Controversy and consensus on pediatric donation after cardiac death: ethical issues and institutional process.

Donation after cardiac death (DCD) remains controversial in some pediatric institutions. An evidence-based, consensus-building approach to setting institutional policy about DCD can address the controversy openly and identify common ground. To resolve an extended internal debate regarding DCD policy at Children's Hospital Boston, a multidisciplinary task force was commissioned to engage in fact finding and deliberations about clinical and ethical issues in pediatric DCD, and attempt to reach consensus regarding the development of a protocol for pediatric DCD. Issues examined included values and attitudes of staff, families, and the public; number of possible candidates for DCD at the hospital; risks and benefits for child donors and their families; and research needs. Consensus was reached on a set of foundational ethical principles for pediatric DCD. With assistance from the local organ procurement organization (OPO), the task force developed a protocol for pediatric kidney DCD which most members believed could meet all the requirements of the foundational ethical principles. Complete consensus on the use of the protocol was not reached; however, almost all members supported initiation of kidney DCD for older pediatric patients who had wished to be organ donors. The hospital has implemented the protocol on this limited basis and established a process for considering proposals to expand the eligible donor population and include other organs.

Glucocorticoid therapy for hypotension in the cardiac intensive care unit.

In recent years, it has been our practice to treat persistent hypotension in the cardiac intensive care unit with glucocorticoids. We undertook a retrospective review in an attempt to identify predictors of a hemodynamic response to steroids and of survival in these patients. Patients who had received glucocorticoids for hypotension over a 2-year period were identified retrospectively. Summary measures of blood pressure, heart rate, urine output, inotrope score, and volume of infused fluid were calculated for the 12 hours before and the 24 hours following initiation of glucocorticoid therapy. A hemodynamic response was defined as a > or =20% increase in mean blood pressure without an increase in inotrope score following initiation of steroid therapy. Fifty-one patients were included, of whom 6 (11.8%) died. Serum cortisol was measured in 43 patients (84.3%) and was below the lower limit of normal (<5 microg/dl) in 20 of these (46.5%). Following initiation of steroid therapy, blood pressure and urine output increased, whereas heart rate, inotrope score, and infused volume decreased. There were 21 (41.1%) hemodynamic responders, all of whom survived, whereas 6 of 30 (20%) nonresponders died (p = 0.036). No predictors of a hemodynamic response to steroid were identified. Some critically ill children with cardiac disease and inotrope refractory hypotension demonstrated hemodynamic improvement following glucocorticoid administration. An improvement in blood pressure following administration of glucocorticoid was associated with survival, but we were unable to identify predictors of that response.

Bispectral index monitoring in children undergoing mild hypothermic cardiopulmonary bypass.

BACKGROUND: In this prospective, cohort study of 15 children (median age 7.7 years, range 4.9-16.5 years) undergoing atrial septal defect repair, we evaluated changes in the Bispectral index (BIS) as a potential monitor of level of consciousness during cardiac anaesthesia. METHODS: Identical cardiac surgery, cardiopulmonary bypass (CPB) and anaesthetic techniques were used, including mild hypothermia and an early extubation protocol. BIS, mean arterial pressure, heart rate and tympanic temperature were recorded at baseline postinduction (Tbaseline), skin incision (Tincis), sternotomy (Tsternot), aortic cannulation (Tcann), nadir temperature (Tnadir), rewarmed (Trewarmed), immediate post-CPB (TpostCPB), chest drain insertion (Tdrains), sternal wires (Twire), skin closure (Tclosed) and spontaneous movement (Tmove). As a measure of stress response, serum lactate, glucose, norepinephrine and epinephrine levels were measured at Tbaseline, Tsternot, Tcann, Tnadir, Trewarmed and Tdrains. Explicit memory testing was undertaken prior to hospital discharge. RESULTS: BIS increased significantly during the rewarming phase (Trewarmed versus Tbaseline and Tnadir, P<0.001). Lactate, epinephrine and glucose levels were also significantly elevated at Trewarmed. There were no correlations between BIS and the increase in epinephrine, lactate and glucose during rewarming, nor with changes in heart rate or mean arterial pressure during surgery. All patients had an uneventful recovery without evidence for explicit recall. CONCLUSIONS: The increase in BIS during the rewarming phase could reflect an increase in conscious level, and is consistent with the reported risk for awareness during this phase of cardiac surgery.

Bispectral index monitoring during infant cardiac surgery: relationship of BIS to the stress response and plasma fentanyl levels.

BACKGROUND: We evaluated the relationship of the bispectral index (BIS) to commonly used indices of depth of anaesthesia in 19 infants enrolled in a prospective study of the stress response to hypothermic cardiopulmonary bypass. METHODS: Group 1 (n=8) received high-dose fentanyl by bolus technique; group 2 (n=6) received high-dose fentanyl by continuous infusion; and group 3 (n=5) received a fentanyl-midazolam infusion. Blood pressure (BP), heart rate (HR) and plasma epinephrine, norepinephrine, cortisol, ACTH, glucose, lactate and fentanyl were analysed 15 min postinduction, 15 min poststernotomy, 15 min on CPB during cooling and during skin closure. RESULTS: Mean BIS (SD) values for all 19 patients were 45.3 (12.3), 40.4 (14.5), 24.4 (12.4) and 47.9 (13.9), at the successive time points. No significant differences were observed in changes in BIS over time between the groups. A significant correlation was found 15 min postinduction between BIS and BP (systolic r=0.51, mean r=0.56) in all groups, but not between BIS and HR. BIS did not correlate with BP or HR at any other time point. There was no significant correlation between BIS and hormonal, biochemical or plasma fentanyl levels for any group at any time point. CONCLUSIONS: We were unable to demonstrate a relationship between the BIS and haemodynamic, metabolic or hormonal indices of anaesthetic depth. Further evaluation of the BIS algorithm is required in neonates and infants.

Mechanical circulatory support for the treatment of children with acute fulminant myocarditis.

BACKGROUND: Viral myocarditis may follow a rapidly progressive and fatal course in children. Mechanical circulatory support may be a life-saving measure by allowing an interval for return of native ventricular function in the majority of these patients or by providing a bridge to transplantation in the remainder. METHODS: A retrospective chart review of 15 children with viral myocarditis supported with extracorporeal membrane oxygenation (12 patients) or ventricular assist devices (3 patients) was performed. RESULTS: All patients had histories and clinical findings consistent with acute myocarditis. The median age was 4.6 years (range 1 day-13.6 years) with a median duration of mechanical circulatory support of 140 hours (range 48-400 hours). Myocardial biopsy tissue demonstrated inflammatory infiltrates or necrosis, or both, in 8 (67%) of the 12 patients who had biopsies. Overall survival was 12 (80%) of 15 patients, with 10 (83%) survivors of extracorporeal membrane oxygenation and 2 (67%) survivors of ventricular assist device support. Nine (60%) of the 15 patients were weaned from support, with 7 (78%) survivors; the remaining 6 patients were successfully bridged to transplantation, with 5 (83%) survivors. All survivors not undergoing transplantation are currently alive with normal ventricular function after a median follow-up of 1.1 years (range 0.9-5.3 years). CONCLUSION: Eighty-percent of the children who required mechanical circulatory support for acute myocarditis survived in this series. Recovery of native ventricular function to allow weaning from support can be anticipated in many of these patients with excellent prospects for eventual recovery of full myocardial function.

Prediction of safe duration of hypothermic circulatory arrest by near-infrared spectroscopy.

OBJECTIVE: Hypothermic circulatory arrest is widely used for adults with aortic arch disease as well as for children with congenital heart disease. At present, no method exists for monitoring safe duration of circulatory arrest. Near-infrared spectroscopy is a new technique for noninvasive monitoring of cerebral oxygenation and energy state. In the current study, the relationship between near-infrared spectroscopy data and neurologic outcome was evaluated in a survival piglet model with hypothermic circulatory arrest. METHODS: Thirty-six piglets (9.36 +/- 0.16 kg) underwent circulatory arrest under varying conditions with continuous monitoring by near-infrared spectroscopy (temperature 15 degrees C or 25 degrees C, hematocrit value 20% or 30%, circulatory arrest time 60, 80, or 100 minutes). Each setting included 3 animals. Neurologic recovery was evaluated daily by neurologic deficit score and overall performance category. Brain was fixed in situ on postoperative day 4 and examined by histologic score. RESULTS: Oxygenated hemoglobin signal declined to a plateau (nadir) during circulatory arrest. Time to nadir was significantly shorter with lower hematocrit value (P <.001) and higher temperature (P <.01). Duration from reaching nadir until reperfusion ("oxygenated hemoglobin signal nadir time") was significantly related to histologic score (r (s) = 0.826), neurologic deficit score (r (s) = 0.717 on postoperative day 1; 0.716 on postoperative day 4), and overall performance category (r (s) = 0.642 on postoperative day 1; 0.702 on postoperative day 4) (P <.001). All animals in which oxygenated hemoglobin signal nadir time was less than 25 minutes were free of behavioral or histologic evidence of brain injury. CONCLUSION: Oxygenated hemoglobin signal nadir time determined by near-infrared spectroscopy monitoring is a useful predictor of safe duration of circulatory arrest. Safe duration of hypothermic circulatory arrest is strongly influenced by perfusate hematocrit value and temperature during circulatory arrest.

The differences in the bispectral index between infants and children during emergence from anesthesia after circumcision surgery.

UNLABELLED: The bispectral index (BIS) correlates with consciousness during adult anesthesia. In this prospective, blinded study of children (n = 24) and infants (n = 25) undergoing elective circumcision, we evaluated BIS and consciousness level during emergence from anesthesia. Anesthesia was maintained with sevoflurane, and a penile nerve block was performed in each patient before surgical stimulation. At the completion of surgery, the sevoflurane was decreased stepwise from 0.9% in increments of 0.2%, and arousal was tested with a uniform auditory stimulus given after a steady state of end-tidal sevoflurane concentration was achieved at each step. The BIS increased significantly as the sevoflurane concentrations decreased in children (0.9%, 62.5 +/- 8.1; 0.7%, 70.8 +/- 7.4; and 0.5%, 74.1 +/- 7.1; P < 0.001 for 0.7% and 0.5% compared with 0.9%), but a similar relationship was not demonstrated in infants. The BIS values at 0.7% and 0.5% sevoflurane were significantly higher in children than infants (P < 0.02 and P < 0.002, respectively). In both children and infants, the BIS increased significantly from pre- to postarousal (children, 73.5 +/- 7 to 83.1 +/- 12, P = 0.01; infants, 67.8 +/- 10 to 85.6 +/- 13.6, P < 0.001). The BIS at which arousal was possible with the stimulus tended to be higher in children than in infants (P = 0.06). IMPLICATIONS: In this study comparing the Bispectral index (BIS) in infants and children undergoing circumcision surgery by use of a standardized surgical and anesthetic technique, a significant decrease in BIS was detected in children during a stepwise decrease in end-tidal sevoflurane concentration. A similar relationship was not demonstrated in infants less than 1 yr old. In both children and infants, BIS increased significantly from pre- to postarousal. Additional studies are necessary to determine changes in BIS with maturational changes in the electroencephalogram.

Neonates with congenital heart disease.

Early reparative surgery in neonates and infants with congenital heart disease, as opposed to initial palliation and later repair, is now commonplace. Changes to the conduct of cardiopulmonary bypass, timing of surgery and surgical techniques, and perioperative management substantially have reduced the postoperative mortality and morbidity for these patients. The success of this strategy of early reparative surgery now has been extended to the premature and low-birth-weight newborn, and, along with this, new challenges to postoperative care in the intensive care unit. However, the low mortality associated with two-ventricle repairs has not been the experience in newborns undergoing palliation for single-ventricle defects, in particular, hypoplastic left heart syndrome. A number of articles regarding management of newborns with single-ventricle defects have been published during the past 12 months, ranging from classification, prenatal diagnosis, treatment options, and predictors of both early and late outcome, which may provide a guide for patient management. As mortality has declined, there has been an increased emphasis on identifying indices that may predict outcome or morbidity both before and after surgery, along with possible strategies to attenuate adverse clinical responses. The inflammatory response to bypass is heightened in neonates and infants, and several reports have addressed possible techniques for attenuating the response. In addition, reports regarding the risk for necrotizing enterocolitis, the utility of lactate as an index of systemic perfusion, potential markers of myocardial and neurologic injury, and the use of mechanical support of the circulation in newborns with congenital heart disease are summarized.

Stress response in infants undergoing cardiac surgery: a randomized study of fentanyl bolus, fentanyl infusion, and fentanyl-midazolam infusion.

UNLABELLED: There have been significant changes in the management of neonates and infants undergoing cardiac surgery in the past decade. We have evaluated in this prospective, randomized, double-blinded study the effect of large-dose fentanyl anesthesia, with or without midazolam, on stress responses and outcome. Forty-five patients < 6 mo of age received bolus fentanyl (Group 1), fentanyl by continuous infusion (Group 2), or fentanyl-midazolam infusion (Group 3). Epinephrine, norepinephrine, cortisol, adrenocortical hormone, glucose, and lactate were measured after the induction (T1), after sternotomy (T2), 15 min after initiating cardiopulmonary bypass (T3), at the end of surgery (T4), and after 24 h in the intensive care unit (T5). Plasma fentanyl concentrations were obtained at all time points except at T5. Within each group epinephrine, norepinephrine, cortisol, glucose and lactate levels were significantly larger at T4 (P values < 0.01), but there were no differences among groups. Within groups, fentanyl levels were significantly larger in Groups 2 and 3 (P < 0.001) at T4, and among groups, the fentanyl level was larger only at T2 in Group 1 compared with Groups 2 and 3 (P < 0.006). There were no deaths or postoperative complications, and no significant differences in duration of mechanical ventilation or intensive care unit or hospital stay. Fentanyl dosing strategies, with or without midazolam, do not prevent a hormonal or metabolic stress response in infants undergoing cardiac surgery. IMPLICATIONS: We demonstrated a significant endocrine stress response in infants with well compensated congenital cardiac disease undergoing cardiac surgery, but without adverse postoperative outcome. The use of large-dose fentanyl, with or without midazolam, with the intention of providing "stress free" anesthesia, does not appear to be an important determinant of early postoperative outcome.

Parameters associated with perioperative baffle fenestration closure in the Fontan operation.

OBJECTIVE: To identify clinical parameters indicating perioperative fenestration closure in children who underwent the fenestrated Fontan operation. DESIGN: Retrospective. SETTING: Single children's hospital. PARTICIPANTS: Patients who underwent a fenestrated Fontan operation in 1996 through 1997 (n = 101). INTERVENTION: A fenestrated Fontan operation was performed in children with single-ventricle physiology. MEASUREMENTS AND MAIN RESULTS: Early perioperative closure of the fenestration occurred in 14 patients (group 1), whereas the fenestration remained patent in 87 patients (group 2). The groups were compared by the following parameters: demographics, cardiac catheterization and ultrasound data, and use of aspirin or warfarin preoperatively and intraoperatively by assessing the composition of the cardiopulmonary bypass solution, use of ultrafiltration and antifibrinolytics, protamine dose, last hematocrit on cardiopulmonary bypass, and requirement of blood products. Immediately postoperatively in the intensive care unit (ICU), cardiac filling pressures (central venous and left atrial pressure), coagulation profile, cardiac rhythm, chest tube drainage, length of stay in the ICU, and use of atrial pacing were reviewed. Significant indicators of early fenestration closure in this study as determined by multivariate stepwise logistic regression were a high transpulmonary pressure gradient (p = 0.015) and a higher oxygen saturation (p = 0.001) 1 hour after arrival in the ICU, a low fibrinogen level (p < 0.0001), and the need for temporary atrial pacing (p = 0.029). The fenestration was reopened in 13 patients in group 1. In 101 patients, there was no early mortality, and all patients survived to discharge. CONCLUSION: Factors that correlated with postoperative fenestration closure in the fenestrated Fontan operation in this study were a high transpulmonary pressure gradient and a high oxygen saturation 1 hour after arrival in the ICU, a low fibrinogen level, and the need for temporary atrial pacing.

Intraoperative recurrent laryngeal nerve monitoring during video-assisted throracoscopic surgery for patent ductus arteriosus.

OBJECTIVE: To develop a technique to identify and localize the recurrent laryngeal nerve (RLN) during video-assisted thoracoscopic surgery (VATS) for patent ductus arteriosus. DESIGN: Prospective clinical study. SETTING: Children's hospital. PARTICIPANTS: Sixty infants and children scheduled for elective closure of patent ductus arteriosus. INTERVENTIONS: With parental informed consent, 60 infants and children undergoing elective VATS for patent ductus arteriosus were studied. A thin, pencil-point, Teflon-coated, stimulating probe allowed direct stimulation (<2 mA, 100-msec pulse width) of the left RLN inside the thorax. A commercially available 4-channel neurologic monitor recorded compound evoked electromyograms (EMGs) from the left RLN and right RLN (as control) by needle electrodes placed percutaneously in the neck. Hoarseness, stridor, feeding difficulties, and voice changes were assessed postoperatively. MEASUREMENTS AND MAIN RESULTS: Left RLN EMGs were easily obtained in 59 of the 60 patients. The surgeon correctly identified the RLN visually once in the first 7 patients; this ability subsequently improved. EMG localization of the location or course of the RLN altered dissection, clip size, or clip position in 37 of 59 patients. CONCLUSION: Intraoperative EMG to identify location and route of the RLN was easy to perform, was effective in identifying RLN position, and appeared to facilitate dissection and clipping of the ductus.

Whole blood ionized magnesium: age-related differences in normal values and clinical implications of ionized hypomagnesemia in patients undergoing surgery for congenital cardiac disease.

OBJECTIVES: We sought to (1) determine reference values for whole blood ionized magnesium concentrations in newborns, children, and young adults and (2) evaluate the frequency and clinical implications of ionized hypomagnesemia in patients undergoing surgery for congenital heart disease. METHOD: We prospectively measured ionized magnesium concentrations in 299 subjects (113 control subjects and 186 patients undergoing surgery for congenital heart disease). Subjects were categorized by age. In the surgical group blood samples were obtained before bypass, during bypass (cooling and rewarming), after bypass, and during admission to the intensive care unit. Ionized hypomagnesemia was defined as ionized magnesium level 2 standard deviations below the mean of control subjects in the same age group. Patients were analyzed, controlling for cardiopulmonary bypass time. RESULTS: In the control group ionized magnesium concentrations differed by age. Neonates and adults showed lower ionized magnesium concentrations compared with those of other age groups. Infants exhibited the highest ionized magnesium concentration. In the surgical group patients older than 1 month showed a higher proportion of ionized hypomagnesemia compared with that found in neonates at baseline (P <.001), after bypass (P =. 03), and at admission to the intensive care unit (P =.02). Controlling for cardiopulmonary bypass time, patients older than 1 month who were hypomagnesemic during bypass showed longer intubation time (P =.001) and longer intensive care stay (P =.01) and tended to have a higher pediatric severity of illness score on intensive care admission (P =.14) compared with patients without ionized hypomagnesemia. CONCLUSIONS: There are age-related differences in normal ionized magnesium concentrations. Ionized hypomagnesemia is a common and clinically relevant occurrence among patients older than 1 month of age undergoing surgery for congenital heart disease.

Postoperative recovery in children after minimum versus full-length sternotomy.

BACKGROUND: Minimal access incisions for pediatric cardiac surgery have been reported to hasten postoperative recovery. This prospective study compared recovery after a minimum versus full-length sternotomy for repair of atrial septal defects in children. METHODS: We studied 35 children undergoing atrial septal defect repair using a full-length sternotomy (n = 18) or ministernotomy (n = 17) according to the surgeon's preference. All children were managed according to an established clinical practice guideline. Intraoperative comparisons included patient demographics, bypass and cross-clamp times, and, as a measure of stress response, epinephrine, norepinephrine, and lactate levels at six time intervals throughout the surgical procedure. Postoperative comparisons included pain scores at 6, 12, and 24 hours, frequency of emesis, analgesic requirements, respiratory rate and gas exchange, and length of intensive care unit and total hospital stay. Nurse and parent assessment scores of overall recovery were constructed using visual analog and Likert scales. RESULTS: No significant differences between mini- versus full-length sternotomy were detected for the measured outcome variables. No adverse outcomes were detected. CONCLUSIONS: In this prospective study, a ministernotomy did not enhance postoperative recovery, and the primary advantage appears to be an improved cosmetic result.

Synchronized independent lung ventilation in palliated congenital heart disease with variable sources of pulmonary blood flow.

OBJECTIVE: Presentation of two patient studies demonstrating the use of synchronized independent lung ventilation in the management of acute respiratory failure in patients with complex palliated congenital heart disease and variable sources of pulmonary blood flow. DESIGN: Clinical course of two patients. SETTING: Cardiac intensive care unit in a tertiary care, university-affiliated pediatric teaching hospital. PATIENTS: Patient 1 was a 22-yr-old woman with a single ventricle and right lung blood flow supplied by a classic Glenn shunt and left lung blood flow through a systemic-to-pulmonary artery shunt. Patient 2 was a 12-yr-old boy with tetralogy of Fallot and complete common atrioventricular canal defect with right lung blood flow supplied by a classic Glenn shunt and left lung blood flow supplied by the right ventricle. Both patients presented with acute, left-sided lung disease and hypoxemia. INTERVENTIONS: We used selective bronchial intubation via a double-lumen tracheal tube with a bronchial extension for synchronized independent lung ventilation to permit high-pressure ventilation of the abnormal left lung low-pressure ventilation of the normal right lung supplied by a Glenn shunt. Inhaled nitric oxide was administered to both patients and continued in one when improved oxygenation was observed. MEASUREMENTS AND MAIN RESULTS: Serial arterial blood gas measurements, mechanical indices of pulmonary function, and chest radiographs were closely followed. Synchronized independent lung ventilation contributed to improvements in systemic arterial blood oxygenation and alveolar ventilation allowing resumption of conventional ventilation in both patients. No adverse effects related to bronchial tube placement or maintenance occurred. CONCLUSION: Independent lung ventilation is an effective means of isolating the two lungs for differential ventilation, as well as the selective delivery of inhaled medications. In patients with unilateral lung disease and a Glenn shunt supplying the unaffected lung, selective lung ventilation allows aggressive treatment of the abnormal lung while optimizing flow through the Glenn shunt to maximize effective pulmonary blood flow, systemic oxygenation, and hemodynamics.

Changes in whole blood lactate levels during cardiopulmonary bypass for surgery for congenital cardiac disease: an early indicator of morbidity and mortality.

OBJECTIVE: Our objective was to evaluate the change in lactate level during cardiopulmonary bypass and the possible predictive value in identifying patients at high risk of morbidity and mortality after surgery for congenital cardiac disease. METHODS: We prospectively studied lactate levels in 174 nonconsecutive patients undergoing cardiopulmonary bypass during operations for congenital cardiac disease. Arterial blood samples were taken before cardiopulmonary bypass, during cardiopulmonary bypass (cooling and rewarming), after cardiopulmonary bypass, and during admission to the cardiac intensive care unit. Complicated outcomes were defined as open sternum as a response to cardiopulmonary instability, renal failure, cardiac arrest and resuscitation, extracorporeal membrane oxygenation, and death. RESULTS: The largest increment in lactate level occurred during cardiopulmonary bypass. Lactate levels decreased between the postbypass period and on admission to the intensive care unit. Patients who had circulatory arrest exhibited higher lactate levels at all time points. Nonsurvivors had higher lactate levels at all time points. A change in lactate level of more than 3 mmol/L during cardiopulmonary bypass had the optimal sensitivity (82%) and specificity (80%) for mortality, although the positive predictive value was low. CONCLUSIONS: Hyperlactatemia occurs during cardiopulmonary bypass in patients undergoing operations for congenital cardiac disease and may be an early indicator for postoperative morbidity and mortality.

The effect of hematocrit on cerebral blood flow velocity in neonates and infants undergoing deep hypothermic cardiopulmonary bypass.

UNLABELLED: Varying degrees of hemodilution are used during deep hypothermic cardiopulmonary bypass. However, the optimal hematocrit (Hct) level to ensure adequate oxygen delivery without impairing microcirculatory flow is not known. In this prospective, randomized study, cerebral blood flow velocity in the middle cerebral artery was measured using transcranial Doppler sonography in 35 neonates and infants undergoing surgery with deep hypothermic cardiopulmonary bypass. Patients were randomized to low Hct (aiming for 20%) or high Hct (aiming for 30%) during cooling on cardiopulmonary bypass (CPB). Systolic (V(s)), mean (Vm), and diastolic (Vd) cerebral blood flow velocity, as well as pulsatility index (PI = [V(s) - Vd]/Vm) and resistance index (RI = [V(s) - Vd]/V(s)) were recorded at six time points: postinduction, at cannulation, after 10 min cooling on CPB, rewarmed to 35 degrees C on CPB, immediately off CPB, and at skin closure. Vm was significantly lower in the high Hct group compared with that in the low Hct group during cooling (P < 0.01). Postinduction, the high Hct group demonstrated significantly lower Vd immediately off CPB (P < 0.01) and significantly lower Vm and V(s) at skin closure (P < 0.001). We conclude that there is an inverse relation between hematocrit and cerebral blood flow velocity during deep hypothermic cardiopulmonary bypass in neonates and infants. IMPLICATIONS: There is an inverse relation between hematocrit and cerebral blood flow velocity during deep hypothermic cardiopulmonary bypass in neonates and infants. Further studies correlating Hct and cerebral blood flow velocity with cerebral metabolic rate and neurologic outcome are necessary to determine the optimal Hct during deep hypothermic cardiopulmonary bypass.

A novel sialyl Lewis X analog attenuates cerebral injury after deep hypothermic circulatory arrest.

BACKGROUND: The initial step in the inflammatory process, which can be initiated by cardiopulmonary bypass and by ischemia/reperfusion, is mediated by interactions between selectins on endothelial cells and on neutrophils. We studied the effects of selectin blockade using a novel Sialyl Lewis X analog (CY-1503) on recovery after deep hypothermic circulatory arrest in a piglet model. METHODS: Twelve Yorkshire piglets were subjected to cardiopulmonary bypass, 30 minutes of cooling, 100 minutes of circulatory arrest at 15 degrees C, and 40 minutes of rewarming. Five animals received a bolus of 60 mg/kg of CY-1503 and an infusion (3 mg/kg per hour) for 24 hours from reperfusion (group O), and 7 randomly selected control piglets received saline solution (group C). Body weight and total body water content were evaluated 3 hours and 24 hours after reperfusion by a bio-impedance technique. Neurologic recovery of animals was evaluated daily by neurologic deficit score (0 = normal, 500 = brain death) and overall performance categories (1 = normal, 5 = brain death). The brain was fixed in situ on the fourth postoperative day and examined by histologic score (0 = normal, 5+ = necrosis) in a blinded fashion. RESULTS: Two of 7 animals in group C died. The neurologic deficit score was significantly lower in group O than in group C (postoperative day 1, P <.001; postoperative day 2, P =.02). The overall performance category was significantly lower in group O than in group C on postoperative day 2 (P =.01). Percentage total body water after cardiopulmonary bypass was significantly higher in group C than in group O (P =.03). Histologic score tended to be higher in group C than in group O, but this difference did not reach statistical significance (group O = 0.5 +/- 0.7; group C = 1.3 +/- 1.off CONCLUSION: Blockade of selectin adhesion molecules by saturation with a Sialyl Lewisx analog accelerates recovery after 100 minutes of deep hypothermic circulatory arrest in a piglet survival model.

Mechanical circulatory support in children with cardiac disease.

OBJECTIVE: To review the experience from a single center that uses both extracorporeal membrane oxygenation and ventricular assist devices for children with cardiac disease requiring mechanical circulatory support. METHODS: A retrospective chart review was performed for all pediatric patients with cardiac disease who required support with extracorporeal membrane oxygenation or ventricular assist devices. Statistical analysis of the impact of multiple clinical parameters on survival was performed. RESULTS: From 1987 through 1996 we provided mechanical circulatory support for children with a primary cardiac diagnosis using extracorporeal membrane oxygenation (67 patients) and ventricular assist devices (29 patients). Twenty-seven of 67 (40.3%) patients supported with extracorporeal membrane oxygenation and 12 of 29 (41.4%) patients supported with ventricular assist devices survived to hospital discharge. Failure of return of ventricular function within 72 hours of the institution of support was an ominous sign in patients supported with either modality. Univariate analysis revealed the serum pH at 24 hours of support, the serum bicarbonate at 24 hours of support, the urine output over the first 24 hours of support, and the development of renal failure to have a statistically significant association with survival in children supported with extracorporeal membrane oxygenation. None of the clinical parameters evaluated by univariate analysis were significantly associated with survival in the patients supported with ventricular assist devices. CONCLUSIONS: Extracorporeal membrane oxygenation and ventricular assist devices represent complementary modalities of mechanical circulatory support that can both be used effectively in children with cardiac disease.

Postischemic hyperthermia exacerbates neurologic injury after deep hypothermic circulatory arrest.

BACKGROUND: Aggressive surface warming is a common practice in the pediatric intensive care unit. However, recent rodent data emphasize the protective effect of mild (2 degrees - 3 degrees C) hypothermia after cerebral ischemia. This study evaluates different temperature regulation strategies after deep hypothermic circulatory arrest with a survival piglet model. METHODS: Fifteen piglets were randomly assigned to 3 groups. All groups underwent 100 minutes of deep hypothermic circulatory arrest at 15 degrees C. Brain temperature was maintained at 34 degrees C for 24 hours after cardiopulmonary bypass in group I, 37 degrees C in group II, and 40 degrees C in group III. Neurobehavioral recovery was evaluated daily for 3 days after extubation by neurologic deficit score (0, normal; 500, brain death) and overall performance category (1, normal; 5, brain death). Histologic examination was assessed for hypoxic-ischemic injury (0, normal; 5, necrosis) in a blinded fashion. RESULTS: All results are expressed as mean +/- standard deviation. Recovery of neurologic deficit score (12.0 +/- 17.8, 47.0 +/- 49.95, 191.0 +/- 179.83; P = .05 for group I vs III), overall performance category (1.0 +/- 0.0, 1.4 +/- 0.6, 2.8 +/- 1.3; P < .05 for group I vs III), and histologic scores (0.0 +/- 0.0, 1.0 +/- 1.2, 2.8 +/- 1.8; P < .05 for group I vs III cortex) were significantly worse in hyperthermic group III. These findings were associated with a significantly lower cytochrome aa3 recovery determined by near-infrared spectroscopy in group III animals (P = .0041 for group I vs III). No animal recovered to baseline electroencephalographic value by 48 hours after deep hypothermic circulatory arrest. Recovery was significantly delayed in the hyperthermic group III animals, with a lower amplitude 14 hours after the operation, which gradually increased with time (P < .05 for group III vs groups I and II). CONCLUSIONS: Mild postischemic hyperthermia significantly exacerbates functional and structural neurologic injury after deep hypothermic circulatory arrest and should therefore be avoided.