Control of core temperature and blood pressure stability during hemodialysis

Abstract

Background and objectives: Cool dialysate may ameliorate intradialytic hypotension (IDH). It is not known whether it is sufficient to prevent an increase in core temperature (CT) during hemodialysis (HD) or whether a mild decline in CT would yield superior results. The aim of this study was to compare both approaches with regard to IDH.

Design, setting, participants, & measurements: Fourteen HD patients with a history of IDH were studied. During three mid-week HD treatments, CT was set to decrease by 0.5 degrees C ("cooling") or to remain unchanged at the baseline level ("isothermic"). "Thermoneutral" HD (no energy is added to or removed from the patient) was used as a control. Central blood volume (CBV), BP, skin temperature, heart rate variability [low and high frequency] were recorded.

Results: CT increased during thermoneutral and remained respectively stable and decreased during isothermic and cooling. Skin temperature decreased significantly during isothermic and cooling, but not during thermoneutral. Nadir systolic BP (SBP) levels were lower during isothermic and thermoneutral compared with cooling. CBV tended to be higher during cooling compared with isothermic and thermoneutral. Three patients complained of shivering during cooling. Change in LF/HF was not different between cooling, isothermic, and thermoneutral.

Conclusions: IDH may be slightly improved by cooling compared with the isothermic approach, possibly because of improved maintenance of CBV. The hemodynamic effects of mild blood cooling should be balanced against a potentially higher risk of cold discomfort.

Figure 1.

Accumulated energy removal. “Isothermic” is hemodialysis (HD) under core temperature (CT) control conditions (i.e., no change in CT). “Cooling” is HD under CT control conditions (i.e., decline in CT of 0.5°C versus baseline). “Thermoneutral” is HD under energy-neutral conditions (i.e., no change in energy flow). Boxes indicate 25 to 75% with median value; capped bars indicate the range of data.

Figure 2.

Systolic BP (SBP) at various points during HD. “SBP start” is SBP at the start of dialysis, “SBP lowest” is lowest SBP during the treatment, and “SBP end” is SBP at the end of dialysis.