Shock Management Seyed Tayeb Moradian MSc, Critical Care Nursing Ph.D Candidate
Definition of Shock The definition of shock does not involve low blood pressure, rapid pulse or cool clammy skin - these are merely the signs. Simply stated, shock results from inadequate perfusion of the body s cells with oxygenated blood.
Simply... oxygen requirement > oxygen delivery
Stages / Spectrum of Shock Preshock compensated/warm shock Body is able to compensate for perfusion Up to ~10% reduction in blood volume Tachycardia to cardiac output & perfusion Shock Compensatory mechanisms overwhelmed See signs/symptoms of organ dysfunction ~20-25% reduction in blood volume End-organ dysfunction Leading to irreversible organ damage/death
Low Blood Pressure Signs and Symptoms Systolic BP is usually below 90 mmhg Pulse is rapid and weak Respiration is rapid and shallow Skin is pale, cool, and clammy Drowsiness
The Shock Cycle
Determinants of Blood Pressure blood pressure cardiac output total peripheral resistance stroke volume heart rate preload contractility afterload
Classification of Shock Hypovolemic Septic/Inflammatory Cardiogenic (Intrinsic, compressive & Obstructive) Neurogenic Anaphylactic
HypovolemicShock Decreased preload->small ventricular end-diastolic volumes -> inadequate cardiac generation of pressure and flow Causes: -- bleeding: trauma, GI bleeding, ruptured aneurysms, hemorrhagic pancreatitis -- prolonged vomiting or diarrhea -- adrenal insufficiency; diabetes insipidus -- dehydration -- third spacing: intestinal obstruction, pancreatitis, cirrhosis
Hypovolemic Shock Signs & Symptoms: Hypotension, Tachycardia, MS change, Oliguria, Deminished Pulses. Markers: monitor UOP,CVP, BP, HR, Hct, MS, CO, lactic acid and PCWP Treatment: CABs, IVF (crystalloid), Trasfusion if there is Blood Loss Patients on β-blockers, w/ spinal shock & athletes may not be tachycardic
Determinants of Blood Pressure Hypovolaemic shock blood pressure cardiac output total peripheral resistance stroke volume heart rate preload contractility afterload
CardiogenicShock Mechanism: Intrinsic abnormality of heart -> inability to deliver blood into the vasculature with adequate power Causes: 1. Cardiomyopathies: myocardial ischemia, myocardial infarction, cardiomyopathy, myocardiditis, myocardial contusion 2. Mechanical: cardiac valvular insufficiency, papillary muscle rupture, septal defects, aortic stenosis 3. Arrythmias: bradyarrythmias (heart block), tachyarrythmias (atrial fibrillation, atrial flutter, ventricular fibrillation) 4. Obstructive disorders: PE, tension peneumothorax, pericardial tamponade, constrictive pericaditis, severe pulmonary hypertension
Cardiogenic Shock Characterized by high preload (CVP) with low CO Signs/SXS: Dyspnea, rales, loud P2 gallop, low BP, oliguria Monitor/findings: CXR pulm venous congestion, elevated CVP, Low CO. Tx: CHF diuretics & vasodilators +/- pressors. LV failure pressors, decrease afterload, intraaortic ballon pump & ventricular assist device.
Determinants of Blood Pressure Cardiogenic shock blood pressure cardiac output total peripheral resistance stroke volume heart rate preload contractility afterload
Obstructive Shock impaired diastolic filling increased right- or left-ventricular afterload
Obstructive Shock causes: tension pneumothorax pulmonary emboli (thrombo-, air-, amniotic) mediastinal tumours pericardial tamponade, constrictive pericarditis acute pulmonary hypertension aortic dissection valvular (mitral stenosis, aortic stenosis) vena-caval compression
Determinants of Blood Pressure Obstructive shock blood pressure cardiac output total peripheral resistance stroke volume heart rate preload contractility afterload
Septic/Inflammatory Shock Mechanism: release of inflammatory mediators leading to 1. Disruption of the microvascular endothelium 2. Cutaneous arteriolar dilation and sequestration of blood in cutaneous venules and small veins Causes: 1. Anaphylaxis, drug, toxin reactions 2. Trauma: crush injuries, major fractures, major burns. 3. infection/sepsis: G(-/+ ) speticemia,pneumonia, peritonitis, meningitis, cholangitis, pyelonephritis, necrotic tissue, pancreatitis, wet gangrene, toxic shock syndrome, etc.
Septic/Inflammatory Shock Signs: Early warm w/ vasodilation, often adequate urine output, febrile, tachypneic. Late-- vasoconstriction, hypotension, oliguria, altered mental status. Monitor/findings: Early hyperglycemia, respiratory alkalosis, hemoconcentration, WBC typically normal or low. Late Leukocytosis, lactic acidosis Very Late Disseminated Intravascular Coagulation & Multi-Organ System Failure. Tx : CABs, IVF, Blood cx, ABX, Drainage (ie abscess) pressors.
Rule Shock states will all result in low SvO2 values Exception distributive shock
Determinants of Blood Pressure Distributive shock blood pressure cardiac output total peripheral resistance stroke volume heart rate preload contractility afterload
Causes: 1. Spinal cord injury NeurogenicShock Mechanism: Loss of autonomic innervation of the cardiovascular system (arterioles, venules, small veins, including the heart) 2. Regional anesthesia 3. Drugs 4. Neurological disorders
Neurogenic Shock Characterized by loss of vascular tone & reflexes. Signs: Hypotension, Bradycardia, Accompanying Neurological deficits. Monitor/findings: hemodynamic instability Tx: IVF, vasoactive medications if refractory
Pulmonary Artery Catheterization Allows for accurate and continuous hemodynamic monitoring in shock patients 1. Evaluate Fluid Resuscitation 2. Titration of Vasoactive Medications 3. Allows for Assessment of Cardiovascular Performance. 4. Monitor the Effects of Changes in Mechanical Ventilation. K l k j
Pulmonary Artery Catheterization K l k j
Hemodynamic Profiles Shock PCWP CVP CO/CI SVR/I Hypovolemic Low Low Low High Cardiogenic High High Low High Inflammatory Low / N Low/N High Low Neurogenic Low Low Low Low K l k j
Immediate Management
Immediate Management Maintain normal body temperature In most cases, elevate the feet and legs above the level of the heart Exceptions include: Neck injury immobilize in the position found Head injury elevate the head and shoulders Leg fracture splint and elevate
Secondary Management Vital Signs Pulse Respiration Blood pressure Temperature Skin color Pupils Level of consciousness Movement Abnormal nerve response