The Protective Effect Of Remote Ischemic Preconditioning On Lung After Thoracoscopic Lobectomy

Objective:Previous studies have confirmed that limb remote ischemic preconditioning（RIPC）can induce organ protection against ischemia and hypoxia by regulating nervous,body fluid,immune and other mechanisms.This study intends to explore the influence of RIPC on perioperative oxygenation parameters and lung injury-related indicators in patients with thoracoscopic lobectomy and the possible mechanism through a randomized controlled study.To provide some clinical reference for perioperative lung protection strategy.Methods:Fifty-four patients who were suffered from thoracoscopic lobectomy were selected according to the inclusion and exclusion criteria.They were randomly divided into preconditioning group（RIPC group）and blank control group（NC group）.There were 27 patients in each group.Limb RIPC intervention was performed after anesthesia induction and before surgery.Limb RIPC used limb ischemia preadaption instrument to inflate to 200 mm Hg on the opposite thigh of the patient during surgery,at the lower margin 4～5 cm away from the knee joint.After blocking the lower limb blood flow for 5 minutes,the cuff was relaxed and reperfused for 5 minutes,and 5consecutive cycles were carried out.At the same time,the limb ischemia preadaption instrument was also placed on the thigh of the NC group,but it was not inflated.Four time points were observed after anesthesia induction（T0）,OLV for 30 min（T1）,OLV for 90 min（T2）,and restoration of double lung ventilation for 30 min（T3）.In this study,the main observation indicators were oxygenation index（OI=Pa O₂/Fi O₂）at the above four time points,while the secondary observation indicators were mainly club cell secreted protein CC16,biomarker of lung injury,inflammatory factor interleukin-6（IL-6）and serum malonaldehyde（MDA）.Other variables related to the lungs(respiratory index（RI）,alveolar-arterial oxygen partial pressure A-a DO₂,arterial-alveolar oxygen partial pressure ratio（a/A ratio）,and blood p H.At the same time,the demograp Hic characteristics of the patients were recorded.Heart rate,mean arterial pressure,plateau pressure and peak airway pressure at the above four time points were recorded.The operation time,single lung ventilation time,urine volume,blood loss,length of hospital stay and incidence of pulmonary complications were recorded.Results:There were no significant differences between the two groups in terms of demograp Hic data（age,sex,body mass index,etc.）,duration of anesthesia,duration of one-lung ventilation,duration of surgery and urine volume（P>0.05）.In our primary outcome measures,oxygenation index（OI）was not significantly different between the two groups（P>0.05）,but the OI of RIPC group showed an increased trend at 30 min（T1）,90 min（T2）,and 30 min（T3）restoration of double-lung ventilation,compared with NC group.In the secondary observation indicators,the changes of plasma CC16 were significantly different between the two groups at each time point from T1 to T3.Plasma CC16 content at the RIPC group was significantly lower than NC group after single lung ventilation（all P<0.05）.Similarly,plasma MDA and IL-6 contents in RIPC group were significantly lower than those in NC group at various time points from T1 to T3,and the differences between the two groups were statistically significant（all P<0.05）.Arterial p H,Pa CO₂,lactic acid and lung-related variables（respiratory index（RI）,alveolar-arterial oxygen partial pressure difference（A-a DO₂）and arterial-alveolar oxygen partial pressure ratio（A/a ratio））were similar between the two groups at each observation point（all P>0.05）.There was no significant difference between the two groups in alveolar-arterial oxygen partial pressure（A-a DO₂）,butcompared with the NC group,A-a DO₂ showed a downward trend at T1-T3 time points in the RIPC group.There was no significant difference in arterial-alveolar oxygen partial pressure ratio（a/A ratio）between the two groups,but compared with the NC group,the a/A ratio also showed a downward trend at T1 and T2 time points in the RIPC group.In addition,in heart rate,mean arterial pressure,plateau pressure and peak airway pressure,there were no significant differences between the two groups at each time point from T0 to T3（P>0.05）.There were no significant differences in PACU duration,incidence of lung-related complications,and length of hospital stay（P>0.05）.Conclusion:Our study shows that RIPC can significantly reduce serological indexes related to lung damage during single lung ventilation during lobectomy,thus producing lung protection,which may be mainly through reducing inflammatory response and oxidative stress response.