الفهرس 
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Abstract
RDS is one of the most important diseases affecting neonates, especially premature infants, and is considered as the commonest cause of respiratory failure and death in this age group. Today, RDS is an uncommon cause of neonatal mortality in developed nations because it can be successfully prevented and/ or treated.
Cyanotic heart diseases can mimic RDS both clinically and radiologically. Persistent pulmonary hypertension of the neonate must be also considered, but can generally be differentiated from RDS. The major decline in pulmonary resistance from the high fetal levels to the low adult levels in the human infant -at sea level- usually occurs within the first 2-3 days of life. However, this may be prolonged for 7 days or more. In normal babes, over the first several weeks of life, pulmonary vascular resistance decreases even further secondary to remodeling of the pulmonary vasculature, including thinning of the vascular smooth muscle and recruitment of new vessels. However, these changes is not the rule in RDS.
Pulmonary hypertension is associated with increased morbidity and mortality in cardio-respiratory disorders, such as persistent pulmonary hypertension of the newborn and respiratory distress syndrome. Right ventricular patho-physiology is potentially important in these conditions. The ability of the right ventricle to maintain adequate pulmonary blood flow despite increased pulmonary vascular resistance may be critical for optimal oxygenation. However, there are few data on right ventricular volumes or function and other echocardiographic parameters in RDS infants.
Echocardiography is a simple non invasive diagnostic modality that can be done for RDS babes. Echographic findings can be used as both diagnostic and prognostic factors and it seemed to be a better index of the outcome of RDS than either clinical, laboratory or radiological parameters.
Although our study does not impute that the elevated pulmonary vascular resistance was a mechanism in pathogenesis of RDS, it demonstrated the association of severe RDS with echographic evidence of elevated pulmonary vascular resistance or impaired RV function. All infants with RDS regardless the severity had elevated MPAP. 90% of infants with severe RDS had fair or impaired RV function and had higher mortality and morbidity, only one infant from the severe group had good function.
We concluded that severe RDS is associated with some hemdynamic abnormalities including high RVSP, high MPAP, impairedRV dunctionand high incidence of TR with higher grade of reurge.
When RDS was coupled with echographic finding of elevated pulmonary vascular resistance and impaired contractility, the disease was severe and the outcome was poor. These echographic findings seemed to be a better index of the outcome of RDS than either clinical, laboratory or radiological parameters.