Pathophysiology of newborn hypotension outside the transitional period
Section snippets
Normal blood pressure
Although the exact gestational- and postnatal-age dependent autoregulatory blood pressure range has not been defined for the neonatal patient population [1], findings of recent studies on organ blood flow and its autoregulation have provided some novel information in this area [2]. However, several theoretical and clinical aspects of developmental cardiovascular pathophysiology relevant to neonatal shock remain unclear [3]. One area where the available information certainly needs further
Definition and phases of neonatal shock
Shock is a state of cellular energy failure caused by the inability of tissue oxygen delivery to satisfy tissue oxygen demand. Shock presents in phases of advancing severity characterized by specific pathological alterations in cardiovascular, renal and neuroendocrine function [1], [6]. In the initial compensated phase, vital organ (brain, heart and adrenal glands) perfusion and blood pressure are maintained by neuroendocrine compensatory mechanisms via redistribution of blood flow from the
Definition and clinical relevance of neonatal hypotension
Although there is some prospectively collected information on the relationship between blood pressure and organ blood flow in the transitional period especially in the VLBW patient population, very little data exist for the post-transitional neonatal period (from the 2nd to the 28th postnatal days). Except for the VLBW neonate during the first 24 postnatal hours, the general assumption is that the laws of cardiovascular physiology as we know from studies on mature animals and humans govern the
Hypovolemia
Although in the pediatric patient population absolute hypovolemia is the most frequent primary cause of hypotension, in neonates, abnormal peripheral vasoregulation with or without myocardial dysfunction is the most frequently encountered primary etiological factor [1]. The lack of a relationship between blood volume and blood pressure and the finding that dopamine is more effective in normalizing blood pressure than is volume administration support that absolute hypovolemia is a less frequent
Key guidelines
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The normal postnatal increase in blood pressure is primarily the result of increase in peripheral vascular resistance.
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Prompt recognition of neonatal shock in the compensated phase is difficult.
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Unlike older children, the most common cause of hypotension in preterm and term infants is dysregulation of vascular tone with or without myocardial dysfunction rather than hypovolemia.
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The structural and functional immaturity of the myocardium makes neonates, especially preterm infants, vulnerable to the
Research directions
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Prospective clinical trials to define the gestational and postnatal age-specific normal blood pressure based on organ blood flow autoregulation during well-being and disease.
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Prospective clinical trials to study the hemodynamic changes in different forms of neonatal shock and in response to different treatment modalities.
References (14)
- et al.
Blood pressure measurements in the newborn
Clin Perinatol
(1999) Blood pressure in the very low birth weight neonates
Early Hum Dev
(2001)The heart and development
Semin Perinatol
(1996)- et al.
Non-invasive assessment of myocardial contractility, preload, and afterload in healthy newborn infants
Am J Cardiol
(1995) - et al.
Predictive agreement between the fetal arterial oxygen saturation and scalp pH: results of the German multicenter study
Am J Obstet Gynecol
(1998) - et al.
Controversies in the diagnosis and management of hypotension in the newborn infant
Curr Opin Pediatr
(2001) - et al.
Low superior vena cava flow and intraventricular hemorrhage in preterm infants
Arch Dis Child
(2000)
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2018, Hemodynamics and Cardiology: Neonatology Questions and ControversiesVascular regulation of blood flow to organs in the preterm and term neonate
2018, Hemodynamics and Cardiology: Neonatology Questions and Controversies
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