Sodium bicarbonate causes dose-dependent increases in cerebral blood flow in infants and children with single-ventricle physiology.

BACKGROUND: Sodium bicarbonate (NaHCO3) is a common treatment for metabolic acidemia; however, little definitive information exists regarding its treatment efficacy and cerebral hemodynamic effects. This pilot observational study quantifies relative changes in cerebral blood flow (ΔrCBF) and oxy- and deoxyhemoglobin concentrations (ΔHbO2 and ΔHb) due to bolus administration of NaHCO3 in patients with mild base deficits. METHODS: Infants and children with hypoplastic left heart syndrome (HLHS) were enrolled before cardiac surgery. NaHCO3 was given as needed for treatment of base deficit. Diffuse optical spectroscopies were used for 15 min postinjection to noninvasively monitor ΔHb, ΔHbO2, and ΔrCBF relative to baseline before NaHCO3 administration. RESULTS: Twenty-two anesthetized and mechanically ventilated patients with HLHS (aged 1 d to 4 y) received a median (interquartile range) dose of 1.1 (0.8, 1.8) mEq/kg NaHCO3 administered intravenously over 10-20 s to treat a median (interquartile range) base deficit of -4 (-6, -3) mEq/l. NaHCO3 caused significant dose-dependent increases in ΔrCBF; however, population-averaged ΔHb and ΔHbO2 as compared with those of controls were not significant. CONCLUSIONS: Dose-dependent increases in cerebral blood flow (CBF) caused by bolus administration of NaHCO3 are an important consideration in vulnerable populations wherein risk of rapid CBF fluctuations does not outweigh the benefit of treating a base deficit.

Anesthesia and postoperative analgesia in pediatric patients undergoing cardiac surgery.

Pediatric cardiac anesthesiologists care for patients ranging from premature infants weighing <2 kg to adults requiring surgical intervention for congenital heart disease. Along with their cardiac pathophysiologies, many of these patients also have other co-existing diseases that can affect their anesthetic management. Recent advances in monitoring include non-invasive neuromonitors, such as near-infrared spectroscopy and trans-cranial Doppler, which are assuming increasing importance in intraoperative management, particularly during cardiopulmonary bypass. A variety of anesthetic techniques, including regional anesthesia, can be used to facilitate early extubation in older infants and children with stable postoperative hemodynamics. In addition to regional anesthesia, other modalities for the management of postoperative pain include opioid infusions in critically ill children and the use of patient- or nurse-controlled analgesia pumps. Multiple pain assessment tools are available for children of varying ages and developmental levels to assist in providing appropriate postoperative pain management.

Increasing cumulative exposure to volatile anesthetic agents is associated with poorer neurodevelopmental outcomes in children with hypoplastic left heart syndrome.

OBJECTIVES: Despite improved survival in children with hypoplastic left heart syndrome (HLHS), significant concern persists regarding their neurodevelopmental (ND) outcomes. Previous studies have identified patient factors, such as prematurity and genetic syndromes, to be associated with worse ND outcomes. However, no consistent relationships have been identified among modifiable management factors, including cardiopulmonary bypass strategies, and ND outcomes after cardiac surgery in infancy. Studies in immature animals, including primates, have demonstrated neurodegeneration and apoptosis in the brain after certain levels and extended durations of anesthetic exposure. Retrospective human studies have also suggested relationships between adverse ND effects and anesthetic exposure. METHODS: Cumulative minimum alveolar concentration hours (MAC-hrs) of exposure to volatile anesthetic agents (VAA) (desflurane, halothane, isoflurane, and sevoflurane) were collected from an anesthetic database and medical record review for 96 patients with HLHS or variants. ND testing was performed between ages 4 and 5 years, including full-scale IQ, verbal IQ, performance IQ, and processing speed. Four generalized linear modes were hypothesized a priori and tested using a Gaussian (normal) distribution with an identity link. RESULTS: Cumulative VAA exposure ranged from 0 to 35.3 MAC-hrs (median 7.5 hours). Using specified covariates identified previously as significant predictors of ND outcomes, statistically significant relationships were identified between total MAC-hrs exposure and worse full-scale IQ and verbal IQ scores (P's < .05) alone and after adjusting for relevant covariates. CONCLUSIONS: Increased cumulative MAC-hrs exposure to VAA is associated with worse ND outcomes in certain domains in children with HLHS and variants.

Usefulness of real-time navigator magnetic resonance imaging for evaluating coronary artery origins in pediatric patients.

Navigator coronary magnetic resonance imaging (MRI) was evaluated in assessing coronary artery origins in a pediatric and adolescent population. Sixty-five consecutive infants, children, or adolescents (age range 11 days to 21 years) were referred for MRI evaluations to assess coronary artery origins. Coronary artery origins were unambiguously delineated in 62 of 65 patients. In 3 patients, irregular arrhythmias precluded cardiac gating of the magnetic resonance acquisition. Two patients had anomalous coronary artery origins detected. Twenty-six patients required sedation for the studies. Free-breathing 3-dimensional MRI with real-time navigator correction is a robust method for delineating the coronary artery origins in pediatric and adolescent patients.

Sternal wall pressure comparable to leaning during CPR impacts intrathoracic pressure and haemodynamics in anaesthetized children during cardiac catheterization.

AIM: Force due to leaning during cardiopulmonary resuscitation (CPR) negatively affects haemodynamics and intrathoracic airway pressures (ITP) in animal models and adults, but has not been studied in children. We sought to characterize the effects of sternal force (SF) comparable to leaning force on haemodynamics and ITP in anaesthetized children. METHODS: Children (6 months to 8yrs) presenting for routine haemodynamic cardiac catheterization with anaesthesia and mechanical ventilation >6 months after cardiac transplant were studied. Haemodynamics and ITP were measured before and during incremental increases in SF of 10% and 20% body weight. RESULTS: 20 subjects (5.4±1.7yrs of age and 18.3±3.3kg) were studied. Mean right atrial pressure (6.5±2.6 at baseline vs. 7.7±2.6 at 10% SF vs. 8.6±2.7mmHg at 20% SF), mean pulmonary capillary wedge pressure (10.2±2.9 at baseline vs. 11±3.3 at 10% SF vs. 11.8±3.4mmHg at 20% SF) and ITP (16.3±3.2 at baseline vs. 17.9±3.9 at 10% SF vs. 19.5±4cm H2O) all increased significantly with incremental SF (p<0.001 for all). Aortic systolic pressure (85±10mmHg at baseline vs. 83±10mmHg at 10% SF vs. 82±10mmHg at 20% SF, p=0.014) and coronary perfusion pressure (42±7mmHg at baseline vs. 39±7mmHg at 10% SF vs. 38±7mmHg at 20% SF, p<0.001) both decreased significantly with incremental SF. CONCLUSIONS: In asymptomatic, anaesthetized children after cardiac transplantation, sternal forces comparable to leaning previously reported to occur during CPR elevate ITP and right atrial pressure and decrease coronary perfusion pressure. These haemodynamic effects may be clinically important during CPR and warrant further study.

Cardiac magnetic resonance and the need for routine cardiac catheterization in single ventricle patients prior to Fontan: a comparison of 3 groups: pre-Fontan CMR versus cath evaluation.

OBJECTIVES: This study investigated whether cardiac magnetic resonance (CMR) and echocardiography (echo) can replace catheterization (cath) for routine evaluation prior to Fontan and under what circumstances CMR and cath are used together. BACKGROUND: Routine cath prior to Fontan has been utilized for years; noninvasive methods, however, may be sufficient. METHODS: This study reviews clinical data in 119 consecutive patients investigating 3 groups: those who underwent CMR alone (MR; n = 41), cath alone (C; n = 41), or both cath and CMR (C+M; n = 37) prior to Fontan. RESULTS: No clinically significant differences were noted in patient characteristics, hemodynamics, or clinical status prior to or after surgery between the C and MR groups. CMR added information in 82%. There were no discrepant findings between CMR and cath data in the C+M group. Diagnostic success was ≥95% in all groups. Of those undergoing Fontan completion, the C+M group had similar outcomes to C and MR; C and CMR were utilized in combination to assess aortopulmonary collaterals or the need for an intervention or evaluate its success. Echo could not delineate pulmonary arterial anatomy in 46% to 53% of patients. The C+M and C groups were exposed to 6.8 ± 4.1 mSv of radiation. CONCLUSIONS: Single ventricle patients not requiring an intervention can undergo successful Fontan completion with CMR and echo alone with similar short-term outcomes to C, which was used as a control, preventing an invasive test and exposure to radiation. CMR can add information in a significant number of patients. Cath and CMR are utilized together for interventions and assessment of aortopulmonary collaterals.

Validation of diffuse correlation spectroscopic measurement of cerebral blood flow using phase-encoded velocity mapping magnetic resonance imaging.

Diffuse correlation spectroscopy (DCS) is a novel optical technique that appears to be an excellent tool for assessing cerebral blood flow in a continuous and non-invasive manner at the bedside. We present new clinical validation of the DCS methodology by demonstrating strong agreement between DCS indices of relative cerebral blood flow and indices based on phase-encoded velocity mapping magnetic resonance imaging (VENC MRI) of relative blood flow in the jugular veins and superior vena cava. Data were acquired from 46 children with single ventricle cardiac lesions during a hypercapnia intervention. Significant increases in cerebral blood flow, measured both by DCS and by VENC MRI, as well as significant increases in oxyhemoglobin concentration, and total hemoglobin concentration, were observed during hypercapnia. Comparison of blood flow changes measured by VENC MRI in the jugular veins and by DCS revealed a strong linear relationship, R=0.88, p<0.001, slope=0.91±0.07. Similar correlations were observed between DCS and VENC MRI in the superior vena cava, R=0.77, slope=0.99±0.12, p<0.001. The relationship between VENC MRI in the aorta and DCS, a negative control, was weakly correlated, R=0.46, slope=1.77±0.45, p<0.001.

Sedating the child with congenital heart disease.

The number of pediatric patients requiring sedation for procedures performed outside the operating room environment continues to grow yearly, as does the number of patients surviving to adulthood with the residua and sequelae of congenital heart disease. Ongoing efforts to develop guidelines to enhance the safety of these pediatric sedative encounters have resulted in great strides in the prevention of adverse events. In addition, the Society for Pediatric Sedation, associated with the Pediatric Sedation Research Consortium, provides an important forum for practitioner education and the promotion of safe care for infants and children undergoing sedative experiences. Care of the subset of patients with congenital heart disease or pulmonary hypertension remains especially demanding. The additional safety challenges posed by remote locations make the highest level of vigilance essential when planning and performing sedation for these children.

Extubation in the operating room after Fontan's procedure: effect on practice and outcomes.

BACKGROUND: Timely extubation is a well-accepted strategy in the postoperative intensive care unit management of Fontan patients to minimize the deleterious effects of positive-pressure ventilation. In October 2002, this strategy was extended to extubating selective Fontan patients in the operating room (EOR). This retrospective study examines how EOR has affected outcomes and practice in our Fontan population. METHODS: Between October 2002 and June 2006, 112 patients underwent primary Fontan procedures; 38 (34%) were EOR and 74 (66%) were non-EOR. These two cohorts were not different (p < 0.05) in age, weight, surgery time, dominant ventricular morphology, hypoplastic left heart syndrome, prior bidirectional Glenn, concomitant procedures, atrioventricular valve regurgitation, and ventricular function. Analysis of variance was used to compare mean pulmonary artery pressure, mean arterial blood pressure, and mean common atrial pressure as a function of time. RESULTS: During the first 12 hours postoperatively, mean pulmonary artery pressure and mean common atrial pressure were significantly lower and mean arterial blood pressure was significantly higher in the EOR group than the non-EOR group (p < 0.05). No EOR patient required reintubation. Mean durations of inotropic agents (1.1 versus 2.4 days), chest tubes (5.8 versus 7.2 days), intensive care unit stay (3 versus 4.7 days), and hospital stay (8.6 versus 11.3 days) for EOR patients were shorter than for non-EOR patients (p < 0.05). Intensive care unit and hospital costs for EOR patients were 35% and 31% lower, respectively, than for non-EOR patients (p < 0.05). Kaplan-Meier survival for EOR patients (3 years, 100%) was not different (p = 0.3) than for non-EOR patients (1 and 3 years, 96%). CONCLUSIONS: After the Fontan procedure, selective EOR can be performed safely and improves postoperative hemodynamics, decreases hospital resource utilization, and reduces hospital recovery time.

Survey of the use of peripherally inserted central venous catheters in neonates with critical congenital cardiac disease.

Neonates with congenital cardiac disease are a special population. They are often critically ill, and need prolonged intravenous access. To date, no study has evaluated the efficacy and safety of peripherally inserted central venous catheters placed in this unique population. Our goal was to evaluate the use of such catheters in neonates with critical congenital cardiac disease, and to study features such as duration of use, reasons for removal of catheters, and complications. We inserted a total of 124 catheters in 115 neonates with critical congenital cardiac disease who were admitted to the Intensive Care Unit at Texas Children's Hospital from August 2002 to August 2004. The patients had a mean age of 10 days, and a mean weight of 3.1 kilograms. The peripherally inserted catheters were in place for a mean of 22.3 days. Therapy was completed in 76.6% patients at the time of removal of the catheter. The incidence of occlusion, dislodgement, and thrombus was 4.0%, 2.4%, and 1.6%, respectively. The infection rate was 3.6 per 1000 catheter-days, with a median onset on 37 days after placement. We conclude that central venous catheters, when inserted peripherally, provide reliable and safe access for prolonged intravenous therapy in neonates with critical congenital cardiac disease.

Bilateral monitoring of cerebral oxygen saturation results in recognition of aortic cannula malposition during pediatric congenital heart surgery.

Congenital heart surgery is associated with a 2-25% reported incidence of neurological complication. Near-infrared spectroscopy (NIRS) can detect changes in regional cerebral saturation index (rSO2i) during cardiac surgery. If rSO2i decreases significantly, treatment algorithms are used to restore baseline values, potentially avoiding neurological complications. The efficacy of bilateral NIRS monitoring in pediatric congenital heart surgery has been debated. We report a case in which bilateral NIRS monitoring detected an abrupt decrease in rSO2i (right greater than left) after initiation of bypass without abnormalities detected by standard monitors. This resulted in prompt surgical intervention that restored rSO2i, potentially preventing neurological injury.

New developments in pediatric cardiac anesthesia.

As the practice of pediatric cardiac anesthesia continues to grow, anesthesiologists now routinely care for patients ranging in size from less than 2 kg to more than 100 kg. New clinical and laboratory research has enhanced our understanding of the effects of anesthetic drugs on the pediatric myocardium, and improvements in survival statistics for even the smallest and sickest infants have shifted the emphasis to evaluation of quality of life and neurological outcome in pediatric cardiac patients. The use of circulatory support in infants and children, both for rapid resuscitation and for more chronic indications such as bridge to transplantation, also continues to evolve, with the recent introduction of pulsatile and axial pumps for pediatric use. This article reviews anesthetic agents, bleeding and coagulation, neurological monitoring, and mechanical circulatory support in the treatment of infants and children.

Tracheoesophageal fistula and associated congenital heart disease: implications for anesthetic management and survival.

BACKGROUND: Infants with tracheoesophageal fistula (TEF) and/or esophageal atresia (EA) frequently have other associated congenital anomalies which can have a significant impact on their anesthetic care and survival to discharge. METHODS: A medical record review and retrospective data analysis were performed in a university affiliated children's hospital of all infants undergoing TEF/EA repair between January 1998 and July 2004. The incidence of intraoperative complications during the TEF repair and overall survival to hospital discharge was compared in two groups of infants: 26 patients with TEF/EA and coexisting congenital heart disease (CHD), and 27 patients with TEF/EA and no CHD. RESULTS: The overall incidence of intraoperative critical events during repair of TEF/EA was significantly higher in infants with associated cardiac pathology (P = 0.003). Six of 53 infants died during hospitalization (overall mortality, 11.3%) and all had associated cardiac pathology. In comparison with nonductal-dependent lesions, the presence of a ductal-dependent cardiac lesion appeared to significantly increase patient mortality (57% vs. 10%, P = 0.028). CONCLUSIONS: Low birth weight (<1500 g) and associated cardiac pathology were found to be independent predictors of mortality in infants undergoing surgery for TEF/EA repair. The presence of a ductal-dependent cardiac lesion further increased the risk of morbidity and mortality, in addition to necessitating special anesthesia considerations.

Hemodynamic response to caudal epidural clonidine in a pediatric cardiac patient.

IMPLICATIONS: Postoperative management of sedation and analgesia in pediatric cardiac patients presents many challenges. This case report describes a child who experienced dramatic clinical improvement with the postoperative use of caudal morphine and clonidine after conventional therapy had failed.

Neurological monitoring for congenital heart surgery.

The incidence of neurological complications after pediatric cardiac surgery ranges from 2% to 25%. The causes are multifactorial and include preoperative brain malformations, perioperative hypoxemia and low cardiac output states, sequelae of cardiopulmonary bypass, and deep hypothermic circulatory arrest. Neurological monitoring devices are readily available and the anesthesiologist can now monitor the brain during pediatric cardiac surgery. In this review we discuss near-infrared cerebral oximetry, transcranial Doppler ultrasound, and electroencephalographic monitors for use during congenital heart surgery. After review of the basic principles of each monitoring modality, we discuss their uses during pediatric heart surgery. We present evidence that multimodal neurological monitoring in conjunction with a treatment algorithm may improve neurological outcome for patients undergoing congenital heart surgery and present one such algorithm.

Is bilateral monitoring of cerebral oxygen saturation necessary during neonatal aortic arch reconstruction?

UNLABELLED: In this study, we measured cerebral oxygenation in both cerebral hemispheres by using near-infrared spectroscopy before, during, and after regional low-flow cerebral perfusion (RLFP) to determine whether bilateral monitoring was necessary. Neonates undergoing aortic arch reconstruction with RLFP were studied. The bilateral regional cerebral oxygenation index was measured and recorded at 1-min intervals during the following periods: 1) before bypass, 2) during bypass before RLFP, 3) during RLFP, 4) on bypass after RLFP, and 5) post-bypass. Before bypass and on bypass before RLFP, the correlation (r = 0.979 and 0.852) and agreement (mean bias, right versus left, 0 and +2) between hemispheres were excellent. During RLFP, however, correlation (r = 0.35) and agreement (mean bias of the right versus left side, +6.3) worsened and only partially returned to baseline values after RLFP. Nine of 19 patients had sustained differences in cerebral oxygen saturation of >10%, always with the left side values less than the right. Bilateral monitoring detects desaturation in the left cerebral hemisphere during RLFP. The long-term consequences of lower saturations on the left side of the brain are unclear. IMPLICATIONS: Left-sided cerebral hemisphere oxygen saturation, measured with near-infrared spectroscopy, was less than right-sided cerebral oxygen saturation during regional low-flow cerebral perfusion used for neonatal aortic arch reconstruction.

Changes in respiratory mechanics among infants undergoing heart surgery.

UNLABELLED: Children with excessive pulmonary blood flow (PBF) from congenital heart disease have abnormal respiratory mechanics. Exposure to hypothermic cardiopulmonary bypass (CPB) adversely affects lung function. We designed this study of 106 patients to determine the changes in respiratory mechanics in infants younger than 1 yr undergoing heart surgery. Dynamic respiratory compliance (Cdyn) and total respiratory resistance (Rrs) were measured before surgical incision, after sternal closure in the operating room, and after arrival in the intensive care unit. The following data were recorded: age, weight, preoperative pulmonary infiltrates, preoperative mechanical ventilation, evidence of increased PBF before surgery, duration of CPB, duration of aortic cross-clamp, duration of deep hypothermic circulatory arrest, use of steroids, and volume of ultrafiltrate removed. Repeated-measures analysis of variance with covariate analysis was used to determine the effect of each covariate on Cdyn and Rrs at the three time periods. Rrs improved after cardiac surgery correcting increases in PBF, and this was most pronounced in neonates. Among infants with normal or reduced PBF, cardiac surgery with CPB led to a reduction in Cdyn. We consider that the benefits of surgical correction of pulmonary overcirculation outweigh the negative effects of CPB on respiratory mechanics. IMPLICATIONS: The benefits of surgical correction of pulmonary overcirculation outweigh the negative effects of cardiopulmonary bypass on respiratory mechanics in infants.