Understanding Hemo-dialysis

      As the days, months and years pass by I gradually witness the unfolding of the realities and processes of Hemo-Dialysis. Now I know that the word dialysis came from the greek words: "dialusis" which means dissolution, "dia" meaning through, and "lysis" means loosening or splitting. Dialysis is done to patients with either acute, chronic and End-Stage renal or kidney failure to remove excess nitrogenous waste, mineral salts and water. There are mainly two types of dialysis: the Hemo (blood) Dialysis and the Peritoneal (abdominal cavity) Dialysis. Hemo-Dialysis involves a dialysis machine and is recommended to patients with considerably healthy heart and liver while those with ailing heart, Peritoneal dialysis is advised. With my almost three years of experience, I come to understand how the dialysis machine works and how it affects my body. The dialysis machine is a wonderful piece of machinery originally designed by Dr. Willem Kolff, a Dutch physician in 1943. Through the years with constant researches, tests and adjustments it evolved into a state of the art machinery which is safer and really suits the need of dialysis patients.

      Before a patient undergoes dialysis, the bloodline (long tube where blood flows) and dialyzer (this is the filter where the blood passes through and cleaned while in contact with the dialysate or dializing solution) are primed or cleaned with Normal Saline Solution (NSS) or "suero" in Tagalog to clean and make it sure that it passes the conditions that are set by the machine. Then while priming, the patient is prepared by sitting him/her on a "lazy boy chair" or laid comfortably on a cushioned bed whichever his/her choice. The nurse take the blood pressure of the patient to determine if dialysis will push through or not (patients with very high or low blood pressure cannot be dialyzed until his/her BP normalizes or comes back within acceptable range). If the BP is okay, the nurse inserts the Cannula (dialysis) needles. Other dialysis centers have local anesthesia to dull the pain of insertion of big needles in the vein or Fistula (artery and vein joined together to make the vein larger to make it possible to insert the needles for dialysis). For new patients that do not have a Fistula, their dialysis access is either through the neck, wrist and thigh. This has less pain compared to venous insertions of needles. After the needles are inserted and the machine is ready for dialysis, the patient is "hooked" or connected to the dialysis machine. First, the Cannula needle which is inserted into the artery or Fistula is connected to the bloodline and blood rushes within the tube into the dialyzer, filling it and into the other end of the bloodline where the venous Cannula needle is connected and blood is returned to the body. Blood flow is accomplished by a rotating external mechanical pump which squeezes the tube of the bloodline forcing blood through the tube. The faster the pump rotates, the faster the flow of blood and the more the blood is cleaned; but at the initial phase of dialysis the normal flow rate should be 180 ml or cc per minute or lower depending on the condition of the patient's health and his/her dialysis access if the flow of blood in the vein is strong or weak. Then a regular or low dose of Heparin (an anti-coagulant to prevent blood clot) is injected into the bloodline. If the patient is bleeding due to her period or other wound, no Heparin is injected and clotting is prevented by regular flushing with Normal Saline Solution (NSS). After the patient is connected to the machine, it is advisable for the nurse to take a second reading of the patient's BP to see if it is still normal. Some patients experience hypo-tension after they are hooked on the machine due to the amount of blood circulating outside the patient’s body which is about 237 ml or cc.  If the patient’s BP is still normal, dialysis continues for two or four hours depending on the recommendation of the doctor. Dialysis period for first timers is only two hours to acquaint the patient’s body to Hemo-Dialysis.

     The dialysis machine is a complex machine that combines modern computing and medical science into one. The machine “knows” if the pH (acidity or alkalinity), concentration, amount and temperature of the dialysate (dialyzing solution) are not right by sounding an alarm. The dialysate is composed of an acid and base or electrolytes that are separately contained in one gallon plastic containers. The one with the red cap is the acid and the one with the blue cap is the bicarbonate or base. In solution they contain physiological (in equilibrium or equal quantity in the dialysate and the patient’s blood, these electrolytes are consistent with the normal functioning of the patient) amounts of Potassium, Calcium, Glucose, Sodium and other minerals and water. The machine also monitors the arterial and venous pressure of the blood in the bloodline. If the pressure is either too high or too low, the machine automatically sounds an alarm or even stops the blood flow if necessary. It can also detect air bubbles in the blood line and blood leak in the dialyzer and will also sound the alarm. During power interruption or brownouts, the machine automatically draws power from its own Uninterrupted Power Supply (UPS) and will sound an alarm.

     Once the patient is connected to the machine, the nurse checks for the arterial and venous pressure readings if they are not high or too low and record them in the patient's chart. The nurse also checks if air bubbles are trapped properly in the air trap of the bloodline. If everything is okay, the nurse monitors the patient’s BP every hour or as needed. Dialysis or cleaning the patient’s blood is accomplished by the dialyzer and the dialysate. The blood flow into the dialyzer downward while the dialysate in the opposite direction. Through the process of diffusion (movement of molecules in a solution is from higher concentration to lower concentration) the nitrogenous waste and excess mineral salts in the patient’s blood are drawn out through the semi-permeable membrane of the dialyzer into the dialysate. The faster the flow of blood and dialysate, the blood is more cleaned. Now, the question is: why do the blood and other proteins in the blood are not drawn out into the dializate together with the waste? That is because the dialyzer is made up of fine fibers and openings in the membrane are so small that it limits the passage of larger particles of blood such as RBC, WBC, proteins. Thus, it prevents blood loss that may result to hypo-tension. Another question that arises is how does excess water from the patient’s blood taken out from the body through the dialyzer? This is accomplished by the process of reverse osmosis (movement of water molecules is from lower to higher concentration of water). The amount of water in the blood (plasma) circulating in the dialyzer is lower compared to the amount of water circulating in the dialysate. Diffusion and osmosis are enhanced by a negative pressure in the dialysate compartment of the dialyzer. A negative pressure exerts a pulling action of the fluids in a tube while a positive pressure pushes the fluid in the tube. The dialysis machine can be set at the prescribed volume of water to be taken from the patient’s body at a specific time period by increasing or decreasing the pressure. Too much water taken from the body could result to painful cramps, temporary hearing loss and hypo-tension. My practice is when I feel that my toes are twitching or my leg muscle starts to contract or there is pressure in my ear, it is a sign that excess water has been taken from my body and I would instruct the nurse to limit the remaining volume of water to be taken to just 20 ml while cleaning of my blood continues. The normal practice of nurses is to flush the bloodline with NSS. When the prescribed time of dialysis is reached, the nurse terminates the dialysis session by returning the patient’s blood in the bloodline and injects Erythropoietin intra-venous (into the bloodline  or Subcutaneous (below the skin) depending on the patient’s decision. Swimming in pools or sea water in beaches is discouraged for Hemo-Dialysis patients to prevent infections through the punctured wound in the skin where the needles were inserted.

     During my first year in dialysis I experienced high blood pressure. Even with the hypertensive drugs prescribed by the physician at the Regional Hospital, my BP is not lower than 150/90. During dialysis, my BP will shoot up to 200/110 and I would feel pain at the back of my neck and I experienced severe headache. I would take sub-lingual dose of Clonidine or Catapres and my BP will go down near normal values. As a result of my hypertensive condition, water entered the cavity of my left lung and found it hard to breathe especially when walking or lying flat while I slept. I was diagnosed as having Pneumonia and enlargement of the heart. When I went to Manila for a vacation, I had my dialysis in the Capitol Dialysis Center near the Capitol Medical Center where my daughter is a pediatric staff nurse. I had bouts of hypertension and cramps during dialysis so their physician prescribed me oral maintenance dose of Catapres (Clonidine) 75 mg 3 times per day aside from my maintenance medicine of Olmesartan 40 mg. once a day and Amlodipine 5 two times per day. I took Clonidine 75 mg. only two times per day since I monitored regularly my BP with my digital BP reader. To my amazement my BP returned to normal value and the water has left my lungs. Now I take the Clonidine 75 mg once a day or every other day.

     I have learned that it is very important for the patient to fully understand what dialysis is all about and he/she should observe what are the factors affecting his/her body functions. The number one factor is fluid control especially for end-stage patients whose urine output is low or very low. This is also the cause of water in the lungs if there is too much water in the blood. This also affects the heart since the volume of blood is above normal values. Excess water is also deposited in the abdominal cavity and the legs. The patient should stick close to his/her diet especially avoiding salty foods that can cause water retention. Too much intake of animal protein will significantly increase the nitrogenous wastes in the blood and will cause Uremia that can affect the patient’s heart and brain. During this condition, the body compensates by triggering the patient to vomit constantly until his/her Esophagus is so irritated that he/she vomits blood. Excess intake of animal protein also causes the dark pigmentation in the skin of the patient. Intake of food rich in uric acid or purines causes painful gout and arthritis. Phosphorous in the blood is also removed by dialysis but the bulk of it is located in the tissues and almost all the food that we eat contain some phosphorous. With damaged kidneys, excess Phosphorus is not efficiently removed through urination so there is a danger of build-up of Phosphorous in the blood which is dangerous. This mineral will bind with calcium in the blood and will deplete the Calcium that causes Hypo-Calcemia that can result to weakening of the bones and osteoporosis. To counteract this, the patient should take at most 1500 mg of calcium carbonate per day depending on the Calcium level to replenish the calcium in the blood. Calcium also binds with phosphorous in the food taken in by the patient and excess phosphorous will not enter the bloodstream and instead will go through the digestive tract and excreted with the other bodily wastes. Other phosphate binder such as Sevelamer is very expensive but very effective if taken in the right dose and timing. Monthly monitoring of the chemistry and uric acid content of the blood is recommended aside from other monthly laboratory tests. The Hemoglobin level in the blood will indicate if the patient is advisable to have blood transfusion. A Hemoglobin level of seven or lower is already critical and the patient is not advised to have dialysis unless he/she can have blood transfusion during dialysis. At very low level of Hemoglobin, the patient can strain his/her heart during dialysis since it is the Hemoglobin together with iron that helps distribute oxygen in the body cells. My practice is if my Hemoglobin level is below 10, I would inject 4,000 units of Erythropoietin Alpha twice or three times per week to elevate my Hemoglobin back to 10 or 11. Too much Erythropoietin could cause high blood pressure due to the thickening of the blood. At a Hemoglobin value of 10.8 to 11 or more, the dose of Erythropoietin is at once a week. Blood transfusion is discouraged by the physician unless it is really needed by the patient to prevent Hepatitis infection. Erythropoietin should be combined with a daily dose of Ferrous Gluconate or other organic iron supplements to be effective. Dialysis patients should not eat too much fat in their diet since it could contain Cholesterol that blocks arteries and veins resulting to stroke and heart attack. So it is also advisable to regularly monitor the Cholesterol level in the patient’s blood. Too much fat also causes fatty liver which could affect its function. Remember that without the kidneys, it is the liver that performs the function of breaking down harmful chemicals and substances that are supposed to be excreted by the kidneys. Drinking alcohol is also not advisable since it can harm the liver. If the above practices are followed religiously, I can vouch for the efficiency of dialysis of at least twice a week and the survival period of the patient can be prolonged to a maximum of twenty years!

     Headaches and high blood pressure during dialysis especially of new patients can also be caused by Dialysis Disequilibrium Syndrome (DDS). In theory, DDS results when the blood waste, Blood Urea Nitrogen (BUN) level in the patient’s blood is abruptly or drastically brought down by aggressive hemodialysis (fast blood flow rate). My practice now is I would start my dialysis at a blood flow rate of 180 ml per minute and after one half to one hour my blood flow rate should be 250 ml per minute for two to three hours. At the fourth hour of my dialysis my blood flow rate should be lowered to 200 ml per minute. One half hour before I am through with my dialysis, my blood flow rate should be back at 180 ml per minute. This would allow the gradual removal of nitrogenous waste in my blood at the same time allowing my heart to cope up easily with my dialysis. My maximum blood flow rate is only 250 ml per minute because of my heart condition which is already enlarged but is not yet failing. Other patients can tolerate a blood flow rate of more than 300 ml per minute.  The Blood Urea Nitrogen (BUN) shoots up when the patient has eaten a large amount of animal protein for two or three or more days. Three times or more dialysis per week is recommended for patients with very high level of BUN and suffering from Uremia and this is also true for diabetic patients. Most patients have two times dialysis per week due to the high cost of dialysis especially in private hospitals and dialysis centers. The ideal frequency of dialysis is three times or more per week.

     I hope that I could learn more from the processes of hemo-dialysis so I can share more learning with other dialysis patients. God willing, I can accomplish this task. We praise and thank you Lord God almighty!