anesthesia, temperature, cerebral perfusion pressure, and overall metabolic state Patients suspected of having a clinical seizure should undergo continuous EEG monitoring along with brain imaging Novel Noninvasive Algorithms Based on High-Fidelity Continuous Physiologic Data Computer algorithms based on high-fidelity physiologic data such as the iDO2 index described earlier have become important adjuncts in the postoperative management following palliation An acute or sustained rise in the iDO2 index is associated with inadequate DO2 and may be an early indicator of impending myocardial failure These algorithms may prove to be of particular value in detecting impending cardiovascular collapse following interventions such as sternal closure Urinary Catheters Though not traditionally considered a monitoring device per se, the urinary catheter provides a continuous assessment of urine output, which is an important surrogate for cardiac output as well as renal function Given the risk for infection, urinary catheters are often discontinued as soon as a steady physiologic state is achieved, as the risk of the continuous monitoring of urine output can be mitigated by simple intermittent monitoring of urine output without an indwelling catheter Temperature Monitors Continuous monitoring of core body temperature is an important component of postoperative care The maintenance of normothermia or mild hypothermia minimizes oxygen demand on the recovering myocardium Temperature probes may be inserted into the esophagus, bladder, or rectum Although risk of mucosal injury is small, continuous temperature probes are typically removed as soon as a steady physiologic state is reached Comparison of the core temperature to a peripheral temperature (e.g., at the toe) is a helpful additional surrogate for cardiac output Bleeding Maturation of the hemostatic system continues throughout the first year of life; this system differs from that in adults The levels of many clotting factors and inhibitors are low and can contribute the challenges of achieving hemostasis following surgery in the neonate and infant.111,112 It is essential to achieve hemostasis at the completion of any cardiac procedure but is especially important in the patient undergoing neonatal palliation with a continued multidistribution circulation Volume loss and anemia will result in decreased total cardiac output and worsening hypoxemia Ongoing bleeding can result in cardiac tamponade and cardiovascular collapse In most closed procedures— such as pulmonary artery banding, creation of a systemic-to-pulmonary artery shunt, or coarctation repair—bleeding is uncommon In these cases, bleeding is nearly always surgical—that is, it is not due to a defect in the coagulation system After cases using cardiopulmonary bypass such as a DKS, especially when combined with hypothermia, as in a Norwood procedure, bleeding is common and due to both surgical site bleeding and the coagulopathic effect of cardiopulmonary bypass, especially when combined with hypothermia Reactions in the coagulation cascade are temperature-dependent, and it is essential that normothermia be achieved prior to weaning from bypass Calcium is an important cofactor in hemostasis and essential for normal cardiomyocyte function; it should therefore be normalized prior to weaning from bypass Heparin is used for anticoagulation during cardiopulmonary bypass, and once the patient has been successfully weaned from it, complete reversal of heparin with protamine is the first step in achieving hemostasis To achieve stable clot formation, both platelets and fibrinogen are necessary and should be targets for supplementation.113,114 Although individual supplementation of these factors based on measured deficiency would be ideal, practically the most common approach is empiric supplementation of platelets and fibrinogen using either fresh frozen plasma or cryoprecipitate Although platelets and fibrinogen are being supplemented, the operative field should be evaluated for surgical bleeding If bleeding persists despite supplementation of platelets and fibrinogen and important surgical bleeding has been ruled out, additional hemostatic agents may be considered A variety of topical agents are used to help achieve hemostasis These include agents with a large surface area of material that activates the contact activation system, such as gelatin foams, oxidized cellulose, and microfibrillar collagen These agents are often combined with thrombin, either bovine derived or recombinant human types Many fibrin sealants (e.g., Tisseel and Evicel) are commercially available; these combine fibrinogen and thrombin at the bleeding site, creating a fibrin clot These agents are commonly applied to bleeding sites, venous oozing from raw areas or sutures lines The externally applied materials create a clot matrix that slows bleeding from the source and augments local hemostatic mechanisms at the bleeding site More cohesive biologic sealants can be used on suture lines in advance of bleeding, such as polyethylene glycol hydrogels (e.g., Coseal), glutaraldehyde cross-linked collagen (e.g., Bioglue), or polyaldehyde cross-linked bovine serum albumin (e.g., Preveleak) All of these agents are absorbable and in small quantities can be left in place They are frequently combined to take advantage of different mechanisms of hemostasis Gelatin foams, oxidized cellulose, microfibrillar collagen, and fibrin sealants can all swell and compromise flow in vascular structures If the biologic sealants are placed circumferentially around vascular structures, they can cause constriction.115,116 In addition to blood component replacement, intravascular agents can be used to inhibit fibrinolysis or accelerate the coagulation system These can be divided into two groups: (1) prophylactic agents, specifically antifibrinolytics including aprotinin, tranexamic acid, and epsilon-aminocaproic acid, and (2) agents given to treat excessive bleeding, including recombinant factor VIIa and prothrombin complex concentrates Antifibrinolytics are commonly used in cardiac surgery, typically initiated at the beginning of the case and continued until after heparin reversal with protamine With the possible exception of aprotinin, which is no longer available in the United States, the antifibrinolytics are low risk, modestly effective, and do not increase the risk of mortality.117 Agents given to treat excessive bleeding include recombinant activated factor VIIa and prothrombin complex concentrates Recombinant activated factor VIIa is a form of blood factor VII manufactured via recombinant technology for the treatment of hemophilia; it has been used to treat hemorrhage in a variety of settings including congenital heart surgery.118 Recombinant activated factor VIIa augments the intrinsic pathway of coagulation and acts locally, at the site of endothelial damage, by binding to tissue factor This leads to thrombin generation, fibrin clot formation, and the activation of platelets Prothrombin complex concentrates are a mixture of purified human plasma–derived vitamin K-dependent factors II, VII, IX, and X and proteins C and S.119 Both recombinant activated factor VIIa and prothrombin complex concentrates can be very helpful in achieving hemostasis, but they are also associated with an increase in thrombotic complications and should be used with caution.120–122