beginning of the night period elicited an instantaneous blood flow rate increment of 30-40% in accordance with a decrease in central and local postural sympathetic vasoconstrictor activity. During sleep, characteristic variations in subcutaneous blood flow were disclosed. The 133Xe washout curve could be divided into three segments with significantly different slopes. Approximately 90 min after the subject went to sleep, an additional blood flow rate increment of considerable magnitude was observed. The mean increase was 84%, but in several cases a greater than 200% increment was measured (maximum 244%). The intra-individual coefficient of variation for the nocturnal blood flow response was in triplicate measurements 25% (n = 9). The hyperemic phase lasted approximately 100 min after which the blood flow rate returned to the level measured at the beginning of the night period. The blood flow rates measured on the second day did not differ from those on the first day. Control measurements performed under similar thermal conditions, but with the subjects kept awake, did not reveal any hyperemic phases. This points toward changes in cardiovascular regulatory mechanisms during sleep.(ABSTRACT TRUNCATED AT 250 WORDS)

Fetal renal artery impedance in pregnancies affected by preeclampsia

2020 ◽  
Vol 48 (4) ◽  
pp. 313-316
Author(s):  
Marwan Ma’ayeh ◽  
Vidhya Krishnan ◽  
Stephen E. Gee ◽  
Jessica Russo ◽  
Cynthia Shellhaas ◽  
...  
Keyword(s):  
Blood Flow ◽  
Renal Artery ◽  
Resistance Index ◽  
Renal Arteries ◽  
Control Group ◽  
Vascular Endothelial ◽  
Adverse Health Effects ◽  
Significant Difference ◽  
Renal Vascular

AbstractBackgroundPreeclampsia (PE) is a pregnancy-specific vascular endothelial disorder characterized by multi-organ system involvement. This includes the maternal kidneys, with changes such as continuous vasospasm of renal arteries and reduced renal blood flow. However, it is unclear whether similar renal vascular changes are seen in the fetus. This study sought to compare renal artery impedance in fetuses of women with and without PE.MethodsThis was a prospective Doppler assessment study of the fetal renal artery impedance in 48 singleton fetuses. The group with PE consisted of 24 appropriately grown fetuses in pregnancy complicated by both mild and severe PE and a control group of 24 uncomplicated pregnancies. Doppler studies included renal artery systolic/diastolic (S/D) ratio, pulsatility index (PI), resistance index (RI), and identification of end-diastolic blood flow.ResultsFetuses of mothers with PE were more likely to have a lower renal artery Doppler S/D ratio (7.85 [6.4–10.2] vs. 10.8 [7.75–22.5], P = 0.03) and lower RI (0.875 [0.842–0.898] vs. 0.905 [0.872–0.957], P = 0.03). However, there was no statistically significant difference in PI. There was also no difference in the incidence of absent end-diastolic flow.ConclusionThis study suggests that PE results in changes in blood flow to the renal arteries of the fetus. This may be associated with long-term adverse health effects later in adulthood.

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