Balogh D, Wieser C, Mair P, Furtwängler W, Weimann S, Gruber E
Klinik für Anästhesie und Allgemeine Intensivmedizin, Universität Innsbruck.
Anaesthesist. 1995 Aug;44(8):552-7. doi: 10.1007/s001010050188.
Oxygen uptake (VO2) and carbon dioxide elimination (VCO2) can be measured with an indirect calorimeter, this method is well established in routine monitoring of ICU patients to evaluate metabolic state as a reflection of stress. In various experimental studies it was demonstrated that anaesthetics can influence whole-body metabolism. The purpose of this study was to examine whether indirect calorimetry can be used intraoperatively during routine anaesthesia and whether presumable changes in metabolism can be detected immediately. Abdominal aortic cross-clamping changes circulation, nutritional supply of the lower extremities and thus VO2 and VCO2. We therefore used this operation for our study. METHOD. Eleven patients, mean age 64 years, undergoing reconstruction of the aortic bifurcation, were studied. After premedication with piritramid and atropine, total intravenous anaesthesia (TIVA) was performed with fentanyl and midazolam after an induction with thiopental. Patients were ventilated with a Servo-Ventilator 900 D and a constant FiO2 of 0.5, without N2O. Routine monitoring consisted of ECG, pulsoximetry, CVP and continuous AP. VO2 and VCO2 were measured with a Deltatrac (Datex), and data were registered every minute. For statistical evaluation we used a Wilcoxon-Ranksum test for matched pairs, p < 0.05 was considered significant. Data from specific time (5 min after intubation, 5 min before clamping; 5, 10 and 15 min after clamping, before declamping and 5 and 10 min after declamping and at the end of surgery) were calculated. In addition to absolute values, we compared the measured VO2 and VCO2 to baseline (5 min before clamping = MP2). RESULTS. Mean operating time was 139 min +/- 37; aortic cross-clamping time for the first extremity was 38 min and 55 min for the second. As expected, there was a significant decrease in VO2 (90% of baseline) and VCO2 (75% of baseline) during aortic cross-clamping. After declamping VO2 again rose to 110% of baseline, or to 103% for the second limb. VCO2 increased to only 90% and 82%, respectively. At the end of surgery VO2 reached baseline, whereas VCO2 remains at 83%. The respiratory quotient VCO2: VO2 was markedly reduced from 0.95 +/- 0.156 to 0.73 +/- 0.06 during surgery. The Deltatrac showed every change in VO2 without delay; changes in VCO2 seem to occur somewhat retarded. DISCUSSION. Aortic cross-clamping leads to a marked decrease in VO2 and VCO2 reflecting the temporary reduction in whole-body metabolism. Declamping results in a compensatory rise, especially in VO2. VCO2 seems to increase less after declamping, perhaps due to the CO2 pool of the organism or to a change in metabolism from carbohydrate to mainly fat oxidation. The results of this study demonstrate that indirect calorimetry can easily be performed during anaesthesia and surgery. Preconditions are a non-rebreathing system without airleak, constant FiO2 < 0.6 and no use of nitrous oxide.
氧摄取量（VO₂）和二氧化碳排出量（VCO₂）可用间接热量计测量，该方法在ICU患者的常规监测中已得到充分确立，用于评估代谢状态以反映应激情况。在各种实验研究中已表明麻醉剂可影响全身代谢。本研究的目的是检验间接热量测定法在常规麻醉期间是否可用于术中，以及是否能立即检测到代谢的可能变化。腹主动脉交叉钳夹会改变循环、下肢的营养供应，进而影响VO₂和VCO₂。因此我们将此手术用于我们的研究。方法：对11例平均年龄64岁、接受主动脉分叉重建手术的患者进行了研究。在使用匹米诺定和阿托品进行术前用药后，经硫喷妥钠诱导，随后用芬太尼和咪达唑仑进行全静脉麻醉（TIVA）。患者使用Servo - Ventilator 900 D呼吸机进行通气，固定吸入氧浓度（FiO₂）为0.5，不使用氧化亚氮。常规监测包括心电图、脉搏血氧饱和度测定、中心静脉压和连续动脉压。VO₂和VCO₂用Deltatrac（Datex）测量，数据每分钟记录一次。为进行统计学评估，我们对配对数据使用Wilcoxon秩和检验，p < 0.05被认为具有显著性。计算特定时间（插管后5分钟、钳夹前5分钟；钳夹后5、10和15分钟、松开钳夹前、松开钳夹后5和10分钟以及手术结束时）的数据。除绝对值外，我们将测得的VO₂和VCO₂与基线值（钳夹前5分钟 = MP2）进行比较。结果：平均手术时间为139分钟±37分钟；第一下肢的主动脉交叉钳夹时间为38分钟，第二下肢为55分钟。正如预期的那样，在主动脉交叉钳夹期间VO₂（降至基线的90%）和VCO₂（降至基线的75%）显著下降。松开钳夹后，VO₂再次升至基线的110%，第二下肢升至103%。VCO₂分别仅升至90%和82%。手术结束时VO₂达到基线水平，而VCO₂仍为83%。呼吸商VCO₂:VO₂在手术期间从0.95±0.156显著降至0.73±0.06。Deltatrac能即时显示VO₂的每一个变化；VCO₂的变化似乎出现得稍晚。讨论：腹主动脉交叉钳夹导致VO₂和VCO₂显著下降，反映全身代谢的暂时降低。松开钳夹会导致代偿性升高，尤其是VO₂。松开钳夹后VCO₂的升高似乎较少，这可能是由于机体的二氧化碳储备或代谢从碳水化合物氧化转变为主要是脂肪氧化所致。本研究结果表明，间接热量测定法在麻醉和手术期间可轻松进行。前提条件是无漏气的非再呼吸系统、固定FiO₂<0.6且不使用氧化亚氮。
