Metabolic and hemodynamic effects of saline infusion to maintain volemia on temporary abdominal aortic occlusion

Abstract

Objective -To analyze hemodynamic and metabolic effects of saline solution infusion in the maintenance of blood volume in ischemia-reperfusion syndrome during temporary abdominal aortic occlusion in dogs.Methods -We studied 20 dogs divided into 2 groups: the ischemia-reperfusion group (IRG, n=10) and the ischemia-reperfusion group with saline solution infusion aiming at maintaining mean pulmonary arterial wedge pressure between 10 and 20 mmHg n=10 . Severe hypotension, associated with a decrease in cardiac output is a well-known event occurring after declamping, and hypovolemia is considered the main cause of this event [3][4][5][6][7][8] . Maintenance of renal function, prevention of hepatic and splanic circulatory failure and preservation of gastroinstestinal tract intensity are important consequences of hemodynamic stability [8][9][10][11] . Fluid administration followed by adequate monitoring based on the physiology of cardiac function, according to the Frank-Starling mechanism, promotes good myocardial performance during surgical stress and in the postoperative period. It improves cardiac output and maintains systemic blood pressure, which is important for maintaining adequate coronary blood flow, thereby protecting the heart, especially in patients with significant coronary occlusive disease 11 . Several authors [4][5][6]12,13 showed that maintenance of pulmonary artery wedge pressure between 10 and 18 mmHg during this procedure could prevent a decline in cardiac output and hypotension after aortic declamping.However, management of fluid infusion is difficult in these patients due to the complexity of factors involved, such as preoperative cardiac function and multiple risk factors present in the intraoperative period, such as administering anesthetic drugs and mechanical positive pressure ventilation. This is important especially in these patients that usually have heart disease, where inappropriate volume loading is dangerous 5 . Acknowledging the importance of the study of ischemia-reperfusion lesion and knowing the capacity of it in determining systemic alterations, even in distant organs, we studied the effects of saline solution infusion to maintain mean pulmonary artery wedge pressure between 10 and 20 mmHg during aortic ischemia-reperfusion in an experimental model in dogs, especially in the shock phase after aortic declamping, over hemodynamic and metabolic alterations. MethodsTwenty adult, male, mongrel dogs, weighing between 12 and 23 kg were intravenously anesthetized with sodium

Effect of saline infusion for the maintenance of blood volume on pulmonary gas exchange during temporary abdominal aortic occlusion

“…As demonstrated in several studies, saline infusion with maintenance of mean pulmonary arterial wedge pressure is suitable for minimizing hemodynamic changes after release of the aortic clamps, mainly avoiding hypotension and a decrease in cardiac index (5)(6)(7)(13)(14)(15). However, in the present study this procedure caused worsening of gas exchange as shown by an increase in P(A-a)O 2 after aortic declamping in IRG-SS, determining a progressive decrease in PaO 2 .…”

“…Maintenance of pulmonary artery wedge pressure between 10 and 18 mmHg during this procedure could prevent a decline in cardiac output and hypotension after aortic declamping (5)(6)(7)(13)(14)(15). However, few studies have evaluated the impact of fluid infusion on pulmonary gas exchange.…”