The Shock Tool study is designed to improve the clinical evaluation for differentiating shock in the emergency department. The goal of this study is to evaluate and improve the accuracy of physicians differentiating causes of shock.

Specific Aim #1: To study the epidemiology of shock in the emergency department Hypothesis 1: We will better understand shock states if we determine shock etiology among patients presenting to the emergency department in a carefully conducted observational prospective study.

Specific Aim #2: To determine the accuracy of physician diagnosis for the underlying etiology of shock.

Hypothesis 2: Physician assessment of the underlying cause of shock is challenging and often inaccurate in the early stages of care in the emergency department.

Specific Aim #3: To optimize the evidence-based approach to assist in the diagnosis of shock etiology from elements readily available when a patient demonstrates shock physiology in the Emergency Department.

Hypothesis 3: An evidenced-based, standardized approach to clinical decision making integrating elements of the history, physical exam, and early testing will improve a physician's ability to accurately differentiate etiologies of shock.

Inclusion Criteria:

• Age 18 years or great
• For pre-shock cohort: HR > 130, RR>24, Shock index > 1, lactate > 4.0mmol/L, SBP < 90mm/hg)
• For shock cohort: persistent blood pressure <90mm/hg after resuscitation

Exclusion Criteria:

• seizure
• isolated atrial fibrillation with discharge after rate control achieved
• discharged from the emergency department
• intoxication or withdrawal

Emergency Department patients