Accordingly, IV induction of anesthesia followed by endotracheal intubation and mechanical ventilation is the preferred approach for patients with impaired ventricular function, elevated pulmonary artery pressures, severe hypoxemia, and neonates with complex congenital cardiac disease Immobility for imaging or diagnostic studies with limited painful stimulation can be achieved in older patients with continuous sedation via indwelling IV access or following induction of general anesthesia and IV placement Propofol has become a popular agent for inducing deep sedation and general anesthesia In clinically relevant plasma concentrations, propofol has been found to have minimal negative inotropic effects in isolated animal cardiac preparations23 or in human adult atrial muscle strips.24 In children with normal hearts, induction doses of propofol consistently decrease systolic and mean arterial pressure by 5% to 25% as well as reduce systemic vascular resistance, without changes in heart rate, cardiac output, or pulmonary vascular resistance.25 In patients with intracardiac shunts, increases in right-to-left shunt and decreases in the pulmonary to systemic flow ratio (Qp:Qs) have been observed, which may result in a significant decrease in PaO2 and SpO2.26 Propofol should therefore be used judiciously in patients who cannot tolerate systemic afterload reduction and in patients whose pulmonary blood flow depends on balancing their systemic and pulmonary vascular resistances However, it has no significant effect on sinuatrial atrioventricular node conduction or on the ability to induce supraventricular tachycardia, rendering it desirable as the principal anesthetic agent for electrophysiology studies and radiofrequency ablations.27 Importantly, however, its long-term use in the intensive care setting is contraindicated, with several reports of lactic acidosis and myocardial failure thought to be due to disruption of fatty acid oxidation28 following prolonged (>48 hours) or highdose use in pediatric patients.29,30 A drug frequently used to induce anesthesia in hemodynamically unstable children is ketamine This N-methyl D-aspartate receptor antagonist is a potent analgesic and provides dissociative anesthesia.31 It increases heart rate, blood pressure, and cardiac output through central nervous system–mediated sympathomimetic stimulation and inhibition of the reuptake of catecholamines It has been shown to have minimal or no effect on pulmonary artery pressures or pulmonary vascular resistance if oxygenation is maintained.32–34 However, it is a direct myocardial depressant when studied in isolated myocyte preparations35 and in failing adult human atrial and ventricular muscle trabeculae,16 thought to be due to inhibition of L-type voltage-dependent Ca2+ channels in the sarcolemmal membrane.36 This may explain the myocardial depression observed in patients whose sympathomimetic responses are already maximally stimulated, such as in decompensated heart failure Moreover, in patients chronically treated with β-adrenergic agonists, catecholamine receptors may be down regulated, resulting in a diminished response to endogenously generated catecholamines This direct myocardial-depressing effect is greater than that produced by etomidate.24 Other well-recognized side effects associated with ketamine include emergence delirium, excessive salivation, and increases in cerebral metabolism, intracranial pressure, cerebral blood flow, and cerebral oxygen consumption.31 Etomidate is an imidazole-derived hypnotic/sedative agent whose anesthetic effects are produced by stimulating gamma-aminobutyric acid receptors Its desirable effects include minimal myocardial depression, reductions in cerebral blood flow, cerebral metabolic rate for oxygen consumption (by 30% to 50%) and intracranial pressure, as well as minimal respiratory depression.16,24 Undesirable effects include pain on injection, myoclonic movement, hiccups, nausea and vomiting, and adrenal suppression Dexmedetomidine is an imidazole derivative and a selective α2 adrenergic receptor agonist with sedative, analgesic, and anxiolytic properties It is increasingly used as a sedative for noninvasive imaging studies37 as well as intraoperatively and postoperatively to help blunt the sympathetic stress response, to decrease anesthetic requirements, and to control postoperative pain.38,39 Its side effects include a dose-dependent decrease in heart rate, hypotension or hypertension, and potentiation of opioid and sedative drugs.40 Of note, dexmedetomidine clearance is decreased in premature and full-term neonates, necessitating lower doses in this age group and heightened monitoring for side effects.41 Monitoring and Vascular Access In addition to the standard noninvasive monitoring required by the American Society of Anesthesiologists, which include pulse oximetry, noninvasive blood pressure measurement, ECG, temperature, and capnography, if available, invasive monitoring is frequently utilized for pediatric cardiac surgical procedures These may include invasive arterial and central venous catheters, intracardiac lines, or transesophageal echocardiography, and utilization varies substantially by institution Neonates frequently have umbilical arterial and venous catheters placed either in the intensive care unit (ICU) or upon arrival to the OR These catheters provide accurate pressure monitoring and reliable vascular access, respectively, and allow other vascular sites to be preserved for future anticipated surgical procedures and catheterizations If umbilical arterial access is not available, radial, ulnar, or femoral arterial access is obtained prior to the operation Posterior tibial and dorsalis pedis arterial pressure monitoring are often unreliable following cardiopulmonary bypass or deep hypothermic circulatory arrest Moreover, use of the brachial and axillary arteries are not commonly employed due to the risk for distal limb ischemia Consideration regarding laterality is given to prior or anticipated systemic to pulmonary artery shunts or descending aortic cross-clamping, which affect the ability to measure hemodynamics distally Modality of arterial cannulation is dependent on provider level of training and familiarity with insertion techniques, such as palpation, Doppler or ultrasound guidance, or cut-down with direct visualization of the vessel A recent Cochrane review demonstrated higher first-attempt success rates and lower complication rates with ultrasound guidance for arterial line placement in the pediatric population compared with palpation or Doppler auditory assistance.42 The use of percutaneous central venous catheters varies among institutions While a central venous catheter may provide central venous pressure monitoring, access for vasoactive infusions, and large-bore central access for rapid volume delivery, their placement can add significant time to the pre-bypass period and placement carries the risk of pneumothorax, hematoma, inadvertent arterial puncture, infection, and central vein thrombosis, which may be particularly deleterious in infants in the single-ventricle pathway If umbilical venous access is not available, internal jugular or subclavian venous access are usually preferred, although femoral vein access may be advantageous in children with ... pressure measurement, ECG, temperature, and capnography, if available, invasive monitoring is frequently utilized for pediatric cardiac surgical procedures These may include invasive arterial and central venous catheters,... success rates and lower complication rates with ultrasound guidance for arterial line placement in the pediatric population compared with palpation or Doppler auditory assistance.42 The use of percutaneous central venous catheters varies among institutions