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    Circulatory shockCirculatory shock Types Etiology PathophysiologyTypes Etiology PathophysiologyTypes, Etiology, PathophysiologyTypes, Etiology, Pathophysiology

    Blagoi Marinov, MD, PhDBlagoi Marinov, MD, PhD Pathophysiology Dept.Pathophysiology Dept.

    Physiology of Circulation:Physiology of Circulation: The VesselsThe Vessels

     600 000 miles of vessels containing 5600 000 miles of vessels containing 5--6 liters of blood6 liters of blood 600,000 miles of vessels containing 5600,000 miles of vessels containing 5 6 liters of blood6 liters of blood

     Vessel tone is controlled by the sympathetic and Vessel tone is controlled by the sympathetic and parasympathetic nervous system.parasympathetic nervous system.

     PrePre--capillary sphincters control blood flow through the capillary sphincters control blood flow through the capillaries in response to Ocapillaries in response to O22 demand of the tissue.demand of the tissue.

     Preload is dependant on constant peripheral vascular Preload is dependant on constant peripheral vascular resistance. resistance.

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    MicrocirculationMicrocirculation

    Responsive to local tissue needsResponsive to local tissue needsResponsive to local tissue needsResponsive to local tissue needs Capillary beds can adjust size to supply Capillary beds can adjust size to supply

    undernourished tissue and bypass tissue undernourished tissue and bypass tissue with no immediate needwith no immediate need

    PrePre--capillary sphincters and post capillary capillary sphincters and post capillary ee cap a y sp c e s a d pos cap a ycap a y sp c e s a d pos cap a y sphincters open and close to feed or sphincters open and close to feed or bypass tissuesbypass tissues

    Causes of Inadequate PerfusionCauses of Inadequate Perfusion

    Inadequate pumpInadequate pump Inadeq ate preloadInadeq ate preloadInadequate preloadInadequate preload Poor contractilityPoor contractility Excessive afterloadExcessive afterload Inadequate heart rateInadequate heart rate

    Inadequate fluid volumeInadequate fluid volume HypovolemiaHypovolemiaHypovolemiaHypovolemia

    Inadequate containerInadequate container Excessive dilationExcessive dilation Inadequate systemic vascular resistanceInadequate systemic vascular resistance

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    Hemodynamic ParametersHemodynamic Parameters

     Systemic Vascular Resistance (SVR)Systemic Vascular Resistance (SVR) Systemic Vascular Resistance (SVR)Systemic Vascular Resistance (SVR)

     Cardiac Output (CO)Cardiac Output (CO)

     Mixed Venous Oxygen Saturation (SvO2)Mixed Venous Oxygen Saturation (SvO2)

     Central Venous Pressure (CVP)Central Venous Pressure (CVP)

    SyncopeSyncope

    FaintingFainting -- lack of blood flow to the brainlack of blood flow to the brainFainting Fainting lack of blood flow to the brainlack of blood flow to the brain Can be confused with a neurological Can be confused with a neurological

    condition (seizure)condition (seizure) DifferenceDifference Episode begins in a standing positionEpisode begins in a standing position Patient remembers feeling faint or lightheadedPatient remembers feeling faint or lightheaded Patient becomes responsive almost Patient becomes responsive almost

    immediately after becoming supineimmediately after becoming supine Skin is usually pale and moistSkin is usually pale and moist

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    Shock Shock definitiondefinition

    Profound and widespread failure ofProfound and widespread failure ofProfound and widespread failure of Profound and widespread failure of the circulation leading to the circulation leading to

    inadequate tissue perfusioninadequate tissue perfusion (e.g. cellular hypoxia and injury and vital organ (e.g. cellular hypoxia and injury and vital organ

    dysfunction)dysfunction)y )y )

    Leads to Multiple Organ Dysfunction Leads to Multiple Organ Dysfunction Syndrome (Syndrome (MODSMODS))

    Shock Shock –– OverviewOverview

    The effects of tissue hypoperfusion areThe effects of tissue hypoperfusion areThe effects of tissue hypoperfusion are The effects of tissue hypoperfusion are initally reversible, but lead to cellular initally reversible, but lead to cellular hypoxia which can cause:hypoxia which can cause: Cell membrane and ion pump dysfuctionCell membrane and ion pump dysfuction  Intracelluar edemaIntracelluar edema Leakage of intracellular contents into the Leakage of intracellular contents into the

    extracelluar spaceextracelluar space  Inadequate regulation of intracelluar pHInadequate regulation of intracelluar pH

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    General Pathophysiology of General Pathophysiology of Shock StatesShock States

    Classifications of ShockClassifications of Shock

    11.. Hypovolemic shock; (classic shock)Hypovolemic shock; (classic shock)11. . Hypovolemic shock; (classic shock)Hypovolemic shock; (classic shock)  The most common form. It is a standard used to The most common form. It is a standard used to

    compare other forms of shock in differential compare other forms of shock in differential diagnosis.diagnosis.  Hemorrhagic / Blood lossHemorrhagic / Blood loss  Dehydration / Fluid lossDehydration / Fluid loss

    22.. Extracardiac Obstructive Shock:Extracardiac Obstructive Shock:  Pulmonary Embolism / Blocked pulmonary circulationPulmonary Embolism / Blocked pulmonary circulation  Tension Pneumothorax / Increased intrathoracic Tension Pneumothorax / Increased intrathoracic

    pressure pressure  Cardiac Tamponade / Pressure on myocardium. Cardiac Tamponade / Pressure on myocardium.

    Decreased preload.Decreased preload.

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    33. . Cardiogenic Shock:Cardiogenic Shock: ::

    Classifications of ShockClassifications of Shock

     Heart (pump) Failure (40% of Myocardium damaged by AMI)Heart (pump) Failure (40% of Myocardium damaged by AMI)

    44.. Distributive ShockDistributive Shock::  NeurogenicNeurogenic // Spinal cord injury , drug overdose or poisoning Spinal cord injury , drug overdose or poisoning

    which affects nervous systems ability to maintain vascular tone which affects nervous systems ability to maintain vascular tone leading to vasodilation.leading to vasodilation.

     AnaphylacticAnaphylactic / Vasodilation and fluid shifting from capillary to cell. / Vasodilation and fluid shifting from capillary to cell. Leads to micro clotting (hives) and smooth muscle contraction Leads to micro clotting (hives) and smooth muscle contraction (brochospasm)(brochospasm)

     SepticSeptic / vasodilation and fluid shifting due to / vasodilation and fluid shifting due to overwhelming infection.overwhelming infection.

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    HYPOVOLEMIC SHOCKHYPOVOLEMIC SHOCK

     Shock due to loss of intravascular fluid volumeShock due to loss of intravascular fluid volume Shock due to loss of intravascular fluid volumeShock due to loss of intravascular fluid volume  Possible causesPossible causes

     Internal or external hemorrhageInternal or external hemorrhage  Traumatic hemorrhageTraumatic hemorrhage  Long bone or open fracturesLong bone or open fractures  Severe dehydration from GI lossesSevere dehydration from GI losses  Plasma losses from burnsPlasma losses from burns  Diabetic ketoacidosisDiabetic ketoacidosis  Excessive sweatingExcessive sweating

    HYPOVOLEMIC SHOCKHYPOVOLEMIC SHOCK

     Also can result from internal thirdAlso can result from internal third--space lossspace loss Also can result from internal thirdAlso can result from internal third--space lossspace loss  Possible causesPossible causes

     Bowel obstructionBowel obstruction  PeritonitisPeritonitis  PacreatitisPacreatitis  Liver failure resulting in ascitesLiver failure resulting in ascites

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    CARDIOGENIC SHOCKCARDIOGENIC SHOCK

     Inability to pump enough blood to supply allInability to pump enough blood to supply all Inability to pump enough blood to supply all Inability to pump enough blood to supply all body partsbody parts

     Primary cause is severe left ventricular failure Primary cause is severe left ventricular failure (AMI, CHF)(AMI, CHF)  Accompanying hypotension decreases coronary Accompanying hypotension decreases coronary

    artery perfusion, worsening the situationartery perfusion, worsening the situationy p , gy p , g  Other compensatory mechanismsOther compensatory mechanisms--increased increased

    peripheral resistance, increased myocardial O2 peripheral resistance, increased myocardial O2 demand demand --worsen situationworsen situation

    CARDIOGENIC SHOCKCARDIOGENIC SHOCK

     Other causesOther causes Other causesOther causes  Chronic progressive heart diseaseChronic progressive heart disease  Rupture of papillary heart muscles or Rupture of papillary heart muscles or

    intraventricular septumintraventricular septum  EndEnd--stage valvular diseasestage valvular disease

     Patients may be normovolemic or hypovolemicPatients may be normovolemic or hypovolemic

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