Emergency Ultrasound: More Than Just F.A.S.T.

Haney Mallemat, MD*
Dartmouth-Hitchcock Medical Center
Lebanon, New Hampshire, USA 

Emergency ultrasound has improved patient care for more than 25 years. While the Focused Assessment of Sonography in Trauma (FAST) examination is one of the original applications, there are many more uses for ultrasound in emergency medicine.(1,2) Ultrasound provides more efficient and safer ways to diagnose and perform procedures. Its role in the assessment of emergency department patients is so interwoven into the discipline, the American College of Emergency Physicians now requires trainees to demonstrate competency before graduation.(3)

As a procedural aid, ultrasound increases safety by identifying anatomical structures to be targeted and those to be avoided. As a diagnostic tool, ultrasound extends the physical examination, allowing real-time assessment of anatomy and function without subjecting the patient to the risk of ionizing radiation. It reduces the need to transport unstable patients to radiology, as assessments can be made at the bedside.(4) There are several applications beyond FAST where ultrasound guidance improves diagnostic and procedural success while minimizing patient risk.

Ultrasound and Lumbar Puncture. Patients with headache, fever and neck stiffness require lumbar puncture as part of the workup. If the patient is morbidly obese, performing the procedure using anatomical landmarks may be difficult. Ultrasound can identify vertebral landmarks and the best needle insertion site,(5-8) which may eliminate multiple “blind” procedural attempts and reduce patient discomfort and injury. Using ultrasound also eliminates the unnecessary ionizing radiation of fluoroscopy that difficult lumbar punctures may require.

Ultrasound and Vascular Access. Central line placement is often required in critically ill emergency department patients for hemodynamic monitoring, vasopressor administration and vascular access. Several studies demonstrate that ultrasound guidance for central line placement improves success rates and reduces the number of attempts, thereby decreasing the number of complications associated with catheter insertion.(9- 12) Given the overwhelming evidence, the Agency for Healthcare Research and Quality has recommended all internal jugular central lines be placed under ultrasound guidance.

Arterial catheterization is also an integral part of managing the critically ill. Placing radial arterial catheters by the traditional “palpation” method can be challenging in patients with obesity, peripheral edema, and/or hypotension with a weak pulse. As a procedural aid, ultrasound reduces complications (e.g., hematoma), time to cannulation, and number of attempts.(13)

Ultrasound and Suprapubic Catheterization. Suprapubic catheters may be required for a variety of clinical conditions (e.g., urethral injury, urethral or prostatic obstruction) in the emergency department. The procedure traditionally has been performed by palpating anatomical landmarks and inserting the introducer needle “blindly” into the bladder, a technique associated with complications, such as hematoma and intestinal perforation.(14) Using ultrasound increases successful catheter placement and reduces complications by visualizing the bladder while avoiding abdominal contents.(15)

Ultrasound and Increased Intracranial Pressure. Early detection of increased intracranial pressure can be difficult during physical examination. Because the optic nerve is a direct extension of the central nervous system, it will be affected by pressure changes within the brain.(16) Studies show that ultrasound measurements of the optic nerve positively correlate with changes in intracranial pressure. This relationship has been found across a variety of conditions and patient populations.(17-20) As a rapid triage tool in the emergency department, ultrasound can be helpful in cases of unexplained altered mental status and/or focal neurologic findings.

Ultrasound and Undifferentiated Shock. Shock is categorized as cardiogenic, distributive, hypovolemic or obstructive; each classification has a different pathophysiology and treatment. All four classes initially may appear similar upon physical examination, and determining the etiology can be challenging. Sustained hypotension is an independent predictor of increased mortality, so early and appropriate treatment of shock is essential.(21) Applying the Rapid Ultrasound in Shock (RUSH) examination can uncover the etiology of shock and promote early goal-directed therapy with a three-step evaluation of “the pump” (limited cardiac echocardiogram), “the tank” (evaluating the inferior vena cava and the pleural and abdominal spaces for volume status), and “the pipes” (visualizing arteries and veins for rupture or obstruction).(22) The RUSH examination is quick, noninvasive and provides vital information to emergency physicians.

Ultrasound and Cardiac Arrest. Patients with non-arrhythmogenic cardiac arrest (pulseless electrical activity or asystole) have poor outcomes because of uncertainty and inability to reverse precipitating causes (e.g., tension pneumothorax, tamponade, hypovolemia).(23) The Cardiac Arrest Ultrasound Exam (CAUSE) is an algorithm performed during resuscitation to uncover potentially reversible causes and facilitate appropriate therapy.(24)

Ultrasound predicts when resuscitation for cardiac arrest will be futile. Blaivas et al demonstrated that the absence of ultrasonographic evidence of cardiac activity in emergency department patients has 100% positive predictive value for death.(25) The cardiac examination is fast and can be performed during cardiopulmonary resuscitation pulse breaks with minimal interruption of resuscitative efforts. The ability to predict futility in these cases helps emergency department clinicians deliver appropriate care to patients.

Ultrasound and Pneumothorax. Pneumothorax secondary to blunt chest injury is not always detected on chest radiograph,(26,27) and chest computed tomography (CT) may be necessary if clinical suspicion is high. CT is costly, exposes patients to ionizing radiation, and requires transport out of the emergency department. The sensitivity of bedside ultrasound for occult pneumothorax is comparable to that of chest CT.(28)

For all pneumothoraces (i.e., occult and non-occult), the sensitivity of ultrasound is better than that of a supine chest radiograph.(29) This, in addition to its rapid application during trauma evaluations, has led to its incorporation into the Extended-FAST (E-FAST) examination used in many emergency departments.(30)

Ultrasound and Deep Vein Thrombosis. Many hospitals do not have a sonographer or radiologist available after hours to test for lower extremity deep vein thrombosis (DVT). Therefore, if an emergency department physician suspects DVT, the patient is often admitted and placed on anticoagulation until definitive testing can be performed. Risks of complications, such as bleeding, are not insignificant with this approach. Several studies have demonstrated that emergency physicians can perform lower extremity duplex ultrasound examinations accurately.(31-33) The institution of this practice is likely to reduce hospital admissions, avoid serious complications from unnecessary anticoagulation, and result in reduced healthcare costs.

Integrating procedural and diagnostic ultrasound applications in emergency medicine improves patient care by diagnosing illness without ionizing radiation, increasing the safety and efficiency of invasive procedures, and reducing travel outside the department. There is also a financial benefit in decreasing expensive diagnostic imaging and emergency department length of stay.(34-35) Emergency medicine has come a long way since the origination of the FAST examination, and quality of care will continue to improve with the rapid growth of ultrasound technology and research quality.

References:

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2. Jehle D, et al. Emergency department sonography by emergency physicians. Am J Emerg Med. 1989;7:605-611. 

3. Policy statement: Emergency ultrasound guidelines. American College of Emergency Physicians Web site. http://www.acep.org/practres.aspx?id=32334. Published 2008. Accessed April 5, 2010.

4. Eurle B, et al. Diagnostic ultrasonography in emergency medicine. Critical Decisions in Emergency Medicine. 2004;18:1-8.

5. Peterson MA, et al. Bedside ultrasound for difficult lumbar puncture. J Emerg Med. 2005;28:197-200.

6. Stiffler KA, et al. The use of ultrasound to identify pertinent landmarks for lumbar puncture. Am J Emerg Med. 2007;25:331-334.

7. Ferre RM, et al. Emergency physicians can easily obtain ultrasound images of anatomical landmarks relevant to lumbar puncture. Am J Emerg Med. 2007;25:291-296.

8. Murphy M, et al.  Focus on: Ultrasound-guided lumbar puncture. American College of Emergency Physicians Web site. http://www.acep.org/publications.aspx?LinkIdentifier=id&id=33402&fid. Published 2007. Accessed April 5, 2010.

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10. Slama M, et al. Improvement of internal jugular vein cannulation using an ultrasound-guided technique. Intensive Care Med.1997;23:916-919.

11. Gualtieri E, et al. Subclavian venous catheterization: greater success rate for less experienced operators using ultrasound guidance. Crit Care Med. 1995; 23:692–697.

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13. Shiver S, et al. A prospective comparison of ultrasound-guided and blindly placed radial arterial catheters. Acad Emerg Med. 2006;13:1275-1279.

14. Moustaki M, et al. Complications of suprapubic aspiration in transiently neutropenic children. Pediatr Emerg Care.  2007;23:823-825.

15. Aguilera PA, et al. Ultrasound-guided suprapubic cystostomy catheter placement in the emergency department. J Emerg Med. 2004;26:319-321.

16. Hayreh SS. Pathogenesis of oedema of the optic disc (papilloedema). Br J Ophthalmol. 1964;48:522–543.

17. Moretti R, et al. Reliability of optic nerve ultrasound for the evaluation of patients with spontaneous intracranial hemorrhage. Neurocrit Care. 2009 Jul 28. [Epub ahead of print].

18. Stone MB. Ultrasound diagnosis of papilledema and increased intracranial pressure in pseudotumor cerebri. Am J Emerg Med. 2009;27:376.e1-376.e2.

19. Geeraerts T, et al. Ultrasonography of the optic nerve sheath may be useful for detecting raised intracranial pressure after severe brain injury. Intensive Care Med. 2007;33:1704-1711.

20. Kimberly HH, et al. Correlation of optic nerve sheath diameter with direct measurement of intracranial pressure. Acad Emerg Med. 2008;15:201-204.

21. Jones AE, Aborn LS, Kline JA. Severity of emergency department hypotension predicts adverse hospital outcome. Shock 2004;22:410–414.

22. Perera P, et al. The RUSH exam: Rapid Ultrasound in SHock in the evaluation of the critically lll. Emerg Med Clin North Am. 2010;28:29-56, vii.

23. Nadkarni VM, et al. First documented rhythm and clinical outcome from in-hospital cardiac arrest among children and adults. JAMA. 2006;295:50-57.

24. Hernandez C, et al. C.A.U.S.E.: Cardiac arrest ultra-sound exam--a better approach to managing patients in primary non-arrhythmogenic cardiac arrest. Resuscitation. 2008;76:198-206.

25. Blaivas M, et al. Outcome in cardiac arrest patients found to have cardiac standstill on the bedside emergency department echocardiogram. Acad Emerg Med. 2001;8:616-621.|

26. Lichtenstein D, et al. Ultrasound diagnosis of occult pneumothorax. Crit Care Med. 2005;33:1231-1238.

27. Ball CG,  et al. Factors related to the failure of radiographic recognition of occult posttraumatic pneumothoraces. Am J Surg. 2005;189:550-556.

28. Soldati G, et al. Occult traumatic pneumothorax: diagnostic accuracy of lung ultrasonography in the emergency department. Chest. 2008;133:204-211.

29. Wilkerson RG, et al. Sensitivity of bedside ultrasound and supine anteroposterior chest radiographs for the identification of pneumothorax after blunt trauma. Acad Emerg Med. 2010;17:11-17.

30. Kirkpatrick AW,  et al. Hand-held thoracic sonography for detecting post-traumatic pneumothoraces: the Extended Focused Assessment with Sonography for Trauma (EFAST). J Trauma. 2004;57:288-295.

31. Burnside PR, et al. Systematic review of emergency physician-performed ultrasonography for lower-extremity deep vein thrombosis. Acad Emerg Med. 2008;15:493-498.

32. Kline JA, et al. Emergency clinician-performed compression ultrasonography for deep venous thrombosis of the lower extremity. Ann Emerg Med. 2008;52:437-445.

33. Blaivas M, et al. Lower-extremity Doppler for deep venous thrombosis--can emergency physicians be accurate and fast? Acad Emerg Med. 2000;7:120-126.

34. Burgher SW, et al. Transvaginal ultrasonography by emergency physicians decreases patient time in the emergency department. Acad Emerg Med. 1998;5:802-807.

35. Salen PN, et al. Emergency physician bedside ultrasound decreases length of stay, intravenous usage, and patient charges in the evaluation of ureteral colic compared with computed tomography and intravenous pyelography. Ann Emerg Med. 2000;36:S20.

Disclosures:

*Author has no disclosures to report