Lugo G, Arizpe D, Domínguez G, Ramírez M, Tamariz O
Department of Critical Care Medicine and Anesthesiology, Instituto Nacional de la Nutrición, Salvador Zubirán, Mexico City, México.
Crit Care Med. 1993 Jan;21(1):64-9. doi: 10.1097/00003246-199301000-00014.
To identify critical oxygen delivery (DO2) and oxygen extraction ratio in high-risk surgical patients studied preoperatively and intraoperatively.
Prospective study. Consecutive series of intraoperatively monitored patients.
The surgical ICU in a tertiary care center.
High-risk surgical patients undergoing major noncardiac surgery.
None.
Twenty high-risk patients were studied during the preoperative and intraoperative periods. All patients were monitored with triple-lumen thermodilution catheters. Hemodynamic profiles consisted of determinations of intravascular pressures, cardiac output, and arterial and venous pulmonary gases. Oxygen transport variables were calculated by standard formulas. Multiple determinations were carried out during the perioperative period in each patient. The critical levels of DO2, determined by a polynomial regression method, were 375 and 390 mL/min/m2 in the preoperative and intraoperative periods, respectively. Oxygen extraction reached at the critical level of DO2 was significantly (p < .01) lower during the intraoperative period (31 +/- 4.5% vs. 18 +/- 2.3%). Critical mixed venous oxygen tension was significantly (p < .01) higher in the intraoperative period (36 +/- 5 vs. 46 +/- 4 torr [4.8 +/- 0.7 vs. 6.1 +/- 0.5 kPa]).
Our data show that the intraoperative period might be associated with a reduction in tissue ability to extract oxygen. If this reduction in oxygen extraction is proportionately higher than the reduction in metabolic oxygen demand produced by anesthetic agents and hypothermia, then the critical value for DO2 may be similar to, or higher than, that value in the preoperative period. Thus, the intraoperative period represents, for this patient population, a high-risk condition for the development of a tissue oxygenation debt in the presence of a limitation in DO2. Cautious dosing of inhaled agents, maintenance of normothermia, and early optimization of the oxygen delivery/oxygen consumption relationship seem to constitute reasonable measures in the intraoperative handling of these patients in order to reduce perioperative morbidity and mortality.
确定术前和术中接受研究的高危手术患者的临界氧输送（DO2）和氧摄取率。
前瞻性研究。对术中监测的患者进行连续系列研究。
三级医疗中心的外科重症监护病房。
接受重大非心脏手术的高危手术患者。
无。
对20例高危患者在术前和术中进行了研究。所有患者均使用三腔热稀释导管进行监测。血流动力学参数包括血管内压力、心输出量以及动脉和静脉血气的测定。氧输送变量通过标准公式计算得出。在围手术期对每位患者进行了多次测定。通过多项式回归方法确定的术前和术中DO2临界水平分别为375和390 mL/min/m²。在临界DO2水平时，术中氧摄取率显著降低（p < 0.01）（31 ± 4.5% 对 18 ± 2.3%）。术中临界混合静脉血氧张力显著升高（p < 0.01）（36 ± 5 对 46 ± 4 托 [4.8 ± 0.7 对 6.1 ± 0.5 kPa]）。
我们的数据表明，术中可能与组织摄取氧的能力降低有关。如果这种氧摄取的降低比例高于麻醉剂和低温导致的代谢氧需求的降低，那么DO2的临界值可能与术前相似或更高。因此，对于该患者群体，术中在DO2受限的情况下存在发生组织氧债的高风险状况。谨慎使用吸入剂、维持正常体温以及早期优化氧输送/氧消耗关系似乎是术中处理这些患者的合理措施，以降低围手术期发病率和死亡率。
