Critically ill patients presenting to the ED represent the most time-sensitive patient encounter for the emergency physician (EP), as delays in restoring physiological homeostasis increase the risks of organ dysfunction and death. Management and treatment strategies in critically ill patients have evolved from the routine use of invasive catheters and radiography for cardiopulmonary evaluation to a variety of noninvasive devices and pathways. The widespread adoption of point-of-care ultrasound (POCUS) in EDs provides the opportunity to rapidly obtain invaluable information about the diagnosis and etiology to guide resuscitation in critically ill patients—particularly those in shock and acute dyspnea.
Over the last two decades, EPs and critical care physicians have employed POCUS to assist in identifying emergent reversible causes of shock and cardiac arrest, including cardiac tamponade, massive pulmonary embolism (PE), and hemoperitoneum. Recent advances in hemodynamic and cardiopulmonary POCUS allow for a nuanced approach to hemodynamic evaluation. 1 In addition, the use of ultrasound “first” in the critical care setting may reduce the dependence on radiographic-based management, catheter-based protocols, and the need for invasive procedures.
Bedside cardiopulmonary ultrasound to evaluate the hemodynamic status of hypotensive patients can help determine the etiology of shock, provide evidence of fluid-volume responsiveness, visualize hemodynamic abnormalities that would alter fluid resuscitation strategies, and assess patient response to an intervention. The use of ultrasound can also identify the etiology of acute respiratory failure—providing the opportunity to initiate the appropriate interventions prior to patient decompensation. Findings such as pneumothorax or pleural effusion may require immediate procedural intervention, while other findings may only require noninvasive positive pressure ventilation and diuresis.
The tools to implement these concepts include basic POCUS education common to emergency medicine and critical care (American College of Emergency Physicians Guidelines and American College of Chest Physicians/Society of Critical Care Medicine guidelines); ultrasound machines with phased array, linear, and curvilinear probes; and ultrasonographic instrumentation such as M-Mode, color Doppler, and spectral Doppler. An understanding of common Doppler imaging techniques optimizes the examination, and the use of presets common to cardiac packages may further assist the provider with adoption.
When evaluating critically ill patients, we recommend the following step-wise approach:
- Identify a clinical question to be answered prior to doing the examination;
- Determine the hemodynamic profile of the patient to guide therapeutic maneuvers; and
- Monitor the response to any therapeutic maneuver and adjust accordingly. (In these complicated patients, repeat examinations are invaluable, as the hemodynamic profile can change rapidly.)
Emergency physicians are increasingly utilizing POCUS to rapidly evaluate the thoracic cavity in critically ill patients. This modality is an appealing alternative to formal chest radiography because of the ease of rapid image acquisition, lack of ionizing radiation, and the ability to repeat the examination in real-time.
When critically ill patients present in respiratory distress, POCUS allows the EP to rapidly diagnose potential etiologies, such as pleural effusion, pneumothorax, or pulmonary edema, and employ emergent intervention, which can greatly alter the patient’s clinical course. Additionally, the rapid diagnosis of consolidation permits earlier appropriate management of sepsis and respiratory failure when the clinical setting is consistent with pneumonia.