Barnea O, Santamore W P, Rossi A, Salloum E, Chien S, Austin E H
Biomedical Engineering Department, Tel Aviv University, Israel.
Circulation. 1998 Oct 6;98(14):1407-13. doi: 10.1161/01.cir.98.14.1407.
The management of neonates with complex congenital anomalies depends on careful interpretation of arterial blood gas values. Improved interpretation of these oxygen parameters may allow clinicians to avoid unexpected cardiovascular events. This study examined whether systemic oxygen delivery (DO2) can be maximized by the use of indices derived from oxygen saturation measurements in neonates with hypoplastic left heart syndrome.
For the single-ventricle heart with both circulations in parallel, we used a previously developed computer simulation to obtain DO2 as a function of systemic arterial (SaO2) and venous (SvO2) oxygen saturation, arteriovenous oxygen difference (Sa-vO2), or pulmonary-to-systemic flow ratio (Qp/Qs). We also examined the oxygen excess factor, SaO2/Sa-vO2 (Omega). We found that (1) slight increases in SaO2 may be associated with large decreases in DO2. (2) Low values for SvO2 indicate low values for DO2. (3) Curves for Sa-vO2 and Qp/Qs are redundant in the data provided. (Qp/Qs, however, provides these data in more physiologically relevant terms.) (4) High values for Qp/Qs (>4) are associated with low DO2. (5) Estimating Qp/Qs from oxygen saturation measurements may result in errors when pulmonary venous oxygen saturation is not available. (6) Maximizing DO2 is extremely difficult using SaO2, SvO2, and Qp/Qs. (7) A linear relationship exists between Omega and DO2, and this linear relationship is not altered by changes in cardiac output.
Patients with low SvO2 values require attention. Ideally, after reducing Qp/Qs to <1.5, Omega might be a better index to guide further therapy and maximize DO2. Interventions that increased Omega would be considered beneficial, whereas interventions that decreased Omega would be considered detrimental.
患有复杂先天性异常的新生儿的管理依赖于对动脉血气值的仔细解读。对这些氧参数的更好解读可能使临床医生避免意外的心血管事件。本研究探讨了在左心发育不全综合征的新生儿中，使用从氧饱和度测量得出的指标是否能使全身氧输送（DO2）最大化。
对于双循环并行的单心室心脏，我们使用先前开发的计算机模拟来获取DO2作为全身动脉（SaO2）和静脉（SvO2）氧饱和度、动静脉氧差（Sa-vO2）或肺循环与体循环血流量之比（Qp/Qs）的函数。我们还研究了氧过剩因子，即SaO2/Sa-vO2（Ω）。我们发现：（1）SaO2的轻微增加可能与DO2的大幅下降相关。（2）SvO2值低表明DO2值低。（3）在提供的数据中，Sa-vO2和Qp/Qs的曲线是冗余的。（然而，Qp/Qs以更符合生理意义的术语提供这些数据。）（4）Qp/Qs值高（>4）与DO2低相关。（5）当无法获得肺静脉氧饱和度时，根据氧饱和度测量估算Qp/Qs可能会导致误差。（6）使用SaO2、SvO2和Qp/Qs使DO2最大化极其困难。（7）Ω与DO2之间存在线性关系，且这种线性关系不会因心输出量的变化而改变。
SvO2值低的患者需要关注。理想情况下，在将Qp/Qs降至<1.5后，Ω可能是指导进一步治疗并使DO2最大化的更好指标。增加Ω的干预措施将被视为有益，而降低Ω的干预措施将被视为有害。
