The Influence Of Different Vasoactive Drugs On Oxygenation And Intrapulmonary Shunt During One-lung Ventilation In Patients Undergoing Thoracic Epidural Anesthesia Combined With General Anesthesia

Objective:Explore the influence of different vasoactive drugs on oxygenation and intrapulmonary shunt during one-lung ventilation in patients undergoing thoracic epidural anesthesia combined with general anesthesiaMethods:A prospective randomized controlled study was adopted.In the first stage,15 patients were included.The main observation indexes of the study were the oxygen saturation of the superior vena cava（ScvO₂）,the oxygen partial pressure of the superior vena cava（PcvO₂）,the oxygen saturation of the right atrial vein（SvO₂）,the oxygen partial pressure of the right atrial vein（PvO₂）,and the depth of deep venous catheter placement when the P wave changed significantly in patients with TLV15min、OLV15min、OLV30min、OLV45min、and OLV60min.The corresponding indicators were statistically analyzed.In the second stage,63 patients were randomly divided into 3 groups:control group（C）,thoracic epidural anesthesia combined with phenylephrine group（P+TEA）,thoracic epidural anesthesia combined with norepinephrine group（N+TEA）.The main observation indexes were arterial partial pressure of oxygen（PaO₂）and shunt fraction（Qs/Qt%）at TLV15min、OLV15min、OLV30min,OLV45min、and OLV60min.The secondary observation indexes were the changes of other blood gas analysis parameters at each time point,the dosage of total anesthetics during operation,the dosage of vasoactive drugs、the dosage of epidural ropivacaine and fentanyl in P+TEA group and N+TEA group,and the changes of blood pressure after 10 minutes of epidural dose,the extubation time after operation,the visual analogue scale（VAS）score of pain in cough and active state at 6h、12h、24h、36 h、and 48h after operation,the use of postoperative remedial analgesics,and the adverse reactions after operation（nausea,vomiting,skin itching,urinary retention,hypotension）and their incidence.The corresponding indicators of each group were statistically analyzed.Results:The first stage of patients with superior vena cava oxygen saturation（ScvO₂）and right atrial oxygen saturation（SvO₂）correlation was significant,r=0.775,superior vena cava partial pressure of oxygen（PcvO₂）and right atrial partial pressure of oxygen（PvO₂）correlation was significant,r=0.907,patients height and P wave significantly changed the depth of deep venous catheter placement correlation was significant,r=0.873.In the second stage,the dosage of propofol in P+TEA group and N+TEA group was significantly lower than that in C group（P=0.012,P=0.001<0.05）,and the dosage of remifentanil was significantly lower than that in C group（P=0.036,P=0.010<0.05）.There was no significant difference in SBP,DBP,MAP,HR,Paw,SpO₂,PaCO₂,Hb,PvO₂,SvO₂,PH among the three groups（P>0.05）.At OLV 15 min,PaO₂ in P+TEA group and N+TEA group was significantly lower than that in C group（P=0.028,P=0.046<0.05）,and Qs/Qt（%）was significantly higher than that in C group（P=0.018,P=0.027<0.05）.At OLV 45 min,PaO₂ in N+TEA group was significantly higher than that in the P+TEA group,and the difference was statistically significant（P=0.035<0.05）.At OLV15min,Paw,Qs/Qt of three groups were higher than TLV15min（P<0.05）,PaO₂,PvO₂,SaO₂,SvO₂ were lower than TLV15min（P<0.05）;At OLV30min and OLV45min,PaO₂ in N+TEA group was higher than OLV15min（P<0.05）,At OLV45min,PaO₂ in P+TEA group was higher than OLV15min（P<0.05）.PaO₂ in the C group began to increase after 45 min of OLV;There was significant difference in postoperative extubation time among the three groups（P=0.006<0.05）.Compared with group C,the extubation time of group P+TEA and group N+TEA was significantly shortened,and the difference was statistically significant（P=0.007,P=0.009<0.05）.The VAS scores at 6h,12h,24h,36h and 48h after operation in P+TEA group and N+TEA group were significantly lower than those in C group（P<0.05）.The postoperative analgesic application rate and the incidence of postoperative nausea and vomiting in the P+TEA group and the N+TEA group were lower than those in the C group（P=0.000,P=0.000<0.05）,and the difference was statistically significant.Conclusion:.1.The use of phenylephrine and norepinephrine may improve the oxygenation of patients with thoracic epidural anesthesia combined with general anesthesia,and the effect of norepinephrine may be greater than phenylephrine;2.The analgesic quality of thoracic epidural anesthesia is better than intercostal nerve block+intravenous analgesia,but it may have a certain inhibitory effect on hypoxic pulmonary vasoconstriction,resulting in increased intrapulmonary shunt and oxygenation damage.Patients who may develop hypoxemia during one-lung ventilation should be used with caution;3.There is a significant correlation between ScvO₂ and SvO₂,PcvO₂ and PvO₂ in patients undergoing thoracic surgery,ScvO₂ and PcvO₂ can be used as good substitutes for the calculation of shunt fraction.