Tricky Dry Weight in Hemo Dialysis and how to Establish it

The most important parameter in successful hemo dialysis is the mystical ‘dry weight’. It is the ideal and most desirable weight of a patient at the conclusion of the dialysis. Dry weight is one of the parameters inputted into the dialysis machine at the start of the treatment along with the initial weight of the patient. The difference between the dry weight and initial weight of the patient is assumed to be equal to the fluid to be removed in this treatment. If the dry weight is less than the ideal one, the patient suffers cramps before the conclusion of dialysis, which the technician solves by injecting salt solution into the patient blood stream. Starting with 100ml the technician increases in lots of 100ml in successive steps till the cramps stop. This problem is one that all dialysis patients will inevitably face at some point in their treatment. In the initial stage of treatment, the dry weight for treatment is arbitrarily chosen and decreased by small amounts in successive treatments until the patient experiences cramping. The lowest dry weight possible before the patient experiences discomfort is typically designated as dry weight for that patient in subsequent treatments. The patient’s initial weight varies not only for individual persons but also for the same patient through several treatments. The reasons for this are discussed below. Let us examine a patient whose dry weight for a treatment is determined at say 75Kg, and this is the one the patient is expected to reach at the conclusion of treatment. The weight of the patient just before start of the treatment depends on a number of factors, including the amount of fluid and solid food, the patient has consumed, the amount of urine passed, if any, and the clothing the patient is wearing and finally the amount of stool passed since last treatment. These five parameters vary from day to day since any patient will not consume same food every day, may have bowel movement or not every day, does not pass same amount of urine every day and does not wear same dress for all treatments. The solution to the problem is very simple. 

The patient records weight with simple dress at home every morning after waking up and every evening before sleeping. The weight gains of the patient in one day is an indication of the net gain in weight in one day taking into account all the parameters listed above. It is ideal for the patient to record the weight just before and immediately after bowel movement to assess approximate weight loss due to bowel movement. In case of the patient does not have a bowel movement before any future treatment, this correction can be added to the patient’s dry weight to arrive at more realistic dry weight preventing patient’s discomfort. The cumulative weight gain since the preceding treatment is used for next treatment. This way, one can arrive at the optimum dry weight for the next treatment to prevent cramps. Based on these observations, one can conclude that active participation of hemodialysis patient is needed to compliment that of the technician.