BENEFICIAL EFFECT OF COLD DIALYSATE FOR THE PREVENTION OF HEMODIALYSIS-INDUCED HYPOXIA

Hypoxia occurs frequently during routine hemodialysis (HD). In this st udy the effect of dialysate temperature on arterial blood gas paramete rs was investigated. Ten stable HD patients (2 smokers) were dialyzed for 240 min with each of three different dialysate temperatures: 36.5 degrees C (normal temperature HD; NHD), 38.5 degrees C (warm HD; WHD) and 34.5 degrees C (cold HD; CHD). A cuprophane plate dialyzer was use d. The ultrafiltration volume was identical in each patient. Arterial blood gas samples were frequently (similar to 10 times/treatment) take n during the dialysis and immediately analyzed. The dialysate temperat ure significantly affected PaO2 (p < 0.001) but not PaCO2. We also com pared the effect of NHD with that of WHD and CHD, respectively, as reg ards PaO2. NHD and WHD differed significantly (p < 0.01), whereas NHD and CHD were not significantly different. However, the relative PaO2 v alue (% of the baseline value) at the end of CHD (105 +/- 5%) was sign ificantly higher than after both NHD (96 +/- 4%, p < 0.01) and WHD (91 +/- 3%, p < 0.01). In the case of NHD and WHD the fraction of time du ring which the patients had a PaO2 value below 80 mm Hg was 62 and 64% , respectively. The corresponding figure for CHD was 44%. Arterial oxy gen saturation (SaO(2)) increased during CHD from 95.2 +/- 0.6 to 96.7 +/- 0.6% (p < 0.05), while SaO(2) was unchanged during NHD and WHD. T he positive effect of CHD was evident in 7 patients. In 1 patient PaO2 was not affected by the dialysate temperature, while in the remaining 2 patients (smokers) a decrease in PaO2 was induced by WHD as well as CHD. A separate statistical analysis with the 2 smokers excluded was performed, which showed that the dialysate temperature significantly a ffected PaO2 (p < 0.001). A comparison between NHD and CHD showed a si gnificant difference (p < 0.001), whereas NHD and WHD did not differ s ignificantly. When the 2 smokers were excluded from the analysis the f raction of time with. PaO2 value below 80 mm Hg was 60% during NHD and 56% during WHD, but it was reduced to 31% during CHD. In conclusion, despite the existence of interindividual variations most patients seem ed to benefit from cold dialysate for the prevention of dialysis-induc ed hypoxia.