Search

INTRODUCTION Simulators are increasingly used for training in echocardiography. However, there is no objective method to assess the skills acquired. Our objective was to develop and test an automated method to assess echocardiography skills. METHODS To automate the image quality evaluation, we expanded our previously developed neonatal echocardiography simulator to enable recording of images of the 26 standard cuts and process the image quality. We then compared the automated and visual methods in scoring image quality of the echocardiograms obtained by 22 trainees. RESULTS Each echocardiographic image representing a slice of a three-dimensional volume possesses 3 axes (X, Y, and Z) that correspond to the roll, pitch, and yaw angles of the transducer, respectively. Therefore, if the placement and orientation of the transducer are correct, the acquired image represents the appropriate cardiac window with the desired orientation in all 3 axes. The automated system gives a score of 0 if the transducer is not in the appropriate cardiac window. A score of 1, 2, or 3 is given if the image falls within the range of one, two, or three angles, respectively. There was no difference in the image quality score between automated and visual assessment methods (46.0 ± 13.0 vs 45.1 ± 14.4, P = .19). The two methods had excellent correlation (r = .95). The bias and precision were 0.9 and 8.8, respectively. CONCLUSIONS The automated method is comparable to visual method for assessment of image quality. The automated process allows for instantaneous feedback and has the potential to standardize assessment of echocardiography skills of trainees.

Objective The objective of this study was to test the hypothesis that simulation training improves echocardiography skills. Study Design In this prospective study, 43 participants (16 neonatologists, 26 neonatology fellows, and 1 nurse practitioner) were tested on the simulator after 4 hours of didactic sessions on topographical cardiac anatomy and standard echocardiographic views. Participants were given 20 minutes to obtain and save the standard views. After the simulation hands-on training for 8 hours over 3 days, they were tested again. Each image was scored from 0 to 3 based on the image quality. Pre- and postsimulator training data were compared using both automated and visual scoring methods. Results After the hands-on simulator training, the automated median (interquartile) score for the quality of acquired images increased from 36 (22, 43) to 55 (48, 58), p Conclusions Echocardiography simulation is an effective tool in improving echocardiography skills among neonatology care providers. Key Points

Background Nitric oxide (NO) plays an important role in normal postnatal transition. Our aims were to determine whether adding inhaled NO (iNO) decreases supplemental oxygen exposure in preterm infants requiring positive pressure ventilation (PPV) during resuscitation and to study iNO effects on heart rate (HR), oxygen saturation (SpO2), and need for intubation during the first 20 min of life. Methods This was a pilot, double-blind, randomized, placebo-controlled trial. Infants 25 0/7–31 6/7 weeks’ gestational age requiring PPV with supplemental oxygen during resuscitation were enrolled. PPV was initiated with either oxygen (FiO2–0.30) + iNO at 20 ppm (iNO group) or oxygen (FiO2–0.30) + nitrogen (placebo group). Oxygen was titrated targeting defined SpO2 per current guidelines. After 10 min, iNO/nitrogen was weaned stepwise per protocol and terminated at 17 min. Results Twenty-eight infants were studied (14 per group). The mean gestational age in both groups was similar. Cumulative FiO2 and rate of exposure to high FiO2 (>0.60) were significantly lower in the iNO group. There were no differences in HR, SpO2, and need for intubation. Conclusions Administration of iNO as an adjunct during neonatal resuscitation is feasible without side effects. It diminishes exposure to high levels of supplemental oxygen.

Several limitations and controversies surround the definition of hypotension; however, it remains one of the most common problems faced by neonates. Approximately 15% to 30% of neonates with hypotension fail to respond to volume and/or vasopressor or inotropes. They are considered to have refractory hypotension. Although it is thought to have multiple causes, absolute and relative adrenal insufficiency is considered as the main reason for refractory hypotension. This article focuses on the role of adrenal insufficiency in causing refractory hypotension in preterm and term infants, the different options of corticosteroids available, and their risk/benefit profiles.

Ischemia followed by reperfusion plays a significant role in the pathogenesis of peri/intraventricular hemorrhage (P/IVH). Delayed cord clamping promotes placental transfusion to newborn and is associated with decreased P/IVH. We hypothesized that extremely low birth weight (ELBW) infants with higher initial hematocrit (Hct) after birth are less likely to develop P/IVH. Pre- and postnatal data on inborn ELBW infants over 7 years were reviewed. We examined the relationship between P/IVH in the first week and initial Hct using logistic regression modeling. We studied 225 infants with a median gestational age (GA) 25.7 (22.4–31.7). Forty-one percent had grade I–IV P/IVH. In univariate analysis, cesarean section (CS) and higher GA, birth weight, 5-minute Apgar, and initial Hct were associated with decreased likelihood of P/IVH while higher maximum PCO2 in first 3 days and use of inotropes/vasopressors, postnatal steroid for hypotension, hypernatremia, transfusion, and use of insulin for hyperglycemia during the first week of life were associated with increased likelihood of P/IVH. In multiple regression analysis, only GA, CS, and initial Hct remained significantly associated with P/IVH. Adjusting for GA and CS, the odds of P/IVH was higher with Hct

Although patent ductus arteriosus is essential in fetal life, interventions to close or minimize the adverse hemodynamic effects associated with the left-to-right shunt are often needed after birth, especially in extremely premature infants. However, there are clinical conditions where maintaining patency of the ductus is essential for survival. In this article we discuss use of prostaglandin E1 in the management of congenital heart defects, pulmonary hypertension and left ventricular failure in early neonatal period.

There is a great need for training in pediatric echocardiography. In addition to physicians being trained in pediatric cardiology and echocardiography technologists, neonatologist, pediatric intensivists, and other health care professionals may be interested in such training. Since, there is limited opportunity of training on live patients, echocardiographic simulators may be of help. No simulator with complete range of echocardiographic modalities is available for neonates and infants. The aim of this project was to develop a mannequin-based echocardiographic simulator capable of simulating full range of pediatric 2D, color flow Doppler, spectral Doppler, and M-mode echocardiograms. A mannequin, a laptop computer, a magnetic tracking device, and a six-degree freedom (6DOF) sensor incorporated in a dummy transducer serve as the hardware platform of the simulator. We obtained six to seven 4D echocardiographic datasets in DICOM format through five acoustic windows from each infant along with a complete set of 2D video clips of color flow, Doppler, and M-mode. The 4D datasets are sliced into 3D slices using the visualization toolkit and are displayed as 2D echocardiograms through the information obtained by the 6DOF sensor. The coordinates from specific 3D slices triggers display of video clips of color flow, M-mode, and Doppler echocardiogram. Software written in C++ programming language controls the basic function of the program. The main simulator screen displays the full range of 2D echocardiograms including color flow Doppler, spectral Doppler, and M-mode from each acoustic window, whereas the side screen display the position and motion of the cutting planes through a 3D heart model. The system includes a software module to perform hemodynamic measurements from specific video clips images. Our hybrid, mannequin-based pediatric echocardiography simulator provides full range of pediatric echocardiography training experience. This simulator may help training in pediatric echocardiography for which there is a growing demand in clinical medicine., We present the design and validation of an echocardiographic simulator (the Virtual Echocardiographic Training System, or VETS) for teaching basic skills for transthoracic echocardiography of pediatric patients, especially neonates and infants.

Objective To investigate the changes in systemic and cerebral haemodynamics between supine and prone sleep in healthy term infants during the early postnatal period. Design/methods Healthy term infants without congenital anomalies, patent ductus arteriosus and/or small for gestational age status were enrolled. Infants were placed in supine (SP 1 ), prone (PP) and back in supine (SP 2 ) position for 15 min each while asleep. Cardiac output (CO) and stroke volume (SV) were assessed by electrical velocimetry (EV) and echocardiography (echo), and cerebral regional oxygen saturation (CrSO 2 ) in the frontal lobes was monitored by near-infrared spectroscopy. Heart rate (HR) and SpO 2 were continuously monitored by conventional monitoring. Results In 34 healthy term infants (mean age 3.7±1.2 days; 16 females), 66 sets of serial CO measurements (34 EV and 32 echo) in three sleep positions were obtained. Mean CO EV and CO echo were 182±57 (SP 1 ), 170±50 (PP) and 177±54 (SP 2 ), and 193±48 (SP 1 ), 174±40 (PP) and 192±50 (SP 2 ) mL/kg/min, respectively. Mean SV EV and SV echo were 1.46±0.47 (SP 1 ), 1.36±0.38 (PP) and 1.37±0.39 (SP 2 ), and 1.54±40 (SP 1 ), 1.38±0.38 (PP) and 1.51±0.41 (SP 2 ) mL/kg, respectively. Repeated measures analysis of variance revealed a decrease in CO and SV during prone positions by both EV and echo, while HR, SpO 2 and CrSO 2 did not change. Thirty-eight per cent of the CO measurements decreased ≥10% during prone positioning. Conclusions In healthy term infants, CO decreases in prone position due to a decrease in SV and not HR. CO recovers when placed back in supine. However, frontal lobe CrSO 2 does not change in the different positions.

Transition from fetal to postnatal life is a complex process. Even in the absence of congenital heart disease, about 4–10% of newborns require some form of assistance in the delivery room. Neonates with complex congenital heart disease should be expected to require significant intervention and thus the resuscitation team must be well prepared for such a delivery. Prenatal assessment including fetal and maternal health in general and detailed information on fetal heart structure, function and hemodynamics in particular are crucial for planning the delivery and resuscitation. In addition, understanding the impact of cardiac structural anomaly and associated altered blood flow on early postnatal transition is essential for success of resuscitation in the delivery room. In this article, we will briefly review transitional circulation focusing on altered hemodynamics of the complex congenital heart diseases and then discuss the process of preparing for these high-risk deliveries. Finally, we will review the pathophysiology resulting from the cardiac structural anomaly with resultant altered fetal circulation and discuss delivery room management of specific critical congenital heart diseases.

To characterize the effects of a patent ductus arteriosus (PDA) on different organ blood flows in infants born preterm.Infants born preterm at ≤30 weeks of gestational age had daily echocardiography and Doppler assessments of middle cerebral artery, celiac artery, superior mesenteric (SMA), and renal arteries (RA) during the first postnatal week. Abnormal organ blood flow was defined as either reverse or absent diastolic flow, abnormally low mean or systolic velocities, or abnormally high pulsatility or resistance index.Twenty-five infants born very preterm (gestational age 27.0 ± 2.1 weeks) were enrolled. PDA presence at time of measurement increased the risk of abnormal organ blood flows (39% vs 8%, P .001). Ductal diameter and left atrium-to-aortic root (LA/Ao) ratio correlated positively with resistance index (celiac artery, SMA, RA), and negatively with mean velocity (ductal diameter: SMA, RA; LA/Ao ratio: RA). A PDA2.0 mm, LA/Ao ratio1.4, and their combination were associated with 8.0 (95% CI 1.6-39.4)-, 6.7 (1.3-34.7)-, and 38.2 (3.2-455.5)-fold increase in risk of abnormal organ blood flow index, respectively. Abnormal descending aorta flow was detected in only 2% of measurements.Ductal size2.0 mm and LA/Ao1.4, especially in combination, are associated with a greater risk of abnormal organ blood flows. We suggest that Doppler assessment of the renal and superior mesenteric arteries are more likely to detect systemic hypoperfusion than the descending aorta.

In the PDA-TOLERATE trial, persistent (even for several weeks) moderate to large patent ductus arteriosus (PDA) was not associated with an increased risk of BPD when the infant required

ObjectiveTo compare early routine pharmacologic treatment of moderate-to-large patent ductus arteriosus (PDA) at the end of week 1 with a conservative approach that requires prespecified respiratory and hemodynamic criteria before treatment can be given.Study designA total of 202 neonates of

Respiratory insufficiency and the resultant need for ventilatory support can have a significant impact on cardiovascular function. Similarly, cardiac dysfunction may adversely affect lung function. Compared with older children and adults, newborn infants are more vulnerable to the deleterious effects of these interactions. This increased vulnerability is due not only to immaturity of the cardiovascular and respiratory systems but also secondarily to the rapid transformation starting at birth, from fetal to adult-type circulation and from fluid-filled lungs to an air-filled organ of gas exchange. Furthermore, because of the immaturity of other organs, especially the brain, the consequence of the impaired respiratory and cardiovascular function can be particularly devastating. To minimize the impact of mechanical ventilation on cardiovascular function, optimal pressure for given lung compliance should be used. Both inappropriately high and low airway pressure are associated with adverse hemodynamic effects, including a reduction in left and right ventricular output, a decrease in venous return, and an increase in pulmonary vascular resistance. In addition to the direct effects of ventilator settings on the cardiovascular system, common treatment strategies, such as administration of surfactant, tolerating ductal patency, and the degree of permissive hypercapnia and acidosis can affect the respiratory and cardiovascular function.

Although a patent ductus arteriosus (PDA) can easily be visualized using ultrasound, the challenge is in differentiating a hemodynamically significant and potentially harmful ductus arteriosus from one which does not significantly affect the hemodynamics and therefore does not contribute to organ injury. Selection of the “right” PDA to treat is particularly important in this era when management of PDA has become even more controversial. Over the past decade, there has been an increased recognition of the need to better define the PDA that requires treatment and as such different classifications and scoring tools have been proposed. Attention to certain variables such as gestational and chronologic age, associated morbidities, and subpopulation characteristics with regard to the risk of complications attributable to the PDA can be helpful in the diagnosis of a pathologic PDA and subsequent selection for treatment.

There is growing controversy in the field of neonatal hemodynamics about the diagnosis and treatment of neonatal cardiovascular compromise in the very preterm infant. Accordingly, fundamental questions such as the timely recognition of the subpopulation of neonates at high risk for the development of hemodynamic compromise in the transitional period, the definition of individual patient-dependent blood pressure (BP) thresholds associated with inadequate tissue oxygen delivery (DO2), the role of physiologic cord clamping, the recognition of the hemodynamic antecedents of peri-intraventricular hemorrhage, and other related issues are yet to be answered. In the absence of such information, applying the principles of developmental cardiovascular physiology and pathophysiology can help in establishing the diagnosis and determining the optimal management of neonatal circulatory compromise. The past two decades have seen a growing controversy in the field of neonatal hemodynamics in general and over the diagnosis and treatment of neonatal cardiovascular insufficiency especially in the very preterm infant. The complexities and difficulties associated with the design and execution of randomized controlled trials (RCTs) targeting clinically relevant outcome measures in very preterm neonates with cardiovascular compromise are the primary reasons for the ongoing controversy. Indeed, questions such as the BP threshold associated with inadequate tissue DO2 and thus necessitating treatment in a selected patient population can be answered only by properly designed RCTs. In the absence of such information, applying the principles of developmental cardiovascular physiology and pathophysiology can aid the diagnosis and management of neonatal circulatory compromise. In addition, designing RCTs in this area also requires a thorough understanding of developmental cardiovascular physiology. Therefore this chapter first reviews the principles of fetal, transitional, and posttransitional hemodynamics, with an emphasis on the principles of developmental cardiovascular physiology. Building on the physiologic principles reviewed, the second part of the chapter then discusses the etiology and pathophysiology of neonatal cardiovascular compromise. The major goals of this chapter are to help the reader to appreciate the impact of immaturity and/or pathologic events on the physiology of neonatal cardiovascular transition and understand the primary factors leading to cardiovascular compromise in the preterm and term neonate. Using this knowledge, along with carefully selected and relevant information from clinical trials, the clinician can best assess and manage hemodynamic disturbance in the immediate transitional period and beyond and potentially reduce the end-organ damage caused by decreased DO2 to the organs, especially the immature brain in affected neonates.

Objective There is no consensus on the definition of a hemodynamically significant patent ductus arteriosus (hsPDA). In this review article, our objective is to discuss the main variables that one should consider when determining the hemodynamic significance of a PDA. Results We describe the various approaches that have been utilized over time to define an hsPDA and discuss the strengths and weaknesses of each echocardiographic index. Finally, we propose a comprehensive and individualized approach in determining the hemodynamic significance of the PDA. Conclusion There are several PDA-related clinical, echocardiographic, and other objective variables to take into consideration when defining an hsPDA. However, vulnerability based on gestational or chronological age is an important contributor as well.

Novel hemodynamic monitoring technologies have contributed to the understanding of developmental cardiovascular physiology and pathophysiology in general, and of developmental hemodynamics in particular. Hemodynamic disturbances play a significant role in the pathogenesis of peri/intraventricular hemorrhage (P/IVH) in preterm infants. Immaturity of the myocardium, delayed and incomplete cardiopulmonary transition, sustained patency of the ductus arteriosus, and unintended consequences of respiratory and cardiovascular supportive care are all likely to be involved in the presentation of low cardiac output syndrome and decreased organ blood flow in a large number of very preterm neonates (gestational age ≤28 weeks). Forebrain vessels in very preterm infants may not have achieved a "high-priority vasculature" status at the time of delivery; in these patients, forebrain perfusion is not protected during the compensated phase of shock. Reperfusion may be attenuated by the careful use of medications decreasing cerebrovascular reactivity, thus providing a potential target for the development of careful pharmacological support of transitional hemodynamics in selected patients at high risk for the development of P/IVH.

With the advances in biomedical research and neonatal intensive care, our understanding of cardiovascular developmental physiology and pathophysiology has significantly improved during the last few decades. Despite this progress, the current management of circulatory compromise depends primarily on experts' opinions rather than high level of evidence. The lack of reliable, accurate, continuous and preferably non-invasive monitoring techniques has further limited our ability to collect the information needed for the design and execution of more sophisticated clinical trials with a better chance to provide the evidence we need. Given the lack of randomized, placebo-controlled trials investigating clinically relevant outcomes of novel treatments of neonatal cardiovascular compromise, we must now use the available lower level of evidence and our present understanding of developmental physiology and pathophysiology when providing cardiovascular supportive care to critically ill neonates. However, with recent advances in cardiovascular monitoring capabilities, direct and more objective assessment of the changes in cardiovascular function, organ blood flow, and tissue oxygenation have become possible. These advances have helped in our clinical assessment and enabled us to start designing more sophisticated interventional clinical trials using clinically relevant endpoints.

Point-of-care ultrasonography (POCUS) is becoming increasingly available for neonatologists and pediatric subspecialists (PSS); however, concerns over potential litigation from possible missed diagnoses or incorrect management have been documented. This study aims to define the extent and quality of lawsuits filed against neonatologists and PSS related to POCUS.We conducted a retrospective study of all United States reported state and federal cases in the Westlaw database from January 1990 through October 2015. Cases were reviewed and included if either a neonatologist or PSS were accused of misconduct or the interpretation or failure to perform an ultrasound/echocardiogram was discussed. Descriptive statistics were used to evaluate the data.Our search criteria returned 468 results; 2 cases were determined to be relevant to the study objective. The two cases alleged a failure to perform a diagnostic test and implicated POCUS as an option. There were no cases of neonatologists and PSS being sued for POCUS performance or interpretation.This study of a major legal database suggests that POCUS use and interpretation is not a significant cause of lawsuits against neonatologists and PSS.

• It is difficult to diagnose neonatal shock in its uncompensated phase during the immediate transitional period, while it is even more challenging to diagnose it in its compensated phase with use of a standard clinical monitoring and clinical approach. • It is unclear what gestational age– and postnatal age–dependent blood pressure and systemic and organ blood flow values represent hypotension and poor tissue perfusion respectively warranting timely intervention in the neonate. In addition, there is still some uncertainty about which cardiovascular medication or combination of medications to use in neonatal shock with different causes (hypovolemia, myocardial dysfunction, vasoregulatory disturbance, or a combination of two or all of these factors). • There is very little evidence that management of neonatal hypotension and/or systemic blood flow affects clinically relevant outcomes. • A thorough understanding of the principles of developmental cardiovascular physiology and the cause, pathophysiology, and clinical presentation of neonatal shock along with the mechanisms of action and the pharmacokinetics and pharmacodynamics of the medications used in the treatment of cardiovascular compromise is essential for the neonatologist to apply the most reasonable approach to treatment of neonatal cardiovascular compromise on the basis of the collective experience and little evidence available in the literature. • Recent advances in bedside monitoring technologies such as near-infrared spectroscopy, electrical impedance velocimetry, heart rate variability–based early warning systems, and amplitude-integrated electroencephalogram (EEG) along with the use of point-of-care ultrasonography will enable us to systematically and more thoroughly study neonatal circulatory compromise. These developments, along with the introduction and mathematical modeling of genotypic and phenotypic markers that identify subpopulations at higher risk of developing shock before it happens, will undoubtedly lead to earlier diagnosis and evidence-based management of neonatal shock, resulting in improved short-term and long-term outcomes.

To evaluate the cardiovascular response to short-term prone positioning in neonates.In this prospective study, we continuously monitored heart rate (HR), stroke volume (SV) and cardiac output (CO) by electrical velocimetry in hemodynamically stable neonates in each of the following positions for 10 min: supine, prone and back-to-supine position. Skin blood flow (SBF) was also continuously assessed on the forehead or foot using Laser Doppler technology. Systemic vascular resistance (SVR) index was calculated as mean blood pressure (BP)/CO. Data were analyzed using repeated measures analysis of variance.Thirty neonates (gestational age: 35±4 weeks; postmenstrual age: 36±3 weeks) were enrolled. HR did not change in response to positioning. However, in prone position, SV, CO and SBF decreased and SVR index increased from 1.5±0.3 to 1.3±0.3 ml kg(-1) (mean ±s.d., P0.01), 206±44 to 180±41 ml kg(-1) min(-1) (P0.01), 0.54±0.30 to 0.44±0.29 perfusion units (P0.01) and 0.25±0.06 to 0.30±0.07 mm Hg ml(-1) kg(-1) min(-1) (P0.01), respectively. After placing the infants back-to-supine position, SV, CO, SBF and SVR index returned to baseline. The above pattern of cardiovascular changes was consistent in vast majority of the studied neonates.Short-term prone positioning is associated with decreased SV, CO and SBF and increased calculated SVR index.

We performed a multicenter study of preterm infants, who were about to undergo patent ductus arteriosus ligation, to determine whether echocardiographic indices of impaired myocardial performance were associated with subsequent development of catecholamine-resistant hypotension following ligation.A standardized treatment approach for hypotension was followed at each center. Infants were considered to have catecholamine-resistant hypotension if their dopamine infusion was15 μg kg(-1)min(-1). Echocardiograms and cortisol measurements were obtained between 6 and 14 h after the ligation (prior to the presence of catecholamine-resistant hypotension).Forty-five infants were enrolled, 10 received catecholamines (6 were catecholamine-responsive and 4 developed catecholamine-resistant hypotension). Catecholamine-resistant hypotension was not associated with decreased preload, shortening fraction or ventricular output. Infants with catecholamine-resistant hypotension had significantly lower levels of systemic vascular resistance and postoperative cortisol concentration.We speculate that low cortisol levels and impaired vascular tone may have a more important role than impaired cardiac performance in post-ligation catecholamine-resistant hypotension.

Aim High arterial carbon dioxide (PaCO2) and cerebral reperfusion are associated with peri/intraventricular haemorrhage. Our aim was to study the relationship between PaCO2 and cerebral blood flow (CBF) in preterm infants during postnatal transition. Methods We prospectively studied ≤30 weeks' gestation haemodynamically stable preterm infants during the first three postnatal days (n = 21; gestational age 25.8 ± 1.4 weeks). We measured middle cerebral artery mean flow velocity (MCA-MV) as a surrogate for CBF at the time of blood gas analysis. Results We obtained 78 PaCO2–MCA-MV data pairs. The expected positive linear relationship between PaCO2 and MCA-MV was absent on the first postnatal day, equivocal on the second and present on the third. Using piecewise bilinear regression models, we identified PaCO2 breakpoints at 52.7 and 51.0 mmHg for postnatal days two and three, respectively. Conclusion In haemodynamically stable preterm neonates, the expected positive linear relationship between PaCO2 and CBF may be absent on postnatal day one. On postnatal day three, and possibly day two, a PaCO2 threshold exists for this relationship, above which CBF becomes reactive to PaCO2. We speculate that the enhanced CBF response to PaCO2 above the threshold contributes to the reperfusion injury and partly explains the association between hypercapnia and peri/intraventricular haemorrhage.

Positive pressure ventilation can significantly alter hemodynamics. The reduction in systemic venous return and increase in right ventricular afterload in response to an inappropriately high mean airway pressure can decrease pulmonary blood flow and compromise systemic perfusion as a result. In addition to ventilator parameters, the degree of hemodynamic effects depends on the baseline cardiac function and lung compliance. Furthermore, the chronically ventilated infants often have a multitude of comorbidities which may also impact hemodynamics. These include pulmonary and systemic hypertension which can lead to myocardial dysfunction as a result of the increase in the right and left ventricular afterload, respectively. In this section, we aim to outline the hemodynamic changes associated with chronic lung disease and mechanical ventilation and discuss management options.

Objective Electrical velocimetry (EV) is a noninvasive method of continuous left cardiac output monitoring based on measurement of thoracic electrical bioimpedance. The objective was to validate EV by investigating the agreement in cardiac output measurements performed by EV and echocardiography. Design In this prospective observational study, left ventricular output (LVO) was simultaneously measured by EV (LVO ev ) using Aesculon and by echocardiography (LVO echo ) in healthy term neonates during the fi rst 2 postnatal days. To determine the agreement between the two methods, we calculated the bias (mean difference) and precision (1.96◊SD of the difference). As LVO echo has its own limitations, the authors also calculated the ‘true precision’ of EV adjusted for echocardiography as the reference method. Results The authors performed 115 paired measurements in 20 neonates. LVO ev and LVO echo were similar (534±105 vs 538±105 ml/min, p=0.7). The bias and precision of EV were 4 and 234 ml/min, respectively. The authors found the true precision of EV to be similar to the precision of echocardiography (31.6% vs 30%, respectively). There was no difference in bias and precision between the measurements obtained in patients with or without a haemodynamically signifi cant patent ductus arteriosus. Conclusions EV is as accurate in measuring LVO as echocardiography and the variation in the agreement between EV and echocardiography among the individual subjects refl ects the limitations of both techniques.

Objective To describe cardiac function, cerebral regional oxygen saturation (rSO 2 ), and cerebral blood flow (CBF) that correspond to changes in arterial oxygen saturation (SaO 2 ) in normal term neonates immediately after birth and after the transition. Study design In this prospective observational study, cardiac function and cerebral hemodynamics were assessed by echocardiography and Doppler ultrasonography 3 times during the first 20 minutes after vaginal delivery, then again at 24-48 hours after delivery. Cerebral rSO 2 (by near-infrared spectroscopy) and preductal SaO 2 (by pulse oximetry) were assessed continuously. Results In 20 neonates, SaO 2 increased progressively from 65% at 1 minute after birth to 97% at 17 minutes after birth. Cerebral rSO 2 increased from 47% at 1 minute to 83% at 8 minutes, then decreased progressively to 73% at 20 minutes. Middle cerebral artery mean velocity decreased from 34 cm/s at 7 minutes to 25 cm/s at 14 minutes. The patent ductus arteriosus (PDA) shunt was balanced at 5 minutes but became increasingly left to right. Left ventricular stroke volume was increased. Middle cerebral artery mean velocity demonstrated an inverse relationship with the PDA shunt. Further hemodynamic changes were noted on the posttransitional assessment. Conclusion After birth, ductal shunting rapidly changes from balanced to left to right, with a responsive increase in left ventricular stroke volume. Cerebral rSO 2 increases as SaO 2 rises during the first 8 minutes, subsequently, it decreases due to a drop in CBF and despite a further increase in SaO 2 . The reduction in CBF is likely due to an increase in arterial O 2 content, PDA shunting, or both.

To characterize preterm infants that demonstrates respiratory improvement 7 days after ligation of a patent ductus arteriosus (PDA).We performed a 2-phase study of preterm infants (birthweight1500 g between 2010 and 2016). We first did a retrospective analysis using regression modeling of ligation population. We then performed a case-control study comparing a ligation group with infants matched by gestational age, postnatal age, and preligation respiratory condition (ventilator mode, mean airway pressure [MAP], and fraction of inspired oxygen [FiOForty-five (42%) of 107 preterm infants (gestational age 25.5 ± 1.7 weeks) with ligation showed respiratory improvement at 7 days. Infants on high frequency ventilation (HFV) were more likely to have respiratory improvement (aOR 5.03, 95% CI [1.14-22.18]). In matched-control analysis of 89 pairs, there was no difference in respiratory improvement. Among infants on HFV, the ligation group had an increase in MAP during 3 days prior to ligation. For infants on conventional ventilation, the ligation group had higher MAP and FiOAmong infants undergoing PDA ligation, those on HFV were more likely to have respiratory improvement in the first week, possibly because of the prevention of further respiratory deterioration. For infants on conventional ventilation, ligation was associated with higher respiratory support in the immediate postligation period without respiratory benefits at 7 days. As HFV was used as a rescue mode, our findings suggest that those with worse lung disease may achieve greater short term benefit from PDA ligation.

Objective To delineate the systemic and cerebral hemodynamic response to incremental increases in core temperature during the rewarming phase of therapeutic hypothermia in neonatal hypoxic-ischemic encephalopathy (HIE). Study design Continuous hemodynamic data, including heart rate (HR), mean arterial blood pressure (MBP), cardiac output by electrical velocimetry (COEV), arterial oxygen saturation, and renal (RrSO2) and cerebral (CrSO2) regional tissue oxygen saturation, were collected from 4 hours before the start of rewarming to 1 hour after the completion of rewarming. Serial echocardiography and transcranial Doppler were performed at 3 hours and 1 hour before the start of rewarming (T-3 and T-1; “baseline”) and at 2, 4, and 7 hours after the start of rewarming (T+2, T+4, and T+7; “rewarming”) to determine Cardiac output by echocardiography (COecho), stroke volume, fractional shortening, and middle cerebral artery (MCA) flow velocity indices. Repeated-measures analysis of variance was used for statistical analysis. Results Twenty infants with HIE were enrolled (mean gestational age, 38.8 ± 2 weeks; mean birth weight, 3346 ± 695 g). During rewarming, HR, COecho, and COEV increased from baseline to T+7, and MBP decreased. Despite an increase in fractional shortening, stroke volume remained unchanged. RrSO2 increased, and renal fractional oxygen extraction (FOE) decreased. MCA peak systolic flow velocity increased. There were no changes in CrSO2 or cerebral FOE. Conclusions In neonates with HIE, CO significantly increases throughout rewarming. This is due to an increase in HR rather than stroke volume and is associated with an increase in renal blood flow. The lack of change in cerebral tissue oxygen saturation and extraction, in conjunction with an increase in MCA peak systolic velocity, suggests that cerebral flow metabolism coupling remained intact during rewarming.

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.

Postnatal increase in oxygen promotes constriction of the patent ductus arteriosus (PDA). According to the findings of prospective observational studies, the clinical practice of targeting lower fractional oxygen saturation between 70 and 90% has been associated with a reduced incidence of severe retinopathy of prematurity (ROP) without affecting survival or neurodevelopmental disability at 1 year of age. Our objective was to investigate the impact of the use of a lower oxygen saturation target range on the incidence of early hemodynamically significant PDA (hsPDA) and the need for ductal ligation in extremely low birth weight (ELBW

OBJECTIVE. Because the standard of care has been to attempt to close the patent ductus arteriosus in preterm neonates, there is a paucity of information on the outcome of patients with a persistent patent ductus arteriosus. Our objective was to compare the mortality of preterm infants with and without a persistent patent ductus arteriosus. METHODS. This was a single-center, retrospective study. Very preterm infants (birth weight ≤ 1500 g and gestational age ≤ 29 weeks) who survived beyond the first 3 postnatal days and did not undergo surgical ligation were included in the primary analysis. Mortality of neonates with a persistent and a closed patent ductus arteriosus was compared during the initial hospitalization by using the χ2 test. Cox proportional hazard regression and logistic regression were used to take into account the time until death and assess the independent effect of each risk factor on mortality. We also performed 3 secondary analyses by excluding patients who died during the first 7 and 14 postnatal days and including patients who underwent surgical ligation by using different group assignments. A persistent patent ductus arteriosus was defined as a failure of either spontaneous or pharmacologic ductal closure during the initial hospitalization. RESULTS. Patients with a persistent patent ductus arteriosus (n = 41) had lower birth weight and were less mature than those with a closed ductus (n = 260). Unadjusted mortality rate was higher in patients with a persistent (70.7%) than with a closed (11.2%) ductus. After adjustment for perinatal factors, level of maturity, disease severity, and morbid pathologies, the hazard for death in neonates with a persistent ductus was eightfold higher than in those with a closed ductus. Exclusion of patients who died during the first 2 weeks or inclusion of those who underwent ductal ligation did not change the findings. CONCLUSION. Failure of ductal closure is associated with an increase in mortality in very preterm infants.

The transition of the fetus at birth to extrauterine life is an extremely complex process. As part of the hemodynamic transition, the closure of ductus arteriosus, a fetal shunt, is among the key steps to achieve normal postnatal cardiovascular function. However, significant gaps remain in our knowledge pertaining to the hemodynamics of normal ductal closure, and in case of failure of closure, to the hemodynamic consequences and treatment of the patent ductus arteriosus (PDA) in preterm infants. This paper presents a mathematical model of a newborn's cardiovascular system with five peripheral organ systems, the ductus arteriosus, and the baroreceptor reflex. We present the hemodynamic findings during simulation of sudden ductal closure, an event seen in real life when the PDA is closed surgically. The results of our model match the clinical data.

By continuous assessment of dynamic changes in systemic and regional perfusion during transition to extrauterine life and beyond, comprehensive neonatal hemodynamic monitoring creates numerous opportunities for both clinical and research applications. In particular, it has the potential of providing additional details about physiologic interactions among the key hemodynamic factors regulating systemic blood flow and blood flow distribution along with the subtle changes that are frequently transient in nature and would not be detected without such systems in place. The data can then be applied for predictive mathematical modeling and validation of physiologically realistic computer models aiming to identify patient subgroups at higher risk for adverse outcomes and/or predicting the response to a particular perturbation or therapeutic intervention. Another emerging application that opens an entirely new era in hemodynamic research is the use of the physiometric data obtained by the monitoring and data acquisition systems in conjunction with genomic information.