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Urinary system
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
Some patients with end-stage renal failure require haemodialysis. Ideally this is achieved by the surgical creation of an arteriovenous fistula, typically in the patient’s non-dominant arm. Common sites of fistulae include connection of the radial artery with the cephalic vein at the wrist, or the brachial artery with the cephalic vein or basilic vein at the elbow. As the vein receives high pressure blood directly from the artery, it arterialises (‘matures’), enlarging and becoming thicker walled. Flow though the fistula may be clinically noticeable as a palpable ‘thrill’ (a buzz). This large vein provides easier long term access for the large gauge dialysis needles and allows continuous high volumes of blood flow necessary for efficient dialysis. However, over time stenoses may develop, often around the site of the anastomosis or the needling sites; this can cause reduced blood flow, and if untreated can lead to suboptimal dialysis and/or thrombosis of the fistula. Stenoses may be treated by angioplasty, while thrombosis, if diagnosed early enough, may be treated with thrombolysis, mechanical or aspiration thrombectomy or ‘trawling’ the thrombus with an angioplasty balloon. Alternative access for haemodialysis may be provided via a tunnelled central venous catheter. In difficult cases this can be inserted under radiographic control.
Designing for Hand and Wrist Anatomy
Published in Karen L. LaBat, Karen S. Ryan, Human Body, 2019
Veins of the hand lie close to the surface (superficial) and deep within the tissues. The bulk of the oxygen-depleted blood leaves the hands through the venous system visible on the dorsum of the hand (Figure 7.12). Look at the back of your hand to see the superficial, blue-shaded veins near the skin surface. These veins drain into the major superficial forearm veins, the cephalic and basilic on the dorsomedial and dorsolateral forearm. Smaller superficial veins can be seen on the volar forearm at the wrist. Tight garments or wearable devices that encircle the forearm/arm may compress the relatively thin-walled veins. A swollen, dusky red, or blue-tinged hand warns that venous compression may be occurring.
Thermal Physiology and Thermoregulation
Published in James Stewart Campbell, M. Nathaniel Mead, Human Medical Thermography, 2023
James Stewart Campbell, M. Nathaniel Mead
After passing through the dilated glomus or arteriolar shunts in the skin, the warm blood is carried by superficial veins where it can dissipate heat to the external surroundings. In the upper extremity, the majority of the warmed blood flows in multiple subdermal veins up to the elbow, where these superficial veins coalesce into the basilic vein. This large vein dives to meet the deeper brachial veins, which continue between the biceps and triceps muscles up to the shoulder, too deep to be detected thermographically. The cephalic vein, however, may sometimes be visualized, coursing up the lateral upper arm and across the anterior shoulder.
A narrative review of historic and current approaches for patients with difficult venous access: considerations for the emergency department
Published in Expert Review of Medical Devices, 2022
Andrew Little, Drew G. Jones, Kimberly Alsbrooks
Ultrasound-guided PIV catheter placements may be inserted in any vein of the upper extremities. While deep arm veins (e.g. cephalic, basilic, and brachial veins) are often attempted, these veins may be challenging to access [27,28]. Since standard-length PIV catheters often dislodge from deep arm veins, longer PIV catheters have been recommended [27]. One systematic review of 16 studies of long PIVs (6 cm to 15 cm, with 8 cm being most frequent size, was published by Qin et al., 2020 [29]. This review reported that long PIVs can be safe and reliable in children and adults and shows value in DVA; however, catheter failure rates were shown to vary widely, from 4.3% to 52.5% with leakage, infiltration, and dislodgement, being most frequent causes of failure reported. Furthermore, longer PIV catheters may often not be stocked within emergency departments, further restricting treatment options for DVA in certain situations.
Endovascular arteriovenous fistulas— are they the answer we haven’t been looking for?
Published in Expert Review of Medical Devices, 2021
Bynvant Sandhu, Charlie Hill, Mohammad Ayaz Hossain
The Ellipsys endovascular AVF system utilizes a single catheter to direct heat and pressure to create an AVF between the proximal radial artery and the deep communicating vein in the proximal forearm. Continuous high frequency ultrasound guidance is used to perform retrograde venous puncture of the median basilic or cephalic vein which is then advanced into the proximal radial artery, followed by a wire and a sheath. The Ellipsys catheter creates an elliptical side-to-side anastomosis. Balloon angioplasty is then performed to reduce post-anastomotic stenosis. The manufacturers report a procedure time of less than 30 minutes.