Renal Replacement Therapy Renal Replacement Therapy n HD

Renal Replacement Therapy

Renal Replacement Therapy 透析俗稱洗腎 n HD (hemodialysis) 血液透析 n PD (peritoneal dialysis) 腹膜透析 n Kid/Trans (kidney transplantation) 腎臟移植

Transplantation Peritoneal Dialysis Hemodialysis

Estimated GFR (I) Ccr: overestimates GFR (proximal tubular secretion in advanced RF) n Curea: underestimates GFR (urea is reabsorbed in the distal nephron) n When measurement of GFR by a direct test is not available, the average of the sum of the creatinine and urea clearance is recommended. n Ccr (ml/min)= Ucr X V (24 -hr urine, ml) ----------------Pcr X 1440 (min) n

Estimated GFR (II) n Cockcroft-Gault equation In men: Ccr= (140 - Age) X Body weight in kg ---------------------72 X serum Creatinine In women: men Ccr X 0. 85

Preparation for dialytic treatment n Explain the timing of complete renal failure and provide forms of available therapy 提早準備 n HD: create an AV fistula in advance n PD: implantation of peritoneal catheter 減少尿毒所引發不適的症狀與徴後及合 併症 n 減少雙腔導管放置時的危險。 n

Principles of Hemodialysis

透析用血管通路 n n Blood flow of 200 to 400 ml/min are necessary Blood from veins is inadequate & repeated puncture of a large artery is not feasible 暫時性 vascular access (by Nep Dr. ) Ø femoral, int. jugular vein, subclavian vein Ø A double lumen catheter: temporary or semipermanent with cuffs 永久性 vascular access (by CVS Dr. ) Ø A fistula is created (surgically anastamosing a superficial artery and nearby vein) Ø A prosthetic graft (PTFE: polytetrafluoroethylene), if a native vein is not available because of vessel fibrosis and atrophy (due to prior needling, phlebitis, or other injury)

Standard of A-V Fistula V A

arterialization of the vein

Mechanism of HD n n Diffusion (擴散) t bi-directionally across a semipermeable membrane t 與濃度差、膜表面積大小、膜之擴散係數有關 Ultrafiltration (超過濾) t 因幫浦推動而產生壓力，另外透析液流動製造出負的壓力 Convection (對流): solvent drag Absorption (吸附): some of the dialyzers

Water source Multi-media filter 0. 2 mm filter DI UV sterilizer RO purification unit Carbon filter 1 Dialysis machine UF filtration UF tank Carbon filter 2 Water softener Cartridge filter 5 mm

Dialyzer (hollow fiber) n Membrane material is spun into fine capillaries, thousands of which are packed into bundles with blood flowing through capillaries while dialysate is circulated on the outside of the fiber bundle.

Types of Artificial Kidney (1)

Adequacy of HD n n n Measure the delivered dose of dialysis By use of a pre- and post-dialysis urea sample Urea reduction ratio (URR) or KT/V (K = clearance, T = dialysis time, & V = volume of distribution of the patient) A URR of 65% and a KT/V of 1. 2 per treatment are minimal standards for adequacy Lower levels of dialysis treatment are associated with increased morbidity and mortality

Complications of vascular access n Intimal hyperplasia→stenosis→ thrombosis n Infection (Staphylococcus aureus) n Aneurysm formation, particularly in the prosthetic graft

Critical Care Nephrology -continuous renal replacement therapy