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Three Part Question

In a [patient presenting with a traumatic chest injury] is a [normal clinical examination and normal oxygen saturations on air] sufficient to rule out a [traumatic pneumothorax]?

Clinical Scenario

A 45 year old man presents having been assaulted the day before. He has no signs of external injury to his chest and is in significant discomfort. He denies shortness of breath, he has a normal respiratory examination and his pulse oximetry registers 99% on air. Does he require a chest radiograph to rule out a traumatic pneumothorax?

Search Strategy

Medline 1966-05/2003 using the ovid interface.
[(exp PNEUMOTHORAX /OR pneumothorax.mp. ) AND (exp "Wounds and Injuries"/ OR trauma$.mp.) AND (examination.mp. OR exp PHYSICAL EXAMINATION/ OR clinical sign$.mp OR ga$.mp. OR blood ga$.mp. OR arterial ga$.mp. OR exp RADIOLOGY/ or Radiology.mp. OR exp RADIOGRAPHY THORACIC/ or chest x-ray.mp. OR chest xray.mp. ) AND (chest.mp. OR exp THORAX/ OR thora$.mp)] LIMIT to human AND English language

Search Outcome

184 Papers were found of which 4 were deemed relevant for inclusion.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Wall SD, Federle MP, Jeffrey RB, Brett CM 1983 USA	35 patients with a pneumothorax on CT scans after blunt abdominal trauma.	Retrospective	Numer of pneumothoraces diagnosed prior to CT.	10 cases not diagnosed previously by clinical examination or plain radiographs. Clinical examination not sensitive for diagnosis of pneumothorax.	Abdominal trauma, findings of pneumothorax mostly incidental on CT scan.
Hirshberg A,Thomson SR, Huizinga WK 1988 South Africa	51 patients with penetrating chest trauma	Small prospective case cohort.	Whether clinical examination predicted finding of large pneumothorax or haemothorax	13 out of 14 large pneumothoraces or haemothoraces predicted on clinical examination before CXR. Sensitivity 96%, Specificity 93%. 30 out of 71 had pathology missed.7 out of 71 had isolated pneumothoraces missed.	Small numbers. Only patients with substantial penetrating trauma included.
Chen SC. Markmann JF. Kauder DR. Schwab CW. 1997 Taipei	118 penetrating chest injuries of which 71 patients had either a pneumothorax, haemothorax or pneumohaemothorax	Retrospective review	Accuracy of auscultation in picking up pneumothoraces	Auscultation missed pneumothoraces up to 28% in volume by Rhea's method. Auscultation 58% sensitive and 98% specific for all three chest injuries.	Retrospective. Penetrating trauma. Not specific to pneumothorax
Holmes JF, Sokolove PE, Brant WE, Kuppermann N. 2002 USA	986 patients admitted with blunt chest trauma in children under 16. 80 patients of 986 had thoracic injuries. 20 patients had pneumothoraces .	Prospective	Odds ratio for findings on auscultation and examination.	Auscultation (Odds Ratio 8.6) and examination (Odds Ratio 3.6) predictors of thoracic trauma	Paediatric population. Focused on all types of thoracic trauma. Numbers not large enough for pneumothorax based conclusion.
			Clinical decision rule produced	Only 35% of pneumothoraces detected on auscultation

Comment(s)

There are very few studies relevant to this question. There are no studies looking at the relative sensitivities and specificities of oxygen saturation in the diagnosis of traumatic pneumothorax. There are several studies that have looked at findings on clinical examination [2,3,4] however these are not specific to pneumothoraces, and mostly concern major penetrating trauma [2,3]. One study, in the paediatric population showed 65% of pneumothoraces were missed by chest ausculatation [4]. It would seem that neither a normal clinical examination or normal oxygen saturations are sufficient to rule out a radiologically visible traumatic pneumothorax. Whether the two together are sufficient is not clear and has not been investigated.

Clinical Bottom Line

A normal paO2 on air and normal clinical examination are probably not sufficient to rule out a traumatic pneumothorax

References

1. Wall SD, Federle MP, Jeffrey RB, Brett CM. CT diagnosis of unsuspected pneumothorax after blunt abdominal trauma. American Journal of Roentgenology. Nov.1983;141(5):919-21.
2. Hirshberg A. Thomson SR. Huizinga WK. Reliability of physical examination in penetrating chest injuries. Injury 19(6):407-9, 1988 Nov.
3. Chen SC. Markmann JF. Kauder DR. Schwab CW. Hemopneumothorax missed by auscultation in penetrating chest injury. Journal of Trauma-Injury Infection & Critical Care. 42(1):86-9, 1997 Jan.
4. Holmes JF, Sokolove PE, Brant WE, Kuppermann N. A clinical decision rule for identifying children with thoracic injuries after blunt torso trauma. Annals of Emergency Medicine. 39(5):492-9, 2002 May.