Chest
Volume 108, Issue 5, November 1995, Pages 1345-1348
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Clinical Investigations in Critical Care
A Bedside Ultrasound Sign Ruling Out Pneumothorax in the Critically III: Lung Sliding

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Study objective

To describe and evaluate an ultrasound pattern useful in the diagnosis of pneumothorax.

Design

Ultrasound examination of “lung sliding,” a respiratory movement visible when investigating the chest wall.

Setting

The medical ICU of a university-affiliated hospital.

Patients

The study group included 43 proved pneumothoraces, either by chest radiograph (n=40) or by CT (n=3). The control group included 68 hemithoraces in which the absence of pneumothorax was proved by CT.

Intervention

Analysis of anterior chest wall in supine patients.

Measurements and results

Feasibility was 98.1%. Disappearance of “lung sliding” was observed in 100% of 41 analyzable cases of pneumothorax vs 8.8% of the hemithorax without pneumothorax (6 of 68). In this series, sensitivity was 95.3%, specificity 91.1%, and negative predictive value 100% (p<0.001).

Conclusions

Ultrasound was a sensitive test for detection of pneumothorax, although false-positive cases were noted. The principal value of this test was that it could immediately exclude anterior pneumothorax.

Section snippets

Methods

We have studied 43 pneumothoraces in 42 consecutive, critically ill patients: idiopathic (n=15), iatrogenic (n=11), complicated thoracic trauma (n=2), adult respiratory distress syndrome (ARDS) (n=10), or chronic lung disease (n=4). Average age was 42 years (range, 21 to 75 years). Seventeen patients (40.4%) developed pneumothorax while receiving mechanical ventilation.

We considered as a specific sign of pneumothorax a displacement of the visceral pleura from the parietal pleura by air within

Results

Investigation of the anterior lung/wall interface was possible in 109 of 111 hemithoraces: in two patients, pneumothorax was associated with parietal emphysema, and the lung/wall interface was not analyzable.

Anterior “lung sliding” was absent in 100% of the other 41 proved pneumothoraces, each time over an anterior area larger than three intercostal spaces. Anterior “lung sliding” was present in 91.1% of the hemithoraces in the control group, ie, 62 of 68. In six cases, it was absent without

Discussion

The lung is usually considered poorly accessible to ultrasound. Indeed, the ultrasound image is herein exclusively composed of artifacts, because air stops the progression of the ultrasound beam (Fig 1). The lung is, however, a vital organ. In our study, ultrasound was able to detect at least one elementary sign, probably due to the movement of the lung toward the abdomen during inspiration and vice versa.

The first description of the role of ultrasound in the diagnosis of pneumothorax was given

Conclusions

Ultrasound visualization of “lung sliding” was always correlated with the absence of pneumothorax. From this elementary sign alone, it was possible to exclude at least anterior pneumothorax, promptly and at the bedside of a mechanically ventilated patient. This was the major finding of this study.

The absence of “lung sliding” was suggestive, but not sufficient to affirm pneumothorax. Life-threatening pneumothorax in patients in the ICU is often extensive, with at least anterior involvement. In

Acknowledgments

We are grateful to David Marsh for his precious help in the elaboration and translation of this work. We thank Prof François Jardin for his advice. The CTs were recorded in the Department of Radiology of Prof. Pascal Lacombe, to whom we are grateful.

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