Department of Anesthesiology, Perioperative and Pain Medicine, Children's Hospital Boston, Boston, MA, USA.
Anesth Analg. 2012 Sep;115(3):618-26. doi: 10.1213/ANE.0b013e31825d36a1. Epub 2012 Jun 22.
Although the traditional surgical approach for left hypoplastic heart syndrome is to perform staged, palliative procedures as a single ventricle lesion, certain anatomical subsets of patients are candidates for a 2-ventricle repair either as a primary or as a staged procedure. The pulmonary blood flow (Q(P))/systemic blood flow (Q(S)) range necessary to optimize systemic oxygen delivery (DO(2)) and systemic venous oxygen saturation has been delineated for patients undergoing conventional interventions as a single ventricle physiology where the left ventricle is assumed to make no contribution to systemic cardiac output. However, in the transitional circulations created during staging to a 2-ventricle repair, the left ventricle does contribute to cardiac output. The Q(P)/Q(S) at which systemic DO(2) and systemic venous oxygen saturation are optimized in the latter circulations has not yet been evaluated. Using computer modeling, we investigated parameters to optimize systemic oxygen delivery.
We designed model circulations after both modified stage I operation and modified bidirectional Glenn shunt with Sano shunt, which are transitional circulations created during staging to a 2-ventricle repair. Mathematical equations were derived to describe DO(2) in both models. Using a computer and an Excel spreadsheet, we used the equations to examine the relationships between DO(2) and arterial oxygen saturation (Sao(2)), venous oxygen saturation (SvO(2)), SaO(2) - SvO(2), Q(P)/Q(S), and the oxygen excess factor SaO(2)/(SaO(2) - SvO(2)).
In both circulations, SaO(2) or SvO(2) alone does not accurately predict DO(2) or Q(P)/Q(S). The relationships between these variables are further altered by the degree of systemic cardiac output supplied by the left ventricle. To the contrary, DO(2) demonstrates the linear relationship with the oxygen excess factor Sao(2)/(Sao(2) - Svo(2)) irrespective of the degree of systemic cardiac output supplied by the left ventricle.
Commonly obtained clinical values such as SaO(2) and SvO(2) alone are not accurate assessments of DO(2) or Q(P)/Q(S). Therefore, these cannot be used in isolation to guide perioperative therapy.
尽管左心发育不良综合征的传统手术方法是作为单心室病变进行分期姑息性手术，但某些特定解剖亚组的患者适合进行双心室修复术，无论是作为一期手术还是分期手术。对于接受传统单心室生理学干预的患者，已经确定了优化全身氧输送 (DO2) 和全身静脉血氧饱和度所需的肺血流量 (QP)/体循环血流量 (QS) 范围，其中假设左心室对全身心输出量没有贡献。然而，在进行双心室修复术的分期过程中形成的过渡循环中，左心室确实会对心输出量做出贡献。在这些循环中，优化全身 DO2 和全身静脉血氧饱和度的 QP/Qs 值尚未得到评估。我们使用计算机建模来研究优化全身氧输送的参数。
我们设计了改良一期手术和改良双向 Glenn 分流加 Sano 分流后的模型循环，这些都是在进行双心室修复术的分期过程中形成的过渡循环。我们推导出描述两种模型中 DO2 的数学方程。我们使用计算机和 Excel 电子表格，使用这些方程检查 DO2 与动脉血氧饱和度 (SaO2)、静脉血氧饱和度 (SvO2)、SaO2-SvO2、QP/Qs 以及氧过剩因子 SaO2/(SaO2-SvO2) 之间的关系。
在两种循环中，SaO2 或 SvO2 单独并不能准确预测 DO2 或 QP/Qs。这些变量之间的关系会因左心室提供的全身心输出量的程度而进一步改变。相反，无论左心室提供的全身心输出量的程度如何，DO2 都与氧过剩因子 SaO2/(SaO2-SvO2) 呈线性关系。
通常获得的临床值，如 SaO2 和 SvO2，单独使用并不能准确评估 DO2 或 QP/Qs。因此，这些值不能单独用于指导围手术期治疗。
