The use of TnECHO for evaluation of the cardiovascular system is gaining wide interest. The utilisation of ultrasound in the NICU is evolving and is designed to provide important physiological information in real time, the purpose of which is to support clinical decision making. 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. It is designed to support clinical judgment and provide a better understanding of the physiological processes, and monitor the response to treatment; this approach which combines both clinical examination and bedside echocardiography has been shown to improve clinical diagnosis and patient management. The point-of-care ultrasound examination is usually directed and focused towards a specific clinical problem, and is usually significantly shorter than traditional echocardiography, thereby minimising patient handling. In the adult intensive care units, routine use of trans-oesophageal echocardiography is common practise. The use of this technique by adequately trained intensivists can change the management of 30% of patients based on the results, and in 10% it may detect severe previously unknown diagnoses.
The emergence of this modality in the NICU stemmed from the limitations of clinical assessment in cardiovascular monitoring and providing accurate information on systemic blood flow. In addition the complexity and dynamic nature of the transitional circulation, variable responsiveness of the immature myocardium in the early neonatal period, the presence of intra-cardiac shunting, and the patent ductus arteriosus (PDA) make therapeutic decision making on clinical evaluation alone challenging. Echocardiography is routinely used in the neonate to assess the structure of the heart. However, obtaining these scans depends on the availability of the cardiologists or access to echocardiography technicians. These scans are usually focused on cardiac anatomy, and only provide a limited snapshot of cardiac function. This approach, however, is inadequate for the assessment of the haemodynamic status and does not meet the ongoing needs of critically ill neonates in the intensive care unit. In addition, evaluating the response to therapeutic interventions requires ongoing assessment by ultrasound. There is increasing evidence that the routine use of functional echocardiography in the neonatal unit does identify cardiovascular compromise, change management, and potentially improve short-term outcomes. The introduction of a neonatologist performed screening program for a hemodynamically significant ductus arteriosus (HSDA) on day 3 of life with targeted intervention led to a reduction in the rate of severe intraventricular haemorrhage and duration of ventilation. Recent studies have also demonstrated that echocardiography in the neonatal unit has a high yield for the diagnosis of structural heart disease and impaired cardiac performance often resulting in a change of management. Moss et al reported an 82% complete concordance rate between the scans performed by trained neonatologists and a paediatric cardiologist assessment. The concerns raised by paediatric cardiologists about the reliability of some hemodynamic measurements are valid. It must be recognized, however, that interpretation of individual hemodynamic measurements in isolation or without careful consideration of their application to the clinical context is likely to lead to erroneous conclusions. TnECHO is likely to have greatest impact when the haemodynamic evaluation is of a high quality, comprehensive, and carefully integrated within the clinical scenario.