经食道监测动脉血氧饱和度的实验研究

目的　评价经食道监测主动脉血氧饱和度 (Se O2 )方法的敏感性和精确性。方法　 9只健康犬麻醉诱导后将 Nellcor(D- 2 0 )探头置入食道下段 ,开胸后直视下将探头发光点透过食道壁正对降主动脉 ,连接监护仪 ,连续监测 Se O2 和犬舌粘膜血氧饱和度 (Sm O2 )。改变吸入气中氧浓度 (Fi O2 ) ,Sm O2 从 10 0 %降到 6 0 %恢复供氧 ,记录相同的时间点时 Se O2 、Sm O2 、平均动脉压 (MAP)、心率 (HR)、心电图 (ECG)、呼气末二氧化碳分压 (Pet CO2 )、T、Fi O2 各参数 ,比较 Sm O2 在 90 %、80 %、70 %和 6 0 %时 Se O2 的变化。以股动脉血气 Sa O2 为“金标准”,计算 Se O2 、Sm O2 的绝对偏差与相对偏差。结果　 110 0 %纯氧吸入时 ,Se O2 、Sm O2 和 Sa O2 均为 10 0 % ;在低氧发生时 Se O2 10 0 %下降到90 %比 Sm O2 平均提前 (91.0 3± 2 0 .2 3) s,P<0 .0 0 1。恢复供纯氧后 ,Se O2 上升早于 Sm O2 ,平均提前 (2 5 .9± 6 .0 ) s,P<0 .0 5。 2 Se O2 与 Sa O2 、Se O2 与 Sm O2 有良好的相关关系 ,R2 分别为 0 .9884和 0 .92 96。 Sm O2 与 Sa O2 相对偏差与绝对偏差是 7.6 %和 6 .1% ;Se O2 与 Sa O2 相对偏差与绝对偏差 :1.6 %和 1.3%。 3MAP、HR、ECG、Pet CO2 、T变化无统计意义 (P>0 .0 5 )。结论　

Transesophageal Arterial Oxygen Saturation Monitoring: An Experimental Study

OBJECTIVE: To assess the sensitivity and accuracy of a novel transesophageal approach to monitoring the descending aortic oximetry (SeO2). METHODS: Nine dogs were involved in the experimental study. After the induction of anaesthesia, the carrier of the oximetry probe (Nellcor-D20, USA) was inserted into the lower segment of esophagus to monitor SeO2, and the probe was "locked" in position of post-descending aorta after the opening of thoracic cavity. Another probe was pasted on the surface of lingual mucous membrane. The readings and figures of SeO2 and surface of lingual mucosa oximetry (SmO2) were observed continuously and recorded simultaneously. Vital signs were monitored with pulse oxygen saturation (SpO2), invasive blood pressure by femoral artery, HR, EKG, PetCO2, T, FiO2. The SaO2 of blood gas analysis by femoral artery was used as the "gold standard" to calculated the relative and absolute deviations of SeO2 and SmO2. The changes of SeO2 and SaO2 were compared in case of acute hypoxia when values of SmO2 dropped to 90%, 80%, 70%, 60% and the patient was re-ventilated with 100% oxygen. RESULTS: (1) SeO2, SmO2 and SaO2 were 100% when the patients were ventilated with 100% oxygen. During hypoxia, the descent of SeO2 from 100% to 90% was (91.03+/-20.23) s (P<0.001) earlier than that of SmO2. And after re-supply of pure oxygen, the ascent of SeO2 was (25.9+/-6.0) s (P<0.05) earlier than that of SmO2. (2) SaO2 was well related with SeO2 and SmO2 (R2: 0.9884 and 0.9296) respectively. The relative and absolute deviations of SeO2 were 1.6% and 1.3%, while those of SmO2 were 7.6% and 6.1% from arterial blood samples SaO2. (3) There were no significant differences in MAP, HR, ECG, PetCO2 and T. CONCLUSION: This study showed that SeO2 monitoring is sensitive. It could accurately reflect the arterial oxygen saturation not only in normal condition but also during hypoxia and the re-ventilation with 100% oxygen. SeO2 responds faster and is closer to SaO2, compared with SmO2 measurements. This may be an alternative method in the cases where the monitoring of peripheral SpO2 is difficult.