Shock Flashcards
Define ‘shock’
a potentially life threatening syndrome characterised by inadequate tissue perfusion, resulting in impaired cellular respiration and functioning
Define healthy tissue perfusion
cells can use the oxygen to convert glucose to energy (ATP). This ATP is then used by the cells to carry out their metabolic activities. The process is called cellular respiration
adequate oxygen perfusion allows for aerobic metabolism, inadequate oxygen perfusion becomes anaerobic metabolism
What is the difference between aerobic metabolism and anaerobic metabolism?
aerobic is efficient and produces 36 units of ATP (energy), opposed to anaerobic metabolism, which produces only 2 units of ATP and produces lactic acid which harms cells
What is the cellular respiration equation?
C6H12O6 + 6O2 –> 6CO2 + 6H2O + ATP (36 molecules)
Glucose + Oxygen –> Carbon Dioxide + Water + Energy
Outline the effect of impaired oxygen perfusion on the body
impaired oxygen -> anaerobic metabolism triggered -> decreased ATP production -> loss of cell membrane permeability -> NA+/K+ pump lost -> fluid shifts -> lysosomal enzymes released -> cellular death and organ failure
Outline the effect of impaired glucose on the body
impaired access to and use of glucose by the cell -> access other sources of energy -> increasing acidosis -> protein depletion -> impaired cellular metabolism
What are the three stages of shock?
Compensatory stage, progressive stage, and irreversible/refractory stage
Define the compensatory stage of shock
Compensatory mechanisms activated:
>decreased CO stimulates receptors
>Adrenaline and noradrenaline released
Blood flow to most essential organs (heart & brain) maintained
>decreased blood flow to kidneys, GIT, lungs and skin
>renin-aldosterone system activated
>antidiuretic hormone (ADH) released
If corrected patient can recover from this stage
Define the progressive stage of shock
Compensatory mechanisms fail
Decreased ATP production, Hypoxia of vital organs, Decreased cellular perfusion and tissue ischemia, Metabolic acidosis, Decreased cardiac output, Myocardial ischemia. Increased risk of gastric trauma, Increased risk of developing disseminated intravascular coagulation (DIC) (abnormal clotting), Acute renal failure
Aggressive management required to prevent multiple organ dysfunction syndrome (MODS)
Define the irreversible/refractory stage of shock
Compensatory mechanisms are overwhelmed
Severe tissue hypoxia with ischemia, necrosis and death of the cell occurs
Build up of toxins
Multi-organ failure
Recovery unlikely
What are the four types of shock?
Hypovolaemic shock (loss of intravascular volume)
Cardiogenic shock (pump failure)
Distributive shock (systemic vasodilation)
Obstructive shock (physical obstruction of blood circulation)
These can occur in isolation or in combination (Multifactorial shock)
What are the three types of Distributive shock?
Septic shock (infection), anaphylactic shock (allergic reaction), neurogenic shock (spinal cord injury potential complication)
Outline hypovolaemic shock
Caused by a loss of fluid. This can be from whole blood (haemorrhage), plasma (burns) or interstitial fluid (vomiting, diaphoresis). Shock begins to develop when the total circulating volume is decreased by approximately 15%
What are clinical manifestations of hypovolaemic shock
anxiety, tachypnoea, hypotension (may be HTN at first due to compensatory measures), tachycardia, weak peripheral pulses, clammy moist skin, thirst, acidosis
Outline cardiogenic shock
occurs from cardiac pathology causing inadequate cardiac output leading to tissue hypoxia. Cardiogenic shock occurs in the presence of ADEQUATE intravascular volume
Causes include reduced contractility, inadequate filling, arrhythmia, and failure of forward flow
What are clinical manifestations of cardiogenic shock?
increased WOB, elevated RR, crackles/acute pulmonary oedema (APO), tachycardia, hypotension, distended neck veins, clammy skin, prolonged cap refill, decreased urine output, confusion
Define distributive shock
results from excessive vasodilation and impaired distribution of blood flow.
There are three types of distributive shock: Septic shock, Anaphylactic shock, Neurogenic shock
Define septic shock
Occurs when a patient develops sepsis: a life threatening condition of bacteria has entered in the bloodstream which triggers an inflammatory response.
Septic shock will develop when this response causes widespread vasodilation, tachycardia, decreased myocardial contractility and decreased tissue perfusion
What are clinical manifestations of septic shock?
Tachypnoea, Hypoxia, Hypotension, Systemic oedema, Tachycardia, febrile, Decreased urine output, Hot clammy skin, Confusion