SHOCK

SHOCK Shock is a critical condition that results from inadequate tissue delivery of O2 and nutrients to meet tissue metabolic demand. Shock does not depend upon blood pressure, shock can occur with a normal, increased or decreased systolic blood pressure. In children most shock characterized by low cardiac output ; however in shock caused by sepsis or anaphylaxis, CO may be high. All types of shock result in impairment of vital organs such as Brain and Kidney.

Shock can result from Inadequate blood volume or oxygen carrying capacity (Hypovolemic Shock, including hemorrhagic shock) Inappropriate distribution of blood volume and flow (Distributive shock) Impaired cardiac contractility (Cardiogenic shock) Obstructed blood flow (Obstructive shock)

Hypotension Formula In Children 1 to 10 years of age, hypotension is present if the systolic blood pressure reading is less than 70mmHg + (child’s age in years × 2) mm Hg

Factor influencing O2 delivery Volume of blood present in the ventricle before contraction Preload × Stroke Volume × Heart Rate Cardiac Output × O2 Content O2 Delivery Strength of Contraction Contractility Resistance against which the ventricle is ejecting Afterload

Common Signs of Shock resulting from Cardiovascular Compensatory Mechanisms

Shock progression is Unpredictable This progression is typically an accelerating ProcessSHOCK Possibly hours Possibly hours COMPENSATED SHOCK HYPOTENSIVE SHOCK Potentially minutes CARDIAC ARREST

Shock can be categorized into 4 basic types Hypovolemic Hypovolemic Distributive Distributive – Septic Shock – Anaphylactic Shock – Neurogenic Shock Cardiogenic Cardiogenic Obstructive Obstructive

Hypovolemic Shock Most common cause of shock in children Typically represents depletion of both intravascular and extravascular fluid volume. As a result, adequate fluid resuscitation often require administration of fluid boluses that exceed the volume of the estimated intravascular deficit. Volume loss can result from Diarrhea Vomiting Hemorrhage(Internal and External) Inadequate fluid intake Osmotic diuresis(DKA) Third space losses( Fluid leak in to tissues) Large Burns

Hypovolemic Shock is characterized by decreased preload leading to reduced stroke volume and low cardiac output. Tachycardia, Increased SVR and Increased cardiac contractility are the main compensatory mechanisms.

Distributive Shock It is characterized by inappropriate distribution of blood volume with inadequate organ and tissue perfusion(especially the splanchnic vascular bed) Most common forms are Septic Shock Anaphylactic Shock Neurogenic Shock( Ex: Head Injury, Spinal Injury)

Findings consistent with Distributive Shock

Septic Shock Most common form of Distributive shock. It is caused by infectious organisms or their by products(endotoxin) that stimulate the immune system and trigger the release of inflammatory mediators. Typically evolves from a systemic inflammatory response in early stages to septic shock in the late stages, may evolve over days or just a few hours. In the early stages, signs are often subtle and may be difficult to recognize because peripheral perfusion may appear to be good. Child may have fever or hypothermia and WBC may be decreased, normal or Increased.

Anaphylactic Shock Anaphylactic shock is an acute multisystem allergic response caused by a severe reaction to a drug, vaccine, food, toxin, plant, venom or other antigen. It can occur within seconds to minutes The reaction is characterized by vasodilatation, arterial vasodilation, increased capillary permeability and pulmonary vasoconstriction. Signs may include Anxiety or agitation, Nausea and vomiting, Urticaria, Angioedema(swelling of face,lips and tongue), Respiratory distress with stridor or wheezing, Hypotension, Tachycardia.

Neurogenic Shock Also known as spinal shock, results from a cervical or upper thoracic(above T6) injury that disrupts the sympathetic nervous system of blood vessels and the heart. Sudden loss of the sympathetic nervous system signals to the smooth muscle in the vessel results in uncontrolled vasodilation. Primary signs are Hypotension with a wide pulse pressure Normal heart rate or Bradycardia Other signs include increased RR, Diaphragmatic breathing, motor or sensory deficits.

Cardiogenic Shock Cardiogenic shock results from inadequate tissue perfusion secondary to myocardial dysfunction. Common causes include CHD, Myocarditis, Cardiomyopathy, Arrhythmias, Sepsis, Poisoning or drug toxicity, Myocardial Injury(ex: trauma) Cardiogenic shock is characterized by marked tachycardia, high SVR, and decreased cardiac output.

Findings consistent with Cardiogenic Shock

Obstructive Shock In obstructive shock, cardiac output is impaired by a physical obstruction of blood flow. Causes include Cardiac Tamponade Tension Pneumothorax Duct-dependent congenital heart lesions Massive pulmonary embolism The physical obstruction to blood flow results in low cardiac output, inadequate tissue perfusion and a compensatory increase in SVR.

Cardiac Tamponade

Tension Pneumothorax

Duct-dependent congenital heart lesions Duct-dependent congenital heart lesions Findings of left ventricular outflow obstructive lesions

Pulmonary Embolism

Septic shock algorithm