Emergency Medicine

Shock Backgrounds

Background

In the emergency department (ED), a quick and easy-to-use hemodynamic monitor, such as the EC Monitors, are vital in differentiating shock patients. Shock is a serious, life-threatening medical condition that occurs when there is not enough blood entering the body’s tissue to meet cellular metabolic needs. In most patients shock is identified by extremely low blood pressure (hypotension) and inadequate organ perfusion, caused either by low cardiac output (CO) or low systemic vascular resistance (SVR).

Save Time - Diagnosis & Treament

Current ED protocols for differential diagnosis of shock takes a significant amount of time. For example, to differentially diagnose septic shock it can take from 20 to 45 minutes to perform a thorough investigation. Using the EC Monitors in shock can potentially cut down the time necessary for diagnosis, for treatment, and ultimately improve patient outcomes.1 The EC Monitors provide an easy 3 minute test which can obtain sufficient data for differential diagnoses of the specific type of shock. Additionally, a real-time continuous measurement of hemodynamic parameters allows for physicians to carefully observe the responses to medication and titrate accordingly.

Differential Diagnosis of Shock

Cardiogenic Shock

In these patients, the reason for the shock is pump failure (the heart). The typical characteristics of cardiogenic shock are low stroke volume (SV), low contractility (ICON), high heart rate (HR), low cardiac output (CO), high systolic time ratio (STR), and low left cardiac work (LCW).

Treatment: Immediate inotropes to correct the low contractility of the heart.

Example: Hemodynamic assessment of a patient with cardiogenic shock measured by an EC monitor

  • SV: Low
  • ICON: Low
  • HR: High
  • CO: Low
  • STR: High
  • LCW: Low
  • TFI: Normal to Low
  • SVR: Normal to High

Hypovolemic Shock

In this case of shock, the patient is losing too much blood or fluid. The typical characteristics of hypovolemic shock are low SV, high HR, low TFC, and high SVR.

Treatment: Increase fluids or blood transfusion.

Example: Hemodynamic assessment of a patient with hypovolemic shock measured by an EC monitor

  • SV: Low
  • ICON: Normal
  • HR: High
  • CO: Normal to Low Normal
  • STR: Normal to Low
  • LCW: Normal
  • TFI: Low
  • SVR: High

Septic Shock (early stage)

This type of shock is caused by a massive infection by septicemia of the blood and blood vessels. When the blood vessel walls become infected, they lose their tone which causes severe vasodilatation. In response to vasodilation, CO increases drastically. The typical characteristics of septic shock are a high CO and low SVR.

Treatment: Massive antibiotics and fluids.

Example: Hemodynamic assessment of a patient with septic shock measured by an EC monitor

  • SV: Normal
  • ICON: Normal
  • HR: High
  • CO: High
  • STR: Normal
  • LCW: Normal
  • TFI: Normal
  • SVR: Low

Anaphylactic Shock

Anaphylactic shock is caused by massive vasodilation usually occurring because of sensitivities to medication and/or any other material. It is characterized by very low SVR and normal to high SV, CO and HR to compensate for the low SVR.

Treatment: Vasoconstrictors (and fluids if needed) to correct the low after-load.

Example: Hemodynamic assessment of a patient with anaphylactic shock measured by an EC monitor

  • SV: Normal to high
  • ICON: Normal
  • HR: High
  • CO: Normal to high
  • STR: Normal
  • LCW: Normal
  • TFI: Normal to low
  • SVR: Very Low

Dyspnea

Dyspnea, shortness of breath or difficulty breathing, is a symptom caused by either a cardiovascular or a non-cardiovascular (typically pulmonary) problem. Determining dyspnea, especially in patients with a history of both cardiac and pulmonary disorders, can be difficult. Although, non-invasive hemodynamic measurements of Cardiac Index (CI) and Systolic Time Ratio (STR) have been shown to be a significant aid in differentiating between cardiac and non-cardiac occurrences of dyspnea.2,3

In less than 3 minutes the EC Monitors can determine CI and STR non-invasively to aid in the differential diagnosis of dyspnea. Analyzing CI and STR, has shown to result in a 13% greater sensitivity and specificity in differentiating the cause of dyspnea (being cardiac or pulmonary) compared to using standard criteria and a 39% improvement in chosen treatment plans.4

 

1 Nassef, Y. (2011, June 26). Differentiating Shock.

2 Springfield C, et al. Utility of Impedance Cardiography to Determine Cardiac vs Noncardiac Cause of Dyspnea in the Emergency Department. Congest Heart Fail. 2004; 10(suppl2):14-16

3 Lo, HY, et al. Utility of impedance cardiography for dyspneic patients in the ED. Am. J. Emergency Medicine (2007) 25,437-441

4 Peacock WF et al. Impact of Impedance Cardiography on Diagnosis and Therapy of Emergent Dyspnea: The ED-IMPACT Trial. Acad Emerg Med. 2006; 13(4):365-371