Hoskote Aparna, Li Jia, Hickey Chantal, Erickson Simon, Van Arsdell Glen, Stephens Derek, Holtby Helen, Bohn Desmond, Adatia Ian
Department of Critical Care Medicine, The Hospital for Sick Children, Toronto, Canada.
J Am Coll Cardiol. 2004 Oct 6;44(7):1501-9. doi: 10.1016/j.jacc.2004.06.061.
We investigated the effects of different CO(2) tensions on oxygenation, pulmonary blood flow (Qp), cerebral blood flow, and systemic blood flow (Qs) after the bidirectional superior cavopulmonary anastomosis (BCPA).
Hypoxemia refractory to management of a high pulmonary vascular resistance index (PVRI) may complicate recovery from the BCPA.
After BCPA, CO(2) was added to the inspired gas of mechanically ventilated patients. The Qp, Qs, PVRI, and systemic vascular resistance index (SVRI) were calculated from oxygen consumption, intravascular pressures, and oxygen saturations. Cerebral blood flow was estimated by near infrared spectroscopy and transcranial Doppler.
In nine patients (median age 7.1, range 2 to 23 months), arterial oxygen tension increased significantly (p < 0.005) from 36 +/- 6 mm Hg to 44 +/- 6 to 50 +/- 7 mm Hg at arterial carbon dioxide tensions (PaCO(2)) of 35, 45, and 55 mm Hg, respectively and decreased to 40 +/- 8 mm Hg at PaCO(2) 40 mm Hg. At a PaCO(2) of 55 and 45 compared with 35 mm Hg, Qp, cerebral blood flow, and Qs increased significantly, PVRI, Qp/Qs, and the ratio of Qp to inferior vena caval blood flow were unchanged, but SVRI decreased.
We have demonstrated that after the BCPA, systemic oxygenation, Qp, Qs, and cerebral blood flow increased and SVRI decreased at CO(2) tensions of 45 and 55 mm Hg compared with 35 mm Hg. We suggest that hypoxemia after the BCPA is ameliorated by a higher PaCO(2) and that low PaCO(2) or alkalosis may be detrimental. Hypercarbic management strategies may allow earlier progression to the BCPA, which may contribute to reducing the interval morbidity in patients with a functional single ventricle.
我们研究了双向腔肺吻合术（BCPA）后不同二氧化碳分压对氧合、肺血流量（Qp）、脑血流量和体循环血流量（Qs）的影响。
高肺血管阻力指数（PVRI）难以处理的低氧血症可能使BCPA后的恢复复杂化。
BCPA后，向机械通气患者的吸入气体中添加二氧化碳。根据氧耗量、血管内压力和血氧饱和度计算Qp、Qs、PVRI和体循环血管阻力指数（SVRI）。通过近红外光谱和经颅多普勒估计脑血流量。
9例患者（中位年龄7.1岁，范围2至23个月），动脉血氧分压在动脉二氧化碳分压（PaCO2）分别为35、45和55 mmHg时从36±6 mmHg显著增加（p<0.005）至44±6至50±7 mmHg，在PaCO2 40 mmHg时降至40±8 mmHg。与35 mmHg相比，在PaCO2为55和45 mmHg时，Qp、脑血流量和Qs显著增加，PVRI、Qp/Qs以及Qp与下腔静脉血流量的比值不变，但SVRI降低。
我们已经证明，BCPA后，与35 mmHg相比，在45和55 mmHg的二氧化碳分压下，体循环氧合、Qp、Qs和脑血流量增加，SVRI降低。我们认为，BCPA后的低氧血症通过较高的PaCO2得到改善，低PaCO2或碱中毒可能有害。高碳酸血症管理策略可能允许更早地进展到BCPA，这可能有助于减少功能性单心室患者的间隔期发病率。
