Beneficial Effect of Cold Dialysate for the Prevention of Hemodialysis-lnduced Hypoxia

Abstract

Hypoxia occurs frequently during routine hemodialysis (HD). In this study the effect of dialysate temperature on arterial blood gas parameters was investigated. Ten stable HD patients (2 smokers) were dialyzed for 240 min with each of three different dialysate temperatures: 36.5°C (normal temperature HD; NHD), 38.5 °C (warm HD; WHD) and 34.5 °C (cold HD; CHD). A cuprophane plate dialyzer was used. The ultrafiltration volume was identical in each patient. Arterial blood gas samples were frequently (-10 times/treatment) taken during the dialysis and immediately analyzed.The dialysate temperature significantly affected PaO₂ (p < 0.001) but not PaCO₂. We also compared the effect of NHD with that of WHD and CHD, respectively, as regards PaO₂. NHD and WHD differed significantly (p < 0.01), whereas NHD and CHD were not significantly different. However, the relative PaO₂ value (% of the baseline value) at the end of CHD(105 ± 5%) was significantly 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 during which the patients had a PaO₂value below 80 mm Hg was 62 and 64%, respectively. The corresponding figure for CHD was 44%. Arterial oxygen saturation (SaO₂) increased during CHD from 95.2 ± 0.6 to 96.7 ± 0.6% (p < 0.05), while SaO₂ was unchanged during NHD and WHD. The 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 affected PaO₂ (p < 0.001). A comparison between NHD and CHD showed a significant difference (p < 0.001), whereas NHD and WHD did not differ significantly. When the 2 smokers were excluded from the analysis the fraction of time with a 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 seemed to benefit from cold dialysate for the prevention of dialysis-induced hypoxia.

Why Is Your Patient Still Short of Breath? Understanding the Complex Pathophysiology of Dyspnea in Chronic Kidney Disease

“…In particular, few studies exist on the effects of the newer biocompatible dialyzers on lung function. Moreover, the effect of dialysate cooling in the prevention of intradialytic hypoxemia is interesting and should be further investigated . By using appropriate imaging‐based surrogates, we will be also able to further investigate the consequences of fluid overload on lung volumes and regional ventilation and evaluate the effects of ultrafiltration during dialysis.…”