Shock Differential Diagnosis and Hemodynamic Monitoring Andrew Watt SICU CONFERENCE

Shock Shock is a Cardiovascular Derangement. 1. Deliver Oxygen and Metabolic Substrates 2. Remove Products of Cellular Metabolism 3. Thermoregulation Definition: A physiological state characterized by a significant, systemic reduction in tissue perfusion, resulting in decreased tissue oxygen delivery and insufficient removal of cellular metabolic products, resulting in tissue injury.

Classification of Shock Hypovolemic Septic/Inflammatory Cardiogenic (Intrinsic, compressive & Obstructive) Neurogenic Anaphylactic

Clinical Markers of Shock Klkj Klkj Brachial systolic blood pressure: <110mmHg Sinus tachycardia: >90 beats/min Respiratory rate: 29 breaths/min Urine Output: <0.5cc/kg/hr Metabolic acidemia: [HCO3] 3mEq/L Hypoxemia: 0-50yr: 71yo<70mmHg; Cutaneous vasoconstriction vs. vasodilation. Mental Changes: anxiousness, agitation, indifference, lethargy, obtundation

Etiology & Hemodynamic Changes in Shock Etiology of shock exampleCVPCOSVRVO2 sat preload hypovolemiclow highlow contractility cardiogenichighlowhighlow afterload distributive

Etiology & Hemodynamic Changes in Shock (Afterload) ETIOLOGY OF SHOCK EXAMPLECVPCOSVRVO2 SAT AFTERLOADDISTRIBUTIVE Hyperdynamic Septic Low/HighHighLowHigh Hypodynamic Septic Low/HighLowHighLow/High NeurogenicLow AnaphylacticLow

Hypovolemic Shock Decreased preload->small ventricular end-diastolic volumes -> inadequate cardiac generation of pressure and flow Causes: -- bleeding: trauma, GI bleeding, ruptured aneurysms, hemorrhagic pancreatitis -- protracted 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: ABCs, IVF (crystalloid), Trasfusion Stem ongoing Blood Loss Patients on β-blockers, w/ spinal shock & athletes may not be tachycardic

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 alkylosis, hemoconcentration, WBC typically normal or low. Late – Leukocytosis, lactic acidosis Very Late– Disseminated Intravascular Coagulation & Multi-Organ System Failure. Tx : ABCs, IVF, Blood cx, ABX, Drainage (ie abscess) pressors.

Cardiogenic Shock 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.

Neurogenic Shock Causes: 1.Spinal cord injury 2.Regional anesthesia 3.Drugs 4.Neurological disorders Mechanism: Loss of autonomic innervation of the cardiovascular system (arterioles, venules, small veins, including the heart)

Neurogenic Shock Characterized by loss of vascular tone & reflexes. Signs: Hypotension, Bradycardia, Accompanying Neurological deficits. Monitor/findings: hemodynamic instability, test bulbo- carvernous reflex Tx: IVF, vasoactive medications if refractory

Monitoring Adjuncts in Shock Sphyngomanometry Pulse Oximeter Arterial Line Central Venous Line (Cordice, Triple Lumen, Pulmonary Artery Catheter)

Pulmonary Artery Catheterization Klkj Klkj 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.

Pulmonary Artery Catheterization Klkj Klkj

Pulmonary Artery Catheterization: cardiovascular performance Klkj Klkj Central Venous Pressure (CVP): CVP = right atrial pressure (RAP) = right-ventricular end-diastolic pressure (RVEDP) (Right Ventricular Preload) Pulmonary Capillary Wedge Pressure (PCWP) PCWP = left atrial pressure (LAP) = left-ventricular end-diastolic pressure (LVEDP) (Left Ventricular Preload)

Cardiovascular Performance Klkj Klkj Cardiac Output (CO) = HR x SV (L/min) Normal CO = 4 to 8 L/min Cardiac Index (CI) = CO/BSA (L/min/m 2 ) Normal CI = L/min/m2 Stroke Volume Index (SVI): CI/HR (ml/beat/m 2 ) Normal SVI = ml/beat/m2 Systemic Vascular Resistance = MAP – CVP / CO x 80 Normal SVR = dynes/sec/cm -5 Systemic Vascular Resistance Index = MAP – CVP / CI x 80 Normal SVRI = dynes/sec/cm-5

Pulmonary Artery Catheterization: systemic oxygen transport Klkj Klkj Oxygen Delivery (DO 2 ) [ mL/min x m 2 ]: rate of oxygen transport in arterial blood DO 2 = CI x 13.4 x Hb x SaO 2 Oxygen Uptake (VO 2 ) [ ml/min x m 2 ]: rate of oxygen taken up from the systemic microcirculation VO 2 = CI x 13.4 x Hb x (SaO 2 – SvO 2 )

Hemodynamic Profiles Klkj Klkj PCWPCVPCO/CISVR/I Hypovolemic Low High Cardiogenic High LowHigh Inflammatory Low / N HighLow Neurogenic Low Shock