Rapid Formulation of an Early Working Diagnosis of the Etiology of Shock Defining Features of Shock Blood pressure ⇓

KEY POINTS • Shock is present when there is evidence of multisystem organ hypope fusion; it often presents as reduced mean blood pressure. • Initial resuscitation aims to establish an adequate airway, breathing, and circulation; a working diagnosis or clinical hypothesis of the cause of inadequate circulation should always be made immediately by physical examination and clinical presentation before treatment is initiated. • The most common causes of shock are high cardiac output hypotension, or septic shock, reduced pump function of the heart, or cardiogenic shock, and reduced venous return despite normal pump function, or hypovolemic shock. Overlapping etiologies can confuse the diagnosis, as can a short list of other less common etiologies, which are often separated by echocar-diography and right heart catheterization. • Initial cardiovascular therapeutic interventions are volume infusion for hypovolemic shock or inotropic and vasodilating drugs for cardiogenic shock; each should be regarded as testing the clinical hypothesis concerning the etiology of shock and therefore requires careful evaluation before and soon after implementation. • Identify and correct early all factors aggravating shock; these include suboptimal ventilator therapy, infections, arrhythmias, acidosis, electrolyte abnormalities, and hypothermia. • Shock has a hemodynamic component, which is the focus of the initial resuscitation, but shock also lias a systemic inflammatory component that leads to adverse sequelae including subsequent organ system dysfunction. • Urgent discontinuation of excessive invasive measurements and therapy should follow hemodynamic stabilization of the patient.