Effect of Ultrafiltration on Thermal Variables, Skin Temperature, Skin Blood Flow, and Energy Expenditure during Ultrapure Hemodialysis

Abstract

The cause of the increase in core temperature (CT) during hemodialysis (HD) is still under debate. It has been suggested that peripheral vasoconstriction as a result of hypovolemia, leading to a reduced dissipation of heat from the skin, is the main cause of this increase in CT. If so, then it would be expected that extracorporeal heat flow (Jex) needed to maintain a stable CT (isothermic; T-control ‫؍‬ 0, no change in CT) is largely different between body temperature control HD combined with ultrafiltration (UF) and body temperature control HD without UF (isovolemic). Consequently, significant differences in ⌬CT would be expected between isovolemic HD and HD combined with UF at zero Jex (thermoneutral; E-control ‫؍‬ 0, no supply or removal of thermal energy to and from the extracorporeal circulation). During the latter treatment, the CT is expected to increase. In this study, changes in thermal variables (CT and Jex), skin blood flow, energy expenditure, and cytokines (TNF-␣, IL-1 receptor antagonist, and IL-6) were compared in 13 patients, each undergoing body temperature control (T-control ‫؍‬ 0) HD without and with UF and energy-neutral (E-control ‫؍‬ 0) HD without and with UF. CT increased equally during energy-neutral treatments, with (0.32 ؎ 0.16°C; P ‫؍‬ 0.000) and without (0.27 ؎ 0.29°C; P ‫؍‬ 0.006) UF. In body temperature control treatments, the relationship between Jex and UF tended to be significant (r ‫؍‬ ؊0.51; P ‫؍‬ 0.07); however, there was no significant difference in cooling requirements regardless of whether treatments were done without (؊17.9 ؎ 9.3W) or with UF (؊17.8 ؎ 13.27W). Changes in energy expenditure did not differ among the four treatment modes. There were no significant differences in pre-and postdialysis levels of cytokines within or between treatments. Although fluid removal has an effect on thermal variables, no single mechanism seems to be responsible for the increased heat accumulation during HD. A n inadequate vascular response to hypovolemia is an important contributory factor to intradialytic hypotension. Although various mechanisms have been implicated in the pathogenesis of impaired vascular response during hemodialysis (HD) (1-7), there are strong indications that this phenomenon is often related to changes in body temperature and extracorporeal blood temperature (8 -22).We and others have observed that the core temperature (CT) increased during standard-temperature (37 to 38°C) dialysis (16,18 -24) even with net energy loss from the patient to the extracorporeal system. This phenomenon strongly suggests that the dialysis procedure itself leads to internal heat accumulation. It has been observed that 4 h of standard dialysis leads to a positive internal heat balance of approximately 300 kJ, which represents approximately 30% of the energy expenditure (EEvmax) of the patient (25). The internal heat accumulation might very well be responsible for the impaired vascular response during HD, as the thermoregulatory response (leading to dilation of thermoregulatory vessels) wi...

Control of Core Temperature and Blood Pressure Stability during Hemodialysis

“…The resulting increase in CT would then eventually evoke a reflex cutaneous vasodilation, resulting in a sudden decline in BP. However, in a recent controlled study, differences in the thermal response were not observed between dialysis treatments with or without concomitant ultrafiltration, which would appear to contradict the former hypothesis (18). Various studies have shown vasodilation in the forearm or skin blood vessels during "standard" dialysis sessions with T d of 37°C or higher (26,27).…”

“…Arterial (T art ) and venous (T ven ) blood line temperatures and energy transfer between the extracorporeal circuit and the patient were noninvasively monitored using the BTM device, as described previously (7,13), at 60-s intervals (7,8,17,18). During isothermic, the change in patient temperature was set to zero.…”

Effect of Lowering the Dialysate Temperature in Chronic Hemodialysis

“…Overall, the duration of each trial was short. Eighteen trials reported the effect of cool dialysis on the basis of two sessions of hemodialysis (one session in each arm of the trial) (16,17,21,23,(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)41). Three trials evaluated the intervention in three to six hemodialysis sessions (22-24).…”

Evaluation of Skin Microcirculation during Hemodialysis

“…Using a Laser-based contact skin device in a limited skin area of the palmar part of hands, Van der Sande described skin blood flow change both in isothermic and thermoneutral HD sessions with ultrafiltration, contrary to no change in both thermal regimes of HD without ultrafiltration. [11] To our knowledge, no systematic data about the impact of hemodialysis on the peripheral microvascular blood flow in large surface skin area are available in the literature.…”