Available online 7 June 2025, 101038

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Vascular Interventional Radiologists (VIRs) are increasingly involved in consultation and management of patients with circulatory shock. The ability to recognize the underlying pathophysiology of a patient’s shock and treat appropriately is therefore critical to VIR practice. Here, we discuss the initial evaluation and stabilization of undifferentiated shock. Shock is defined as tissue hypoperfusion from inadequate oxygen delivery and/or impaired tissue oxygen utilization. The etiologies of shock can be grouped into 3 main categories: distributive, hypovolemic, cardiogenic, and obstructive; each of which are associated with characteristic hemodynamic and metabolic derangements such as decreased preload or impaired cardiac contractility. Presentation typically involves 1) hypotension and tachycardia as indicators of impaired cardiac output, and 2) evidence of ongoing end-organ hypoperfusion such as oliguria, altered mental status, and lactic acidosis. Initial management includes control of airway and oxygenation/ventilation, identification of underlying hemodynamic and cardiovascular derangements, and support of cardiac output with intravenous fluid (IVF), blood products, diuresis, and/or vasopressors and inotropes. More detailed hemodynamic analysis can be performed with arterial catheters, blood gases, pulmonary artery catheters, and echocardiography to further tailor therapy. Finally, definitive evaluation for causative etiology should be initiated immediately with biochemical studies, cultures, imaging, and hemodynamic assessment so that etiology-specific treatment (e.g. antibiotics, blood products) can be initiated.

Introduction

Shock is a life-threatening condition characterized by tissue hypoperfusion leading to cellular and organ dysfunction.1 It can be caused by a wide spectrum of pathologies that impair oxygen delivery to tissues and/or impair their ability to utilize delivered oxygen. Vascular Interventional Radiologists (VIRs) must be prepared to manage shock, especially when complications arise during procedures or in consultation or management of critically-ill patients—frequently encountered examples include hemorrhagic shock after trauma, obstructive shock from massive pulmonary embolism (PE), and septic shock from obstructive uropathy. Undifferentiated shock, where the cause is unclear at presentation, requires a systematic approach to identify the underlying pathophysiology while initiating prompt stabilization measures. Key components of diagnosis and treatment include recognition of shock through physical examination, imaging, and laboratory evaluation; securing airway, breathing, and circulation (“ABCs”); hemodynamic stabilization and assessment; correction of underlying etiologies; and restoration of oxygen delivery. This article aims to provide a concise guide for IRs on the presentation and pathophysiology of shock, evaluation and initial stabilization of undifferentiated shock, methods for diagnosing underlying etiologies, identification of hemodynamic derangements, and performance of hemodynamically guided resuscitation to improve patient outcomes.

Section snippetsDefinition and Presentation

Circulatory shock can be defined as a state where tissue oxygenation is inadequate to meet the demands of aerobic metabolism (i.e., a state of hypoxia), leading to cellular and organ dysfunction.2 Shock presents with signs and symptoms of end-organ hypoperfusion that signal ongoing organ dysfunction. These include altered mental status, lactic acid accumulation from anaerobic metabolism and resulting anion gap acidosis, oliguria (urine output < 0.5 mL/kg/hr), acute liver failure (“shock

Pathophysiology

Shock typically occurs due to some combination of decreased oxygen delivery to tissues, impaired oxygen utilization by tissues, and/or elevated tissue oxygen demands. If prolonged and severe, the oxygen available to tissues for uptake will be insufficient to support aerobic metabolism, and anaerobic metabolism will occur, followed by organ dysfunction. Shock can be precipitated by any pathology or condition that decreases oxygen delivery or impairs oxygen utilization. Oxygen delivery to tissues

Initial Stabilization and Evaluation

Clinical management of the shock patient can be divided into 3 functional goals: emergent stabilization, diagnostic workup to assess etiology and category of shock, detailed assessment of hemodynamic derangements, and resuscitation.

Emergent stabilization, particularly of the patient presenting in extremis, should start with evaluation of the airway, breathing, and circulation (“ABCs”) along with continuous monitoring of vital signs.7 Recognizing the need to call for help, such as activating a

Detailed Hemodynamic Assessment

As previously discussed, each category of shock is associated with characteristic hemodynamic changes (Table 1). Therefore, if shock state persists after initial stabilization and treatment of readily identifiable etiologies, a detailed hemodynamic assessment should be performed to identify the hemodynamic category of shock and subsequently tailor resuscitation to particular hemodynamic derangements. This broadly involves assessing CO (including its determinants – preload, afterload, and

Resuscitation

Once a patient’s hemodynamic profile and category of shock has been characterized and etiology-specific treatments initiated, management of shock shifts to resuscitation, or targeted reversal of hemodynamic derangements. This is accomplished through optimization of fluid status using intravenous crystalloids/colloids or diuresis, and administration of vasopressors and/or inotropes to maximize preload, afterload, and myocardial contractility.

Conclusion

Prompt recognition and management of undifferentiated shock are paramount to preventing irreversible organ damage and improving patient outcomes. IRs play a critical role in this process, especially when complications arise during procedures or in the acute care of critically ill patients. Management of shock requires a systematic approach that includes immediate stabilization of airway/breathing/circulation, identification and treatment of underlying etiologies, hemodynamic assessment, and

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