Ebook Extracorporeal life support for adults: Part 2
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Ebook Extracorporeal life support for adults: Part 2
Chapter 7Vascular Access for ECLSSteven A. ConradIntroductionAccess to the central circulation to provide and maintain blood flow necessary for adequa Ebook Extracorporeal life support for adults: Part 2ate gas exchange is one of the most essential aspects for successful extracorporeal support. Inadequate extracorporeal flow can lead to failure to deliver sufflcient support and limit any potential benefit of ECLS. Cannulae and cannula insertion techniques are quite variable, and the choice will dep Ebook Extracorporeal life support for adults: Part 2end on the goals and mode of support, the size of the patient, size of the vessels, as well as institutional and logistical concerns.Cannulas for ExtrEbook Extracorporeal life support for adults: Part 2
acorporeal SupportA variety of cannulae for peripheral vascular access are commercially available. These cannulae differ with respect to the mode of iChapter 7Vascular Access for ECLSSteven A. ConradIntroductionAccess to the central circulation to provide and maintain blood flow necessary for adequa Ebook Extracorporeal life support for adults: Part 2ths and diameters to accommodate the choice of vessel.Cannulae designed for percutaneous peripheral insertion have some minor feature differences from those intended for surgical placement. The loading dilator that accompanies a percutaneous cannula has a long taper and central lumen to accommodate Ebook Extracorporeal life support for adults: Part 2a guidewire, whereas the surgical cannula has a blunt dilator with a short tip and no central lumen. The tip of a percutaneous cannula is designed toEbook Extracorporeal life support for adults: Part 2
fit snuglyS.A. Conrad. MD. PhD. MCC.M. FCCP (Bl)Department of Medicine. Emergency Medicine and Pediatrics. Louisiana State University Health Sciences Chapter 7Vascular Access for ECLSSteven A. ConradIntroductionAccess to the central circulation to provide and maintain blood flow necessary for adequa Ebook Extracorporeal life support for adults: Part 2. Extracorporeal Life Support for Adults. Vb/IÚMM IÁ nói Io 1007/07« I 4Ebook Extracorporeal life support for adults: Part 2
, and prevent collapse when negative pressures are applied to the lumen. Since these complications can result in loss of extracorporeal support, reinfChapter 7Vascular Access for ECLSSteven A. ConradIntroductionAccess to the central circulation to provide and maintain blood flow necessary for adequa Ebook Extracorporeal life support for adults: Part 2ular access, and are an optional approach for venovenous access. Two fundamental designs are manufactured, intended for drainage or for reinfusion (referred to as venous and arterial cannulas, respectively). The venous design is characterized by a greater length (up to approximately 50 cm), greater Ebook Extracorporeal life support for adults: Part 2available diameter (up to 28 Fr). and a longer distal segment with multiple side holes to facilitate drainage. The length allows insertion into more cEbook Extracorporeal life support for adults: Part 2
entral veins such as the superior (SVC) or inferior vena cava (IVC). The arterial design is characterized by a shorter length and a shorter distal segChapter 7Vascular Access for ECLSSteven A. ConradIntroductionAccess to the central circulation to provide and maintain blood flow necessary for adequa Ebook Extracorporeal life support for adults: Part 2excess number of side holes can increase the risk of hemolysis in arterial cannulas.Recently introduced expandable, w ire-reinforced cannulas that incorporate a distal segment of w all-free w ire mesh (Smartcanula LLC. Switzerland) are available in some markets. These cannulas expand to a larger dia Ebook Extracorporeal life support for adults: Part 2meter within the vessel to minimize flow resistance, and the distal mesh maintains vessel patency for improved drainage.Dual-Lumen DesignCannulae thatEbook Extracorporeal life support for adults: Part 2
incorporate two lumens with two drainage and a single infusion port are a more recent design that has greatly facilitated the application of venovenoChapter 7Vascular Access for ECLSSteven A. ConradIntroductionAccess to the central circulation to provide and maintain blood flow necessary for adequa Ebook Extracorporeal life support for adults: Part 2 available that have features to support different needs.The cavo-atrial design [ 1.21 (OriGen*,OriGen Biomedical) (Fig. 7.1) is inserted via the internal jugular vein w ith the tip positioned in the low right atrium near the IVC ostium. It has two drainage ports, one distal at the inferior atrium a Ebook Extracorporeal life support for adults: Part 2nd one proximately in the superior vena cava, with the reinfusion port in the mid right atrium directed at the tricuspid valve. The proximity of the dEbook Extracorporeal life support for adults: Part 2
istal lumen to the reinfusion port allows some recirculation, but effective blood flow remains adequate. Placement is somewhat easier than the bicavalChapter 7Vascular Access for ECLSSteven A. ConradIntroductionAccess to the central circulation to provide and maintain blood flow necessary for adequa Ebook Extracorporeal life support for adults: Part 2VC and inferior right atrium with reinfusion into the mid right atrium. (Reprinted with permission from OriGen Biomedical)The bicaval design (Avalon Elite”, Maquet) requires insertion via the internal jugular vein with the cannula traversing the right atrium and the tip positioned in the I VC [3, 4] Ebook Extracorporeal life support for adults: Part 2 (Fig. 7.2). The drainage lumen extends the length of the cannula with drainage ports in both the IVC and SVC. The reinfusion lumen is shorter, terminEbook Extracorporeal life support for adults: Part 2
ating in the right atrium with the reinfusion port directed toward the tricuspid valve. This bicaval drainage design effectively separates the upper aChapter 7Vascular Access for ECLSSteven A. ConradIntroductionAccess to the central circulation to provide and maintain blood flow necessary for adequa Ebook Extracorporeal life support for adults: Part 2single proximal drainage lumen and a distal reinfusion lumen [5]. This catheter is intended for low-flow extracorporeal circuits used for carbon dioxide removal (ECCO;R; Chap. 4). If the cannula flow exceeds the insertion vessel flow, recirculation w ill limit effective flow, but placement in the in Ebook Extracorporeal life support for adults: Part 2ternal jugular or femoral and iliac veins usually assures adequate blood flow.Determinants of Cannula Blood FlowBlood flow through vascular cannulas iEbook Extracorporeal life support for adults: Part 2
s driven by the difference between the pressure at the hub of the cannula and the intravascular pressure at the tip of the cannula. Although a cannulaChapter 7Vascular Access for ECLSSteven A. ConradIntroductionAccess to the central circulation to provide and maintain blood flow necessary for adequa Ebook Extracorporeal life support for adults: Part 2ip is only approximately linear over a portion of the flow' range (Fig. 7.3).S.A. Conrad136Fig. 7.2 A dual-lumen venous cannula, designed for combined drainage from lhe IVC and SVC and reinfusion of blood into the right atrium for venovenous extracorporeal supportFig. 7.3 Representative pressure-flo Ebook Extracorporeal life support for adults: Part 2w relationships for various size single-lumen cannulac. The graph depicts the nonlinear relationship between flow and pressure due to a combination ofEbook Extracorporeal life support for adults: Part 2
laminar and disturbed/turbulent flow resulting from the complex geometry of the catheterThe ĩĩagen-Poisseullc equation for laminar flow, although notChapter 7Vascular Access for ECLSSteven A. ConradIntroductionAccess to the central circulation to provide and maintain blood flow necessary for adequaChapter 7Vascular Access for ECLSSteven A. ConradIntroductionAccess to the central circulation to provide and maintain blood flow necessary for adequaGọi ngay
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