الفهرس 
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Abstract
Background: Late-onset sepsis (LOS) is common in infants admitted to neonatal intensive care units (NICUs). Mortality from LOS is high in preterm infants especially those with infected with Gram-negative organisms. In addition, there is significant morbidity among survivors, including poor neurodevelopmental outcomes. Unfortunately, the clinical presentation of LOS in infants is often subtle. Blood culture is the gold standard for the diagnosis of sepsis; however, its usefulness, is limited by the time needed to isolate the organism and by difficulties in obtaining adequate blood volume to reliably isolate organisms. Novel laboratory markers, such as cytokines and molecular analyses, have been developed; however, it is unlikely that they will be of value in the near future because they are not very cost effective. Heart rate variability (HRV) analysis is a useful tool to study the interaction between the sympathetic and parasympathetic effects on heart rate. There are 2 main ways to evaluate in HRV: time and frequency domain analysis. Time domain indices are derived from statistical methods from the beat-to-beat interval (RR). Frequency-domain or power spectral analysis, which takes into account the occurrence of high and low frequency oscillations in heart rate, which reflect autonomic nervous system balance. Sepsis has a strong association with decreased HRV in animal models and in humans of all ages. Dampening of heart rate variability during sepsis likely reflects impairment of normal autonomic homeostatic functions. In a mouse model of sepsis-like illness, administration of endotoxin from Gram negative bacteria caused a dose-dependent decrease in heart rate variability. Human volunteers administered intravenous endotoxin also exhibit a significant decrease in HRV concurrent with other symptoms of illness such as fever, tachypnea, tachycardia, and hypotension. In neonates, sepsis is associated with decrease in multiple measures of HRV and lower HRV generally correlates with higher illness severity scores and higher mortality. HRV are more sensitive than traditionally used vital signs, such as cardiac output and mean arterial blood pressure, in the confirmation of sepsis in extreme low-birth-weight neonates, allow for earlier identification of septic physiology. Reduced variability and transient decelerations in heart rate (HR) may be present in the hours to days before diagnosis of late-onset proven or clinical neonatal sepsis. A monitor was developed – the HeRO monitor–(Heart Rate Observation) to analyse Heart rate characteristics (HRC) of decreased HRV and transient decelerations which are both incorporated into the HRC index, or HeRO score, which indicates the risk of an infant deteriorating from sepsis in the next day. Study design : Prospective observational study. The neonates were recruited from NICU’s of Mansoura University Children’s Hospital and Mansoura University Hospital. Sixty preterm Neonates divided to two groups;30 preterm neonates suspected of having LOS and 30 preterm neonates with matched gestational age without clinical or laboratory evidence of sepsis (control group). EC was applied once the baby was suspected of having LOS by putting four standard surface electrocardiogram electrodes over infants forehead, left lower neck, left mid-axillary line at level of xiphoid process and lateral aspect of left thigh. We recorded the following hemodynamic parameters: heart rate, HRV, stroke volume, cardiac output, cardiac index, thoracic fluid content, index of contractility, and systemic vascular resistance. For each item we took the average of six readings (measured every 5 minutes) over a period of 30 minutes. Conclusion: our study established the value of HRV monitoring and hemodynamic assessment using EC in evaluating preterm neonates with LOS. where the HRV and HRC showed high sensitivity at identifying neonatal sepsis. The use of this novel monitoring platform allows for analysis and significant discrimination between healthy neonates and septic neonates. Recommendations: Measurement of HRV and HRC in septic neonates with EC, further studies with a larger sample size should be conducted. Further studies to evaluate patient before developing sepsis are needed and these results may allow for an earlier diagnosis and treatment, which may lead to decreased morbidity and mortality.