Shock due to superior vena cava obstruction detected with point of care ultrasound

Definition, Classification, and Management of Primary Noncardiac Causes of Cardiogenic Shock

Cardiogenic shock (CS) is a complex syndrome, presenting with a critical state of cardiac output insufficient to support end-organ perfusion requirements. Contemporary CS classification recognizes broad categories of primary cardiac etiologies of CS, such as acute myocardial infarction and heart failure. Primary noncardiac etiologies of CS, however, are poorly described in literature and have not been captured by any contemporary classification, leading to challenges in diagnosing and managing these cases. In this review, we propose that primary noncardiac causes of CS be recognized as its own category that builds on the original Shock Academic Research Consortium classification with its own additional modifiers. We present a detailed framework that groups each noncardiac cause by its underlying disease mechanism (vascular, infectious, inflammatory, traumatic, toxic, cancer related, endocrine, metabolic) and review available literature on their respective management strategies. We expect that the ability to classify primary noncardiac causes of CS will help with early identification and targeted management of the primary noncardiac insult, support patients through their shock state, and may lead to improvement of in-hospital CS mortality rates in clinical practice. Moreover, this new framework can further assist clinical trial classifications to properly phenotype CS for clinical research purposes.

Hypotensive patient with superior vena cava obstruction diagnosed using resuscitative transesophageal echocardiography

BACKGROUND

Superior vena cava syndrome (SVCS) is a malignancy-related emergency. It is caused by obstruction of blood flow in the superior vena cava (SVC) secondary to intraluminal thrombosis, external compression, or direct invasion of tumor.

CASE SUMMARY

A 49-year-old male presented to the emergency department (ED) with acute hypoxemic respiratory failure. He was intubated and treated as pneumonia. Post-intubation, he became hypotensive, requiring fluid resuscitation and inotropic support. Resuscitative transesophageal echocardiography (TEE) showed external compression by a lung mass and an intraluminal thrombus causing SVC obstruction. Computed tomography (CT) angiography was performed, and it confirmed the TEE findings. A provisional diagnosis of lung carcinoma was made, and he underwent endovascular therapy for rapid symptomatic relief.

DISCUSSION

This case report highlights the role of resuscitative TEE in evaluating a hypotensive patient with clinical suspicion of SVCS at the emergency department. TEE performed at the bedside could help to diagnose and demonstrate the pathology causing SVCS in this case. TEE allowed high-quality image acquisition and was able to overcome the limitation of transthoracic echocardiography (TTE). TEE should be considered as an alternative ED imaging modality in the management of SVCS.

LEARNING POINTS

Not all Shock States Are Created Equal: A Review of the Diagnosis and Management of Septic, Hypovolemic, Cardiogenic, Obstructive, and Distributive Shock

Shock in the critically ill patient is common and associated with poor outcomes. Categories include distributive, hypovolemic, obstructive, and cardiogenic, of which distributive (and usually septic distributive) shock is by far the most common. Clinical history, physical examination, and hemodynamic assessments & monitoring help differentiate these states. Specific management necessitates interventions to correct the triggering etiology as well as ongoing resuscitation to maintain physiologic milieu. One shock state may convert to another and may have an undifferentiated presentation; therefore, continual re-assessment is essential. This review provides guidance for intensivists for management of all shock states based on available scientific evidence.

Application Value of Emergency Bedside Echocardiography in Early Warning of Acute and Severe Shock and Clinical Classification

Objective

A case-control study was conducted to explore the application value of emergency bedside echocardiography in early warning of acute and severe shock and clinical classification.

Methods

A total of 135 critically ill patients admitted to ICU from August 2019 to November 2020 were divided into shock group (n = 53) and nonshock group (n = 82) according to the occurrence of shock. The internal diameter index of inferior vena cava was measured and recorded by bedside ultrasound in patients with shock before and after treatment and in patients without shock. Shock index and inferior vena cava diameter deformation index (SCI) were calculated according to the results. The diagnostic time and curative effect of different ultrasonic examination methods for the types of shock were compared and analyzed.

Results

At admission, the maximum and minimum ventilation of inferior vena cava in patients without shock were higher than those in the shock group, and the internal diameter deformation index of inferior vena cava in the shock group was higher than that in the shock group (P < 0.05). In the shock group, IVCmax and IVCmin before and after treatment were higher than those before resuscitation, while SCI was lower than that before resuscitation. The results of ROC curve analysis showed that SCI and IVCmin were significantly better than IVCmax and IVCmin in predicting shock area and slightly better than IVCmin. There was significant difference in diagnosis time between the two groups (P < 0.05). The specificity, positive predictive value, and negative predictive value of emergency ultrasound diagnosis were lower than those of clinical diagnosis (P < 0.05). The sensitivity, specificity, positive predictive value, and negative predictive value of emergency ultrasound diagnosis were lower than those of clinical diagnosis (P < 0.05). The sensitivity and positive predictive value of the emergency ultrasound group were higher than those of the routine ultrasound group (P < 0.05). The diagnosis rate of shock type AUC in the emergency ultrasound group was 0.854, and the diagnostic value was high.

Conclusion

IVCmax, IVCmin, and SCI obtained by bedside ultrasound have certain clinical significance for the diagnosis and treatment of shock. Emergency bedside ultrasound examination and measurement of shock patients are helpful to quickly evaluate and identify the types of early shock.