From Dr Daniel Lin, Renal Physician, CMDHB
Renal Replacement Therapies (RRTs)
RRTs are treatments for people whose kidneys have failed almost totally to work as a cleaning organ in the body. Their aim is to replace what native kidneys do normally, so toxins and extra body water can be excreted from body. RRTs include two main groups: Dialysis and kidney transplantation.
What is dialysis? 什麼是透析？
Dialysis is a way of replacing kidney function by using a filter membrane ( either native or artificial) to clean blood and filter out toxins, wastes, and extra body water that produced by normal metabolism. It is important to know that it does not treat the kidneys, which means, it will not improve the original kidney function.
Who needs dialysis? Is dialysis absolutely necessary? When to start? Do I need dialysis life-long once started?
In general, people who have severe chronic kidney disease (stage 5) with either glomerular filtration rate (GFR) below 10 ml/min or symptoms of uraemia will need to be started on dialysis. However, it also subjects to other factors, such as people’s wishes and preference, functional capacity, and other medical conditions that may subject dialysis to cause more harm.
一般情況下，若是有嚴重的慢性腎臟病（ 5級），無論是腎小球濾過率（GFR）低於10毫升/分鐘，或是有尿毒症的症狀（當病人呈現尿毒症狀 ： 噁心、嘔吐、食慾不振、皮膚搔癢、呼吸困難、四肢及心肺積水、口腔有異味），亦即腎功能不及正常的十分之一等情形，都會建議開始接受透析治療。然而，也有其他因素需要考量，如個人的意願和喜好，病人平時的自理能力，和其他可能使透析造成更多傷害的醫療病史。
Dialysis is necessary to prolong life when kidney function fails completely. People who have end stage kidney failure will only have few weeks to months to live if dialysis is not started promptly. People started on dialysis in average will have 5 or more years to live depending on other medical conditions. People on dialysis die later mostly not due to dialysis itself, but due to heart attack, stroke, and infections. These are mainly caused by their underlying health problems such as diabetes and high blood pressure. Again, dialysis is life-saving.
當腎功能不及正常的十分之一等情形、腎臟是無法維持生命，透析是必要的。如果透析不及時開始的話，終末期腎功能衰竭的病人通常只會有幾週到幾個月的生命。根據其他醫療條件，一般病人在開始透析之後，都有平均 5 年或以上的生命。這些病人後來的死因大多不是由於透析本身，而是由於心臟發作，中風和感染。這些主要是因為他們的潛在的健康問題，如糖尿病和高血壓。透析是救命的腎臟替代療法。
The decisions on the timing of starting dialysis are normally made by kidney physicians in conjunctions with patient’s understanding and agreement. It is important to understand the concept of dialysis and start the process of preparing for dialysis way before the time comes. The entire process of preparation for dialysis may take up to few months. This process include patient education, medical and psychological assessment, choosing type of dialysis, and dialysis access formation. Although dialysis can be started urgently without this process via a neck line, but the fact is that people who had planned dialysis do better and have less complications compared to those who started urgently.
Once dialysis is started, almost all will need it life-long. It has a huge impact on people’s daily activity, family, occupation, finance, and mental health. People will need lots of support from family, social services, and health professionals. Kidney department in Hospital can provide most of supports for difference aspects.
There are other indications for start on dialysis such as severe acute kidney injury, poisoning, or some haematological malignancies and conditions. In most of these cases, dialysis is temporary until the kidney function returns.
How to do dialysis? Are there different types of dialysis? 如何做透析？有不同類型透析？
There are two main type of dialysis: Haemodialysis and Peritoneal dialysis.
Haemodialysis (HD) uses an artificial membrane filter to clean blood. It needs blood to be transported out of body into the filter for cleaning before returning to the body. It needs a large blood vessel access such as an arteriovenous fistula (AVF) or a large venous catheter to transport large volume of blood per minute for cleaning. Once started, most of people will need 3 sessions per week, 4-5 hours per session. This can be done in a hospital or in-centre setting, or sometimes people can be trained to do it themselves at home or community houses with machine provided.
Peritoneal dialysis (PD) uses people’s own peritoneal membrane overlying the abdominal organs as the filter. It is an effective natural filter to excrete toxins and extra water in the body. People who chose PD needs to have a tube to be inserted into their abdominal cavity. Clean dialysis fluid (normally with glucose in it) is infused into the cavity and stays in for 3-4 hours allowing toxins and extra water to be exchanged. The resultant fluid in the cavity (dirty fluids) is then drained out before another clean bag is infused in. In general, people need to do 4 exchanges a day. In between exchanges, PD patients are able to carry on with their normal activities. Instead of being attached or hooked to a machine for hours 3 times a week like in haemodialysis, PD provides more freedom and all can be done in the community with minimal hospital contact.
腹膜透析俗稱「洗肚子」，腹膜是腹腔內一層包覆在內臟器官的薄膜，有豐富的微血管分佈，腹膜透析就是利用腹膜作為過濾、排除體內水分及廢物的一種方式，乃利用人體的腹膜作為半透膜，藉由進入肚子的透析液將身體過多的水分及代謝廢物進行移除。首先需在腹腔內植入一條永久性導管，經由導管將透析液灌入腹腔存留一段時間，將體內廢物及水分移除至腹腔內的透析液中，再引流出來，且透析液留置在腹腔內的時間，平均約 4 至 6 個小時，在這段時間，行動不受限制，可以做自己想做的事， 4 至 6 小時後，再重複換液，每天依醫囑進行數次換液，換液的時間和地點，可依日常生活作息調整。換液場所可以選擇在家裡、辦公室或其他常去且密閉之空間，換液環境必須符合特定的條件，以避免受到感染。
The choice of dialysis modality is dependent on individual circumstances and largely people’s choice to suit their life style. There are limited data suggesting which one is better or worse, and they can be inter-changed when situation changes.
What are the side effects of dialysis? 透析的副作用？
Although dialysis is an artificial way of mimicking what normally good kidneys will do, it does not replace all functions of kidneys. Hormones such as vitamin D and erythropoietin that are processed or secreted by kidneys are not produced by dialysis. People need medications to replace these hormones while they are on dialysis.
雖然透析是模仿腎臟功能的一種人工方式，它並不能代替腎臟的全部功能。由腎臟加工或分泌的激素（如維生素 D 和促紅細胞生成素）是不會因為透析過程而產生的。透析治療的病人需要透過藥物來攝取這些激素。
Dialysis itself may also create side effects or complications. These include bleeding due to clotting disturbance, low blood pressure, stress to heart causing irregular heartbeats, stroke, infections, cramps, nerve damage, immune system suppression, skin changes and calcium deposition, etc. Most of complications only develop after years of dialysis.