When a patient goes into shock in the POCUS in the ED (ED), every second counts. For emergency physicians, knowing how to treat a patient in shock can make all the difference in preventing an injury or a fatal event. In this life or death scenario, Point of Care Ultrasound (POCUS) can effectively assess, treat, and manage shock, especially when used in conjunction with other methods.
POCUS can help reduce the time to diagnosis, and it enables physicians to narrow their differential diagnosis—which is critical for administering the appropriate treatment quickly. It can guide treatment, such as whether to give more or less fluids, as well as resuscitation protocols. Making these decisions quickly can reduce mortality.
How POCUS Increases Diagnostic Accuracy of Undifferentiated Shock
Shock is a life-threatening condition that occurs when the body does not get enough blood flow. It usually happens as a result of trauma or infection, but there can be other causes such as an allergic reaction or damage to the nervous system. Shock requires immediate treatment; studies have shown that most deaths from trauma due to shock take place within the first 24 hours.1
Compared with standard care, POCUS can increase the diagnostic accuracy of patients with undifferentiated shock (when shock is recognized but the cause is unclear). Jones et al. found that the diagnostic accuracy of POCUS in patients with undifferentiated shock was 80%—compared with 50% in a control group that received no ultrasound.2 After receiving a POCUS exam, the percentage of correct diagnoses increased from 50% to 78% for the control group. A second study, conducted in 2017, found that diagnostic accuracy increased from 60.6% before a POCUS exam to 85% after POCUS.3
POCUS can also increase the accuracy of assessing the type of shock. Javali et al. found that adding POCUS by a trained emergency physician to the clinical information increased the accuracy of evaluation of the type of shock from 45% to 89%.4
Since ultrasound is a versatile tool that can be used to evaluate multiple organs such as the heart and lungs for signs of shock, it can also be used to examine the abdomen for free fluid. Evidence has shown that POCUS can obtain good diagnostic accuracy in patients with hypotension.
How POCUS Helps to Identify Shock
A shock diagnosis is clinical and includes blood pressure measurement and measurement of tissue hypoperfusion. Therapies for shock include supplemental oxygen and airway management. Ultrasound is an essential part of early shock diagnosis and can answer several key questions:
Are the left and right ventricles dilated or impaired?
Is the inferior vena collapsing?
Is there a pericardial effusion?
Is there pleural effusion?
There are several standardized scan protocols that utilize POCUS to evaluate shock. One is the RUSH (Rapid Ultrasound for Shock and Hypotension) Protocol. The RUSH exam was created to provide a quick bedside assessment for patients with undifferentiated shock.5 The exam allows emergency physicians to conduct a structured ultrasound exam in less than two minutes. This is important because time is of the essence when it comes to diagnosing and treating shock.
The components of the RUSH exam are: heart, inferior vena cava, Morrison's abdominal views, aorta, and pneumothorax (HI-MAP). The exam can be simplified into three steps: the pump, the tank, and the pipes.
The RUSH protocol is easy to learn and implement. The streamlined accuracy of POCUS allows physicians to quickly answer questions about the patient's status and works well as a complement to a physical examination.
How POCUS Can Detect Different Types of Shock
The versatility of POCUS makes it an excellent tool for detecting different types of shock in the ED or critical care setting. For example, a major cause of obstructive shock is cardiac tamponade. The presence of hypotension and pericardial effusion can raise suspicion of cardiac tamponade. POCUS can confirm the presence of pericardial effusion, and it can obtain and assist in the diagnostic accuracy of hypotension.6 POCUS can also assess the heart to determine if the right ventricle is dilated and can determine if the inferior vena cava are non-collapsible, which would also point to obstructive shock.
POCUS can also assess the lungs for B lines that can indicate the possibility of pulmonary edema and cardiogenic shock. Decreased left ventricular function would also point to cardiogenic shock.
Once in the ED, patients in shock should be given high-flow oxygen and receive basic monitoring, such as non-invasive blood pressure, pulse oximetry and continuous ECG.7 The patient may then need intubation or ventilation and, in cases where shock has been caused by hypovolemia, IV fluids should be started.
How AI Helps Physicians Diagnose Shock Faster
Time is of the essence when it comes to treating patients with shock, and artificial intelligence can help physicians get a diagnosis faster. For example, GE Healthcare's Venue™ family of POCUS systems are equipped with Real-Time ejection fraction (EF), an AI-enabled tool that continuously calculates the heart's ejection fraction in real time during live scanning. Real-Time EF also provides an integrated quality indicator that lets providers know when they have an adequate view of the heart to generate accurate cardiac measurements. Shock can lead to decreased cardiac output, so it is important to be able to quickly assess how the heart is performing before administering treatment.
Machine learning and AI used with the Venue family of POCUS systems also suggest measurements for physicians to use when making a final decision. The physician can edit the measurement as needed. Additionally, machine learning enables auto distinguishing between real B-lines and other artifacts, and AI enables the classification between artifacts and B-lines. The Auto B-lines tool highlights and counts B-lines in real time, and the Venue system can automatically search for and display the frame with the highest B-line count, helping save time over manually counting B-lines.
The Auto-IVC tool calculates the collapsibility index for the physician and searches for the appropriate place to measure the minimum and maximum inferior vena cava (IVC) diameters. This also saves the physician multiple steps and time.
POCUS is extremely beneficial for determining how to treat a patient in shock. It can draw a distinction between the different types of shock and reduce the time to diagnosis, enabling physicians to rapidly administer treatment. It can also guide treatment and resuscitation protocols and significantly improve patient outcomes.
References
- Tisherman SA, Schmiker RH, Brasel KJ, et al. Detailed description of all deaths in both the shock and traumatic brain injury hypertonic saline trials of the resuscitation outcomes consortium. Annals of Surgery. March 2015. 261(3): 586–90. https://europepmc.org/article/PMC/4309746.
- Jones AE, Tayal VS, Sullivan DM, Kline JA. Randomized, controlled trial of immediate versus delayed goal-directed ultrasound to identify the cause of nontraumatic hypotension in emergency department patients. Critical Care Medicine. August 2004. 32:1703-8. 10.1097/01.ccm.0000133017.34137.82.
- Sasmaz MI, Gungor F, Guven R, et al. Effect of focused bedside ultrasonography in hypotensive patients on the clinical decision of emergency physicians. Emergency Medicine International. 2017:6248687. https://www.hindawi.com/journals/emi/2017/6248687/.
- Javali RH, Loganathan A, Srinivasarangan M, et al. Reliability of emergency department diagnosis in identifying the etiology of nontraumatic undifferentiated hypotension. Indian Journal of Critical Care Medicine. May 2020. 24:313-20. https://www.ijccm.org/doi/pdf/10.5005/jp-journals-10071-23429.
- Yanagawa Y, Ohsaka H, Nagasawa H, et al. An analysis using modified rapid ultrasound for shock and hypotension for patients with endogenous cardiac arrest. Journal of Emergencies, Trauma, and Shock. April-June 2019. 12(2):135–140. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6557051/.
- Melgarejo S, Schaub A, Noble VE. Point of care ultrasound: an overview. American College of Cardiology. October 31, 2017. https://www.acc.org/latest-in-cardiology/articles/2017/10/31/09/57/point-of-care-ultrasound.
- Graham CA, Parke TRJ. Critical care in the emergency department: shock and circulatory support. Emergency Medicine Journal. 2004. 22-1. http://dx.doi.org/10.1136/emj.2003.012450.
