Department of Critical Care Medicine, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China.
Shock. 2012 Feb;37(2):152-5. doi: 10.1097/SHK.0b013e31823cc1c0.
The transcutaneous partial pressure of oxygen (PtcO₂) index has been used to detect low-flow state in circulatory failure, but the value of the transcutaneous oxygen challenge test (OCT) to estimate low cardiac output has not been thoroughly evaluated. The prospective observational study examined 62 septic patients requiring PiCCO-Plus for cardiac output monitoring. Simultaneous basal blood gases from the arterial, central venous catheters were obtained. Cardiac indices were measured by the transpulmonary thermodilution technique at the same time, then the 10-min inspired 1.0 fractional inspired oxygen concentration (FIO₂) defined as the OCT was performed. Transcutaneous partial pressure of oxygen was measured continuously by using a noninvasive transcutaneous monitor throughout the test. The values for arterial pressure of oxygen (PaO₂) were examined on inspired of 1.0 FIO₂. We calculated the PtcO₂ index = (baseline PtcO₂/baseline PaO₂), 10-min OCT (10 OCT) = (PtcO₂ after 10 min on inspired 1.0 O₂) - (baseline PtcO₂), and the oxygen challenge index = (10 OCT) / (PaO₂ on inspired 1.0 O₂ - baseline PaO₂). Patients were divided into two groups: a normal cardiac index (CI) group with CI of greater than 3 L/min per m (n = 41) and a low CI group with CI of 3 L/min per m or less (n = 21). The 10 OCT and the oxygen challenge index predicted a low CI (≤ 3 L/min per m) with an accuracy that was similar to central venous oxygen saturation, which was significantly better than the PtcO₂ index. For a 10 OCT value of 53 mmHg, sensitivity was 0.83; specificity, 0.86; a positive predictive value, 0.92; and a negative predictive value, 0.72 for detecting CI of 3 L/min per m or less. We propose that the OCT substituted for the PtcO₂ index as an accurate alternative method of PtcO₂ for revealing low CI in septic patients.
经皮氧分压（PtcO₂）指数已被用于检测循环衰竭中的低血流状态，但经皮氧挑战试验（OCT）评估低心输出量的价值尚未得到充分评估。这项前瞻性观察研究检查了 62 例需要 PiCCO-Plus 进行心输出量监测的脓毒症患者。同时从动脉和中心静脉导管获得基础血气。同时使用经肺热稀释技术测量心指数，然后进行 10 分钟吸入 1.0 分比吸入氧浓度（FIO₂）定义为 OCT。在整个试验过程中，使用非侵入性经皮监测仪连续测量经皮氧分压。在吸入 1.0 FIO₂时检查动脉氧分压（PaO₂）值。我们计算了 PtcO₂指数=（基础 PtcO₂/基础 PaO₂），10 分钟 OCT（10 OCT）=（吸入 1.0 O₂ 10 分钟后的 PtcO₂）-（基础 PtcO₂）和氧挑战指数=（10 OCT）/（吸入 1.0 O₂后的 PaO₂-基础 PaO₂）。患者分为两组：心指数（CI）大于 3 L/min/m 的正常 CI 组（n = 41）和 CI 为 3 L/min/m 或更低的低 CI 组（n = 21）。10 OCT 和氧挑战指数预测低 CI（≤3 L/min/m）的准确性与中心静脉血氧饱和度相似，明显优于 PtcO₂指数。对于 10 OCT 值为 53 mmHg，敏感性为 0.83；特异性为 0.86；阳性预测值为 0.92；阴性预测值为 0.72，用于检测 CI 为 3 L/min/m 或更低。我们建议 OCT 替代 PtcO₂指数作为一种准确的替代方法，用于揭示脓毒症患者的低 CI。
