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Pathophysiology-based management of the hemodynamically significant patent ductus arteriosus in the very preterm neonate

Key points The simplistic “treat all or treat none” approach to management of a patent ductus arteriosus (PDA) has been increasingly challenged in recent years as the variation in clinical and hemodynamic presentation has been realized. Spontaneous closure rates, poor efficacy of medical treatment, and a combination of selection bias, high open-label treatment rates, and inappropriate outcome measures in clinical trials are among the major factors…

Interventional management of the patent ductus arteriosus

Key points Percutaneous (or transcatheter) PDA closure is an emerging technique that has gained popularity in the most recent years and is being performed in progressively smaller and younger patients. Advancements in the technique, the launch of devices that are more appropriate for the preterm ductal morphology, and increased experience have expanded the use of percutaneous closure with high rates of technical success and few major…

Pharmacological management of patent ductus arteriosus in the very preterm neonate

Key points The pharmacological management of PDA in the very preterm neonate remains a controversial topic, as the risks and benefits of the pharmacotherapeutic options remain unclear. NSAIDs (indomethacin and ibuprofen) and acetaminophen are the most common and effective pharmacological agents used for PDA closure. No major differences in the efficacy between the three agents have been established in comparative effectiveness trials. However, choice of therapy…

Diagnosis, evaluation, and monitoring of patent ductus arteriosus in the very preterm infant

Key points Although presence of a patent ductus arteriosus (PDA) can easily be confirmed with echocardiography, diagnosis of a hemodynamically significant PDA is more challenging and not standardized. Evaluation of hemodynamic and clinical significance of a PDA should include assessment of the size of the PDA, magnitude of shunt volume, the ability of the heart to accommodate and compensate for the shunt, and the impact of…

Clinical applications of near-infrared spectroscopy in neonates

Key points The status of cerebral oxygenation is not always represented appropriately by systemic arterial oxygenation, especially when there are changes in cerebral blood flow or cardiac output. Oxygenation monitoring of the brain by near-infrared spectroscopy (NIRS) is therefore an important additive measure in neonatal intensive care. Monitoring cerebral oxygenation by NIRS, in addition to arterial saturation monitoring by pulse oximetry, blood pressure, and brain function…

Comprehensive, real-time hemodynamic monitoring and data acquisition: An essential component of the development of individualized neonatal intensive care

Key points Accurate assessment of the hemodynamic status in critically ill neonates requires blood pressure measurements to be interpreted in the context of indirect (clinical signs) and direct (measurements and assessments) indicators of systemic circulation (cardiac output) and regional organ blood flow. Further judiciary validation of emerging technological approaches to evaluate systemic circulation and regional blood flow in a continuous and noninvasive manner is necessary. Comprehensive…

Cardiac magnetic resonance imaging in the assessment of systemic and organ blood flow and the function of the developing heart

Key points Cardiac magnetic resonance (CMR) Imaging techniques provide noninvasive assessments of the newborn circulation with high accuracy and repeatability. Cine CMR produces three-dimensional assessments of chamber volumes and myocardial mass. Phase contrast CMR can quantify blood flow in any major vessel. CMR techniques have provided normative ranges for neonatal left and right ventricular development and quantification of PDA shunt volume and have guided optimization of…

Assessment of cardiac output in neonates: Techniques using the fick principle, indicator dilution technology, doppler ultrasound, electrical biosensing technology, and arterial pulse contour analysis

Key points Cardiac output monitoring in preterm and term neonates is feasible but remains challenging despite the availability of different technologies. The best systems to monitor cardiac output in the clinical setting in neonatal intensive care at present are transthoracic echocardiography, transpulmonary indicator dilution, electrical biosensing technology, and arterial pulse contour analysis. Noninvasive cardiac output monitoring is inversely related to accuracy; hence there will always be…

Advanced cardiac imaging in the newborn: Tissue doppler imaging and speckle tracking echocardiography

Key points Tissue Doppler imaging (TDI) is a modality that employs the Doppler effect to assess muscle wall characteristics throughout the cardiac cycles including velocity, displacement, deformation, and event timings. Two-dimensional speckle tracking echocardiography (2DSTE) is a non-Doppler technique that applies computer software analysis of images generated by conventional ultrasound techniques to assess parameters of myocardial motion (displacement, velocity) and deformation (strain, strain rate) in all…

Assessment of systemic blood flow and myocardial function in the neonatal period using ultrasound

Key points Echocardiography is useful for the assessment of systemic blood flow and myocardial function. Systemic blood flow is a dynamic and complex variable. Blood flow through persistent fetal shunts influences cardiac output measurements from both ventricles. Superior vena cava flow as a measure of cardiac input is a surrogate measure for global cerebral blood flow and systemic blood flow in the transitional period. Fractional shortening…

Ultrasound-guided hemodynamic management

Key points The use of Clinician Performed Ultrasound (CPU) in the care of sick and preterm neonates is rapidly expanding. The benefits of a portable, bedside technique that provides real-time, longitudinal data regarding the physiology of individual patients and allows more targeted treatment are being progressively recognized as important. CPU has an important role in managing the transitioning term or preterm infant, the septic/asphyxiated infant, the…

The immature autonomic nervous system, hemodynamic regulation, and brain injury in the early developing brain

Key points The autonomic nervous system (ANS) plays a key role in maintaining homeostasis in the critically ill preterm or term infant. Prematurity, an adverse intrauterine environment, and intrinsic fetal factors, such as congenital heart disease (CHD), may impact the development and function of the ANS. Autonomic dysfunction may have long-term health (e.g., adult hypertension) and psycho-affective consequences and can be associated with brain injury. Knowledge…

Transitional hemodynamics and pathophysiology of peri-/intraventricular hemorrhage

Key points A period of systemic and cerebral hypoperfusion in the immediate postnatal period predisposes the extremely preterm infant to peri-/intraventricular hemorrhage (P/IVH). Cardiovascular immaturity and maladaptation after birth contribute to postnatal hypoperfusion. Ventilatory support, especially inappropriately high mean airway pressure, can accentuate the early postnatal hypoperfusion. Following the initial hypoperfusion, a period of improvement in systemic and cerebral perfusion precedes occurrence of P/IVH on the…

Hemodynamic significance and clinical relevance of deferred cord clamping and umbilical cord milking

Key points Cardiorespiratory transition at birth is a complex series of changes in which the lungs replace the placenta as the organ of gas exchange and the main source of preload to the left side of the heart. Lung aeration, driven by spontaneous inhalations or mechanical inflation, is the key stimulus leading to pulmonary vascular relaxation. Umbilical cord clamping, prior to lung aeration, reduces cardiac output…

Neonatal cardiovascular drugs

Key points Highlighting the importance of understanding physiology prior to prescribing medications will enable the provider to choose the preferred regimen for each particular patient. Extrapolating data from older pediatric populations and adults must be done with caution, considering the unique physiology and differences in pharmacokinetics and pharmacodynamics in critically ill neonates and infants. Understanding the mechanism of action and therapeutic effects (both desired and side…

Cardiopulmonary interactions in the mechanically ventilated neonate

Introduction Cardiopulmonary interactions are crucial considerations in the intensive care management of critically ill neonates. The understanding of the impact of mechanical ventilation on the heart and lungs permits the prediction of a neonate’s response to the initiation or modification of positive pressure ventilation, or the effect of cardiovascular therapeutics. These interactions are guided by the laws of hydrodynamics as applied to a distensible or compressible…

Blood pressure and cardiovascular physiology

Key points In the context of neonatal care, invasive or noninvasive measurement of blood pressure can be accomplished with acceptable precision across all gestational age categories. Gestational and postnatal-age-dependent population-based normative blood pressure ranges are available. However, their usefulness in the assessment of adequacy of circulatory status remains limited. Interrogation of the individual components of the patient’s blood pressure may provide a greater understanding of the…

Vascular regulation and assessment of blood flow to organs in the neonatal period

Key points Multiple mechanisms operate to regulate blood flow to organs – these are also important in the newborn. Distribution of cardiac output is actively regulated. Autoregulation may best be described as a degree of capacity rather than an on-off phenomenon. Cerebral autoregulation, that is, the ability to buffer the effects of blood pressure on cerebral blood flow, is developed even at the limits of viability.…

Principles of developmental cardiovascular physiology and pathophysiology

Key points 1. A successful hemodynamic transition from fetal to extrauterine life is a complex process and requires the interdependent sequential physiologic changes to take place in a timely manner 2. Immaturity- or pathophysiology-driven disturbances of the transitional process may have significant short- and long-term consequences 3. Timely diagnosis and pathophysiology-targeted management of neonatal shock pose difficult challenges for the clinician 4. Many questions remain unanswered,…