In this post, I link to and excerpt from The Use of Handheld Ultrasound Devices in Emergency Medicine [PubMed Abstract] [Full-Text HTML] [Full-Text PDF]. Curr Emerg Hosp Med Rep. 2021;9(3):73-81. doi: 10.1007/s40138-021-00229-6. Epub 2021 May 11.
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All that follows is from The Use of Handheld Ultrasound Devices in Emergency Medicine [PubMed Abstract] [Full-Text HTML] [Full-Text PDF]. Curr Emerg Hosp Med Rep. 2021;9(3):73-81. doi: 10.1007/s40138-021-00229-6. Epub 2021 May 11.
Abstract
Purpose of review:
Ultraportable handheld ultrasound (HHU) devices are being rapidly adopted by emergency medicine (EM) physicians. Though knowledge of the breadth of their utility and functionality is still limited compared to cart-based systems, these machines are becoming more common due to ease-of-use, extreme affordability, and improving technology.
Recent findings: Images obtained with HHU are comparable to those obtained with traditional machines but create unique issues regarding billing and data management. HHU devices are increasingly used successfully to augment the education of practitioners-in-training, by emergency physicians in austere environments, and in the burgeoning fields of “tele-ultrasound” and augmented reality scanning.
Summary: This review seeks to describe the current state of use of HHU devices in the emergency department (ED) including device overview, institutional concerns, unique areas of use, recent literature since their adoption into clinical EM, and their future potential.
Keywords: Emergency medicine; Emergency ultrasound; Handheld ultrasound; POCUS; Pocket ultrasound; Portable ultrasound.
Introduction
Point-of-care ultrasound (POCUS) is ubiquitous in emergency departments (EDs) and recognized as standard of care in the workup of multiple disease processes encountered by the emergency physician (EP). In addition to its recognition as a workhorse for diagnosis and procedural guidance, POCUS is increasingly used by other medical specialties, ancillary staff, and first responders. POCUS is increasingly used outside the clinical setting as a tool for teaching practitioners-in-training with ultrasound instruction integrated into medical school curricula.
Technological advances have led to the introduction of truly handheld ultrasound (HHU) into the POCUS market [1•]. With smaller footprints, user friendly interfaces, and lower price points, the broad appeal of these devices is clear. However, as with most emerging technology in healthcare, the advent of HHU devices brings a host of clinical and academic potential as well as new challenges and complex questions about the handling of patient data.
While numerous HHU devices are available, and large, robust data to support their interchangeable use with the traditional machines is lacking [2, 3••], the American College of Emergency Physicians (ACEP) released a consensus statement recognizing HHU-generated images as “comparable” to those of traditional machines [1•, 2–4]. In order to better navigate the myriad handheld devices, this paper will serve as an overview of what is currently known about HHU devices: the mechanics of how they work, nuances of their use in practice, how they compare to traditional machines, and what this technology portends for the future of POCUS in the ED and beyond.
Devices
Several HHU devices are currently available. A comparison of specifications between several devices can be found in Fig. Fig.1.1. The image-generating technology between handhelds and traditional machines is similar with one exception. To create ultrasound images, traditional cart-based ultrasound systems and most handhelds use piezoelectric crystal technology. The product from Butterfly Network Inc., however, utilizes capacitive micromachined ultrasound transducers on complementary metal oxide semiconductors, or CMUT-on-CMOS technology. CMUTs replace the traditional vibrating piezoelectric crystals with oscillating drums embedded in a single silicon chip, serving the same function of converting electricity into sound waves [4, 5]. In addition to decreasing the cost of production, this technology allows a single device to operate at a wider range of frequencies, negating the need for multiple probes [5].
Understanding the benefits and limitations of HHU is critical to its proper use in the clinical arena. In the same way a POCUS examination is not a comprehensive evaluation, HHU excels when used to evaluate well-defined clinical questions in a manner that respects the limitations of this new technology [3••, 5].
A primary benefit to HHU is that it is readily available to the clinician for every patient encounter. Starting as low as $2000, these devices are the cheapest available ultrasound (US) systems, opening the door for widespread use in medical education, resource-limited settings, or to any clinician who performs POCUS examinations [2, 3••, 6, 7].
Image quality of HHU has a foundation of published literature establishing its non-inferiority to cart-based machines for POCUS applications1, though anecdotally HHU-generated images are subjectively of lesser quality (Fig. (Fig.2)2) [2, 4, 5, 8–10••]. A notable exception is that CMUT-on-CMOS (i.e., Butterfly iQ) technology has minimal published comparisons against traditional machines. Advanced echocardiographic applications are also lacking in the HHU world. Focused cardiac US can still be qualitatively performed with HHU, but few current devices offer spectral Doppler capabilities, thus precluding their use for quantitative applications [5, 8, 11, 12•, 13].
Image Storing and Sharing
Archiving images and clips for all POCUS exams is best practice and required for billing. HHU devices offer novel solutions to image archiving [5, 8]. When deciding between local PACS vs. cloud-based storage, most of the handheld devices allow either option [2]. Choosing the local storage option most closely mirrors existing workflows with cart-based machines and likely allows more seamless integration with existing PACS systems. Cloud-based image archiving on the other hand prompts important questions about ownership of images, HIPAA compliance, and security of images.
Billing
Per ACEP guidelines, “ultrasound is a separate entity from the physical examination that adds anatomic, functional and physiologic information to the care of the acutely-ill patient” [24]. Comparisons to stethoscopes are inaccurate, as ultrasound presents a new set of data separate from the physical examination that requires archiving and quality assurance [25]. Similar to other procedures, appropriate performance and interpretation of ultrasound requires training, skill development, feedback, credentialing, and time to complete the study. Therefore, imaging studies completed with handheld devices should continue to be billed as independent procedures and not regarded as an extended physical examination [1, 24].
Ownership of the device impacts the type of billing allowed. Hospital device ownership is preferable, allowing billing for both facility and professional fees [2]. It is unlikely that the facility fee can be billed for devices owned by individuals or physician groups. Facility fees are needed to support overhead costs of machine purchases, EMR integration, maintenance, and workflow solutions. This also has the potential to create confusion for coding and billing companies, as device ownership may not be readily apparent [2]. Without approval from hospital administration, IT, security, and legal departments, ACEP’s stance is that personally owned devices should not be used clinically [1•]. Overall, it is recommended that the hospital purchase both the HHU transducer and the device with which it will be used—this will allow for both the professional and technical fees to be charged without changes to extant billing structures [2].
Current Use of HHUs in the ED
POCUS applications in the ED using traditional cart-style machines are well established as standard of care for the management of certain disease processes [24]. Use of HHU devices in the ED is currently informed by mostly small, single-center studies with few randomized control trials (RCTs) available at this time. Nonetheless, the limited data from these studies is promising [3, 8, 31–35]. A retrospective study evaluating POCUS lung scores obtained from ED COVID-19 patients using a Butterfly iQ HHU and traditional GE Venue machine reported a high degree of correlation between images [31]. Two other studies using HHU to differentiate the cause of acute dyspnea in the ED found HHU use feasible for this purpose and demonstrated reliable discrimination between cardiac and non-cardiac causes of dyspnea [33, 34]. Pujol et al. determined that it is feasible to diagnose proximal deep vein thrombosis by performing venous compression studies with a HHU device [32]. Another small RCT found no difference between HHU and traditional machines when used to guide EPs placing IJ central lines on training models [35]. Similarly, a small retrospective study found HHU devices feasible to use for ultrasound-guided paracentesis [36].
Though evidence on HHU use for traditional POCUS applications in the ED is sparse, handhelds already demonstrate great potential to change specific areas of EM practice. One such area is within the scope of ED patient resuscitation. Though no large studies have been performed assessing the non-inferiority of HHU for rapid evaluation ED patients in this context, it stands to reason that smaller, portable equipment would be beneficial in these circumstances. Some data exists that hints HHU would perform adequately as a stand-alone device if used during resuscitation efforts. Previous comparison studies between HHU and standard machines reported general agreement for evaluation of left ventricular ejection fraction, pericardial effusions, and inferior vena cava collapsibility, three clinical questions frequently evaluated by EPs attending critically ill patients [37]. Another study found the results of focused assessment with sonography in trauma (FAST) assessments of trauma patients performed by EPs using HHU devices correlated well with findings from radiologist performed abdominal ultrasounds that immediately followed, suggesting that HHU performs as well as standard machines for this application [38].
Conclusion
The potential benefits of a handheld advanced imaging system are undeniable. With further technologic developments, the gap in functionality between handheld and cart-based systems will continue to decline.
