**2.2.2 Hemodialysis-related hypoxemia**

During hemodialysis, Pa O2 drops to approximately 10-20 mmHg. While such decrease does not lead to significant clinical problems in patients with normal oxygenation, may produce catastrophic results in those with poor oxygenation (De Backer et al.,1983; Hakim & Lowrie,1982). One of the factors that is blamed in the etiology of hypoxemia that emerge during hemodialysis is dialysate containing acetate (De Backer et al.,1983). However, it was demonstrated that it could also be observed in dialysate with bicarbonate. Dialysate with acetate may induce hypoxia in two ways, first by increased oxygen consumption during acetate bicarbonate conversion and second by intradialytic loss of CO2 (Dolan et al.,1981; Oh et al.,1985). The biocompatibility of the membrane used is one of the most frequently blamed factors in hypoxemia (Graf et al.,1980). Especially the use of an acetate-containing dialysate together with a Cuprophan membrane increases hypoxemia (Vanholder et al.,1987). Hypocapnia associated with intradialytic loss of CO2 and adaptation to chronic metabolic acidosis lead to periodic shortness of breath and a tendency to sleep apnea syndrome (De Broe & De Backer, 1989).

#### **Treatment and prevention**

Increasing the level of CO2 in the dialysate by directly adding CO2 to it or by using a dialysate containing bicarbonate,

Using biocompatible membranes (De Backer et al.,1983; Hakim & Lowrie,1982),

Making appropriate ventilator settings for the patients who are known to have hypoxemia prior to the dialysis and are administered mechanical ventilation, nocturnal hemodialysis may be appropriate for those with sleep apnea syndrome (Hanly&Pierratos, 2001),

### **2.2.3 Disadvantages of first-use dialyzers**

New dialyzer syndrome, neutropenia and complement activation as well as reactions associated with the use of ethylene oxide are seen more often.
