Objective To investigate whether changes in cardiac function and cerebral blood flow (CBF) precede the occurrence of peri/intraventricular hemorrhage (P/IVH) in extremely preterm infants. Study ...design In this prospective observational study, 22 preterm infants (gestational age 25.9 ± 1.2 weeks; range 23-27 weeks) were monitored between 4 and 76 hours after birth. Cardiac function and changes in CBF and P/IVH were assessed by ultrasound every 12 hours. Changes in CBF were also followed by continuous monitoring of cerebral regional oxygen saturation (rSO2 ) and by calculating cerebral fractional oxygen extraction. Results Five patients developed P/IVH (1 patient grade II and 4 patients grade IV). Whereas measures of cardiac function and CBF remained unchanged in neonates without P/IVH, patients with P/IVH tended to have lower left ventricular output and had lower left ventricle stroke volume and cerebral rSO2 and higher cerebral fractional oxygen extraction during the first 12 hours of the study. By 28 hours, these variables were similar in the 2 groups and myocardial performance index was lower and middle cerebral artery mean flow velocity higher in the P/IVH group. P/IVH was detected after these changes occurred. Conclusions Cardiac function and CBF remain stable in very preterm neonates who do not develop P/IVH during the first 3 postnatal days. In very preterm neonates developing P/IVH during this period, lower systemic perfusion and CBF followed by an increase in these variables precede the development of P/IVH. Monitoring cardiac function and cerebral rSO2 may identify infants at higher risk for developing P/IVH before the bleeding occurs.
A solid understanding of the mechanisms of action of cardiovascular medications used in clinical practice along with efforts to develop comprehensive hemodynamic monitoring systems to improve the ...ability to accurately identify the underlying pathophysiology of cardiovascular compromise are essential in the management of neonates with shock. This article reviews the mechanisms of action of the most frequently used cardiovascular medications in neonates. Because of paucity of data from controlled clinical trials, evidence-based recommendations for the clinical use of these medications could not be made. Careful titration of the given medication with close monitoring of the cardiovascular response might improve the effectiveness and decrease the risks associated with administration of these medications.
Objective To characterize the changes in systemic hemodynamics and systolic, diastolic, and global myocardial performance after patent ductus arteriosus (PDA) ligation in very-low-birth-weight ...infants. Study design Echocardiograms were performed on 23 neonates (mean gestational age, 26.2 ± 2.2 weeks) at 2.3 ± 2.0 hours before PDA ligation (n = 23) and at 2.0 ± 1.4 hours (n = 23) and 23.5 ± 2.5 hours after (n = 11) PDA ligation. Results Mean blood pressure, heart rate, load-independent contractility, shortening fraction, left ventricular (LV) afterload, and diastolic function did not change. Preload (early and atrial mitral inflow velocities) decreased immediately after ligation but remained unchanged thereafter. LV output decreased and systemic vascular resistance increased after surgery. The LV myocardial performance index (MPI), a measure of global myocardial performance, deteriorated acutely after ligation but improved by 23.5 hours after surgery. Changes in LV MPI were most closely correlated with changes in LV output. Conclusions After PDA ligation, LV output and MPI decrease, due primarily to a decrease in LV preload, although LV contractility and diastolic function do not change. However, the changes in LV MPI after ligation also reflect an acute deterioration followed by an improvement in global cardiac function, because LV loading conditions remained unchanged after surgery and thus cannot explain the improvement in MPI by 24 hours after ligation.
Objective The purpose of this study was to determine risk factors for poor cognitive performance among children who are treated with in utero selective laser photocoagulation of communicating vessels ...for twin-twin transfusion syndrome. Study Design This was a prospectively enrolled cohort study. Cognitive performance at age 2 years (±6 weeks) was assessed with the Battelle Developmental Inventory 2nd Edition (BDI-2). Multilevel regression models evaluated risk factors for poor cognitive performance at shared (pregnancy) and individual (child) levels. In addition to development, blindness, deafness, and cerebral palsy were assessed based on physical examination. A priori power analysis determined that a sample of ≥100 children was required for adequate statistical power (0.80). Results One hundred children (57 families) were evaluated. Total BDI-2 score was within normal range (mean, 101.3 ± SD12.2); 1 child had a BDI-2 score of <70. Individual child-level risk factors for lower BDI-2 included male sex (β = –0.37; P < .01), lower head circumference (β = 0.28; P < .01), and higher diastolic blood pressure (β = –0.29; P < .01). At the pregnancy level, lower maternal education (β = 0.60; P < .001), higher Quintero stage (β = –0.36; P < .01), and lower gestational age at birth (β = 0.30; P < .01) were associated with worse cognitive outcomes. Donor/recipient status, gestational age at surgery, fetal growth restriction, and co-twin fetal death were not risk factors. The rate of neurodevelopmental impairment (blindness, deafness, cerebral palsy, and/or a BDI-2 score <70) was 4%. Conclusion Overall cognitive performance quotients were in the normal range, with risk factors for poor outcomes seen at the pregnancy and child levels. Clinical and socioeconomic characteristics can identify at-risk children who need additional interventions.
Little is known about the effect on clinically relevant outcomes of the complex hemodynamic changes occurring during adaptation to extrauterine life in preterm neonates, particularly in very low ...birth weight neonates. As cardiovascular adaptation in this extremely vulnerable patient population is complicated by immaturity of all organ systems, especially that of the cardiorespiratory, central nervous, and endocrine systems, maladaptation has been suspected, but not necessarily proven, to contribute to mortality and long-term morbidities. This article describes recent advances in the understanding of hemodynamic changes in very low birth weight neonates during postnatal transition, and reviews the complex and developmentally regulated interaction between systemic and cerebral hemodynamics and the effect of this interaction on clinically relevant outcomes.
Objective To noninvasively determine brain temperature of neonates with hypoxic-ischemic encephalopathy (HIE) during and after therapeutic hypothermia. Study design Using a phantom, we derived a ...calibration curve to calculate brain temperature based on chemical shift differences in magnetic resonance spectroscopy. We enrolled infants admitted for therapeutic hypothermia and assigned them to a moderate HIE (M-HIE) or severe HIE (S-HIE) group based on Sarnat staging. Rectal (core) temperature and magnetic resonance spectroscopy data used to derive regional brain temperatures (basal ganglia, thalamus, and cortical gray matter) were acquired concomitantly during and after therapeutic hypothermia. We compared brain and rectal temperature in the M-HIE and S-HIE groups during and after therapeutic hypothermia using 2-tailed t -tests. Results Eighteen patients (14 with M-HIE and 4 with S-HIE) were enrolled. As expected, both brain and rectal temperatures were lower during therapeutic hypothermia than after therapeutic hypothermia. Brain temperature in patients with S-HIE was higher than in those with M-HIE both during (35.1 ± 1.3°C vs 33.7 ± 1.2°C; P < .01) and after therapeutic hypothermia (38.1 ± 1.5°C vs 36.8 ± 1.3°C; P < .01). The brain–rectal temperature gradient was also greater in the S-HIE group both during and after therapeutic hypothermia. Conclusion For this analysis of a small number of patients, brain temperature and brain–rectal temperature gradient were higher in neonates with S-HIE than in those with M-HIE during and after therapeutic hypothermia. Further studies are needed to determine whether further decreasing brain temperature in neonates with S-HIE is safe and effective in improving outcome.
Objective To investigate the effect of pH on cardiac function and systemic vascular resistance (SVR) in preterm infants. Study design In this prospective observational study, we evaluated ...hemodynamically stable, ≤30 weeks' gestation preterm infants during the first 2 postnatal weeks. Cardiac function was assessed by echocardiography at the time of arterial blood draw for clinically indicated blood gas analysis. Data were separately analyzed for the transitional (days 1-3) and post-transitional (days 4-14) periods. Results We evaluated 147 pairs of arterial blood gases and echocardiograms in 29 preterm neonates (gestational age = 26.2 ± 1.5 weeks). Arterial pH ranged from 7.02-7.46. There was no linear relationship between pH and shortening fraction or stress-velocity index in transitional or post-transitional periods. We found a weak negative linear relationship between pH and left ventricular output and a positive linear relationship between pH and SVR only during the post-transitional period. These relationships were maintained after adjustment for the degree of base deficit. Arterial CO2 had effects similar to pH on myocardial function. Conclusions Unlike adults, myocardial contractility remains relatively unaffected by acidosis even at pH values close to 7.00 in hemodynamically stable preterm neonates during the first 2 postnatal weeks. However, as in adults, worsening acidosis in preterm neonates after the immediate transitional period is associated with a decrease in SVR along with an increase in left ventricular output. Thus, although myocardial contractility remains unaffected in preterm neonates during the first 2 postnatal weeks, the vascular response to acidosis undergoes a relatively rapid postnatal maturational process.
PDF