Effects of acid-base correction on hemodynamics, oxygen dynamics, and resuscitability in severe canine hemorrhagic shock

Abstract

To compare the effects of hypertonic saline, sodium bicarbonate, and Carbicarb resuscitation on acid-base balance, hemodynamics, and oxygen dynamics in a reperfused, canine hemorrhagic shock model. Prospective, randomized trial. Laboratory at a university medical center. Thirty-five anesthetized, mongrel dogs. After the administration of anesthesia, the dogs were intubated and mechanically ventilated. Vascular catheters were inserted into each femoral artery, for continuous blood pressure monitoring, intermittent blood sampling, and for establishing controlled hemorrhage. A pulmonary artery catheter was inserted via the right jugular vein. Inhaled and exhaled gases were continuously analyzed using a metabolic gas monitor. The animals were subjected to 90 mins of controlled hemorrhagic shock. They were then randomly given a 2.5-mL/kg equimolar injection of 8.4% sodium bicarbonate, Carbicarb, or 5.84% hypertonic saline. The sodium load per kilogram of body weight was identical in all three groups. Thirty minutes later, the animals were retransfused with the shed blood over 15 mins and further observed for 120 mins. Carbicarb and sodium bicarbonate both significantly increased bicarbonate concentrations compared with saline. Arterial and venous blood pH increased more with Carbicarb than with bicarbonate but this increase was not statistically significant. After shock but before retransfusion, all three treatments moderately increased blood pressure, cardiac index, oxygen delivery index, and oxygen consumption index to a similar extent. After retransfusion, blood pressure, cardiac index, and oxygen dynamics temporarily improved in all groups, without significant improvement in the bicarbonate and Carbicarb-treated animals, despite their excellent acid-base status. In severe canine hemorrhagic shock, Carbicarb, bicarbonate, and hypertonic saline appear to possess similar hemodynamic properties despite the buffering properties of bicarbonate and Carbicarb. The similar responses may be due to their identical sodium content. Arterial pH correction does not appear to further improve the responses to blood retransfusion.