Oxygen delivery in newborns with congenital heart disease

Newborns with hypoplastic left heart syndrome require palliative treatment followed by surgical reconstruction of the cardiovascular system to maintain systemic oxygen delivery. Initial medical treatment prevents closure of interatrial and interarterial shunts. This results in two parallel circulations perfused by the right ventricle. The ratio of pulmonary to systemic blood flow (Q_p/Q_s) becomes a critical parameter once pulmonary resistance begins to decrease after birth. The effects of Q_p/Q_s on systemic oxygen availability was studied using a mathematical model based on oxygen flow in the system The model showed that systemic oxygen delivery can be maximized by altering Q_p/Q_s and that the maximum value can be obtained with Q_p/Q_s that is between 0.4 and 1.0. The upper limit of O_p/Q_s that will generate adequate systemic oxygen supply, can be as high as 8.0. The model also showed that calculation of Q_p/Q _s using oxygen saturation measurements involves a very large error