Emergency ultrasound, employing point-of-care ultrasound, is the application of ultrasound at the point of care to make immediate patient-care decisions. It is performed by the health care professional caring for the injured or ill persons. This point-of-care use of ultrasound is often to evaluate an emergency medical condition, in settings such as an emergency department, critical care unit, ambulance, or combat zone.ACEP Policy Statement: Emergency Ultrasound Guidelines. Ann Emerg Med. 2009;53:550–570.Beck-Razi N, Fischer D, Michaelson M et al. The utility of focused assessment with sonography for trauma as a triage tool in multiple-casualty incidents during the second Lebanon war. J Ultrasound Med 2007;26:1149–1156.Stawicki SP, Howard JM, Pryor JP, et al. Portable ultrasonography in mass casualty incidents: The CAVEAT examination. World J Orthopedics 2010;1(1):10–19.
Setting
Emergency ultrasound is used to quickly diagnose a limited set of injuries or pathologic conditions,Atlas of Emergency Medicine. Kevin J. Knoop, Lawrence B. Stack, Alan B. Storrow. McGraw-Hill Professional, 2002., . specifically those where conventional diagnostic methods would either take too long or would introduce greater risk to a person (either by transporting the person away from the most closely monitored setting, or exposing them to ionizing radiation and/or intravenous contrast agents).Emergency Ultrasound: Principles and Practice. Romolo Joseph Gaspari, J. Christian Fox, Paul R. Sierzenski. Mosby, 2005. , 9780323037501.
Point of care ultrasound has been used in a wide variety of specialties and has increased in use in the last decade as ultrasound machines have become more compact and portable.Levin DC, Rao VM, Parker L, Frangos AJ. Noncardiac point-of-care ultrasound by non-radiologist physicians: How widespread is it?. JACR 2011; 8(11):772–775. It is now used for a variety of exams in various clinical settings at the person's bedside. In the emergency setting, it is used to guide resuscitation and monitor critically ill persons, provide procedural guidance for improved safety and confirm clinical diagnosis.
In contrast to a comprehensive ultrasound examination, which is typically performed by a sonographer and interpreted by a specialist, point-of-care ultrasound examinations are performed and interpreted by the same clinician and are typically narrower in scope.
Scope
Resuscitation of the critically ill
Point of care ultrasound is sometimes the only option in the evaluation of injured persons who are too ill for transport to other imaging modalities (i.e. computed tomography, or CT scan) or whose illness is so acute that medical decisions in their care need to be made in seconds to minutes. It is also increasingly used to guide and triage care in resource-limited situations, in rural or medically under-served areas.Dean AJ, Ku BS, Zeserson EM. The utility of handheld ultrasound in an austere medical setting in Guatemala after a natural disaster. Am J Disaster Med. 2007;2(5):249–256.
For people who present signs of traumatic injury, the focused assessment with sonography for trauma or FAST exam is used to assess hypotensive persons for occult bleeding. Traditionally used by emergency physicians and surgeons treating trauma persons, it has also been used by paramedicsWalcher F, Weinlich M, Conrad G, Schweigkofler U, Breitkreutz R, Kirshning T. Marzi I. Prehospital ultrasound imaging improves management of abdominal trauma. Br J Surg 2006;93(2): 238–42. in combat zones, and for non-traumatic problems such as ruptured ectopic pregnancy. Similarly, emergency ultrasound can also evaluate the lungs for hemothorax (bleeding in the chest), and pneumothorax (a puncture resulting in air trapped in the chest and lung collapse).
People presenting with hypotension of unknown cause, ultrasound has been utilized to determine the cause of shock.Rose JS et al. The UHP Ultrasound Protocol: A Novel Ultrasound Approach to the Empiric Evaluation of the Undifferentiated Hypotensive Patient. AJEM; 19(4):299–301.Jones AE et al. Randomized, controlled trial of immediate versus delayed goal-directed ultrasound to identify the cause of nontraumatic hypotension in emergency department patients. Critical Care Med. 2004;32(8):1703–1708. Evaluation of the heart and inferior vena cava (IVC) can help the clinician at the bedside choose important treatments and monitor the response to the interventions.Labovitz AJ et al. Focused Cardiac Ultrasound in the Emergent Setting: A Consensus Statement of the American College of Emergency Physicians. JASE 2010; 23(12):1225–1230.Hernandez C et al. C.A.U.S.E.:Cardiac arrest ultrasound exam—a better approach to managing patients in primary non-arrhythmogenic cardiac arrest. Resuscitation 2008; 76:198–206.
A person who has hypotension and a bedside ultrasound showing hyperdynamic left heart with a flat, collapsible IVC indicates low blood volume. If the person also has a fever, the clinician may determine sepsis, or severe infection is causing the problem. If that same hypotensive person has back pain instead of a fever, the clinician may see an abdominal aortic aneurysm that is leaking or ruptured. Conversely, weak heart activity and a very full, non-collapsible IVC would indicate a cardiac cause for low blood pressure.
For those presenting with acute shortness of breath, ultrasound assessment of the lung, heart, and IVC can evaluate for potentially life-threatening diseases, including pneumothorax, significant pleural effusions, congestive heart failure, pulmonary edema, pericardial effusion, and some large pulmonary emboli (one standardized method is called the BLUE protocol).Litchenstein DA, Meziere GA. Relevance of lung ultrasound in the diagnosis of acute respiratory failure. The BLUE Protocol. Chest 2008; 134(1):117–125.
With its increased availability, ultrasound is now frequently used more in code situations, in which a person have lost most or all signs of life.Blaivas M, Fox J. Outcome in cardiac arrest patients found to have cardiac standstill on bedside emergency department echocardiogram. Acad Emerg Med. 2001;8:616–621. Practitioners may use the ultrasound to see if the heart is moving, beating in organized fashion or if it has a pericardial effusion or fluid around it. Pericardiocentesis, a procedure in which a needle is used to drain the effusion, can utilize ultrasound guidance of a needle to decrease the risk of hitting lungs, heart or other vital organsSalem K, Mulji A, Lonn E. Echocardiographically guided pericardiocentesis – the gold standard for the management of pericardial effusion and cardiac tamponade. Can J Cardiol 1999;15:1251–1255.
Monitoring therapy
Emergency ultrasound can not only diagnose, but also monitor a person's response to therapeutic interventions. Ultrasound can be utilized to assess a person's intravascular volume status and response to intravenous fluid therapy by measuring the size and respiratory change in the diameter of the IVC, including the assessment of central venous collapsibility as a more standardized measure of intravascular volume status.Stawicki SP, Adkins EJ, Eiferman DS, Evans DC, Ali NA, Njoku C, Lindsey DE, Cook CH, Balakrishnan JM, Valiaveedan S, Galwankar SC, Boulger CT, Springer AN, Bahner DP. Prospective evaluation of intravascular volume status in critically ill patients: does inferior vena cava collapsibility correlate with central venous pressure? J Trauma Acute Care Surg. 2014 Apr;76(4):956–963. More recent evidence suggests that ultrasound assessment of more "peripheral" veins (e.g., subclavian, femoral, internal jugular) may also be helpful in estimating intravascular volume status in the absence of IVC visualization.Kent A, Patil P, Davila V, Bailey JK, Jones C, Evans DC, Boulger CT, Adkins E, Balakrishnan JM, Valiyaveedan S, Galwankar SC, Bahner DP, Stawicki SP. Sonographic evaluation of intravascular volume status: Can internal jugular or femoral vein collapsibility be used in the absence of IVC visualization? Ann Thorac Med. 2015 Jan–Mar;10(1):44–49.Kent A, Bahner DP, Boulger CT, Eiferman DS, Adkins EJ, Evans DC, Springer AN, Balakrishnan JM, Valiyaveedan S, Galwankar SC, Njoku C, Lindsey DE, Yeager S, Roelant GJ, Stawicki SP. Sonographic evaluation of intravascular volume status in the surgical intensive care unit: a prospective comparison of subclavian vein and inferior vena cava collapsibility index. J Surg Res. 2013 Sep;184(1):561–566. Ultrasound of the lungs may demonstrate resolution of pulmonary edema from congestive heart failure.Noble VE et al. Ultrasound assessment for extravascular lung water in patients undergoing hemodialysis: time course for resolution. CHEST. 2009; 135(6) 1433–1439.
Procedural guidance
Using ultrasound to guide needles during procedures may improve success and decrease complications in procedures performed by multiple specialties, including central and venous access,Constantino TG et al. Ultrasonography-guided peripheral intravenous access versus traditional approaches in persons with difficult intravenous access. Ann Emerg Med. 2005; 46:456-61.Blaivas M, Lyons M. The Effect of Ultrasound Guidance on the Perceived Difficulty of Emergency Nurse-Obtained Peripheral IV Access. Journal of Emergency Medicine 31(4):407–410. arterial cannulation, thoracentesis,Tayal VS, Nicks BA, Norton HJ. Emergency ultrasound evaluation of symptomatic nontraumatic pleural effusions. American Journal of Emergency Medicine. 2006. 24, 782–786. paracentesis, pericardiocentesis,Nazeer SR, Dewbre H, Miller AH. Ultrasound-assisted paracentesis performed by emergency physicians vs the traditional technique: a prospective, randomized study. Amer J Emerg Med. 2005; 23:363–367. arthrocentesis, regional anesthesia, incision and drainage of abscesses,Squire BT, Fox JC, Anderson C. ABSCESS: Applied Bedside Sonography for Convenient Evaluation of Superficial Soft Tissue Infections. Acad Emerg Med 2005; 12(7): 601–606.Vivek S. Tayal, MD, Nael Hasan, MD, H. James Norton, PhD, Christian A. Tomaszewski, MD The Effect of Soft-tissue Ultrasound on the Management of Cellulitis in the Emergency Department. Acad Emerg Med 2006; 13(4):384–388. localization and removal of foreign bodies, lumbar puncture, biopsies, and other procedures.Moore CL, Copel JA. Point-of-Care Ultrasonography. NEJM 2011; 462(8):749–757.
Diagnostic
Point-of-care ultrasound is being increasingly used to speed patient care and to avoid ionizing radiation (for example, pediatric or pregnant patients). Quick diagnosis is still valuable for both an injured and healthcare professional. The efficiency of obtaining the answer to a focused question within minutes is one of the driving forces of the popularity of bedside ultrasound. Use of this modality in settings such as the emergency department can decrease waiting times and improve satisfaction among those served.Lindelius A, Torngren S, Nilsson L, Pettersson H, Adami J. Randomized clinical trial of bedside ultrasound among patients with abdominal pain in the emergency department: impact on patient satisfaction and health care consumption. Scand J Trauma Resusc Emerg Med. 2009 Nov 27;17:60.
Cardiac: