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Access for Dialysis: Surgical and Radiologic Procedures - part 5

Hình 7.2. Có hai loại ống thông lọc máu đường hầm: A) đầu đôi hoặc ống thông chia, là điển hình của ống thông chia Ash (polyurethane) và B) tăng gấp đôi lòng ống thông catheter được hiển thị ở đây như là một ống thông Hickman (cao su silicone). | Evaluation and Intervention for Hemodialysis Vascular Access 161 Fig. 7.2. Two types of tunneled dialysis catheters A Double tip or split catheter as typified by the Ash split catheter polyurethane and B the single catheter double lumen catheter shown here as a Hickman catheter silicone rubber . 7 Fig. 7.3. Catheter size has a direct effect on flow. This explains the greater dialysis efficiency with a cuffed catheter 14.5F and a temporary catheter 12F. 7 162 Access for Dialysis Surgical and Radiologic Procedures Fig. 7.4. Anatomy of the superior vena cava and right atrium and ventricle. and optimal catheter tip length and positioning. Knowledge of central venous anatomy is imperative when placing central catheters Fig. 7.4 . I find the best function is achieved when Fig. 7.5 the catheter is low in the neck in the internal or external jugular vein with the tips extending inferior to the cavo-atrial junction in the right atrium the exit site is just lateral to the mid-clavicle and the tissue in-growth cuff is 1-2 cm deep to the skin. These criteria necessitate measurement of the distance to the right atrium to correctly choose a catheter of appropriate length. Also breasts should be retracted caudally when choosing the catheter exit site to prevent displacement of the catheter by gravity. Split catheters are not position dependent but single dual-lumen catheters should have the arterial port facing centrally toward the major pool or right atrial blood. Remember that the catheter is placed when the patient is recumbent and will foreshorten when the patient sits or stands erect. Catheter dysfunction is often related to the catheter tip design employing multiple side holes in the catheter tip to improve flow during dialysis but allowing thrombus to form between dialysis treatments because of hemostasis within the catheter tip Fig. 7.6 . The routine practice of explosive catheter irrigation before Evaluation and Intervention for Hemodialysis Vascular Access 163 7 Fig. .