Advances in Diagnosis and Management of Hemodynamic Instability in Neonatal Shock

Abstract

Shock in newborn infants has unique etiopathologic origins that require careful assessment to direct specific interventions. Early diagnosis is key to successful management. Unlike adults and pediatric patients, shock in newborn infants is often recognized in the uncompensated phase by the presence of hypotension, which may be too late. The routine methods of evaluation used in the adult and pediatric population are often invasive and less feasible. We aim to discuss the pathophysiology in shock in newborn infants, including the transitional changes at birth and unique features that contribute to the challenges in early identification. Special emphasis has been placed on bedside focused echocardiography/focused cardiac ultrasound, which can be used as an additional tool for early, neonatologist driven, ongoing evaluation and management. An approach to goal oriented management of shock has been described and how bed side functional echocardiography can help in making a logical choice of intervention (fluid therapy, inotropic therapy or vasopressor therapy) in infants with shock.

Targeted neonatal echocardiography in neonatal intensive care unit

“…In this period, it is seen that especially ELBW babies are prone to hypotension and their systemic blood flow is low. It may be seen that the immature heart fails to provide systemic blood flow in this patient group even if arterial blood pressure is normal against their increased peripheral resistance 1 . During this transition period, arterial blood pressure is not a clear and definitive indicator of low blood flow and low blood flow causes short and long term adverse outcomes 5 .…”

“…But blood pressure is a poor predictor of systemic flow and there is no reliable evidence from which to identify a blood pressure threshold for intervention or that such intervention improves outcome 1 . Again, although there is no linear relationship between systemic blood pressure and blood flow, there is a blood pressure threshold for the maintenance of systemic blood flow 1,2 . In newborn infants, especially in extremely low birth weight (ELBW) preterm infants, arterial blood pressure below 30 mmHg is considered a threshold for disruption of cerebral autoregulation, and below this threshold, the neurodevelopmental outcome is poor 2 .…”

Evaluation of Tissue Perfusion Status in Moderately Preterm Infants

“…Neonatal myocardial contractile elements were signi cantly fewer compared with older children and adults. The immature myocardial cells tended to exhibit higher basal contractile state and were more sensitive to cardiac afterload [9], hence the mobilization of cardiac reserve may rstly be characterized by an increase in PR rather than BP despite instability of systemic blood perfusion. All infants, especially premature infants, experience a series of hemodynamic changes during transitional period after birth, including intrauterine to extrauterine changes, decreased pulmonary arterial pressure, shunting of blood ow from systemic circulation to pulmonary circulation, closure of ductus arteriosus, and increased volume of systemic circulation.…”

Recommendations for hemodynamic Monitoring for Critically Ill Children – Expert Consensus Statement issued by the Cardiovascular Dynamics Section of the European Society of Paediatric and Neonatal Intensive Care (ESPNIC)

“…Ultrasonography is non-invasive, easily available and can provide a fairly accurate and serial estimation of cardiac output at the bedside to monitor the response to therapy [9,51]. However, it requires speci c skills and is operator-dependent.…”