percutaneous radiofrequency ( rf ) ablation is a minimally invasive and nonsurgical technique used to treat various solid tumors .
many studies have shown that this technique is safe and effective in treating hepatic and renal tumors [ 13 ] .
recent investigations of rf ablation s practicability and outcome as a successful method for extricating primary and metastatic lung tumors have been promising [ 48 ] .
studies have shown that rf ablation is evolving into a suitable alternative and adjuvant method to open thoracic surgery of primary and metastatic lung cancer , which is commonly associated with high morbidity and mortality [ 9 , 10 ] . however , there are many issues concerning rf ablation that need to be addressed .
these questions mainly involve patient selection , location and type of lung malignancy , accessibility of the lesion , possible risks for acute and chronic complications and management , and finally , pain management , both during and after the rf ablation . in this article , we present a case that utilized a technique to decrease the pain associated with rf ablation of a malignancy located within the subpleural lung . under ct guidance
, we created an artificial pneumothorax prior to the rf ablation , which resulted in minimizing the pain usually experienced during and after the procedure .
the patient s written informed consent was obtained after the risk , benefits , and alternatives of the procedure were fully explained . a waiver of informed consent
was obtained from the irb for this report . a 43-year - old woman with a history of metastatic colorectal cancer to
the liver , originally diagnosed in 1999 , presented with newly rising carcinoembryogenic antigen ( cea ) , and ct scan of the chest confirmed the development of three new subcentimeter nodules within both lungs .
these nodules were consistent with pulmonary parenchymal metastases : one within the right middle lobe and , notably , two nodules within the anterior segment of the left upper lobe , one within the subpleural aspect of the lobe ( fig . 
due to slow progression of the tumor within the lung , complications of hypercoagulability related to the patient s current systemic chemotherapy and her prior familiarity with rf ablation for at least three hepatic metastases , rf ablation was preferred over surgical metastasectomy.fig . 
a a 22-gauge chiba needle was placed adjacent to the peripherally located metastasis ( white arrowhead : subpleural tumor ) .
b an intentional and iatrogenic artificial pneumothorax was created displacing the visceral pleura ( white arrows : artificial pneumothorax ) .
c enlargement of the artificially created pneumothorax further separated the ablation site from the parietal pleura .
d following completion of the ablation , the tines were retracted and a localized pneumothorax was decompressed by active aspiration using a syringe sequential ct images of radiofrequency ablation of subpleural tumor .
a a 22-gauge chiba needle was placed adjacent to the peripherally located metastasis ( white arrowhead : subpleural tumor ) .
b an intentional and iatrogenic artificial pneumothorax was created displacing the visceral pleura ( white arrows : artificial pneumothorax ) .
c enlargement of the artificially created pneumothorax further separated the ablation site from the parietal pleura .
d following completion of the ablation , the tines were retracted and a localized pneumothorax was decompressed by active aspiration using a syringe the patient was prepped and draped in sterile fashion , and midazolam hydrochlorate ( 1  mg of versed ; roche laboratories , nutley , nj , usa ) , fentanyl citrate ( 25  g of sublimaze ; akorn , buffalo grove , il , usa ) , and diphenhydramine hydrochloride ( 25  mg of benadryl ; pfizer inc . , new london , ct , usa ) were administered intravenously to induce moderate sedation . utilizing the ge hispeed advantage ct scanner ( ge medical systems , milwaukee , wi , usa ) with the patient in the supine position , a 22-gauge chiba needle ( cook , bloomington , in , usa ) was placed adjacent to the peripherally located metastasis within the anterior segment of the left upper lobe via anterior intercostal approach ( fig . 
following ct confirmation of the needle tip , a rita 6.4-fr starburst - xl multiarray electrode ( rita medical systems , mountain view , ca , usa ) was placed so that its leading tip was situated to enter proximally into the parietal and visceral pleura and the underlying lung . based on results by others using iatrogenic pneumothorax for easy access to a tumor [ 1214 ] , we deduced that iatrogenic pneumothorax may decrease pain by separating the two pleural layers or the visceral from the somatically innervated parietal pleura . with slow and deliberate tine deployment to 3  cm ,
an intentional and iatrogenic artificial pneumothorax was created , the tines of the electrode piercing the lung and surrounding the targeted nodule , while displacing the visceral pleura away from the parietal pleura ( fig . 
in order to further enlarge the potential pneumothorax , the deployed electrode was then advanced , ensuring that its 1-cm active tip was entirely within the pleural space and pneumothorax ( fig . 
subsequently , a single rf ablation was performed according to the manufacturer s guide ( fig . 
1c ) . by separating the visceral and somatically innervated parietal pleura with a potential space , we observed very minimal patient discomfort during the ablation session .
in addition , we were still able to achieve effective capture of the targeted nodule within the expanded array , without negatively affecting the patient s oxygen saturation and vital signs .
following completion of the ablation , the tines were retracted with the electrode tip still residing within the pleural space and pneumothorax . with a 20-ml luer lock syringe attached to the side port of the electrode ,
the rf electrode was withdrawn with negative suction applied to the syringe , thereby manually decompressing the associated localized pneumothorax and actively aspirating any potential air leak ( fig . 
the second nodule was then localized with the chiba needle , and via tandem needle technique , the starburst electrode was driven to the nodule , its tines deployed , and the metastasis ablated using standard technique . due to the second nodule s more central location ,
repeat creation of an artificial pneumothorax was not performed . before rf ablation , as the chiba needle was removed ,
intraprocedural ct scans of the thorax showed no air within the pleural cavity following the first ablation and a minimally sized residual pneumothorax following the second ablation , which required no subsequent intervention or further treatment .
postablation ct images demonstrated progressive ground - glass attenuation envelopment of each targeted nodule , suggestive of a successful rf ablation . throughout the rf ablation procedure and postprocedure observation period , the patient s vital signs , including oxygen saturation , remained stable . following the procedure
the patient was discharged on the same day with minimal oral nsaid for pain control .
nine - month follow - up ct images demonstrated dense bands of scarring with signs of shrinkage of ablation - induced areas of necrosis , as well as complete resolution of the pneumothorax .
rf ablation is a minimally invasive and effective method used to treat various tumors by inducing complete coagulation necrosis and cell death of a targeted tumor , with generally few complications .
the physiological heat insulation created by air surrounding the tumor produces more effective thermal energy for complete cell necrosis ; therefore , rf ablation is thought to be a suitable treatment option for pulmonary malignancy . however , the literature on the percutaneous ablation of thoracic tumors , although expanding , is still incomplete , and multiple technical issues require address and optimization .
one issue that has been a constant challenge for rf operators has been patient pain management . for the most part
, rf ablation has been performed as an outpatient procedure , usually under moderate sedation .
operators have at times favored deep sedation and even general anesthesia , particularly in patients with targeted lesions involving the pleura and/or chest wall , and especially in those seeking palliation for pain .
rf ablation - induced pain causes discomfort and agitation for patients during and following the procedure . it can cause a wide spectrum of pain ranging from tolerably mild pain to severe pain requiring high doses of narcotics or sedatives , or even general anesthesia , which necessitates anesthesiology service
one study has shown that rf ablation - induced pain is the second most frequently cited complication of the rf ablation procedure , requiring general anesthesia at their institution . in particular , rf ablation involving the pleural margin , as in our case , has been known to cause more severe pain , usually requiring multiple intercostal nerve blocks or general anesthesia to proceed with the procedure [ 11 , 17 ] .
the consequences of rf ablation - induced pain can present additional problematic issues . with severe intra - ablational pain and its management , subsequent electrode repositioning for overlapping ablations required in larger tumor therapy
may be jeopardized , in that a higher and deeper level of moderate sedation and pain control during the procedure will diminish lung aeration and expansion and patient cooperation .
the technical difficulties encountered in repeated electrode repositioning and deployment may overly lengthen the procedure and induce additional complications , especially in those patients with advanced lung diseases and poor pulmonary reserve , leading to difficult and prolonged recovery . with prolonged postprocedural pain , patients may splint and limit their respiratory excursion . with decreased lung ventilation and clearance function ,
, rf ablation - induced pain reduces the benefits of the noninvasiveness of rf ablation and may cause relatively extended care and potential hospitalization for post - rf ablation pain control .
therefore , the procedure may become less cost - effective and less attractive as an alternative therapeutic method to surgery .
as previously mentioned , rf ablation of tumors involving the pleural margin is known to incite more pain sensors than others .
however , our case presentation has suggested that an artificially created pneumothorax may mitigate the pain for those patients undergoing rf ablation of those types of tumors . in our patient , the amount of sedation ( 25  g of fentanyl and 1  mg of midazolam ) used was substantially less than what is usually required ( 200  g of fentanyl and 3  mg of midazolam ) in our experience .
despite creation of a pneumothorax , the overall procedure time was not significantly increased , since the pneumothorax was established as the electrode was inserted and not beforehand .
overall , complications related to intraprocedural pain and deep sedation are minimized , potentially with better outcomes than with the other conventional methods of treating subpleural tumors .
although our case may suggest benefits of using iatrogenic pneumothorax to reduce the pain , possible risks and limitation must be evaluated .
no major unpredicted complications are expected other than the usual potential complications that rf ablation of the lung may cause . however ,
a larger than planned pneumothorax or a pneumothorax related to an actual air leak may be anticipated .
this may cause respiratory distress , but immediate awareness and treatment should minimize further deleterious respiratory deterioration .
there are reports of utilizing artificially created pneumothorax to reach tumors in other target organs , such as the upper pole of the kidney , the hepatic dome , and the mediastinum / pulmonary hilum   to prevent traversal of aerated lung parenchyma .
however , this is one of the first observations of utilizing an artificial pneumothorax to reduce rf ablation - induced pain in ablation of an intrathoracic intrapulmonary subpleural tumor .
future investigation focused on followings will be useful to potentiate the pain - reducing effect of iatrogenic pneumothorax in lung rf ablation : ( i ) evaluating a cohort of patients utilizing a subjective and objective pain scale , both during and after the procedure ; and ( ii ) investigating how reproducible and feasible this technique is in different clinical settings such as patients with a history of lung / pleural surgery with scarring or patients with emphysematous disease .
 one of the main issues with radiofrequency ( rf ) ablation of the subpleural lung malignancy is pain management during and after rf ablation . in this article , we present a case that utilized a technique to decrease the pain associated with rf ablation of a malignancy located within the subpleural lung . under ct guidance 
 , we created an artificial pneumothorax prior to the rf ablation , which resulted in minimizing the pain usually experienced during and after the procedure . 
 it also decreased the amount of pain medications usually used in patients undergoing rf ablation of a subpleural lung lesion . 
Introduction
Case Report
Discussion