Pages

Thursday, September 23, 2010

7.13 Renal Dialysis - the Reality

Physician's Notebooks 7  - http://physiciansnotebook.blogspot.com - See Homepage


13. Facing Dialysis  Update 28 Octr 2018
I spent time in a dialysis unit in Tokyo. I saw dialysis patients and asked questions in order to get a hands-on knowledgeIt gives my view of practical hemodialysis, and for those who experience dialysis in USA a comparison to Japan.

The below table lists the content headings in the chapter in order as they appear and can be used with search and find or to get an idea of the chapter.

Two types of dialysis, hemodialysis (HD) and peritoneal dialysis (PD)
Planning for dialysis will depend on blood test creatinine number
 Vascular Access
Diagram of Renal Dialysis
  Problems with Hemodialysis and Pearl Points
 Dialysis Machine
Dialysis Fluid Composition:
Problems with Peritoneal Dialysis  
Controversial Factors Common to both HD and PD 


    Two types of dialysis, hemodialysis (HD) and peritoneal dialysis (PD), have kept kidney-failure patients alive. (The first HD patient I saw in Tokyo was a 50 y/o lady on HD for 27 years and she looked good despite the years of 3 HDs a week)

   The HD is mostly in hospital or special equipped clinic. (The Tokyo unit does 15 a session, morning from 8:30 to 12;30 and afternoon 1 to 5. The weekday schedule is one set of patients MonWedFri and another set TTS). Each session lasts 3 to 4 hours. 

   Most patients on HD come to hospital and clinic for it; a few do it at home (In USA there is a growing number of home HD); it is more expensive and needs self-responsibility but gives a greater feeling of freedom and control. (Home HD in Tokyo is mostly of medical professional, doctor or nurse and, although a very small proportion of all HD, has been satisfactory. But it is usually discontinued in favor of clinic dialysis as patients get old)


Planning for dialysis will depend on blood test creatinine number. (These numbers are approx.; your clinician will determine more exactly)
1) Creatinine 1.5 to 3 mg/dL (133 to 266 microM/L) should signal effort to diagnose cause of kidney failure and to reverse it by nutrition and lifestyle changes and expertly ordered medications.
2) Creatinine 3 to 4 mg/dL (266 to 354 microM/L)  should turn one toward getting familiar with dialysis; visit dialysis clinic or meet online dialysis patient and educational group and be making a tentative decision between HD and PD (ie, best result, least cost to you, local convenience in that order).
3) Creatinine 4 to 5 mg/dL (354 to 442 microM/L) starts preparing for HD: vascular access. In Japan, it is advised when Cr above 6 mg/dL  (530 microM/L) but most patient delay it till Cr 8 mg/dL (707 microM/L), the week before HD starts.
4) With Creatinine above 6 mg/dL the U.S. government guidelines advise HD. There is controversy on whether it is best to start dialysis earlier (ie, Cr 5.5 to 6) because such a patient usually has better nutritional status and less uremic symptom. The earlier the hemodialysis, the greater the rate of kidney loss. HD because the too low blood pressure reduces blood flow to kidneys. Creatinine below 6 mg% patients can be managed by nutrition without dialysis. The best approach to decision on starting dialysis is using the guideline and patient symptom and life quality. The point where Cr is nearing 6 mg/dL is a time to strongly emphasize nutrition. It means a very low protein diet (0.3 to 0.6 gram protein per kg body weight per day) with mix of adequate amount of essential amino acid as powder; but, also, enough total 24-hour calories to prevent using protein for body fuel. It needs dietician and nephrologist and strict adherence for best result. (In Japan, HD is begun at Cr 8 (Rather high compared to USA), and the lowest protein diet is 0.6 mg/kg body weight/day; HD patients are allowed 1.2 mg protein with 5 gram a day sodium low salt diet.

Vascular Access

Because HD will require a stable several-hour, several-day-a-week, for-life connection between artery and vein, a vascular access must be made before HD starts. Forty years experience shows the best permanent access is the surgically-made one between the radial artery and nearby large vein (native fistula) at or near the wrist. The surgery should be done by experienced team; in US it is performed 6 months ahead of 1st dialysis. (In Japan, 2 weeks before is advised but it is usually delayed till week before and no problem) Best result is obtained when a survey of both upper extremities has been made prior to the surgery, using ultra-sound to locate largest size vessels.
   In U.S., the native fistulas account for less than 20% of vascular access. (In Japan, 90%) The alternatives are the arteriovenous graft made of expanded polytetrafluoroethylene (ePTFE) or (less popular, worse result) using cow carotid artery. These grafts have greater risk of infection and thrombosis (1 & 2-yr patency 50 & 25%) than the fistula. They are done when a native fistula has failed or cannot be made for technical reason; but at times also may be getting done because a particular surgeon prefers the more easily performed graft to the fistula. The least preferred is the placement of long term plastic catheter in femoral vein. (Done for emergency acute dialysis) This has the highest rate of infection and blockage.

Diagram of Renal Dialysis
Dialysis patient 


The blood flows out of artery and runs into the dialyzing machine. The outgoing blood is run through an air bubble detector that removes the bubbles then through a small cylinder dialyzer attached to a dialysate composition control. The dialyzer is coils of serial tubules in which dialyzing fluid runs alongside the blood, separated only by membrane that, by filtration from and diffusion with the blood and also with input from the dialysate, controls reservoirs, regulates body water & electrolyte and removes toxic chemicals. After passing the dialyzer, the blood, cleansed of kidney-failure toxins and with normalized electrolyte concentration and blood volume, is run in a circuit by a pump whose rate determines the time duration of the dialysis and then run through a blood temperature monitor and then back into the patient wrist vein at 36.5 to 37 degrees C.

 Problems with Hemodialysis and Pearl Points
Dialyzer Reuse: In the U.S. some dialyses, because they depended on Medicare, Medicaid or other Third Party for payment, were dialyzed on previously used re-sterilized, re-processed dialyzer. Today in 2018 the trend is against reuse. In U.S.A. the cost of dialysis per patient per procedure was (2011) less than in any major industrial nation. This economy was accomplished mostly by re-use of dialyzer. In Japan, which at the time, 2011 had higher survival (80% 5-yr survival on HD for the Tokyo unit) for similar patient on chronic dialysis and paid more money per dialysis, each dialysis used and still uses a never-before-used dialyser that is discarded after first use
Dialysis Machine: The dialyzer is a modular replaceable cartridge containing cellulose-like membrane coils for dialyzer fluid and blood flow entering from patient’s artery and exiting into the vein. It needs to be separated (in the reader's mind) from the dialysis machine, which is the electronic equipment and pump that controls the rate of flow of blood and the dialysate and controls the amount of blood volume in the system and also controls the temperature of the blood; and also separated in one's mind from the fluid and hydraulic controls that can vary the rate, power and efficiency of filtration. The newer machines are called “high efficiency”, “high-flux” ‘(separate functions, “flux” referring to speed of movement of fluid through the membrane), and have finer control and feedback monitor system, and on-line computer function for information storage and exchange. (The Tokyo unit in 2011 had all these functions and no machine older than 8 years use) The newer machines allow delivery of a higher hemodialysis dose in shorter time, making the HD more comfortable and convenient; they allow what is called “modeling” of substances like sodium ion, potassium ion and bicarbonate ion buffer concentration, and of conditions like dialysate temperature and hydraulic pressure during the course of a single dialysis session to custom the dialysis for patient safety and efficiency.
Dialysis Fluid Composition: Questions are connected to substances in the dialyzing fluid. Acid-base buffers have changed from the older, 20-year use of acetate to the more recent preference for bicarbonate. But bicarbonate has a higher reported incidence of infection even though it has other, superior qualities. (In the Tokyo unit, the buffer was bicarbonate-lactate in ratio 27.5: 7.5 in 2006; by 2011 it was 100% bicarbonate, which continues the trend toward a more alkaline buffer). In 2018 it is exclusively bicarb. Also, the question “What is best Na+ concentration?” is controversial in terms of incidence of too low blood pressure during dialysis and hypertension after. (Tokyo unit used 135 mEq/L in 2006 and by 2011, 140 meQ/L same as in USA)
  The glucose level of the PD dialysate fluid (In HD, no glucose)  may affect diabetes. In Tokyo presently it is 1.5 gram glucose per liter (cf 150 mg/dL in blood) 

Problems with Peritoneal Dialysis

Peritoneal Dialysis is done at home in the USA (In Japan, patients get it done at the dialysis unit). Two weeks before starting PD a surgical opening is made into the abdomen and a permanent catheter (plastic tubing) that can be accessed for each dialysis is put in place. The usual PD dialysis exchange is done by hanging up liter-size plastic bags of dialysis fluid attached and open to the catheter and allowing the fluid to run in. Continuous Ambulatory PD (CAPD) does 4 or 5 dialysis exchanges a day - 3 daytime exchanges 5 hrs each and 1 or 2 all-night exchanges. At end of each exchange the used fluid must be drained from abdomen. In Cycler PD, a cycler pumps 3 or more exchanges overnight and the patient starts a final pumping in morning and walks around with it all day.

As of year 2000, hemodialysis was 80%, peritoneal dialysis 12%, and the remainder home hemodialysis in USA. (In Japan in 2011, PD was 2%) Studies show both HD and PD to have equal survival rates. US national policy favors HD in Medicaid and Medicare payments. (Today in 2018 in USA the trend is toward more PD)
Access to Peritoneal Cavity is to PD what vascular access is to HD. Complications of blockage, catheter migration or infection are reasons for stopping PD. Of the 3 modes of insertion: 1) the surgical incision, 2) the laparoscope, and 3) the blind needle catheter stab; the making of a surgical opening by experienced PD catheter-insertion team is advised and the use of double-cuffed swan-neck (Moncrief-Popovich) catheter with curled tip has given best result. Inserting the catheter at least 2 weeks before starting PD is the standard. (In Tokyo, all catheters are inserted surgically and are double cuffed)
PD Dialysis Solutions: Choices are: dextrose 1.5% (In Tokyo standard), 2.5% and 4.25% solution. The higher and more concentrated the solution, the more rapidly and greater are body water and toxic chemical removed through the peritoneal membrane but also the high-dextrose has more complication so 1.5 to 2.5% is standard. Worry over the bad metabolic effect of concentrated dextrose solution has led to introduction of polyglucose solution, the most popular and best of which is Icodextrin. But it is expensive compared to dextrose. As in HD, controversy exists concerning what buffers should be used and the concentration. More recently an acetate-lactate buffer is favored but because of its irritating the peritoneal cavity and sometimes causing a severe chemical peritonitis it is likely to be replaced in future by bicarbonate buffer.(In 2018 in USA bicarb is favored)  The best Na+ concentration also is controversial for same reason as in HD – control of BP during and after dialysis. For years, a 140 mEq Na+ was favored but more recently 132 mEq is used in Tokyo. Additionally, there are controversies about the best concentration of magnesium Mg2+, potassium K+, calcium Ca2+ concentrations. (In Tokyo they have noticed an incidence of vascular calcification in PD patient not seen in HD patient and they blame it on a relatively high bicarbonate buffer used in PD)
Controversial Factors Common to both HD and PD
Adequate Dialysis Dose: The dialysis dose is the product of the dialyzing fluid’s efficiency and the dialysis time in hours per session and sessions per week. Dialysis time (Number of hours per dialysis session) is an important modifiable factor, and it is controversial. The shorter the dialysis time, the less the cost of dialysis but after a certain point, shortening dialysis time gives inadequate dialysis and increases premature death rate. In the U.S. this has led to the routine 4-hr hemodialysis session; in Japan to 4-hr sessions. Studies have shown that the best results are 6 to 8-hr dialysis sessions but as a routine for a whole nation the inconvenience to patient and the increased costs of doubling the present hemodialysis session time is unacceptable.
   In PD, a similar question relating to time of dialysis has arisen but since PD is only a small minority of dialyses in USA (and in Japan it is unpopular), similar question has not arisen, and patient at home, supervised by nephrologist is free to experiment with increasing or decreasing time and frequency of PD sessions.
  Use of Erythropoietin (EP) Against Anemia: EP has been used to prevent the anemia of renal failure since 1985. The subcutaneous injections are better than intravenous use. In the USA, the preferred hematocrit range is 36% to 39%.  Going above a hematocrit of 39% or hemoglobin 13 gm/dL risks a high rate of blood clot in vein and artery. 
Because of EP’s pull on the body iron store, dialysis patients need iron. Often they get iron dextran injection but it has risk of allergic reaction. (It is used on Tokyo unit HD patients as iron dextran intravenous with no incidence of serious reaction) In USA iron sucrose and iron gluconate complex have received FDA approval and now replace iron dextran injection. For those who tolerate iron by mouth, ferrous fumarate is best.

  Cardiovascular Complication such as coronary artery disease, atherosclerosis and hypertension continue to affect dialysis patient. It points up the importance of keeping cholesterol low with a statin drug and using ACE-Inhibitor or Blocker medication (ARB) under medical supervision plus a low cholesterol diet.
  Problem of Calcium leached from Bones continues to raise question on use of phosphate binder by mouth, dose of calcium ion in dialysate, and use of vitamin D by mouth or injection. (All used in the Tokyo unit in 2011)
  Other Dialysis Problem: Aluminum toxicity causing dementia, anemia and bone disease from Aluminum contamination of the dialysis water supply and use of aluminum phosphate binder used to be a worry but today no longer used. (Dialysis dementia has not been a problem in the Tokyo unit which does not use any aluminum buffers)
END OF CHAPTER. To read next now, click 7.14 Transplant of Kidney

No comments: