RESUMEN
Birth is a moment of transition from intra- to extra-uterine life, which is characterized as switching of gas-exchanging organs from the placenta to the lungs. It is achieved by aeration as well as perfusion of the lungs (increase in pulmonary blood flow). This is, without doubt, the most challenging event in human life. Assessment of circulatory status of the newborn in this critical period is challenging as well. For monitoring those tiny, vulnerable, and unstable creatures, technology requires non-invasiveness and a reasonably high signal/noise ratio. Conventionally, we have monitored circulatory status of newborns by inspection and physical examination, including vital signs such as body temperature, skin color, heart rate and blood pressure. Echocardiography was introduced in the 1980's and its function has been developing and advancing ever since. It is certainly the most powerful tool for both the assessment and management of circulation in the newborn infants. Although echocardiography is actually not a 'continuous monitor' but an 'intermittent check-up'. Its disadvantage can be overcome to some extent by performing it quickly and frequently. However, some novel methods for monitoring circulation are being developed and becoming available in clinical neonatology. For example, near-infrared spectroscopy, electrical cardiometry and laser Doppler flowmetry may be useful for monitoring other aspects of circulation.