- •
Thoracic ultrasonography (US) provides a better and faster diagnostic alternative to traditional radiographic techniques in the dyspneic and critically ill patient.
- •
Traditional resources on bedside US emphasize that the lung is not an organ amenable to US evaluation. Over the last few years, this claim has been shown to be false, and many pulmonary applications have become widely prevalent in clinical use.
- •
US can be used in the evaluation for pneumothorax, pleural effusions, pulmonary edema,
Thoracic Ultrasonography
Section snippets
Key points
Introduction: thoracic ultrasonography - its history and evolution
In the past, ultrasonography (US) was a relatively neglected aspect of bedside emergency ultrasound (EUS). Due to increased resistance in the passage of sound waves through the air-filled lung, image acquisition and interpretation can be challenging. However, sound waves can easily travel through fluid-filled areas of the chest. Thus, US is more sensitive than chest radiographs for detecting disease such as pleural effusions.1 In addition, US guidance has been found to offer a dramatic decrease
Case presentation
A 64-year-old woman with a history of hypertension, congestive heart failure (CHF), chronic obstructive pulmonary disease (COPD), and intravenous drug use (IVDU) presented to the emergency department (ED) with severe and sudden dyspnea, which progressed over 15 minutes while at rest. The patient did not have relief after paramedics administered albuterol by nebulizer, high-flow oxygen, aspirin, and nitroglycerin.
On evaluation, the patient was in obvious respiratory distress, in the tripod
Benefits of thoracic US
Dyspnea is a common complaint in the ED and is disproportionately involved in higher-acuity patients.7 The Centers for Disease Control document that more than 3.5 million visits each year are made to US EDs with a chief complaint of dyspnea.8 Accurate and rapid diagnosis is paramount to making correct treatment and disposition decisions. Dyspneic patients often find it difficult to relate the full details of their history. Furthermore, their physical examination findings often have poor
US probe selection for thoracic applications
Traditionally, lung US was performed with an intermediate frequency US probe at 5 to 7 MHz.3, 12 Because many US systems in use in the ED and intensive care unit (ICU) do not have this probe, more modern sonographic studies emphasize use of either the high-frequency 10-MHz to 13-MHz linear array probe or the 3-MHz to 5-MHz phased-array probe for pulmonary applications.
Normal lung US anatomy
US techniques for assessment of the lung rely on the imaging of the pleural line, which represents the interface of the visceral and parietal pleura of the lung closely opposed to one another. In normal lung, the pleural line is found just deep to the ribs and appears as an echogenic horizontal line that moves back and forth as the patient breathes. It often has a shimmering or twinkling appearance known as lung sliding. The comet-tail artifact is another sonographic finding seen in normal lung
Imaging for pneumothorax (PTX)
Patients with PTX may have rapid decompensation, necessitating acute management with placement of a needle or tube thoracostomy. Chest radiographs have served as the traditional diagnostic test for this disease in both medical and trauma patients. However, they have limited sensitivity, because air released from a PTX typically accumulates in the nondependent anterior-medial and apical aspects of the thoracic cavity, areas that are difficult to evaluate on chest radiography.16
Although CT is the
Imaging for pleural effusion
Pleural effusions are common manifestations of both pulmonary and systemic diseases. Patients with significant pleural effusions may be in acute respiratory distress and require immediate diagnosis, as well as expedited drainage of the fluid. Although chest radiography has been the reference screening test for pleural effusion, portable films may miss significant amounts of fluid.30 Upright and lateral films aid in the detection of smaller effusions. The generally recognized amount of fluid
US-guided thoracentesis and thoracostomy
US can be used to guide thoracentesis and tube thoracostomy placement. During a thoracentesis, the pleural effusion can first be examined for septations or loculations, which may suggest a more complicated procedure (Figs. 19 and 20). The British Thoracic Society recommends that pleural effusions amenable to safe thoracentesis have at least a 10 mm depth, resulting in sufficient separation of the lung from the outer parietal pleura.39 The movement of lung should also be viewed over a full
Imaging of pulmonary edema/CHF
Acute decompensated heart failure is the most common cause of hospital admissions in patients older than 65 years, accounting for greater than 1 million hospitalizations annually in the United States alone.43 Chest radiography is relatively specific (76%), but poorly sensitive (67%), for pulmonary edema.44 The result is that the clinician may have diagnostic uncertainty in diagnosing this condition in up to one-third of patients presenting with acute dyspnea.45 US techniques used in the
US evaluation of COPD
As life expectancy increases, COPD and CHF are becoming more prevalent and may coexist in a subset of patients. With sometimes very similar acute presentations, the physician must correctly differentiate between these 2 different pathophysiologic processes. Although there are no definitive US markers for COPD, the A-lines that are seen in normal lung may be more prominent with COPD. Of more help to the clinician is the lack of identifiers suggesting an alternative diagnosis (i.e., B-lines).52
US evaluation of PNA
PNA comprises both accumulation of alveolar fluid and consolidation within the lung. Although a common diagnosis in the acute care setting, it is not always noted on chest radiographs and may be confused with other disease.54 However, as lung consolidation progresses, this organ becomes fluid filled and more compact.
Lung masses
Lung masses may also be detected on thoracic US.4 Lung masses are more easily visualized if they are peripherally located close to the pleura or are large. Lung masses appear similar to consolidated lung, taking on the appearance of hepatization with the look of a liver in the chest. M-mode may be used to further discriminate a mass from fluid (Fig. 28).
US evaluation of successful endotracheal intubation
Thoracic US has also been used during endotracheal intubations.6, 61 With US, an esophageal intubation that must be quickly recognized and removed can be easily distinguished. An esophageal intubation has the appearance of 2 discrete round structures within the neck, because the ETT is seen within the esophagus as 1 circular structure posterolaterally to the round, anteriorly located trachea (Fig. 29). This structure is best evaluated by placement of the high-frequency linear array probe in a
Role of thoracic US in resuscitation of the critically dyspneic patient
Several resuscitation techniques now emphasize both thoracic and lung US techniques in the resuscitation of the critical patient with acute shortness of breath.64 These protocols include the BLUE (Bedside Lung Ultrasound in Emergency) protocol and the RADIUS (Rapid Assessment of Dyspnea with Ultrasound) protocol.65, 66 The BLUE protocol focuses on placement of the probe on 3 distinct areas of the chest to diagnose PTX, pulmonary edema, pulmonary consolidation, and effusions. The RADIUS protocol
Case discussion follow-up
On arrival to the ED, the patient was noted to be in severe respiratory distress and preparations for intubation were made. A bedside US was performed immediately and showed significant B-lines in 6 of the 8 chest zones bilaterally, associated with small pleural effusions, normal lung sliding, and comet-tail artifacts. Evaluation of the heart showed normal left ventricular contractility, without pericardial effusion or evidence of right heart strain. Electrocardiography did not show any signs
Summary
Bedside point-of-care thoracic US is a tool that may easily be used to evaluate the critically ill patient presenting with acute dyspnea or shortness of breath, because it can rule in and rule out a wide variety of emergent conditions. As detailed in the case presentation and in this article, US is useful in a wide range of pulmonary disease, including PTX, pleural effusions, pulmonary edema, PNA, lung masses, and COPD. In addition, US has been found to be helpful in the guidance of thoracic
References (67)
- et al.
A bedside ultrasound sign ruling out pneumothorax in the critically ill. Lung sliding
Chest
(1995) - et al.
Thoracic ultrasonography for the pulmonary specialist
Chest
(2011) - et al.
Implementation of real-time ultrasound in a thoracic surgery practice
Ann Thorac Surg
(2009) - et al.
Tracheal rapid ultrasound exam (T.R.U.E.) for confirming endotracheal tube placement during emergency intubation
Resuscitation
(2011) - et al.
Identifying high-risk patients for triage and resource allocation in the ED
Am J Emerg Med
(2007) - et al.
Relevance of lung ultrasound in the diagnosis of acute respiratory failure: the BLUE protocol
Chest
(2008) - et al.
A-lines and B-lines: lung ultrasound as a bedside tool for predicting pulmonary artery occlusion pressure in the critically ill
Chest
(2009) - et al.
Factors related to the failure of radiographic recognition of occult posttraumatic pneumothoraces
Am J Surg
(2005) - et al.
How accurate is ultrasonography for excluding pneumothorax?
Ann Emerg Med
(2013) - et al.
Ultrasound detection of the sliding lung sign by prehospital critical care providers
Am J Emerg Med
(2012)
Pneumothorax in the critically ill patient
Chest
COPD can mimic the appearance of pneumothorax on thoracic ultrasound
Chest
Can chest ultrasonography replace standard chest radiography for evaluation of acute dyspnea in the ED?
Chest
“Ultrasound comet-tail figures”: a marker of pulmonary edema: a comparative study with wedge pressure and extravascular lung water
Chest
Bedside ultrasound of the lung for the monitoring of acute decompensated heart failure
Am J Emerg Med
Diagnosis of radio-occult pulmonary conditions by real-time chest ultrasonography in patients with pleuritic pain
Ultrasound Med Biol
lung ultrasound in the diagnosis and follow-up of community-acquired pneumonia multicenter study of pneumonia: a prospective, multicenter, diagnostic accuracy study
Chest
The dynamic air bronchogram: a lung ultrasound sign of alveolar consolidation ruling out atelectasis
Chest
Diagnostic utility and clinical application of imaging for pleural space infections
Chest
Pilot study to evaluate the accuracy of ultrasonography in confirming endotracheal tube placement
Ann Emerg Med
Integrating lung ultrasound in the hemodynamic evaluation of acute circulatory failure (the fluid administration limited by lung sonography protocol)
J Crit Care
Bedside Lung Ultrasound in Emergency (BLUE) protocol: a suggestion to modify
Chest
The rapid assessment of dyspnea with ultrasound: RADIUS
Ultrasound Clin
Value of sonography in determining the nature of pleural effusion: analysis of 320 cases
AJR Am J Roentgenol
Pneumothorax following thoracentesis: a systematic review and meta-analysis
Arch Intern Med
Diagnosing pneumonia by physical examination: relevant or relic?
Arch Intern Med
Bedside lung ultrasound in the critically ill patient with pulmonary pathology: different diagnoses with comparable chest X-ray opacification
Crit Ultrasound J
The comet-tail artifact: an ultrasound sign ruling out pneumothorax
Intensive Care Med
The comet-tail artifact. An ultrasound sign of alveolar-interstitial syndrome
Am J Respir Crit Care Med
Decreased sensitivity of lung ultrasound limited to the anterior chest in emergency department diagnosis of cardiogenic pulmonary edema: a retrospective analysis
Crit Ultrasound J
A prospective comparison of supine chest radiography and bedside ultrasound for the diagnosis of traumatic pneumothorax
Acad Emerg Med
Ultrasound diagnosis of occult pneumothorax
Crit Care Med
Cited by (29)
Bedside Chest Ultrasound in Postoperative Pediatric Cardiac Surgery Patients: Comparison With Bedside Chest Radiography
2022, Journal of Cardiothoracic and Vascular AnesthesiaCitation Excerpt :According to Tusman et al,32 lung ultrasound has favorable features for assessing lung recruitment due to its high specificity and sensitivity to detect lung collapse, together with its noninvasiveness, availability, and simple use. The use of point-of-care ultrasonography to detect intrathoracic pathologies for adult cardiothoracic postoperative patients and critically ill patients has gained popularity over the recent years.5,27,33 The same can be extrapolated to the pediatric age group through the authors' results.
Update on the use of ultrasound in the diagnosis and monitoring of the critical patient
2022, Revista Espanola de Anestesiologia y ReanimacionPoint-of-care lung ultrasound patterns in late third-trimester gravidas with and without preeclampsia
2021, American Journal of Obstetrics and Gynecology MFMCitation Excerpt :Transthoracic point-of-care ultrasonography (POCUS) of the lungs has become a standard technique in critical care and emergency medicine as an adjunct to the physical examination1–3 but has not been thoroughly studied in pregnant women.4 Lung ultrasound (US) can rapidly and accurately diagnose pulmonary pathology at the bedside and allows for immediate correlation of clinical status with imaging findings, facilitating prompt therapeutic management.5,6 In addition, lung US is dynamic and can be repeated throughout the clinical course for monitoring effects of therapy or disease progression without concern for exposure to ionizing radiation.7–10
Disco spotlight sign: A sign that may be useful for diagnosis of pneumomediastinum
2017, American Journal of Emergency MedicineCitation Excerpt :Thus, the diagnosis may need confirmation with CT [2]. Previous literature on ultrasonography of a pneumomediastinum reported difficulty in evaluating the heart due to obscuration by air artifacts [1,2,3]. However, we found that the sonographic B-line obscuring the heart in the systolic phase can be squeezed out laterally in the diastolic phase.
Perioperative anesthesiology ultrasonographic evaluation (PAUSE): A guided approach to perioperative bedside ultrasound
2016, Journal of Cardiothoracic and Vascular AnesthesiaAdvances in Point-of-Care Thoracic Ultrasound
2016, Emergency Medicine Clinics of North AmericaCitation Excerpt :Bedside ultrasound has been a core competency of American Board of Emergency Medicine–accredited emergency medicine training programs since 2008, and most medical schools now have extensive ultrasound education integrated into their curriculum. Although user dependent, in the right hands, ultrasound is more sensitive than chest radiographs for many types of pulmonary pathology1–3 and approaches sensitivities and specificities of CT for pneumonia.4–6 Additionally, it is easily done at the bedside without patient care interruption and can be used in real time to guide procedures (eg, reduction of pneumothorax).
Funding Sources: None.
Conflict of Interest: V. Lobo, D. Weingrow, S.R. Williams, L. Gharahbaghian: None; P. Perera, Educational consultant: SonoSite Ultrasound.