Instrument definition of «dry weight» and optimal volume ultrafiltration for the patients on a programme hemodialysis

Abstract

On the basis of a thoracic rheography is designed a non-invasive method of definition of «dry weight» for the patients on a programme hemodialysis (HD). The 50 patients with terminal renal failure on hemodialysis were studied. The changes of transthoracic impedance, koefficient of thoracic impedance (L2/Z), mass of body of the patients, parameters of a central hemodynamics in intradialysis period, before and after HD were investigated. 25 healthy persons was a control group. All surveyed patients regarding a koefficient of thoracic impedance were divided into 3 groups. The first group (10) included the patients, for whom L2/Z in intradialysis period did not differ from of healthy people and was 21,1 ± 0,5 sm2/om. The second group (30) included the patients, for whom L2/Z was higher 21,1 ± 0,5 sm2/om and on the average it was 31,1 ± 0,6 sm2/om in the group. The third group included the 10 patients, whom L2/Z was less than in control and on the average it was had 16,8 ± 0,7 sm2/om. Besides it turned out, that the faces the 3-rd group had reliably more often (on the average in 6,3 times p < 0,05) than the patients of the 1-st and 2 groups the cramps and sequences of a hypotension when carrying out HD. The analysis of changes of a koefficient of thoracic impedance shoved, that this parameter before and immediately after HD reliably decreased on the average by 19,6% (with 28,1 ± 1,6 up to 22,6 ± 1,3 sm2/om, p < 0,001) within the all surveyed patients. The high correlation (r = 0,81, p < 0,001) between alterations of body mass of the patients and L2/Z in reply to ultrafiltration (UF) was noted. The formula for calculation of optimum of a liquid offered, which one is necessary for removing during UF on a haemodialysis. Thus, the patients having koefficient of thoracic impedance more than 21,1 sm2/om, even in the absence of clinical exhibiting of a hyperhydratation, need to decrease «dry weight». For optimization of a regime of a ultrafiltration during a procedure HD the calculation of removed fluid can be conducted under the formula: ∆Н2О = 0,23 × (L2/Z - 21,1) + 1,9. The patients with a koefficient of thoracic impedance less than 21,1 sm2/om are in a state of dehydratation and need to increase «the dry mass of a body».