Neonatologist-performed functional echocardiography in the neonatal intensive care unit
Introduction
Point-of-care ultrasound is increasingly used by neonatologists in the intensive care setting to support clinical decisions. The technology may be applied to evaluation of the neonatal heart, brain, abdomen/pelvis and to facilitate vascular access. This review will focus mostly on neonatologist-performed functional echocardiography. The provision of real-time information on cardiovascular performance and systemic hemodynamics, non-invasive nature of the technique, rapidity of data acquisition and report generation, and ability to perform longitudinal functional assessments have all contributed to the increased use of functional echocardiography by neonatologists in the neonatal intensive care unit (NICU). The lack of a reliable measure of systemic blood flow is one example of a clinical situation which has prompted neonatologists to perform point-of-care echocardiography examinations. Clinical signs such as heart rate, blood pressure, and capillary refill time, which traditionally physicians have relied upon, provide limited insight into the adequacy of systemic blood flow and organ perfusion.1 Finally, issues of access to echocardiography or a pediatric cardiology service have prompted neonatologists to develop these advanced skills.
This review examines the potential clinical role of ultrasound methods in the NICU; specifically, its applications in different disease states, and how the technology may be introduced safely in the NICU.
Section snippets
Evolution of ultrasound in the NICU
The use of point-of-care focused ultrasound for evaluation of the cardiovascular system within the context of clinical decision-making is gaining wide interest. In the acute care setting, non-ultrasound specialists can be trained to provide focused imaging and measurements. This approach does not aim to replace the detailed structural assessments provided by consultative services such as cardiology or radiology. It is designed to support clinical judgment and provide a better understanding of
Imaging the newborn
Echocardiography evaluation of the newborn is complicated by issues related to patient size and transthoracic acoustic windows. The interpretation of hemodynamic data is totally dependent on the quality of the images, hence the competence of the operator is important. Serial scans of the same patient should ideally be performed by one examiner to limit interobserver variability, and to maximize patient benefit. Functional echocardiography includes evaluation of the heart using two-dimensional
Assessment of myocardial function, hypovolemia and organ perfusion
Systemic hypotension is a relatively common problem affecting about one-third of preterm neonates with up to 40% receiving vasopressor therapy.11 The overreliance by neonatologists on blood pressure in isolation as a surrogate marker of the adequacy of systemic blood flow is problematic for several reasons. First, the arbitrary threshold of mean arterial pressure approximating the gestational age proposed in 1992 is a physiologic oversimplification which lacks scientific validation. Second,
Other potential applications
The expanded role of point-of-care ultrasound includes screening for IVH, umbilical or percutaneous catheter insertion and monitoring, evaluation of intra-abdominal organs, e.g. bladder size or screening for ascites or other cavity effusions. The role of point-of-care ultrasound in facilitating catheter insertion and monitoring is particularly important. With echocardiography, the inferior vena cava–right atrial junction can be easily visualized using a parasagittal subcostal view. This may
Impact of neonatologist-performed functional echocardiography on neonatal nutcomes
The availability of functional echocardiography in the neonatal unit may influence management and short term outcome. In a retrospective review of 241 infants admitted to a tertiary NICU, echocardiography performed by neonatologists under the supervision of cardiologists was associated with a direct change of management in 66% of infants examined.59 The diagnoses included structural heart disease (33%), hemodynamically significant PDA (3%), PPHN (6%), and LV dysfunction (3%).
In another
Standards for practice
There is a growing acceptance that neonatologist-performed functional echocardiography is a useful tool in the NICU, with increasing evidence of improved patient outcomes. What is lacking at present is a formalised training and accreditation program necessary for the development of echocardiography skills.60 The potential risks of introducing this skill set without formal training include a divergence from clinical assessments and misdiagnosis of congenital heart disease (CHD). This may result
Conclusion
The expanded role of neonatologist-performed functional echocardiography is gaining momentum. There is mounting evidence that it can provide a more comprehensive assessment of the hemodynamic status of infants, and may influence management. There is an urgent need to encourage collaboration with pediatric cardiologists to establish standards for training and maintenance of competency, to develop guidelines for clinical practice and finally to ensure that the necessary clinical governance is in
Acknowledgments
The authors would like to acknowledge the support, training and mentorship obtained from the Paediatric Cardiologists and Neonatologists in Dublin, Ireland and Toronto, Canada.
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