Hyperoxia for management of acid-base status during deep hypothermia with circulatory arrest

Background. Which blood gas strategy to use during deep hypothermic circula tory arrest has not been resolved because of conflicting data regarding the advantage of pH-stat versus alpha-stat. Oxygen pressure field theory sugge sts that hyperoxia just before deep hypothermic circulatory arrest takes ad vantage of increased oxygen solubility and reduced oxygen consumption to lo ad tissues with excess oxygen. The objective of this study was to determine whether prevention of tissue hypoxia with this strategy could attenuate is chemic and reperfusion injury. Methods. Infants who had deep hypothermic circulatory arrest (n = 37) were compared retrospectively. Treatments were alpha-stat and normoxia (group I) , alpha-stat and hyperoxia (group II), pH-stat and normoxia (group III), an d pH-stat and hyperoxia (group IV). Results. Both hyperoxia groups had less acidosis after deep hypothermic cir culatory arrest than normoxia groups. Group IV had less acid generation dur ing circulatory arrest and less base excess after arrest than groups I, II, or III (p < 0.05). Group IV produced only 25% as much acid during deep hyp othermic circulatory arrest as the next closest group (group II). Conclusions. Hyperoxia before deep hypothermic circulatory arrest with alph a-stat or pH-stat strategy demonstrated advantages over normoxia. Furthermo re, pH-stat strategy using hyperoxia provided superior venous blood gas val ues over any of the other groups after circulatory arrest. (Ann Thorac Surg 2000;70:751-5) (C) 2000 by The Society of Thoracic Surgeons.