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Three Part Question

In a [patient with chest trauma] can [transthoracic ultrasonography] accurately diagnose [a traumatic pneumothorax]

Clinical Scenario

A 35 year old male is brought into the Emergency department after falling from a height. He is tachypnoeic and tachycardic and has tenderness on the left anterior chest and left upper abdomen. Your department has an ultrasound scanner and this is used to assess the patient's abdomen. You wonder whether it could also be used to diagnose a pneumothorax.

Search Strategy

Medline 1951 to Decemeber 2004 and Embase 1974 to December 2004 using the Dialog Datastar interface.
[(pneumothorax#.W.DE. OR pneumothorax) AND (ultrason$12) AND (wounds.and.injuries#.DE. OR trauma)]
Editors note: In OVID Medline an equivalent search strategy would be:
[exp pneumothorax/ OR pneumothorax.mp] AND [ultras$12.mp] AND [exp wounds and injuries/ OR trauma.mp]

Search Outcome

46 papers were found from the Medline search 42 of which were of insufficient quality or relevance for inclusion. The remaining papers are shown in the table.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Dulchavsky SA et al, 2001, USA	382 stable surgical patients (95% post-traumatic)	prospective diagnostic study	USS v CXR diagnosis	Sensitivity 95% (89-95) Specificity 100% (99-100)	Only stable patients were recruited. CXR used as gold standard
Rowan et al, 2002, Canada	27 patients sustaining blunt chest trauma who had CT scans	Prospective blinded diagnostic study	USS v CT diagnosis	sensitivity 100%(82.6-100) Specificity 94% (82-94)	May have selection bias for large pneumothoraces Small numbers
Knudtson et al, 2004, USA	328 consecutive trauma patients.	prospective diagnostic study	USS v CXR diagnosis	Sensitivity 92.3% (74.4-97.9) Specificity 99.7% (98.9-99.9)	Not clearly blinded. CXR used as gold standard.
Kirkpatrick et al, 2004, Canada	225 trauma patients	Prospective diagnostic study	USS v CT diagnosis or escape of air on thoracostomy	Sensitivity 58.9% (45.0-71.9) Specificity 99.1% (97.6-99.8)	Unclear if CT radiologists blinded to USS. [BUT SEE EDITORS COMMENTS BELOW]

Comment(s)

These studies were relatively small and only two were obviously blinded. Sensitivity for pneumothorax reported varied between 58.9% and 100% and specificity varied between 94% and 100%. It is interesting to note that the study with the lowest sensitivity used CT as part of the gold standard. 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 (IPPV) is being considered). All ultrasound examinations are known to be operator dependent. There is some variation in the ultrasonographic signs used to confirm pneumothorax.

Editor Comment

The following letter was submitted to the EMJ by Dr Kirkpatrick, author of one of the included studies, following the publication of this BET. _________________________________ Dear Editor, We appreciate both the effort towards and the conclusions of the recent Best evidence topic report (BET) by Jaffer and McAuley that concluded that bedside clinician-performed ultrasound may detect post- traumatic pneumothoraces. We hope to take the opportunity to follow up on their comments. In terms of methodology, the CT radiologists were blinded to the results of the US. Most importantly, all US studies were performed as the first imaging study, prior to the availability of any other imaging information. It is a very minor point to note that the country of the study should be Canada. We completely concur that further studies regarding the integration of these techniques into the trauma resuscitation are warranted. _____________________________________ We thank Dr Kirkpatrick for his comments and clarification. Simon Carley BestBets editor

Clinical Bottom Line

Rapid and accurate bedside ultrasound can be performed by emergency physicians to diagnose pneumothorax after chest trauma. The clinical role of this in the resuscitation of trauma patients is not clear.

Level of Evidence

Level 2 - Studies considered were neither 1 or 3.

References

1. Dulchavsky SA, Schwarz KL, Kirkpatrick AW et al. Prospective evaluation of thoracic ultrasound in the detection of pneumothorax. J Trauma 2001. 50; 201-205.
2. Rowan KR, Kirkpatrick AW, Liu D et al. Traumatic pneumothorax detection with thoracic US: correlation with chest radiography and CT--initial experience. Radiology 2002. 225; 210-214
3. Knudtson JL, Dort JM, Helmer SD, & Smith RS. Surgeon-performed ultrasound for pneumothorax in the trauma suite. J Trauma 2004. 56; 527-530.
4. 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;57:288-295.