Cardiovascular system

Special considerations are needed when providing perioperative care for children who have congenital or acquired heart disease. This is true for the cardiac operating room, but increasingly these children are undergoing noncardiac procedures in various stages of palliation both at and outside of specialized centers. It is likely with the successes of modern congenital cardiac surgery that this population will continue to increase in coming years. Understanding of congenital cardiac physiology and anatomy (including postpalliation) will be paramount for the pediatric anesthesiologist and for the general anesthesiologist taking care of adults with congenital heart disease. Cardiovascular effects on anesthetic uptake and delivery Induction is a particularly critical time in any anesthetic, but particularly so for the child or adult with congenital heart disease (CHD). Understanding how the pharmacology of inhaled anesthetics is affected by underlying CHD is mainly dictated by the presence or absence of intracardiac shunts. Shunting of blood affects the relative pulmonary to systemic blood flow (Qp/Qs), which is 1 under normal conditions. A right to left intracardiac shunt, which decreases Qp/Qs, will slow the uptake of inhaled anesthetic, prolonging induction times due to decreased pulmonary blood flow relative to systemic. A large left to right shunt, which increases Qp/Qs, speeds the uptake of inhaled anesthetic due to the increase of pulmonary blood flow assuming that the cardiac output is relatively normal; however, smaller left to right shunts have a negligible effect on uptake. It is also important to consider that shunting may be dynamic and that decreased SVR may decrease Qp/Qs and even reverse some left to right shunts. The overall effect of this would be to prolong induction. The effect of shunting on uptake increases as solubility decreases, therefore nitrous oxide and desflurane will be more affected than the relatively soluble isoflurane.