التنقية الدموية لمرضى الفشل الكلوي
وهي جلسات تنقية دموية لمدة 3 إلى 5 ساعات بمعدل 2 إلى 3 مرات في الأسبوع ويتم خلالها توصيل دم المريض بجهاز طبي يحتوي على مرشح لتنقية الشوائب المتراكمة نتيجة قصور الكليتين ويتم تجهيز المريض مسبقاً بإعداد جراحي عن طريق توصيل شريان ووريد يساعد المريض ويمكن من خلاله سحب كميات كبيرة من الدم في فترة وجيزة وفي حالات الطوارئ يمكن اللجوء إلى قسطرة بوريد كبير من الأوردة كوريد الفخذ أو العنق أو غيرهما . وهذه الجلسات تسمح كذلك بتعديل نسب الماء والأملاح حسب مواصفات الطبيب
CRRT, is an extracorporeal process where fluid, electrolytes, and small and medium-sized molecules are removed from the blood. CRRT may utilize several processes including diffusion, adsorption, convection, and/or ultrafiltration to continually remove unwanted waste products, manage pH and electrolytes, and help balance the patient’s fluid status.
The process of diffusion is the primary mechanism for removing small sized solutes in IHD. While this method may be applied to CRRT, other options exist such as convection and adsorption. Diffusion is dependent upon a dialysate being present. Dialysate is circulated in the hemofilters, outside of the fibers that contain the blood. The hemofilter fibers are a semipermeable membrane that allows the transfer of small molecular sized solutes, including urea and electrolytes. The solutes move based on a concentration gradient. If urea is more concentrated in the blood and less concentrated in the dialysate, it moves to the dialysate and is then carried away. The movement across the membrane can also occur in the opposite direction. If an electrolyte is at higher concentration in the dialysate compared to the blood, that electrolyte will move into the blood until equilibrium is reached
Adsorption is the process by which certain substances in the blood have a particular affinity to the material that the hemofilter’s fibers are composed of. These substances literally adhere to the membrane wall, and are therefore removed from the blood.
Convection has the ability to remove small molecules as well as medium sized molecules. Convection is highly dependent upon ultrafiltration, or the removal of plasma water. As the plasma water passes through the hemofilter membrane it drags along small and medium sized molecules. While the ultrafiltration is taking place, replacement fluid is administered back to the extracorporeal circuit in a volume comparable to the amount of solution removed. More volume may be replaced if the patient needs to gain volume, or more typically, less volume is replaced in order to result in a net negative fluid balance, or a fluid loss.
Unlike IHD, CRRT is performed continuously over several days to slowly remove excess fluid and solutes from the blood (see Table 1). Because it is a slow, continuous process, CRRT avoids the hemodynamic instability seen with IHD
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Native speaker of: Arabic
PRO pts in category: 98