• 
• 

Three Part Question

Can [bedside ultrasound] sensitively diagnose [occult pneumothorax] in adult patients with [normal chest radiographs]?

Clinical Scenario

A 35-year-old man was sent to the emergency department after being hit by an electric car. He complained of right chest pain, no tenderness in the ribs and normal chest X-ray, but the patient still unwell consider sending him for a chest CT but your colleague told you that you could first scan the chest ultrasound for diagnose occult pneumothorax. You want to know whether patients with negative chest X-ray can diagnose the presence of occult pneumothorax by ultrasound.

Search Strategy

Medline/PubMed Search Strategy(up to - 2024/1/27, 128 results): (((((((normal X-ray[Title/Abstract]) OR (normal chest X-ray[Title/Abstract])) OR (normal X ray[Title/Abstract])) OR (normal Xray[Title/Abstract])) OR (X-ray normal[Title/Abstract])) AND ((((("Pneumothorax"[Mesh]) OR (pneumothorax[Title/Abstract])) OR (Spontaneous Pneumothorax[Title/Abstract])) OR (Tension Pneumothorax[Title/Abstract])) OR (Pressure Pneumothorax[Title/Abstract]))) OR (occult pneumothorax[Title/Abstract])) AND (((((((((((("Ultrasonography"[Mesh]) OR (Ultrasonography[Title/Abstract])) OR (ultrasound[Title/Abstract])) OR (Diagnostic Ultrasound[Title/Abstract])) OR (Diagnostic Ultrasounds[Title/Abstract])) OR (Ultrasound, Diagnostic[Title/Abstract])) OR (Ultrasound Imaging[Title/Abstract])) OR (Echotomography[Title/Abstract])) OR (Medical Sonography[Title/Abstract])) OR (Echography[Title/Abstract])) OR (Diagnosis, Ultrasonic[Title/Abstract])))

Search Outcome

Altogether 128 papers found of which 121 were irrelevant or of insufficient quality for inclusion. The remaining 7 papers are shown below.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Dallis Q. Ngo 2021 USA	A 65-year-old woman who had a bronchoscopic biopsy.	Case	CR	2 times: normal.	Only one case.
			Lung Ultrasound	M-mode: Lung slip sign disappeared.
			Right lateral decubitus CR	The pleural line is visible.
Halil Donmez 2012 Turkey	120 blunt thoracic trauma patients. CT examinations were performed in 68 patients.	Prospective study	CT(-) n=101	93/101 CR(-)/Ultrasound(-) 3/101 CR(-)/Ultrasound(+) 5/101 CR(+)/Ultrasound(-)	The sample size is small and the repeatability is uncertain. Chest radiographs of all patients were taken in the supine position.
			CT(+) n=35	24/35 CR(+)/Ultrasound(+) 8/35 CR(-)/Ultrasound(+) 3/35 CR(+)/Ultrasound(-)
			occult pneumothorax	8 of the 11 occult pneumothorax were identified by ultrasound. Sen=72.7% Spe=97% (98/101)
Daniel A Lichtenstein 2005 France	200 consecutive undifferentiated ICU patients who received a chest CT scan in addition to ultrasound and CR.	Retrospective study.	CT, CR, Ultrasound	occult pneumothorax group n=43 43/43 Sen=100% Pneumothorax-free group n=302 65/302 Spe=78.5%	A single-center retrospective study.
Shokei Matsumoto 2016 Japan	159 consecutive blunt chest trauma patients were enrolled. Occult pneumothorax group n=70	Retrospective study.	Ultrasound	Anterolateral (n=19): 18/19 Sen=94.7% Anterior (n=32): 24/32 Sen=75% Minuscule (n=19): 2/19 Sen=10.5%	Anterolateral group patients 89.5% need for chest tube, anterior group 40.6%, minuscule group 10.5%. Ultrasound/OXR may be effective at detecting occult pneumothorax with a risk of progression.
			OXR	Anterolateral (n=19): 18/19 Sen=94.7% Anterior (n=32): 22/32 Sen=68.8% Minuscule (n=19): 3/19 Sen=15.8%
Jarrett E Santorelli 2022 California	All 568 patients. 362 pneumothorax patients.	Retrospective study.	CT, CR, Ultrasound	No comparison of ultrasound scans with negative chest radiographs. Only 126/362 use ultrasound diagnosed pneumothorax. Significant Pneumothorax: 111/171 Occult pneumothorax: 15/191	The data in this study were slightly different from those in other studies, and ultrasound was evaluated in emergency bedside trauma ultrasound, not lung ultrasound alone.
Daniel J Jakobson 2022 Israel	80 patients after thoracic surgery.	Blinded, prospective, single-center study	CT, CR, Ultrasound	51 Occult pneumothorax patients.(CT+, but CR-) Ultrasound: 43/51 Sen: 84.3%	The sample size is small.
Gino Soldati 2006 Italy	186 patients with blunt chest trauma	Retrospective study.	CT, CR, Ultrasound	26 Occult pneumothorax patients.(CT+, but CR-) Ultrasound: 25/26 Sen: 96.2% Spe: 100%	The sample size is small.

Comment(s)

These studies are single-center studies, the sample size is small, and the level of ultrasound technology may be inconsistent. One of the articles mentioned that the sensitivity of ultrasound in the diagnosis of occult pneumothorax is very low, and the scenario set in this article is a comprehensive ultrasound evaluation of trauma patients, so the focus on lung ultrasound is short. In addition to this article, other articles have concluded that the sensitivity of ultrasound to occult pneumothorax is between 72 and 94%, especially for patients with catheter drainage and patients with anterolateral pneumothorax.

Clinical Bottom Line

For emergency trauma patients or patients with highly suspected pneumothorax, if CT can not be completed, it is recommended that chest ultrasonography should be performed after chest X-ray screening is negative. And it can be re-examined by ultrasound many times to reduce radiation and patient cost.

References

1. Dallis Q. Ngo Dr.
2. Halil Donmez Dr.
3. Daniel A Lichtenstein Dr.
4. Shokei Matsumoto Dr.
5. Jarrett E Santorelli Dr.
6. Daniel J Jakobson Dr.
7. Gino Soldati Dr.