INTRODUCTION In uterus the foetus depends on placenta for gas exchange and nutrient delivery from the maternal circulation. The foetal lungs are filled with fluid and are not required for gas exchange.1 Oxygenated blood in umbilical vein mixed with portal venous blood from the foetus, reaches right atrium through the Inferior Vena Cava with an oxygen saturation of 67 %.2 Immediately after delivery the transition from foetus to new born involves extensive changes in all the systems but the most crucial changes occur in cardiovascular and pulmonary system.
After the first breath post-delivery, fluid in the lung pushes out and the lungs will be filled with oxygen and the oxygen content in…show more content… The initial studies of fetal pulse oximeter (SpO2) during labour revealed that normal values were approximately 58 ± 10%.
Traditionally, oxygenation levels of newly born infants have been assessed clinically. However, O’Donnell et al3 showed that there is substantial inter-observer and intra-observer variability in assessments of colour. Assessing of colour is difficult and is a poor proxy for tissue oxygenation therefore experts have recommended the use of pulse oximeter to measure oxygenation in this…show more content… Pulse oximeter is based on the red and infrared light-absorption characteristics of oxygenated and deoxygenated haemoglobin. A sensor is placed around hand or foot and two light-emitting diodes send red and infrared light through to a photo detector on the other side. The changes in absorption during the arterial pulsatile flow and non-pulsatile component of the signal are analysed. SpO2 is estimated from the transmission of light through the pulsatile tissue bed. With each heartbeat, there is a surge of arterial blood that momentarily increases arterial blood volume. This results in more light absorption during surges. As peak occurs with each heartbeat, heart rate can also be measured.
In early studies, investigators placed the sensor over the right Achilles tendon, the fore-foot or mid-foot. Later studies found that measurements were obtained fastest from the right hand probably owing to better perfusion, higher blood pressure and oxygenation in pre-ductal vessels. Additionally pre-ductal SPO2 is more representative of SPO2 value of brain
