| PARTIFactors Influencing Pain Related to Microwave Ablation of Lung Tumor by Computed Tomography GuidanceBackground:Reported by the latest research statistics,primary lung cancer ranks the first in both morbidity and mortality in China.Early lung cancer patients can obtain a long-term survival after radical resection.However,some patients with early lung cancer did not meet surgical eligibility criteria due to older age,locally advanced disease,poor cardiopulmonary function,or other medical comorbidities.Meanwhile,lung is also the second most common metastatic site of solid malignant tumors in the human body.Percutaneous thermal ablation by imaging guidance is the most commonly alternative local treatment for pulmonary malignancy,which mainly includes radiofrequency ablation and microwave ablation.Microwave ablation,compared with radiofrequency ablation,is recently recommended for lung tumors as a result of its higher thermal efficiency,larger ablation zone and lower heat-sink effect.CT is correspondingly the preferred image guidance mode for lung tumor ablation on account of its hypersensitivity in pulmonary structure.Pain is a common adverse reaction to all thermal ablation for lung tumor nearby pleura or chest wall,because abundant somatosensory nerve branches parietal pleura and chest wall,contrary to the visceral pleura and lung parenchyma.Severe pain reduced the operative tolerability in patients,forcing the operator to change the treatment plan or suspend the procedure.The research team planned to devise a study on relieving the pain during the microwave ablation of lung tumors.It was found that few relevant research on the risk factors associated with ablative pain were reported.Adequate assessment of the risk factors is essential to sufficient pain relief.Therefore,we will firstly analyze risk factors for pain during microwave ablation of lung tumors in this study.Objective:Retrospectively evaluated and determined the relevant data related to microwave ablation of lung tumor.Analyzed the risk factors for ablation-related pain.Methods:A total of 92 consecutive patients were enrolled from August 2017 to November 2018,who underwent CT-guided microwave ablation of lung tumor in our institute.The inclusion criteria were as follows:(1)The pulmonary tumors met one of the following conditions:1)Pathologically confirmed as pulmonary malignancies but no surgical indications;2)Highly suspected metastasis in lung;3)Residual or new malignant nodules;4)High-risk pulmonary nodules after MDT discussion;(2)No localized treatment before ablation;(3)At least 6 months of progression free survival.Exclusion criteria:(1)Short-term progression of diseases;(2)Intravenous anesthesia or general anesthesia was performed;(3)Repeating ablations for the same lesion;(4)Multiple procedures in a single operation.We collected relevant clinical data and determined underlying contributing factors to the ablation-related pain.The factors are as follows:(1)Patient parameters included gender,age,smoking history,lung disease and treatment history;(2)Lesion parameters included diameter,density,depth,pleural findings and juxta-tumor vessels;(3)Ablation parameters included ablation needle diameter,ablation power,puncture route,and treatment group;(4)Pain VAS scores during microwave ablation.0?4 scores were defined as mild pain and 5-10 scores were defined as severe pain.Patients were classified into two groups with mild or severe pain.Each factor above was assessed by univariate analysis.Multivariable logistic regression analysis was performed for various factors related to pain in ablation.Statistical analysis was performed by using SPSS 21.0(IBM,Inc,Chicago,IL).A p<0.05 was considered to be statistically significant.Results:All microwave ablations of lung tumors were successfully completed,and no serious complications or ablation-related deaths were occurred.PFS of all patients was more than 6 months,meeting the technical success requirements.The VAS scores of all patients were 4.0±2.1,ranging from 0 to 8,60 patients in mild pain group and 32 patients in severe pain group.Univariate analysis suggested that gender(p=0.108),smoking history(p=0.136),depth(p<0.001)and pleural findings(p=0.004)were determined underlying risk factors for pain.Multivariate regression analysis showed that gender and depth were independent factors for pain in microwave ablation(p<0.05).The depth of lesion and pain score were analyzed by linear regression,and the regression equation was established:Y=-4.0×X+26.6,where X was the ablation pain VAS score and Y was the depth of lesion.It was intuitively observed that the pain VAS score was significantly higher in the depth range of 0?10mm than in other depth ranges,through the box diagram of depth and VAS scores(p<0.001).Conclusions:1.Multivariate regression analysis showed that gender and the depth of lesions were independent risk factors for pain in ablation.2.Severe pain could be occurred by microwave ablation of tumors within 10mm from the pleura,which was significantly higher than other sites.Part ?Research on Artificial Pneumothorax Technique Applied in Microwave Ablation of Subpleural Lung TumorsBackground:According to the results of the Part ? in this study,we observed that the depth of lesions and gender were independent risk factors for pain in microwave ablation of lung tumors.Severe pain could be occurred by microwave ablation of the pulmonary tumor within 10mm from the pleura.In this study,the pulmonary tumor within 10mm from the pleura needed to be treated as independent object for research on reducing pain.General anesthesia is the most commonly used treatment mode for thermal ablation,but risk factors such as advanced age,poor pulmonary function and severe cardiopulmonary diseases limit the application of general anesthesia,and many CT interventional departments in China do not have conditions for general anesthesia.Limited literature researches have reported that creation of an artificial pneumothorax for thermal ablation of lung tumors can effectively relieve pain.However,the above studies were only restricted to the effect of artificial pneumothorax on pain relief and safety as well as small samples enrolled.Based on the results in the research of Part I,this study will discuss the application value of artificial pneumothorax in microwave ablation of lung subpleural tumors.Objective:Aim to evaluate the feasibility,safety and efficacy of artificial pneumothorax for CTguided percutaneous microwave ablation of subpleural tumors.Methods:A retrospective analysis was performed on 71 patients with 71 subpleural tumors,who were enrolled into this study and underwent CT-guided microwave ablation with or without creation of artificial pneumothorax in our institute from December 2018 to November 2020.The inclusion criteria were as follows:(1)The depth of lung tumor was no more than 10mm.(2)The diameter of lung tumor was no more than 20mm.(3)The pulmonary nodules met one of the following conditions:1)Pathologically confirmed as pulmonary malignant nodules but no surgical indications;2)Highly suspected metastasis in lung;3)Residual or new malignant nodules;4)High-risk pulmonary nodules after MDT discussion;(4)No localized treatment before ablation.(5)ECOG<3.(6)Expected life span>1 year.Exclusion criteria:(1)Serious lung diseases,including chronic obstructive pulmonary disease,pulmonary fibrosis,etc.;(2)Uncorrected blood abnormalities or severe coagulation disorders;(3)Poor cardiac function(NYHA class ??)or PCI within 3 months;(4)Psychotic patients with uncontrolled behavior or unconsciousness.The enrolled patients were divided into treatment group and control group.Patients in treatment group underwent microwave ablation of pulmonary tumor after performing artificial pneumothorax under CT guidance.Patients in control group suffered conventional CT-guided microwave ablation of lung tumor.A detailed treatment plan was made before ablation,including ablation time,power,operative position,puncture site,puncture route,etc.In the treatment group,microwave ablation antenna firstly punctured in place completely according to the preoperative plan.The artificial pneumothorax was administrated to expand the pleural cavity space around the lesion about 5?10mm.Ablation of tumors was performed after artificial pneumothorax.A CT scan should be performed at each ablation cycle,until the ablation zone completely covered the lesion and expanded ablative margin at least 5mm.Residual gas in the pleural cavity must be removed immediately after ablation.All patients underwent chest CT within 48 hours postoperatively to determine ablation zone and exclude delayed complications.All patients were in hospital for observation at least 24 hours.Patient demographics,characteristics of target lesions were recorded.Pain VAS scores were assessed and recorded respectively,during the MWA procedures,at 6 hours and 24 hours after the procedures.Data related to artificial pneumothorax were recorded and statistically analyzed,including success rate of artificial pneumothorax,amount of gas injected,separation distance of visceral parietal pleura,oxygen saturation of patients before and after artificial pneumothorax and time spent for developing artificial pneumothorax.The ablation time,total ablation tracks and ablation zone in two groups were measured and recorded.The incidence of complications and postoperative observation time in hospital in two groups were recorded.Local control rate and survival were recorded by following-up at 1,3,6,and 12 months postoperatively,and at least every 6 months thereafter.Independent sample T test was applied to evaluate the pain VAS scores between two groups.Pearson correlation analysis was used to evaluate the pain and influencing factors.The incidence of complications between the two groups was analyzed,and the difference in pleural effusion and observation time was compared between the two groups by Chi-square test.Kaplan-Meier function was used to analyze and draw the local control curves of lesions in the two groups.p<0.05 was statistically significant.Results:No statistical difference between the two groups by characteristic baseline was observed.All microwave ablations of lung tumors were successfully completed,and no serious complications or ablation-related deaths were occurred.In the treatment group,the success rate of artificial pneumothorax was 94.7%(36/38),the average operating time was 20.8±4.8 minutes,the average volume of pneumothorax was 225.0±104.5ml,the average separation distance of visceral pleura was 6.7±2.1mm,and the oxygen saturation before and after the establishment of artificial pneumothorax was 98.3±0.7%vs 96.6±2.0%(p<0.001).Ablation time in the treatment group was 4-24min,with an average of 10.1± 6.1 min.In the control group,the ablation time ranged from 1 to 23min,with an average of 7.8±4.4min(p=0.080).The average ablation tracks were 2.1±1.2 in the treatment group and 1.6±0.9 in the control group(p=0.078).The average ablation zone in the treatment group was 33.6±8.0mm and the mean ablation zone in the control group was 29.25±6.8mm(p=0.017).There was significant statistical difference in ablation zone between the two groups.In treatment group,the VAS scores during the ablation,at 6 hours and 24 hours after the procedures were 1.8±1.1,1.2±0.9 and 1.0±0.8,respectively;5.7±1.6,3.3±1.5 and 2.3±1.1,correspondingly,in control group.There was significant difference between the two groups(p<0.001).Pearson correlation analysis showed that there was no correlation between the pain VAS scores with the depth of lesion and gender in treatment group.In the control group,intraoperative pain VAS scores were significantly correlated with depth of lesion(r=-0.658,p<0.001)and gender(r=0.348,p=0.040),pain VAS scores at postoperative 6 hours were significantly correlated with depth of lesion(r=-0.474,p=0.004).Iatrogenic pneumothorax treated with catheter drainage occurred in 5 patients(13.1%)in the treatment group,and 4 patients(11.4%)in the control group(p=0.755).One pulmonary infection was occurred in the treatment group,one pleural reaction and one pleural hemorrhage were observed in the control group.The incidence of pleural effusion was 13.8%(5/36)in the treatment group and 37.1%(13/35)in control group(p=0.024).The mean observation in hospital in the treatment group was 3.0±1.0 days and 3.9±1.1 days in control group(p=0.001).According to follow-up results,local control rate of 1 month,3 months,6 months and 12 months in the treatment group were 100%,100%,100%and 96.5%,respectively.Correspondingly,97.1%,94.3%,88.6%and 82.1%in the control group.There was significant difference in local control rate between the two groups(p=0.042).Conclusions:CT-guided artificial pneumothorax significantly relieves pain during microwave ablation of subpleural lung tumors,improves patient's tolerability and ablative efficiency.In addition,the creation of artificial pneumothorax has a high success rate and low complications.Therefore,it is a feasible,safe and effective CT interventional assistant technology for microwave ablation of lung tumors. |
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