Three Part Question
In [patients with suspected pneumothorax] is [transthoracic ultrasound or chest x-ray] better at [detecting the pneumothorax].
A 26-year-old man presents to the ED with a history of blunt trauma to the left trunk. Clinical signs are inconclusive and a supine chest x ray (CXR) demonstrates no pneumothorax. A subsequent CT scan demonstrates a left anterior pneumothorax. You have heard that focused thoracic ultrasound can detect pneumothorax and wonder whether this imaging modality is superior to plain x ray and whether there is any evidence to support this.
Medline search via NELH from 1950 until November 2008.
[(exp PNEUMOTHORAX/) OR (exp PNEUMOTHORAX, ARTIFICIAL/) ] AND [exp RADIOGRAPHY, THORACIC/] AND [(exp ULTRASONOGRAPHY/) OR (ultrasound.ti,ab) OR (sonography.ti,ab)]
29 papers were found of which 6 papers were relevant
|Author, date and country
||Study type (level of evidence)
|Sartori et al|
|285 patients post lung biopsy of whom 8 developed pneumothorax||Prospective
||USS vs CXR, if disagree CT requested.||Sensitivity 100% vs 87.5% CXR. Specifity 100% vs 100% CXR.||-Low prevalence of pneumothorax in study population (2.8%)
-No gold standard in study group
(only one CT)
|Chung et al |
|97 post needle aspiration and lung biopsy: of whom 35 developed Pneumothorax||Prospective diagnostic study
||USS vs CXR, CT as gold standard||Sensitivity 80% vs 47% CXR. Specificity 94% vs 94% CXR.||-Small study
|Blaivas et al |
|176 non-consecutive blunt trauma patients||Prospective diagnostic study
||Pneumothorax on CT or rush of air on insertion of chest drain USS vs CXR||Sensitivity 98.1% (89.9-99.9) USS vs 75.5% (61.7-86.2) CXR. Specificity 99.2%(95.6-99.9) USS vs 100% (97.1-100) CXR.||-Convenience sampling|
|Kirkpatrick et al|
|225 post-trauma patients||Prospective diagnostic study||Pneumothorax on USS v CXR, CT part of composite standard ||Sensitivity 48.8% (33.3-64.5) USS vs 20.9% CXR. Specificity 98.7% (96.1-99.7) USS vs 99.6% (97.5-100) CXR.||-Unclear whether the investigators were blinded|
|Knudtson et al|
|328 consecutive trauma patients||Prospective diagnostic study||USS v CXR ||Sensitivity 92.3% (74.4-97.9) USS. Specificity 99.7% (98.9-99.9) USS.||-Not clearly blinded
-CXR used as gold standard.
|Dulchavsky SA et al,|
|382 stable surgical patients (95% post-traumatic)||prospective diagnostic study||USS v CXR ||Sensitivity 95%(89-95) Specificity 100% (99-100) ||-Only stable patients were recruited
-CXR used as gold standard
These studies were relatively small and only two were obviously blinded. The sensitivity of transthoracic ultrasound for the diagnosis of pneumothorax varied between 58.9% and 100% and specificity varied between 94% and 100%. The CT gold standard was used in four studies. In such cases CT may be able to find small pneumothoraces not visible on CXR. The clinical relevance of such small pneumothoraces in the resuscitation room is debatable (unless intermittent positive pressure ventilator is being considered). There is agreement on diagnostic ultrasonographic signs used to confirm pneumothorax. These papers suggest that transthoracic ultrasound is a superior modality for the diagnosis of pneumothorax, especially when the patient must remain supine. All ultrasound examinations are known to be operator dependent. These studies do address the training requirements for clinicians wanting to perform this investigation.
Clinical Bottom Line
ED transthoracic ultrasound is better than plain
x ray in the diagnosis of pneumothorax in the
supine patient. CT thorax is the gold standard
Level of Evidence
Level 2 - Studies considered were neither 1 or 3.
- Sartori S, Tombesi P, Trevisani L et al. Accuracy of Thoracic Sonography in Detection of Pneumothorax After Sonographically Guided Comparison with Chest Radioigraphy. American Journal of Roentgenol 2007;188:37-41
- Chung MJ, Goo MJ, Im JG, Cho MJ, Kim JS. Value of high resolution ultrasound in detecting a Pneumothorax. Eur Radiol 2005;15:930-935
- Blaivas M, Lyon M, Duggal S. A Prospective Comparison of Supine Chest Radiography and Bedside Ultrasound for the Diagnosis of Traumatic Pneumothorax. Academic Emergency Medicine 2005; 12(9): 844-850
- Kirkpatrick AW, Sirois M, Laupland KB et al. Hand-held Sonography for detecting post-traumatic pneumothoraces: The extended focussed assessment with sonography for trauma (FAST). J Trauma 2004;57:2
- Knudtson JL, Dort JM, Helmer SD, & Smith RS. Surgeon-performed ultrasound for pneumothorax in the trauma suite. J Trauma 2004 2004;56:527-530
- Dulchavsky SA, Schwarz KL, Kirkpatrick AW et al. Prospective evaluation of thoracic ultrasound in the detection of pneumothorax 6. Dulchavsky SA, Schwarz KL, Kirkpatrick AW et al. Prospective evaluation of thoracic ultrasound in the detection of pneumothorax. J Trauma 2001. 50; 201-205. 2001. 50:201-205