Pleural Puncture that Excludes the Ablation Zone Decreases the Risk of Pneumothorax after Percutaneous Microwave Ablation in Porcine Lung

Abstract

Purpose To test the hypothesis that the geometry of probe placement with respect to the pleural puncture site affects the risk of pneumothorax after microwave (MW) ablation in the lung. Materials and Methods Computed tomography–guided MW ablation of the lung was performed in 8 swine under general anesthesia and mechanical ventilation. The orientation of the 17-gauge probe was either perpendicular (90°) or parallel (< 30°) with respect to the pleural puncture site, and the ablation power was 30 W or 65 W for 5 minutes. After MW ablation, swine were euthanized, and histopathologic changes were assessed. Frequency and factors affecting pneumothorax were evaluated by multivariate analysis. Results Among 62 lung MW ablations, 13 (21%) pneumothoraces occurred. No statistically significant difference was noted in the rate of pneumothorax between the perpendicular and the parallel orientations of the probe (31% vs 14%; odds ratio [OR], 2.8; P = .11). The pneumothorax rate was equal for 65-W and 30-W ablation powers (21% and 21%; OR, 1.0; P = .94). Under multivariate analysis, 2 factors were independent positive predictors of pneumothorax: ablation zone inclusive of pleural insertion point (OR, 7.7; P = .02) and time since intubation (hours) (OR, 2.7; P = .02). Conclusions Geometries where the pleural puncture site excluded the ablation zone decreased pneumothorax in swine undergoing MW ablation in the lung. Treatment planning to ensure that the pleural puncture site excludes the subsequent ablation zone may reduce the rate of pneumothorax in patients undergoing MW ablation in the lung.

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“…Additionally, the total number of pleural punctures in each case is unknown, which may confound the analysis of complications. Finally, recent literature suggests that avoiding the ablation zone with pleural puncture may reduce pneumothorax after microwave ablation, which was unknown at the outset of this study, possibly increasing the complication rate (33).…”

Risk prediction of pneumothorax in lung malignancy patients treated with percutaneous microwave ablation: development of nomogram model

“…Previous studies have found that ablation zones, which include the pleural puncture site, are associated with pneumothorax [31]. Therefore, an indirect approach that leaves at least 2 cm of normal aerated lung between the lesion and pleura is recommended [32].…”

Microwave Ablation in Primary Lung Malignancies

“…The trajectory is planned to traverse the least number of pleural surfaces possible, as this has been shown to decrease the rate of pneumothorax, 29 and to keep the pleural puncture site as far as possible from the ablation zone, as this has been shown to decrease the rate and severity of pneumothorax. 30 For lesions in the periphery of the lung (►Fig. 1), these considerations mean that it is often better to approach the lesion tangentially from a distant pleural puncture site rather than a perpendicular puncture directly through the pleura and into the nodule.…”