SCT III - Circulatory Shock Flashcards
What is circulatory shock?
A medical emergency that results in inadequate oxygen perfusion and tissue oxygenation
What are the factors influencing tissue perfusion (flow)?
Flow (Q) = Pressure (P) x Resistance (R)
What are the four types of circulatory shock?
- Hypovolemic
- Cardiogenic
- Obstructive
- Distributive
What is hypovolemic shock?
Severe fluid/blood loss leads to inadequate blood volume, causing insufficient oxygen delivery to tissues
What could cause hypovolemic shock?
- Hemorrhage
- Dehydration (vomiting, diarrhea, extreme sweating, burns)
- Trauma (contusion: ruptured blood vessels, bruise)
What is cardiogenic shock?
Heart fails to pump blood effectively, leading to insufficient oxygen delivery to tissues
What could cause cardiogenic shock?
- Decreased pump function (ischemia, cardiomyopathy)
- Valve diseases (obstructive, regurgitant)
- Dysrhythmia (Arrythmia)
What is obstructive shock?
Factors extrinsic to myocardium & cardiac valves lead to insufficient oxygen delivery to tissues (i.e. blood clot stops a muscle from getting blood/nutrients)
What may cause obstructive shock?
- Decreased Venous Return:
1. Pericardial tamponade
2. Venacava obstruction
3. Pneumothorax
4. Pulmonary embolism
5. Coarctation of aorta
What is distributive shock? What are the types of distributive shock?
Abnormal blood distribution/blood vessel dilation leads to inadequate perfusion to other tissue (despite normal blood volume)
3 types:
- Neurogenic
- Anaphylactic
- Septic
What is neurogenic shock?
Subtype of distributive shock: damage to spinal cord/nervous system leads to loss of sympathetic tone (widespread Vasodilation)
- Spinal transection
- Brain damage
- Fever
What is anaphylactic shock?
Subtype of distributive shock: allergic reaction which releases lots of histamine that causes widespread vasodilation and increased capillary permeability
What is septic shock?
Subtype of distributive shock: caused by a severe infection, leading to lots of inflammation, vasodilation, low blood pressure, and impaired blood flow (perfusion) to organs
What are the three stages of shock?
- Non-progressive (Compensated)
- Progressive (Decompensated)
- Irreversible
What is meant by compensatory and decompensatory stages?
Compensatory means the body attempts to compensate to the damage
Decompensatory means that the body failed at its attempt
What are the cellular effects of inadequate tissue perfusion?
- ATP Depletion
- Na+/K+ ATPase slowes
- Intracellular Na+ accumulation
- Intracellular Calcium accumulation
- Cell swelling
- Mitochondrial swelling
- Endoplasmic reticulum swelling
Decrease in intracellular pH
- Accumulation of lactic acid
- Accumulation of inorganic phosphates
- Accumulation of ROS
APOPTOSIS
What happens during the first stage of circulatory shock?
Non-progressive - Compensatory
Normal circulatory compensatory mechanisms eventually cause full recovery without the need of outside therapy
What are the symptoms of first stage circulatory shock?
Non-progressive - Compensatory
- Depends on amount of blood-loss
- Pale, cold, sweaty skin
- Rapid breathing
- Tachycardia (weak pulse)
- Maintained blood pressure
- Mild anxiety, restlessness, irritability
What is the key response of the body to the first stage of circulatory shock?
Non-progressive - Compensatory
- Negative feedback: which brings CO and MAP back to normal level
What takes place during the activation of negative feedback in the compensation of first stage circulatory shock?
Seconds
- Baroreceptor reflex
- Chemoreceptor reflex
- CNS ischaemic reflex (cushing’s)
Minutes/Hours
- Cardiopulmonary baroreceptor reflex
- RAAS
- ADH/Vasopressin
- ANF
Baroreceptor Reflex
Chemoreceptor Reflex
What is the MAP difference between the skull and the heart in an orthostatic position?
10-15 mmHg less than the level of the heart
CNS Ischemic Response (Cushing’s)
Cardiopulmonary Baroreceptor Reflex
Long Term Regulatory Factors Summary
Role of SNS in Negative feedback
What are the neuroendocrine responses during circulatory shock?>
Corticotropin Releasing Hormone ↑
- Adenocroticotropin Hormone (ACTH) ↑
- Which Cortisol from Adrenal Cortex ↑
Adrenal Medulla
- Adrenaline & Noradrenalin ↑
Pancreas
- Glucagon ↑
- Insulin ↓
Pituitary gland
- ADH/Vasopressin ↑
What are the symptoms of second stage circulatory shock?
Progressive - Decompensated
- Pale, cold, sweaty skin
- Marked tachycardia
- Low blood pressure
- Empty neck veins
- Altered mental status (confusion, anxiety, etc.)
- Thirst
- Oliguria (low urine output)
- Hyperventilation
- Lactic acid ↑ (Acidosis)
What cycle could occur in second stage circulatory shock?
Progressive - Decompensated
- Without therapy = death
- Vicious positive feedback cycles are developed (decreasing CO & MAP)
- Blood supplies only most important organs
What happens to the cardiac pump function during progressive circulatory shock?
Deteriorates
What happens to tissue and blood during second stage circulatory shock?
Tissue
- Heart: CO ↓
- Kidney: Uremia (Declining renal function)
- CNS: Vasomotor failure
- Acidosis
- ATP ↓
Blood
- Thrombosis ↑
- Endothelial collapse
What happens during the third stage circulatory shock?
Irreversible Stage
Shock has progressed to such an extent that all forms of known therapy are inadequate to save the person’s life.
What are the symptoms of third stage circulatory shock?
Irreversible Stage
- Cold, sweaty, extremely pale skin
- Extreme tachycardia (>140) w/ barely palpable pulse
- Reduced blood pressure
- Confusion, unconsciousness
- Anuria (Absence of urine prod.)
What happens during third stage circulatory shock?
Irreversible Stage
- Endothelial dysfunction
- Inflammation
- Advanced disseminated intravascular coagulation (DIC)
- Therapy resistant cardiac depression (falling systolic and diastolic pressure)
- Marked capillary dilation, increased permeability
- Stagnation of blood in the extremities
