OBJECTIVES: This study examined the effects of the pulmonary (QP)/systemic (QS) blood flow ratio (QP/QS) on systemic oxygen availability in neonates with hypoplastic left heart syndrome. BACKGROUND: The management of neonates with hypoplastic left heart syndrome is complex and controversial. Both before and after surgical palliation and before heart transplantation, a univentricle with parallel pulmonary and systemic circulations exists. It is generally assumed that balancing pulmonary and systemic blood flow is best to stabilize the circulation. METHODS: We developed a mathematical model that was based on the simple flow of oxygen uptake in the lungs and whole-body oxygen consumption to study the effect of varying the QP/QS ratio. An equation was derived that related the key variables of cardiac output, pulmonary venous oxygen saturation and the QP/QS ratio to systemic oxygen availability. RESULTS: The key findings are 1) as the QP/QS ratio increases, systemic oxygen availability increases initially, reaches a maximum and then decreases; 2) for maximal systemic oxygen availability, the optimal QP/QS ratio is < or = 1; 3) the optimal QP/QS ratio decreases as cardiac output or percent pulmonary venous oxygen saturation, or both, increase; 4) the critical range of QP/QS, where oxygen supply exceeds basal oxygen consumption, decreases as cardiac output and percent pulmonary venous oxygen saturation decrease; 5) the relation between oxygen availability and QP/QS is very steep when QP/QS approaches this critical value; and 6) the percent oxygen saturation of systemic venous blood is very low outside the critical range of QP/QS and high within the critical range. CONCLUSIONS: This analysis provides a theoretic basis for balancing both the pulmonary and systemic circulation and suggests that evaluating both systemic arterial and venous oxygen saturation may be a useful way to determine the relative pulmonary and systemic flows. When high systemic arterial and low systemic venous oxygen saturation are present, pulmonary blood flow should be decreased; conversely, when both low systemic arterial and venous oxygen saturation are present, more flow should be directed to the pulmonary circulation.
OBJECTIVES: This study examined the effects of the pulmonary (QP)/systemic (QS) blood flow ratio (QP/QS) on systemic oxygen availability in neonates with hypoplastic left heart syndrome. BACKGROUND: The management of neonates with hypoplastic left heart syndrome is complex and controversial. Both before and after surgical palliation and before heart transplantation, a univentricle with parallel pulmonary and systemic circulations exists. It is generally assumed that balancing pulmonary and systemic blood flow is best to stabilize the circulation. METHODS: We developed a mathematical model that was based on the simple flow of oxygen uptake in the lungs and whole-body oxygen consumption to study the effect of varying the QP/QS ratio. An equation was derived that related the key variables of cardiac output, pulmonary venous oxygen saturation and the QP/QS ratio to systemic oxygen availability. RESULTS: The key findings are 1) as the QP/QS ratio increases, systemic oxygen availability increases initially, reaches a maximum and then decreases; 2) for maximal systemic oxygen availability, the optimal QP/QS ratio is < or = 1; 3) the optimal QP/QS ratio decreases as cardiac output or percent pulmonary venous oxygen saturation, or both, increase; 4) the critical range of QP/QS, where oxygen supply exceeds basal oxygen consumption, decreases as cardiac output and percent pulmonary venous oxygen saturation decrease; 5) the relation between oxygen availability and QP/QS is very steep when QP/QS approaches this critical value; and 6) the percent oxygen saturation of systemic venous blood is very low outside the critical range of QP/QS and high within the critical range. CONCLUSIONS: This analysis provides a theoretic basis for balancing both the pulmonary and systemic circulation and suggests that evaluating both systemic arterial and venous oxygen saturation may be a useful way to determine the relative pulmonary and systemic flows. When high systemic arterial and low systemic venous oxygen saturation are present, pulmonary blood flow should be decreased; conversely, when both low systemic arterial and venous oxygen saturation are present, more flow should be directed to the pulmonary circulation.
Authors: S P McGuirk; M Griselli; O F Stumper; E M Rumball; P Miller; R Dhillon; J V de Giovanni; J G Wright; D J Barron; W J Brawn Journal: Heart Date: 2005-06-06 Impact factor: 5.994
Authors: K D Bourke; H M Sondheimer; D D Ivy; B Pietra; B K Gleason; C Mashburn; M M Boucek Journal: Pediatr Cardiol Date: 2003-09-04 Impact factor: 1.655
Authors: Charles Puelz; Sebastián Acosta; Béatrice Rivière; Daniel J Penny; Ken M Brady; Craig G Rusin Journal: Comput Biol Med Date: 2017-08-25 Impact factor: 4.589