Li Jia, Zhang Gencheng, Benson Lee, Holtby Helen, Cai Sally, Humpl Tilman, Van Arsdell Glen S, Redington Andrew N, Caldarone Christopher A
Division of Cardiology, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, Canada, M5G 1X8.
Circulation. 2007 Sep 11;116(11 Suppl):I179-87. doi: 10.1161/CIRCULATIONAHA.106.679654.
After the Norwood procedure, early postoperative neonatal physiology is characterized by hemodynamic instability and imbalance of oxygen transport that is commonly attributed to surgical myocardial injury and a systemic inflammatory response to cardiopulmonary bypass (CPB). Because the Hybrid procedure (arterial duct stenting and bilateral pulmonary artery banding) avoids CPB, cardioplegic arrest, and circulatory arrest, we hypothesized that the Hybrid procedure is associated with superior postoperative hemodynamics and oxygen transport.
Oxygen consumption (VO2) was continuously measured using respiratory mass spectrometry for 72 hours after Hybrid (n=6) and Norwood (n=13) procedures. Arterial, superior vena cava, and pulmonary venous blood gases and pressures were measured at 2- to 4-hour intervals to calculate systemic and pulmonary blood flows (Qs, Qp), and systemic vascular resistance (SVR), total pulmonary vascular resistance including pulmonary arterial band or B-T shunt (tPVR), cardiac output (CO), oxygen delivery (DO2), and oxygen extraction ratio (ERO2). Rate-pressure product was calculated as heart rate x systolic arterial pressure. When compared with the Norwood procedure, the early postoperative Hybrid patients had lower CO, higher SVR, and higher Qp:Qs ratios. In addition, the DO2 and VO2 were both lower in the Hybrids with higher ERO2 and lactate levels. This early postoperative pattern reversed after 48 hours.
Although Hybrid procedure avoids CPB and cardioplegic arrest, the early hemodynamic profile is not superior to the Norwood in terms of cardiac output and control of pulmonary blood flow. These data strongly suggest that a "hands off" approach to postoperative care in Hybrid patients may not be appropriate in patients with preoperative diminished myocardial function; and in such patients a Norwood-derived management strategy (afterload reduction and inotropic support) should be considered.
在诺伍德手术之后，术后早期新生儿生理状态的特点是血流动力学不稳定以及氧运输失衡，这通常归因于手术造成的心肌损伤以及对体外循环（CPB）的全身炎症反应。由于杂交手术（动脉导管支架置入和双侧肺动脉环扎）避免了CPB、心脏停搏和循环停搏，我们推测杂交手术与术后更好的血流动力学和氧运输相关。
使用呼吸质谱法在杂交手术（n = 6）和诺伍德手术（n = 13）后连续72小时测量氧耗量（VO2）。每隔2至4小时测量动脉、上腔静脉和肺静脉血气及压力，以计算体循环和肺循环血流量（Qs、Qp）、体循环血管阻力（SVR）、包括肺动脉环扎或B-T分流在内的总肺血管阻力（tPVR）、心输出量（CO）、氧输送（DO2）和氧摄取率（ERO2）。心率-血压乘积计算为心率×收缩期动脉压。与诺伍德手术相比，术后早期杂交手术患者的CO较低、SVR较高且Qp:Qs比值较高。此外，杂交手术患者的DO2和VO2均较低，ERO2和乳酸水平较高。这种术后早期模式在48小时后逆转。
尽管杂交手术避免了CPB和心脏停搏，但就心输出量和肺血流量控制而言，早期血流动力学状况并不优于诺伍德手术。这些数据强烈表明，对于术前心肌功能减退的患者，对杂交手术患者采取“放任不管”的术后护理方法可能不合适；对于此类患者，应考虑采用源自诺伍德手术的管理策略（减轻后负荷和使用正性肌力药物支持）。
