A Primer on Dialysis


FEATURE STORY

What this life-extending procedure is, how it works and how much it cost

By ROBERTO C. TANCHANCO, MD, FPCP, FPSN


For 24 hours a day, 7 days a week, the kidneys filter our blood, helping the body get rid of wastes and toxins that accumulate in the blood. When the kidneys are no longer functioning, this filtering function is lost, and waste products accumulate and become toxic in the blood. Urine volume also decreases, and excess fluid accumulates in the body, resulting in hypertension and edema.

When kidney function decreases, the blood levels of urea nitrogen and creatinine, which are breakdown products of daily metabolism, increase – a condition called azotemia. When azotemia is accompanied by certain symptoms (weakness, fatigue, loss of appetite, insomnia, a change in the taste of food, nausea, vomiting, itchiness, even hiccups) and signs (pallor, sallow skin, a urine-like odor to the breath) the condition is called uremia.

Dialysis is an artificial process that filters blood and removes toxic waste substances and excess fluid from the body. The two forms of dialysis are hemodialysis and peritoneal dialysis.

In hemodialysis (HD), the patient is attached to a hemodialysis machine which pumps blood from the patient, through a special filter called the dialyzer, then back into the patient. Within the dialyzer, the patient’s blood flows in one direction through thousands of hollow fibers while a special dialysis solution flows in the opposite direction, separated by a very thin membrane with very small holes. Waste products and excess fluid are continually removed from the patient’s blood and transferred into the dialysis solution, which is then carried away. HD is preferably done 3 or more times a week. Each session usually lasts 3 to 4 hours.

In peritoneal dialysis (PD), the patient’s own peritoneal membrane, which lines the inside of the abdominal cavity and organs, serves as the filter between blood and dialysis solution. There are many ways of doing PD, but the most commonly employed technique is Continuous Ambulatory PD (CAPD). PD solution is introduced through a catheter inserted through the abdominal wall into the abdominal cavity and allowed to dwell there for several hours. Blood flows through the vessels in the peritoneal membrane and waste products and excess fluid are transferred into the PD solution. The solution is drained out, and a fresh bag of PD solution is re-infused into the abdominal cavity. This process is usually repeated 3 to 4 times a day, 7 days a week.

Who needs dialysis

When kidney function is already so low (less than 9 to 14 percent of normal) that it cannot be expected to sustain life for very long, or when there is already uremia or progressive malnutrition, dialysis needs to be started.

A Primer on Dialysis 2

For acute renal failure, dialysis may only be transiently needed and then stopped when kidney function has recovered.

However, for end stage kidney failure, kidney function can no longer recover. In such a case, without kidney transplantation (which would be the treatment of choice), dialysis will have to be continued for the rest of the patient’s life.

How much it costs

Dialysis therapy is very costly. In 2003, the average annual family income was PhP 147,888.00, or PhP 12,324.00 per month; undergoing HD three times a week, or CAPD with four exchanges per day, would cost much more than twice that. This would obviously be inadequate to support maintenance dialysis, even if the family were to spend on nothing else. Many in this country who need to start dialysis are not able to start at all, or are not able to sustain it for very long.

To make matters worse, dialysis patients need to spend not only on dialysis, but also on other medications for the complications attendant to end stage kidney failure (e.g. erythropoietin and iron, phosphate binders, antibiotics, etc.) and for other coexisting illnesses.

Effects on blood sugar

Patients with chronic kidney disease commonly note decreasing insulin requirements. Insulin is removed from the body primarily through the kidneys. When kidney function becomes very low, insulin tends to stay longer in the body. The dosages of most oral anti-diabetes medications also need to be lowered, while some are better avoided (e.g., metformin).

Peritoneal dialysis poses a special problem, since PD solutions contain large amounts of glucose or sugar. Glucose serves as the osmotic agent that draws excess fluid and other substances from the patient’s blood. Unfortunately, glucose may also be absorbed, leading to high blood sugar and its associated complications, and higher insulin dosage requirements. PD solutions that contain non-glucose osmotic agents (e.g. icodextrin) are much more expensive.

Other helpful information

It would of course be best for patients with diabetes to never develop end stage kidney failure at all. Fortunately, most diabetics never do. What you can do, in order to be one of the fortunate majority, are the following:

1. Keep your blood sugar under control (target HbA1c less than 6.5 percent). Follow your doctor’s diet, medication, and exercise regimen for you.
2. Keep your blood pressure under control (target less than 130/80 mmHg).
3. Keep your cholesterol under control.
4. If you have a family history of diabetes and hypertension, encourage other family members to undergo screening for these diseases and assessment of kidney function.
5. If you already have chronic kidney disease, stay on a low salt, low protein diet. Ask your doctor and dietitian for more details.
6. Let your doctor know first whenever you plan to take any new medications, even vitamins and herbal supplements.
7. If you have any questions or concerns, ask your doctor. Some particular questions that you may want to ask:
a. Should I be tested for serum creatinine, proteinuria, microalbuminuria? These are tests for kidney function and the presence of kidney damage.
b. Should I be started on an ACEinhibitor or angiotensin receptor blocker? These are classes of antihypertensive agents that may help preserve kidney function, but patients taking them will need to be closely monitored.
c. Will I need to stop or adjust the dose of medications I am already taking, based on my level of kidney function?
d. Should I already be preparing for kidney replacement therapy, and if so, what are the treatment options?
8. Enroll in PhilHealth if you are not yet a member. It will help defray some of the costs of dialysis, if ever you eventually need it. The average cost of dialysis of PhP7,000 per session may be availed of at PhP600 per session by patients covered by PhilHealth. Also look into other potential funding sources (Employees’ Compensation Commission, Philippine Charity Sweepstakes Office, etc.).

March 2018 Health and Lifestyle

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