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Three Part Question

[In adults with thoracic trauma] does [emergency department ultrasonography have better clinical utility than chest x-ray] at [diagnosing haemothorax]?

Clinical Scenario

A patient arrives in the Emergency Department after suffering thoracic trauma. A member of the team suggests using ultrasound to search for the presence of haemothorax, as an extension of the usual FAST assessment. You wonder how accurate the ultrasound would be compared to either the usual initial supine chest x-ray or to a computed tomography which could be performed later in the patients assessment.

Search Strategy

Medline 1966 to present (accessed 29/05/07) using the OVID interface
The Cochrane Library Issue 2 2007
Medline search: thorax.mp or thoraxic.mp or thoracic.mp or emergancy.mp or chest.mp or pulmonary diseases.mp or thoracic lesions.mp or chest disease.mp]AND [radiography.mp or diagnosis/ or diagnosis, computer assisted/ or diagnosis, differential/ or "diagnostic techniques and procedures"/ or diagnostic imaging/ or radiography or radiography, thoracic/ or tomography, x-ray/ or ultrasonography/ or diagnostic techniques, cardiovascular/ or diagnostic techniques, respiratory system/ or diagnostic tests, routine/ or realy diagnosis or computed tomography.mp or CT.mp or thoracic CT.mp] AND [ltrasound.mp or ultrasonography.mp or explode ultrasonography/ or sonography.mp or radiological diagnosis.mp or ultrasonographic.mp or thoracic radiological procedures.mp or emergency ultrasound.mp or transthoracic ultrasound.mp or thoracic ultrasound.mp] AND [Hemathorax.mp or hemothorax.mp or haemathorax.mp or haemothorax.mp or traumatic effusion.mp]
The Cochrane Library:(hemothorax):ti,ab,kw OR (haemothorax):ti,ab,kw

Search Outcome

Altogether 39 papers were found in Medline, of which 34 were irrelevant or insufficient quality. 25 papers were found in Cochrane – the only relevant paper had already been found in Medline. A further paper was found by scanning the references of relevant papers. All relevant papers are summarised in the table below.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Brooks et al, 2004, UK	Patients triaged to the resuscitation room with thoracic trauma (blunt or penetrating). Ultrasound findings were compared against a combination of other diagnostic methods including supine chest x-ray, intercostal drain, computed tomography or tube thoracotomy.	Prospective study	Clinical utility of ultrasound at detecting the presence of haemothorax,	Sensitivity 92%. Specificity 100% Accuracy 98% PPV 100% NPV: 98%	Composite gold standard
Abboud and Kendall, 2003, USA	Blunt trauma patients who underwent computed tomography (CT) scan of their chest as part of their clinical assessment.	Prospective study	Clinical utility of ultrasound	Sensitivity 12.5%. Specificity 98.4%	None of the haemothoraces detected by CT but not on ultrasound were large enough to be clinically relevant The interval between the ultrasound scan and the CT scan was up to 4 hours.
Ma and Mateer, 1997, USA	240 adults (aged 18 yrs +) presenting to the emergency department with a major blunt or penetrating torso trauma. Accuracy of ultrasound compared with that of initial plain supine chest x-ray for the detection of haemothorax using a combination of CT and tube thoracostomy as the gold standard,	Retrospective analysis of a prior prospective study	Clinical utility of ultrasound vs initial plain supine chest x-ray for the detection of haemothorax	Sensitivity 96.2% vs 96.2% Specificity: 100% vs 100% Accuracy: 99.6% vs 99.6%	The same patients as reference 2
Ma et al, 1995, USA	245 adult (18 years +) patients presenting to the emergency department with major blunt or penetrating torso trauma. Ultrasound's diagnosis was compared to a combination of results of other diagnostic techniques including CT scan, supine chest x-ray, formal 2-dimentional echocardiography or tube thoracostomy	Prospective Cohort	Clinical utility of rapid ultrasound assessment at detecting the presence of haemothorax.	Sensitivity 96%. Specificity 100% Accuracy 99%	Composite gold standard
Rothlin et al, 1993, Switzerland	Adults (aged 15 to 88 years) with blunt thoracic or abdominal injuries USS by surgeons compared to the patients clinical outcome and other diagnostic techniques.	Prospective study	Clinical utility of ultrasound to detect haemothorax	Sensitivity 81%	Poor gold standard Not performed by Emergency Physicians Some of the beginner surgeons initially forgot to check for haemothorax, accounting for 5 of the 11 cases of false negative reports by ultrasound. Some of the effusions developed only after the first 24 hours and therefore would not have been visible on the initial ultrasound scan.
Sisley et al, 1998, USA	Patients with suspected blunt or penetrating torso injury who required a chest radiograph for a complete evaluation	Prospective study	Clinical utility of ultrasound vs supine chest x-ray at detecting the presence of haemothorax.	Sensitivity 97.5% vs 92.5% Specificity 99.7% vs 99.7% PPV 97.5% vs 97.4% NPV 99.7% vs 99.1%	The results of ultrasound were compared to those of supine chest x-ray rather than them both being compared to an independent 'gold standard'. Emergency Physicians did not perform the USS Surgeon- sonographers were used as specialist team members, rather than emergency physicians, who are the people most in need of a specific technique they can use to diagnose haemothorax.

Comment(s)

Ultrasound is a sensitive, specific and accurate technique for detecting haemothorax in thoracic trauma patients. CT does detecting some haemothoraces not seen on ultrasound - but in a clinical situation, the two methods are performed on different patient populations and so are not directly comparable. The most clinically relevant diagnostic imaging method with which to compare ultrasound is the supine chest radiograph as they both are performed in the initial assessment of the patient. When compared directly to the supine chest x-ray, ultrasound is shown to be more sensitive at detecting the presence of the haemothorax and is at least as specific and accurate. It also has the added advantage of being able to be performed in much less time, making it a useful diagnostic tool for the early diagnosis of haemothorax. However, it cannot replace the chest x-ray as many other injuries can be show on the chest-ray that cannot be demonstrated by ultrasound.

Clinical Bottom Line

Ultrasound is a sensitive, specific and accurate method to detect the presence of haemothorax in trauma patients. It cannot however, replace chest radiography because there is additional information on the x-ray that ultrasound cannot provide.

References

1. Brooks A, Davies B, Smethhurst M, Connolly. Emergency ultrasound in the acute assessment of haemothorax. Emergency Med Journal 2004:21:44-46.
2. Abboud PA. Kendall J. Emergency department ultrasound for hemothorax after blunt traumatic injury. Journal of Emergency Medicine. 25(2):181-4, 2003 Aug.
3. Ma J, Mateer J. Trauma ultrasound examination versus chest radiography in the detection of hemothorax. Annals of Emergency Medicine. 29(3):312-5; discussion 315-6, 1997 Mar.
4. Ma J, Mateer J, Ogata M, Kefer M, Wittmann D, Aprahamian C. Prospective analysis of a rapid trauma ultrasound examination performed by emergency physicians. Journal Trauma 1995; 38; 979-95.
5. Rothlin M, Naf, R, Amgwerd M, Candinas D, Frick T, Trentz O. Ultrasound in blunt abdominal trauma. J Trauma 1993,34:488-495.
6. Sisley AC, Rozyyeki GS. Rapid detection of traumatic effusion on using surgeon-performed ultrasonography. J. Trauma 1998;44;291;7 1998.