title: Analysis of the factors associated with radiofrequency ablation-induced pneumothorax.
abstract: OBJECTIVE
  To define the characteristics most likely to result in radiofrequency ablation (RFA)-induced pneumothorax.
  
  
  METHODS
  CT-guided RFA was performed in 79 tumours in 55 lungs in 37 patients, 16 were women, mean age 62 years (range 34-83). Three had primary lung cancer, 34 had metastases. The number, size, and location of tumours, electrode type, treatment parameters, length of electrode trajectory through aerated lung, background emphysema, prior interventions, and use of positive-pressure ventilation were analysed. The size, timing of any pneumothoraces, and intervention were recorded.
  
  
  RESULTS
  Pneumothorax occurred in 21 of the 25 lungs treated (38%), 18 immediate and three delayed. Seventeen of the 21 (81%) occupied less than 30% of the hemithorax, whereas in four cases >31% was involved. Eight of the 55 (15%) pneumothoraces required aspiration. The length of the electrode trajectory through aerated lung in those who developed a pneumothorax was 5.4+/-4.7cm versus 1.9+/-2.7 in those who did not (p=0.001). The mean number of tumours ablated was higher in the pneumothorax group, 1.7+/-1 versus 1.3+/-0.6 (p=0.03), as was the number of electrode positions, 6+/-3.9 versus 3.6+/-2.2 (p=0.01). On multivariate analysis only the needle trajectory through aerated lung was significant (p=0.04).
  
  
  CONCLUSIONS
  The number of tumours, electrode positions, and the anticipated electrode trajectory through aerated lung impacts on the likelihood of a pneumothorax. These considerations should be factored into patient selection, the choice of approach, and trajectory used in RFA.
authors.affiliation: UCLH and UCL Medical School, Special Xray, Podium 2, University College Hospital, 235 Euston Road, London NW1 2BU, UK. a.gillams@medphys.ucl.ac.uk
authors.forename: A R
authors.initials: AR
authors.lastname: Gillams
authors.forename: W R
authors.initials: WR
authors.lastname: Lees
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017115:Catheter Ablation / Q000009:adverse effects*; D004566:Electrodes; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011030:Pneumothorax / Q000000981:diagnostic imaging / Q000209:etiology*; D015641:Radiography, Interventional; D012307:Risk Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*