Shock: Clinical features and pathophysiology

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Shock Clinical features and pathophysiology

• Mahesh Nirmalan
• Critical Care Unit, Manchester Royal Infirmary

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Objectives

• Life-threatening condition
• Immediate or delayed mortality
• Multiple aetiology
• Recognition and Assessment
• Physiological consequences of shock
• clinical features
• Document and report on progression

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Definition of Shock

• Inadequate tissue perfusion
• Decreased oxygen supply
• Anaerobic metabolism
• Accumulation metabolic waste

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Causes of Shock

• Severe or sudden blood loss
• Large drop in body fluids
• Myocardial infarction
• Major infections
• High spinal injuries
• Anaphylaxis
• Extreme heat or cold

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Types of Shock

• Hypovolemic Shock
• haemorrhagic
• or non haemorrhagic
• Other causes of shock
• Cardiogenic Shock
• Septic Shock
• Neurogenic Shock
• Anaphylactic Shock

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Harvest of Death T H OSullivan
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Hypovolaemic Shock

• Haemorrhage Overt or occult
• Reduction in circulating volume
• Reduction in venous return and CO
• O2 supply-demand imbalance
• Lactic acidosis
• Reduction in venous oxygen saturation
• Non haemorrhagic hypovolaemia
• Severe burns, vomiting and diarrhoea

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CO, MAP and SvO2
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Effect of EDV and contractility on SV
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Changes in CO and MAP in haemorrhage
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Clinical Signs of Acute Hemorrhagic Shock
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Signs of Shock

• Cold, clammy and pale skin
• Rapid, weak, thready pulse
• Shallow, rapid breathing
• Oliguria
• Reduction in MAP
• Cyanosis
• Loss of consciousness

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Non-Haemorrhagic Shock

• Cardiogenic Shock
• Septic Shock
• Neurogenic Shock
• Anaphylactic Shock

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Cardiogenic Shock

• Primary myocardial failure
• Arrhythmia
• Tamponade
• Contusion
• Pump failure
• Reduction in cardiac output
• Decreased blood supply
• Decreased oxygen delivery

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Cardiogenic Shock

• Assess for
• Signs of heart failure
• Signs of tamponade
• Cardiac dysrrhythmia
• Myocardial infarction
• Tachycardia
• Muffled heart sounds or third heart sound
• Engorged neck veins with hypotension
• Dyspnoea
• Oedema in feet and ankles

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Septic Shock

• Bacterial, viral, fungal infection
• Gram negative and gram positive bacteria
• High output failure warm shock
• Fever, tachycardia, tachypnoea, leucocytosis
• Inadequate oxygen extraction
• High SvO2, Metabolic acidosis
• Cold shock
• Atypical presentation in immuno-compromised
  patients
• Diabetes, Cirrhosis, immunosuppression

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Septic Shock in trauma patients

• Develops 2 - 5 days after injury occurs
• Carries a poor prognosis
• Assess for
• Penetrating abdominal injuries
• Signs of infection
• Warm pink skin and dry elevated body temperature
• Tachycardia
• Wide pulse pressures

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Neurogenic Shock

• Caused by
• Spinal cord injury
• Certain drugs
• Brain stem, spinal or torso trauma
• Venous pooling and arteriolar dilatation
• Signs and Symptoms
• Hypotension without tachycardia
• Warm pink skin
• Low blood pressure minimal response to fluids

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Anaphylactic shock
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Anaphylactic Shock

• Rapid onset
• Primary systems
• Cardiovascular, Respiratory
• Skin, Gastrointestinal, coagulation
• Face, pharynx and laryngeal oedema
• Adrenaline is life saving

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Anaphylactic Shock

• Diffuse vasodilatation
• Increase size of vascular bed
• Blood is trapped in small vessels and viscera
• Temporary loss in total circulatory volume
• Sudden severe allergic reaction to
• Drugs, Toxins, Foods, Plants

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Symptoms

• Apprehension and flushing
• Wheezing or shortness of breath cough
• Rapid, weak pulse
• Cyanosis
• Generalized itching or burning
• Watering and itching of the eyes
• Hypotension
• Coma

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Stages of shock

• Compensated shock
• Autotransfusion
• Decompensated shock
• Blood moves to more vital organs
• Irreversible shock
• Multiple system / organ damage
• Even with treatment, death is the result

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Plasma Lactate
A priori groups
Post hoc groups
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Evaluation of Shock

• Internal or external hemorrhage
• Underlying cardiac problems
• Sepsis
• Trauma to spine cord
• Contact with known allergic substance
• Determine amount of blood loss
• How long has casualty been bleeding?

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Level of Consciousness

• Report and record
• Alert
• Verbal response to stimuli
• Pain response to stimuli
• Unresponsive to any stimuli

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Early Signs of Shock in Non Complicated Patients

• High index of suspicion
• Minimum tachycardia
• No measurable changes occur in blood pressure
• Pulse pressure is potentially very useful

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Definitive management

• Where?
• By whom?

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Invasive monitoring

• Essential in the definitive treatment
• Direct arterial pressure
• Central venous pressure
• Cardiac output

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Direct arterial pressure
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CVP AND CIRCULATING VOLUME?
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Treatment of Shock
Increase tissue perfusion and oxygenation status

• Maintain airway
• Control bleeding
• Baseline vital signs
• Level of consciousness

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Treatment of Shock

• Positioning
• ABCD approach
• Fluid therapy
• Drug therapy
• Keep patient at normal temperature
• Prevent hypothermia
• Minimize effect of shock
• On-going assessment - every 10-15 minutes

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Specific measures

• Hypovolaemia Blood transfusion
• Electrolyte/acid base imbalance
• Sepsis Antibiotics, ?steroids
• Neurogenic Steroids
• Anaphylactic Adrenalin

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Summary

• Life threatening Early goal directed therapy and
  regular monitoring by trained staff will change
  outcome.
• Early detection DONT RELY ON BP
• High index of suspicion
• Monitor casualties susceptible to shock