Portable ultrasound technology
Ultrasound is one of the most widely used diagnostic techniques in clinical practice. It is non-invasive, easily available and does not expose patients to ionising radiation. Miniaturised pocket-size ultrasound devices were first launched in 2007 (Siemens Acuson P10). Two years later the first device, including both grey tone imaging and colour Doppler mode, Vscan by GE Vingmed Ultrasound was launched. In 2011, the European Association of Echocardiography stated that pocket-size imaging devices had the potential to change the cardiac imaging workflow. Furthermore, this new technology has the potential to propagate portable ultrasound for diagnostic use and for guidance of procedures across different specialties and clinical scenarios.1,2 The implementation has been rapid and these predictions are about to be fulfilled.
The basis for the success of portable ultrasound devices is the combination of the small size of the device and good image quality. This allows the clinicians to bring the ultrasound device to the patient and perform the ultrasound examination at the patient’s point-of-care. Thus, the physicians or other healthcare providers can add information from the ultrasound examination to the information obtained from the medical history and the physical examination. This may improve clinical decision making.3
An overview of the potential use of the pocket-size imaging devices will be outlined, both with respect to the possible applications and limitations of the portable ultrasound devices. Moreover, some of the different clinical situations where the addition of point-of-care ultrasound examinations has been shown to improve clinical practice will be highlighted.
Devices, cost and quality
Pocket-size ultrasound devices are small so that they fit into a clinical white coat pocket, hence the name “pocket-size imaging device”. They are inexpensive relative to medical technology and the price usually ranges from $7–12,000 (€6–11,000). There are trade offs compared to more expensive high-end systems and pocket-size devices offer limited ultrasound modalities. Currently, spectral Doppler to measure the velocity of blood or moving tissue is not available. All commercially available pocket-size imaging devices have live two-dimensional imaging with possibilities for simple measurements of dimensions and one of the available devices has colour Doppler imaging (Vscan; GE Vingmed Ultrasound). A linear probe for the assessment of more superficial structures (vessels, pleura and lung) is available from one vendor. Most devices are delivered as complete units, but there are units available where the probe is attached to a standard smartphone. The laptop-sized ultrasound devices have a wider choice of possibilities with respect to different modalities and probes, but are usually transported on carts, limiting the availability compared to the pocket-size imaging devices. With respect to image quality, they are inferior to the more immobile high-end scanners, but superior to the pocket-size imaging devices and the cost ranges usually between €20,000 and €70,000.
Application of portable ultrasound in diagnostics and procedure guidance
The ease of use and potential high availability of pocket-size imaging devices allows for a quick and focused assessment of cardiac and non-cardiac structures by implementing the ultrasound examination as an integrated part of the routine physical examination. Furthermore, interventional procedures guided by ultrasound may reduce complications and improve success rates.
By routinely implementing the use of point-of-care pocket-size ultrasound examinations of the heart the diagnostic precision may be improved. A significant proportion of patients with dyspnoea have underlying cardiac dysfunction where an ultrasound examination (echocardiography) may be crucial. A great proportion of these patients are usually cared for by pulmologists and a routine use of ultrasound may improve the diagnostic yield. In cardiac as well as non-cardiac patients, the pocket-size imaging devices enable the clinicians to detect potential cardiac abnormalities, acute or chronic aortic disease, as well as pericardial and pleural effusion. The detection of such pathologies may, in many cases, promptly change the therapeutic strategy, especially in situations where the clinician caring for the patients performs the imaging procedure at the point-of-care. In a number of publications this has been shown for personnel performing echocardiography/ultrasound at different level of skills.4–6 Most of the clinical studies were performed with one specific device (Vscan; GE Vingmed Ultrasound); whether these results can be generalised to other vendors is unknown. However, one of the other scanners (Acuson P10; Siemens Medical Solutions, CA, USA) has been shown to be able to provide information on cardiac structures and function as well.
Different clinical scenarios
Point-of-care ultrasonography is already being used by different specialties, by nurses, GPs and intensivists, in metropolitan hospitals, the third world, rural and remote medicine and war zones.7–11 The spectrum of clinical scenarios and diseases differs between specialties and locations. The implementation of pocket-size imaging devices has been tested in various clinical settings. It has been shown that general practitioners, after a short dedicated training period, were able to obtain a simplified assessment of global left ventricular function with a pocket-size imaging device in patients with manifest or latent heart failure.11 In outpatient clinics and echo laboratories, the use of pocket-size imaging devices has been shown to improve diagnostics and enable the selection for complete echocardiography.4,12–14 Similarly, in a variety of in-hospital settings the significance of point-of-care ultrasound has been acknowledged. Studies from intensive care units, cardiac and surgical departments have shown that point of care echocardiography improved diagnostics and patient care.5,15–18 The main advantage of implementing point-of-care ultrasound is improved diagnostic precision, better selection of patients who need or do not need further diagnostic imaging and guided interventions at a low cost.12,13,16,18
Some illustrations of the clinical use of point-of-care pocket-size ultrasound follow. In patients with dyspnoea, chest X-ray has a low sensitivity to detect cardiac dysfunction, pleural and pericardial effusion. Computed tomography (CT) of the chest is sensitive with respect to detect pleural effusion, but it is insensitive to the detection of cardiac dysfunction. Point-of-care ultrasound performed by both experienced cardiologists and medical residents on the other hand has a high sensitivity for the detection of both cardiac dysfunction and pericardial and pleural effusion. This may serve as a guide for a successful drainage of clinical significant effusions. Even inexperienced non-physician users, like nurses, can be trained to reliably detect, for example, pleural effusion.7 In the intensive care units, a rapid focused echocardiographic examination by intensive physicians was recommended some years ago in the absence of cardiologists with experience in echocardiography. Thus, “Focus Assessed Transthoracic Echo” (FATE) was developed to rapidly exclude obvious cardiac pathology, assess wall thickness and dimensions of chambers, assess contractility and visualise both pleural spaces.19 The information obtained by FATE must certainly be related to the clinical context. Recently, recommendations for focused cardiac ultrasound have been published both by associations of cardiologists and non-cardiologist illustrating that these devices are implemented for cardiovascular assessment not only by cardiologists but also by other clinical specialties.1,20,21
Training of personnel
Non-experts must be trained not only to obtain the relevant information by pocket-size ultrasound, but also how to apply the collected data. For the benefit of the patients, sufficient training and education is mandatory and essential to fully implement this technology in an effective and reliable manner. The training consists of a mixture of didactic education and hands-on training with simultaneous image interpretation. With less experience and more complicated assessments the training programme must be more comprehensive.20
Several international courses are provided for focused ultrasound and an Internet-based educational platform for focused echocardiography is available on the website of the European Association of Cardiovascular Imaging (http://learn.escardio.org/echocardiography/homepage.aspx
). For personnel adequately trained in advanced echocardiography no specific training is needed to perform focused echocardiography.
Historically, both the stethoscope and the echocardiographic examination were met with scepticism and protests before they were implemented as a natural part of the physical examination and care of cardiac patients. The pocket-size imaging device has been hailed as the next generation stethoscope by some, but should rather be considered as an add-on and integrated part of the traditional physical examination.2–4,22 The potential benefit of point-of-care echocardiography and non-cardiac ultrasound has been demonstrated in recent publications, both with respect to patient care, patient workflow and potential reduction of healthcare related costs. The implementation of point-of-care cardiac and non-cardiac ultrasound has just started, but with further research and experience the implementation will probably increase rapidly.
Technological development will continue. Helpful tools implemented in the scanner have been tested and may help inexperienced users to cope with more complicated issues. Several vendors will probably provide high quality devices with more sophisticated modalities, dedicated software and transducers. The mobility of the pocket-size scanners and the format of the recorded images and videos make it possible to obtain the recordings on a remote location and have a secondary judgment at another site, even with smartphones as the communication channel.
The development of pocket-sized, affordable and easy to use ultrasound devices has already spread the use of ultrasound as a diagnostic tool to non-experts and preliminary data suggest that even medical students can be trained in the diagnostic application of ultrasound. Thus, the next generation of medical doctors will probably be increasingly familiar with the use of point of care ultrasound and this may improve the care of our patients.
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