Pneumothoraces on Computed Tomography Scan: Observation using the 35 Millimeter Rule is Safe

Abstract

ABSTRACT Introduction The management of a pneumothorax (PTX) either by observation or with a tube thoracostomy (TT) has long been dictated by practitioner discretion rather than objective criteria. Many physicians elect to routinely place a TT for traumatic PTX, particularly when patients undergo positive pressure ventilation (PPV). Placement of unnecessary TT exposes patients to avoidable morbidity and may prolong hospitalization. Based on prior work establishing a cutoff, we hypothesized that all PTXs ≤35 mm in patients who have no physiologic derangement may be safely observed without TT regardless of the need for PPV. Materials and methods Retrospective review of all patients diagnosed with a PTX between 1/2009 and 2/2013. All PTXs visible on chest computed tomography (CT) were identified. Any patient with an associated significant hemothorax or those patients who were moribund were excluded. All PTXs were measured by measuring the perpendicular distance of the largest air pocket between the chest wall and the mediastinal or pulmonary structure. Management of the PTX was categorized as observation or TT. Observed PTXs were labeled as success or failure with failure defined as enlargement of the PTX or physiologic deterioration, requiring a TT. Results Out of 165 PTXs, 17 (10.3%) measured >35 mm, whereas 148 (89.7%) measured ≤35 mm. Of the 17 > 35 mm, 15 (88.2%) received immediate TT. Of the two PTXs >35 mm which were observed, one received a delayed TT for a pleural effusion (6 days after PTX diagnosis) and one (5.9 %) was safely observed. Of the 148 PTXs which measured ≤35 mm, 10 (6.8%) received immediate TT. Of the 138 remaining PTXs, 129 (93.5%) were safely managed without TT. Six (4.3%) of the PTXs initially observed eventually required TT placement for enlargement of the PTX. Only one of those six had manifested ongoing desaturations prior to TT. The remaining three cases received TT for reasons unrelated to the PTX. Of the 27 PPV cases in the ≤35 mm cohort, none contributed to the six failures. A cutoff measurement of 35 mm demonstrated a negative predictive value (NPV) of 95.7% in its ability to predict successful observation of the PTX with an area under the receiver operating characteristic (ROC) curve of 0.90. Conclusion All PTXs measuring ≤35 mm perpendicular to the chest wall without physiologic derangement may be safely observed independent of the need for mechanical ventilation. How to cite this article Cropano C, Mesar T, Turay D, King D, Yeh D, Fagenholz P, Velmahos G, de Moya MA. Pneumothoraces on Computed Tomography Scan: Observation using the 35 Millimeter Rule is Safe. Panam J Trauma Crit Care Emerg Surg 2015;4(2):48-53.