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OBJECTIVES: Hydrostatic compression (HC) occurring during body immersion is considered beneficial for venous return from the lower limbs. No study has evaluated the effects of HC on the veins of the lower limbs using duplex ultrasound (DU). The purpose of this study was to use DU to evaluate the morphology and flow of the leg veins during immersion. DESIGN: The femoral and great saphenous veins were evaluated before and during immersion in a specifically built pool, in normal and varicose limbs. RESULTS: HC reduces vein size in both normal and varicose limbs. During immersion spontaneous flow increases whereas when present, blood reflux decreases. DISCUSSION: This pilot, proof of concept study has demonstrated the feasibility of DU investigation of leg veins during immersion. Larger series of underwater DU evaluations of normal and varicose legs are necessary to quantify and better explain the effects of HC on the veins of the lower limb.

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OBJECTIVES: We investigated popliteal venous haemodynamics of the VenaJet Jet Impulse Technology system within a below-knee fibreglass cast. DESIGN: Randomized controlled trial. PARTICIPANTS: Twenty-four healthy participants aged 18-54 had both feet placed within the Jet Impulse Technology system and were randomised for one or other leg to be within a below-knee fibreglass cast. SETTING: Pacific Radiology, Lower Hutt, Wellington. MAIN OUTCOME MEASURES: The primary outcome variable was peak systolic velocity (cm/s) compared between legs with and without the cast at 60 min (after 10 min Jet Impulse Technology activation), using a mixed linear model and a non-inferiority bound of 4.8 cm/s. Secondary outcome variables were the difference in peak systolic velocity between the casted limb and the non-casted limb at baseline and 40 min after casting, and the difference in mean flow velocity (cm/s), vein diameter (mm), and total volume flow (L/min) between the casted limb and the non-casted limb at baseline, 40 and 60 min. RESULTS: The mean (standard deviation) peak systolic velocity was 4.6(1.5), 4.8(1.1), 28.8(16.1), and 4.3(1.2), 4.8(1.4) and 29.3(19.0) cm/s at baseline, 40 and 60 min in the casted and non-casted leg, respectively. The difference (95% confidence interval) between cast and no-cast at 60 min was -0.8 (-6.5 to 4.9) cm/s, P = 0.78. The peak systolic velocity, flow velocity and total volume flow at 40 min were not statistically significantly different from baseline for both casted and non-casted limb. CONCLUSION: In healthy volunteers, the popliteal venous haemodynamics of the Jet Impulse Technology system was similar between the legs with and without a below-knee fibreglass cast. In-cast Jet Impulse Technology may provide a non-pharmacological option for venous thromboembolism prophylaxis for lower-limb cast-immobility.

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Objective Analyse venous haemodynamics in healthy primigravidae during pregnancy and in the postpartum. Methods Cohort with primigravidae evaluated in the three trimesters of pregnancy and postpartum. Duplex evaluated venous diameters and reflux; air plethysmography evaluated venous filling index, ejection fraction, residual volume fraction and outflow fraction in both limbs. Results During pregnancy, diameters increased in bilateral common femoral and right infravalvar great saphenous, but returned to first trimester values after delivery. Reflux developed in one woman (5%) in the second trimester and in two more women (15%) in the third trimester. No reflux was detected in postpartum. Bilateral venous filling index was higher during pregnancy. Bilateral ejection fraction and residual volume fraction did not change. Bilateral outflow fraction increased progressively. The right limb outflow fraction in left lateral decubitus was similar. All changes returned to first trimester values after delivery. Conclusions Healthy primigravidae presented changes in lower limbs' veins during pregnancy: diameters in bilateral common femoral and infravalvar great saphenous veins increased; new reflux was developed in 15% of women, but there was no venous hypertension. Calf muscular pump function did not change. All changes returned to first trimester values after delivery.

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OBJECTIVE: While chronic cerebrospinal venous insufficiency (CCSVI) can be characterized using cervical plethysmography, much remains unknown about the haemodynamics associated with this procedure. The aim of the study was therefore to gain a deeper understanding of the observed haemodynamics. METHOD: Forty healthy controls and 44 CCSVI patients underwent cervical plethysmography, which involved placing a strain-gauge collar around their necks and tipping them from the upright (90(o)) to supine position (0(o)) in a chair. Once stabilized, they were returned to the upright position, allowing blood to drain from the neck. A mathematical model was used to calculate the hydraulic resistance of the extracranial venous system for each subject in the study. RESULTS: The mean hydraulic resistance of the extracranial venous system was 10.28 (standard deviation [SD] 5.14) mmHg.s/mL in the healthy controls and 16.81 (SD 9.22) in the CCSVI patients (P < 0.001). CONCLUSIONS: The haemodynamics of the extracranial venous system are greatly altered in CCSVI patients.

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