Armando Vegas

Volume loading and vasodilators in abdominal aortic aneurysmectomy

Preoperative infusion of volume to increase the wedge pressure will maintain stable flow and arterial pressure at the time of aortic declamping. Usually 1,500 ml of balanced salt solution given with 75 g of albumin is sufficient to accomplish this purpose. Pressor or inotropic agents are not required. In our experience 14 percent of patients will have a down-slope in the preoperative myocardial performance curves. In these persons, volume infusions should be adjusted to keep the pulmonary arterial wedge pressure on the ascending portion of the curve. The use of vasodilator agents in normotensive patients has a deleterious effect on cardiac performance.

Importance of oxygen transport in clinical medicine.

One or more of the several components of the oxygen transport system may function abnormally in critical illness. Arterial hypoxemia is an important feature of acute respiratory failure. Its prominence may obscure other limitations in oxygen availability such as low cardiac output, anemia, or an increased red cell affinity state. These several components of the oxygen transport system can be influenced by therapeutic maneuvers, but the result may not necessarily be a net benefit. For example, red blood cell transfusion therapy may correct anemia, but increase the red blood cell affinity state so as to adversely affect cardiac function. Treatment programs require consideration of the interaction of these several variables affecting oxygen transport.

Independence of renin production and hypertension in abdominal aortic aneurysmectomy

Seventeen patients undergoing elective repair of abdominal aortic aneurysm were examined to determine the causal mechanism for postoperative hypertension. In nine patients who had elevated systemic pressure after surgery, there were no correlations between mean arterial pressure and values of peripheral renin activity or angiotensin II. Further, no relation was demonstrated between systemic pressure and the volumes of crystalloid, colloid infused or milliequivalents of sodium administered pre- and intraoperatively. Postoperative arterial pressure correlated best with the preoperative value.

Adjustable nylon ties for abdominal wall closure

A study in 64 patients with a high risk of wound dehiscence or eviscerated wounds or in whom repeat laparotomies for peritoneal lavages due to sepsis were planned was accomplished using adjustable nylon ties for the closure of the abdominal wall, either as retention sutures or as one-layer sutures. The adjustable nylon ties are described, as well as the technique for placing and adjusting them. It is concluded that the adjustable nylon ties can substitute advantageously for the conventional retention sutures since the former are wider, easy to place, and can be readjusted to the point that they can be opened completely if it is necessary and then closed again. This is especially useful when repeat laparotomies for peritoneal lavages are required in patients with intra-abdominal sepsis.

Cardiopulmonary function following transfusion of three red blood cell products in elective abdominal aortic aneurysmectomy.

In order to evaluate the importance of red cell 02 affinity of transfused blood on cardiac performance and adverse effects of transfusion on lung function, a prospective double-blind protocol was used in 27 patients undergoing abdominal aortic aneurysmectomy. Three types of blood were administered: packed red cells (PC), washed red cells (VVC) and high 2,3 DPG red cells (2,3 DPG). An average of 4.5 units of blood was used per patient. Transfusion of 2,3 DPG blood resulted in maintenance of in vivo Pso during surgery and an increase to 31.2 torr after operation (p < 0.001). An intraoperative fall in in vivo P50 to 23.2 ± 2.0 torr was observed in patients who were transfused with PC (p < 0.001) and to 25.1 ± 2.6 torr with WC (p < 0.005). A fall in body temperature averaging 2.2 C intraoperatively was noticed in all three groups. After operation, in vitro P;o decreased in patients transfused with PC (p < 0.005) and WC (p < 0.005) while it remained unchanged in the high 2,3 DPG group. This was consistent with the decrease of red cell 2,3 DPG in the PC (p < 0.001) and WC groups (p < 0.01) and maintenance in the 2,3 DPG group. Left ventricular stroke work and volume loading Starling type myocardial performance curves were similar for the three groups. Microaggregates measured by Coulter counting and screen filtration pressure were the same for all three products in samples drawn on both sides of the 40 jum transfusion Alter. There was no relationship of transfusion volumes or type of blood product to changes in lung function (physiologic shunting, dynamic compliance and pulmonary arterial pressure) in the three groups of patients. The false negative, β, error of missing a true 25% difference was less than 10%. It is concluded that 2,3 DPG enriched red cells improved oxygen availability, but that a 4.5 unit transfusion of any of the three blood products did not influence lung function or myocardial performance following aneurysmectomy

Is respiratory failure a consequence of blood transfusion

The pulmonary entrapment of microaggregates, platelets, and white cells in stored blood is thought to contribute to abnormalities in lung function. Washing of red cells removes these potentially damaging elements. This prospective, randomized, double-blind study compares the pulmonary function of patients undergoing abdominal aortic aneurysmectomy who received either washed or unwashed red cell concentrates. Both groups received equivalent volumes of blood, albumin, and balanced salt solution duing surgery. Postoperatively, no differences were observed in the physiologic shunt, QS/QT, pulmonary artery pressure, pulmonary vascular resistance, or effective dynamic compliance. The cardiac index at equivalent left ventricular filling pressures was the same. The results indicate that it is unlikely that microaggregates or other formed elements in stored blood lead to compromised pulmonary function.

Volume Loading and Vasodilators in Abdominal Aortic Aneurysmectomy

Preoperative infusion of volume to increase the wedge pressure will maintain stable flow and arterial pressure at the time of aortic declamping. Usually 1,500 ml of balanced salt solution given with 75 g of albumin is sufficient to accomplish this purpose. Pressor or inotropic agents are not required. In our experience 14 percent of patients will have a down-slope in the preoperative myocardial performance curves. In these persons, volume infusions should be adjusted to keep the pulmonary arterial wedge pressure on the ascending portion of the curve. The use of vasodilator agents in normotensive patients has a deleterious effect on cardiac performance.