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Three Part Question

In [adult ED patients] is [ultrasound better than plain radiography] in [diagnosing pneumonia?]

Clinical Scenario

A 66 year old man presents to emergency department with cough, shortness of breath and pedal oedema. Clinical examination reveals bilateral fine basal crepitations. You wonder if he has got pneumonia or cardiac failure. He has a background history of cardiovascular risk factors.

Search Strategy

Medline from 1946 to present; Embase from 1974 to present; Cochrane

Pneumonia”[Mesh:noexp] OR “Pneumonia, Bacterial” [Mesh:noexp] OR “Bronchopneumonia”[Mesh] OR “Pleuropneumonia”[Mesh] OR “Severe Acute Respiratory Syndrome”[Mesh] OR “Acute Chest Syndrome”[Mesh] OR “Pneumonia, Aspiration”[Mesh] OR “acute chest syndrome”[tw] OR “acute chest syndromes”[tw] OR “pulmonary inflammation”[tw] OR “pulmonary inflammations”[tw] OR “pulmonary inflammation”[mesh] OR “aspiration pneumonia”[mesh] OR “aspiration pneumonia”[tw] OR “bacterial pneumonia”[tw] OR “bronchiolitis obliterans organizing pneumonia”[tw] OR “bronchopneumonia”[tw] OR “bronchopneumonias”[tw] OR “community acquired pneumonia“[tw] OR “health care associated pneumonia”[tw] OR “hospital acquired pneumonia”[tw] OR “legionnaire disease”[tw] OR “legionnaire s disease”[tw] OR “legionnaires disease”[tw] OR “lobitis”[tw] OR “lung infiltrate”[tw] OR “lung inflammation”[tw] OR “lung inflammation”[tw] OR “Lung Inflammations”[tw] OR “nonspecific inflammatory lung disease”[tw] OR “organizing pneumonia”[tw] OR “peripneumonia”[tw] OR “pleuropneumonia”[tw] OR “pneumonia”[tw] OR “pneumonias”[tw] OR “pneumonic lung”[tw] OR “severe acute respiratory syndrome”[tw] OR “pneumonitis”[tw] OR “lower respiratory tract”[tw] OR “lower respiratory tracts”[tw]) AND (“Ultrasonography”[Mesh:noexp] OR “ultrasonography”[tw] OR “ultrasonographies”[tw] OR “ultrasonic”[tw] OR “ultrasonics”[tw] OR “ultrasound”[tw] OR “ultrasounds”[tw] OR “ultra sound”[tw] OR “ultra sounds”[tw] OR “ultrashell”[tw] OR “ultra shell”[tw] OR “LUS”[tw] OR “sonography”[tw] OR “sonographies”[tw] OR “sonofication”[tw] OR “ultrasonography”[tw] OR “ultrasonographies”[tw] OR “echography”[tw] OR “echographies”[tw] OR “sonogram”[tw] OR “sonograms”[tw] OR “echogram”[tw] OR “echograms”[tw] OR “echoscopy”[tw] OR “echoscopies” [tw] OR “lung ultrasound”[tw] OR”chest ultrasound”[tw] OR “thoracic ultrasound”[tw] OR “lung ultrasounds”[tw] OR “chest ultrasounds”[tw] OR “thoracic ultrasounds” [tw] OR “lung ultrasonography”[tw] OR “lung ultrasonographies”[tw] OR “chest ultrasonography”[tw] OR “chest ultrasonographies”[tw] OR “thoracic ultrasonography” [tw] OR “thoracic ultrasonographies”[tw] OR “lung sonography”[tw] OR “lung sonographies”[tw] OR “chest sonography”[tw] OR “chest sonographies”[tw] OR “thoracic sonography”[tw] OR “thoracic sonographies”[tw] OR “lung echoschopy”[tw] OR 'lung echoscopies”[tw] OR “chest echoscopy”[tw] OR “chest echoscopies”[tw] OR “thoracic echoschopy”[tw] OR “thoracic echoschopies”[tw] OR “lung echogram”[tw] OR “lung echograms”[tw] OR “lung sonogram”[tw] OR “lung sonograms”[tw“chest sonogram”[tw] OR “chest sonograms”[tw] OR “thoracic sonogram”[tw] OR “thoracic sonograms”[tw] OR “lung ultra sound”[tw] OR “chest ultra sound”[tw] OR “thoracic ultra sound”[tw]
The studies included studies on adults, comparing the ultrasound with the radiological imaging. The commentaries, review articles, studies done on paediatric population were excluded.

Search Outcome

65 studies identified and abstracts reviewed leaving 10 for analysis with 6 conducted in ED or medical wards, and 4 in ITU.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Cortellaro F, Colombo S, Coen D, Duca PG 2010 Italy	120 patients with suspected pneumonia admitted to the emergency department were entered the study.	Prospective study in ED setting.	Ultrasound Sensitivity	98%	Expert sonographer.
			Ultrasound Specificity	95%
Benci A, Caremani M, Menchetti D, Magnolfi AL 1996 Italy	80 patients with mean age of 38.5 years were hospitalised with pneumonia symptoms Chest x-ray plus chest CT images were compared with ultrasound findings.	Convenience sample of patients with fever and respiratory signs.	Ultrasound Sensitivity	100%	Not an ED population (performed on infectious diseases unit) - young population with high prevalence (50%) HIV positive. Expert sonographer ("considerable experience"). Reference standard not routinely applied.
Lichtenstein D, et al 2004 France	A sample size of 32 patients with ARDS and 10 healthy volunteers was recruited to compare the diagnostic accuracy of auscultation, bedside chest x-ray, and lung ultrasonography with that of CT chest.	Consecutive recruitment of patients admitted to ITU for therapy of ARDS. US compared to bedside chest radiography with CT chest as reference standard.	Ultrasound Sensitivity	93%	Small sample of ventilated patients with ARDS - not representative of ED population. Expert sonographer (several years US experience).
			Ultrasound Specificity	100%
Lichtenstein DA, et al 2004 France	60 consecutive patients with CT proven alveolar consolidation prospectively enrolled.	Comparison of consolidated lungs to non-consolidated controls was performed. 16 patients with infectious pneumonia as the cause for their consolidation identified.	Ultrasound Sensitivity	90%	Not an ED population (ITU setting with 50% ventilated patients). Expert sonographers (several years of experience).
			Ultrasound Specificity	98%
Lichtenstein DA, Meziere GA 2008 France	260 patients were included in this study, comparing the initial ultrasonography findings with the final diagnosis in ICU.	Observational study of 301 consecutive patients admitted to ITU with acute respiratory failure. 83 patients with pneumonia as the underlying aetiology of their acute respiratory failure.	Ultrasound Sensitivity	89%	Not an ED population (ITU setting). Expert sonographers (several years of experience).
			Ultrasound Specificity	94%
Parlamento S, Copetti R, Di Bartolomeo S 2009 Italy	49 patients were recruited with initial chest ultrasonography followed by chest radiography and computed tomography for the patients with a positive ultrasound and negative chest x-ray.	Convenience sample of patients presenting to "second-level general hospital" ED with clinical signs of CAP.	Concordance between lung US and CXR.	k statistic = 0.63	The study was unblinded, sampling was convenient. Study sample size was small and CT (gold standard) was not performed in all patients. Lacking follow-up if chest US and CXR normal. Expert sonographer (10 years experience of lung US).
Xirouchaki N, et al 2011 Greece	42 patients in ICU had a modified lung ultrasound protocol compared with CT scan for consolidation.	Prospective study of 42 mechanically ventilated patients who all had thoracic contrast CT chest. US and CXR performed prior to chest CT in all cases.	Ultrasound Sensitivity for consolidation	100%	The expertise of the sonographer was not mentioned. Not an ED setting (all patients ventilated on ITU).
			Ultrasound Specificity for consolidation	78%
Reissig A, Copetti R, Mathis G, Mempel C, Schuler A, Zechner P, Aliberti S, Neumann R, Kroegel C, Ho 2012 14 European centres	Three hundred sixty-two patients presenting with community acquired pneumonia were enrolled in 14 European centres, with lung ultrasonography findings compared to either chest x-ray or CT scans.	Prospective observational study of patients with a clinical suspicion of CAP.	Ultrasound Sensitivity	93%	Only two ED (of 14) centres recruited to this study. Expert sonographers (prior experience of >100 chest ultrasonography procedures).
			Ultrasound Specificity	97%
Testa A, et al 2012 Italy	98 consecutive patients seen in the emergency department complaining of influenza-like (H1N1) symptoms were enrolled in the study.	Prospective observational study with ultrasound compared to CT scan and chest x-ray.	Ultrasound Sensitivity	94%	Small sample size (n=34). Expert sonographers (10 years experience of emergency ultrasound).
			Ultrasound Specificity	85%
Unluer E, et al 2013 Turkey	Bedside ultrasound was compared in 72 patients with either chest x-ray or CT for patients presenting to the ED with dyspnoea. Standard 6 hour training program prior to performing chest US.	Prospective observational study.	Ultrasound Sensitivity	97%	Large number of patients excluded (40 from 112 - 35%) mostly due to the presence of heart failure.
			Ultrasound Specificity	84%
			Area under the ROC curve for ultrasound (95% CI)	0.90 (0.81 - 0.96)

Comment(s)

The studies did not mention what lung regions were examined as posterior zones are difficult to assess if patients are bedridden. While there are many studies that have compared ultrasound with CT and chest x-rays, there are not enough large sample studies in ED settings on the role of ultrasound in diagnosis of pneumonia. Many of the studies were performed by experts in chest sonography, which may limit the applicability of this technique. However, ultrasound has high accuracy in diagnosis of consolidation.

Editor Comment

KMJ

Clinical Bottom Line

Bedside ultrasound to look for consolidation is highly sensitive and specific when compared to radiological findings. It is a simple and time effective diagnostic tool that can be employed in the ED setting.

References

1. Cortellaro F, Colombo S, Coen D, Duca PG Lung ultrasound is an accurate diagnostic tool for the diagnosis of pneumonia in the emergency department Emergency Medicine Journal 28th October 2010
2. Benci A, Caremani M, Menchetti D, Magnolfi AL Sonographic diagnosis of pneumonia and bronchopneumonia Eur J Ultrasound 1996; 4:169–176.
3. Lichtenstein D, Goldstein I, Mourgeon E, Cluzel P, Grenier P, Rouby JJ: Comparative diagnostic performances of auscultation, chest radiography, and lung ultrasonography in acute respiratory distress syndrome. Anesthesiology 2004, 100:9–15
4. Lichtenstein DA, Lascols N, Meziere G, Gepner A Ultrasound diagnosis of alveolar consolidation in the critically ill. Intensive Care Medicine 2004, 30:276–281.
5. Lichtenstein DA, Meziere GA Relevance of lung ultrasound in the diagnosis of acute respiratory failure: the BLUE protocol. Chest 2008, 134:117–125.
6. Parlamento S, Copetti R, Di Bartolomeo S Evaluation of lung ultrasound for the diagnosis of pneumonia in the ED American Journal of Emergency Medicine 2009, 27:379–384
7. Xirouchaki N, Magkanas E, Vaporidi K, Kondili E, Plataki M, Patrianakos A, Akoumianaki E, Georgopoulos D: Lung ultrasound in critically ill patients: comparison with bedside chest radiography. Intensive Care Medicine 2011, 37:1488–1493
8. Reissig A, Copetti R, Mathis G, Mempel C, Schuler A, Zechner P, Aliberti S, Neumann R, Kroegel C, Hoyer H: Lung ultrasound in the diagnosis and follow-up of community-acquired pneumonia: a prospective, multicenter, diagnostic accuracy study. Chest 2012, 142:965–972.
9. Testa A, Soldati G, Copetti R, Giannuzzi R, Portale G, Gentiloni-Silveri N: Early recognition of the 2009 pandemic influenza A (H1N1) pneumonia by chest ultrasound. Critical Care 2012, 16:R30.
10. Unluer E, Karagoz A, Senturk G, Karaman M, Olow K, Bayata S: Bedside lung ultrasonography for diagnosis of pneumonia. Hong Kong Am J Emerg Med 2013, 20(2):98.