Lecture 11: Haemorrhage & Shock Flashcards
1. Define shock and describe the different categories of shock 2. Describe the classifications of haemorrhage 3. Describe the compensatory responses of the body in response to haemorrhage 4. Describe irreversible shock & the theories surrounding it
Explain the types of shock
- Psychological (mental): Occurs following a physical or emotional traumatic experience
affects the person’s state of mind
give rise to symptoms such as palpitations and feeling faint
doesn’t lead to serious physical collapse
its effects can persist for years - Physiological (circulatory): Acute progressive circulatory failure
treated in the long-term based on the underlying cause
can be life threatening
Explain what circulatory shock is
- Circulatory Shock: Condition where the circulatory system cannot provide adequate blood supply to vital body organs
- MAP drops-> BP drops
- MAP drop-> Inadequate circulation of blood
- Systemic effect = tissue damage due to inadequate supply of oxygen and nutrients
- Cardiac Output-> key determinant of MAP
List the causes of circulatory shock
- Drop in CO
2. Drop in TPR
Explain the mechanisms carried out that cause the common symptoms of circulatory shock is observed and its reasons
- Increased HR-> barorecptor reflex causes cardiact stimulation + increase in sympathetic activity-> offset reduced SV
- Pale, cold skin-> systemic vasoconstriction by RAAS and vasopressin + increase TPR+ increased MAP-> conserve blood flow to vital organs by vasodilation due to secretion of local metabolic factors
- weak,rapid pulse-> decrease SV+ decrease CO+ increase HR
Name the different types of circulatory shock
- Hypovolemic Shock
- Cardiogenic Shock
- Vasogenic Shock
- Neurogenic Shock
Explain the cause and treatment for hypovolemic shock
- Cause= haemorrhage + excessive D+V
- Loss of fluid from plasma
- Loss of blood
= decrease in cardiac output - Treatment= administer fluids
Explain what cardiogenic shock is explain its causes, treatment and complications
- Heart suddenly can’t pump enough blood to meet body’s needs
- Efficiency of heart pumping reduced
Causes =
- MI
- Heart failure- due to coronary heart disease, high blood pressure etc
- Arrhythmias (heart beats with an irregular rhythm)
- Heart pathology such as myocarditis/pericarditis (Inflammation of cardiac muscle + Inflammation of pericardium)
- Valve problems- leaky
Treatment:
- Treat underlying cause
- Inotropes
Complications:
- Left sided heart failure = pulmonary oedema (most common)
-> Left ventricle doesn’t pump efficiently- prevent delivery of O2 rich blood to organs
-> Blood backs up into lungs instead
= shortness of breath and a buildup of fluid
- Right sided heart failure = systemic oedema
-> Usually triggered by left-sided heart failure, or lung disease
-> Accumulation of blood in the lungs caused by left-sided heart failure
= makes right ventricle work harder
-> Can stress the right side of the heart and cause it to fail
-> Marked by swelling of the lower extremities
Explain the causes, pathophysiology, signs and symptoms and treatment for vasogenic shock
SEPTIC SHOCK
-Causes:Invasion by microorganism; mainly gram negative bacteria, fungi, virus
- Pathophysiology: vasodilator substances released from bacteria =sepsis
excessive vasodilation
↓ TPR ↓ MAP
+ inflammation: ↑ body temp, ↑ metabolic rate
- S+S:↑ temp, ↑ WBCs, ↑ MR,
↑ HR, metabolic acidosis (build-up of lactate)
- Treatment: treat underlying cause
ANAPHYLACTIC SHOCK
- Causes: exposure to antigen/allergen= extreme hypersensitivity reaction
acute & life threatening
- Pathophysiology: excessive vasodilation
=↓ TPR ↓ MAP
Release of vasoactive mediators (histamine, cytokines)
Massive vasodilation, peripheral pooling,
↑ capillary permeability
- S+S: Anxiety, dyspnoea (difficult or laboured breathing), hypotension
- Treatment: treat underlying cause priority = maintain airway
Antihistamine administered (benadryl)
Epinephrine (sympathomimetic → vasoconstriction & bronchodilation)
Explain the causes, S+S and treatment for neurogenic shock
Cause: spinal cord injury or drugs
->drugs may inhibit peripheral vasoconstriction
Signs + symptoms: - Paralysis - Absence of reflexes - Hypotension - Bradycardia (dysregulation of heart rhythm) - Loss of temperature regulation Treatment: - treat underlying cause - vasoconstrictors (e.g. dopamine)
Explain how haemorrhage can be classified
- By ATLS
- S&Ss associated with degree of blood loss
State the condition of person in class I and class IV for ATLS
- Class 1= normal healthy state
- Class 4(IV)= hemorrhage is pre-terminal & requires immediate intervention
Explain the immediate consequences of haemorrhage
- decrease in blood vol.
- decrease in venous return
- decrease in SV
- decrease in CO
- decrease in MAP
Explain how the immediate responses are carried out for haemorrhage
Response= Baroreceptor reflex
- Baroreceptors (blood pressure) in the aortic carotid bodies and aortic arch sense drop in blood pressure and initiate:
- Cardiac stimulation = elevated heart rate
- Systemic vasoconstriction = secretion of vasopressin and renin-angiotensin-aldosterone
- Flow & volume redistribution = sympathetic/parasympathetic activity to organs increasing blood flow to heart and brain and reducing to other systems
= INCREASE IN PLASMA VOLUME
- INCREASE IN SYMPATHETIC ACTIVITY= LEADS TO INCREASE IN MAP
Response= Bulk flow
- Decrease in capillary BP= less filtration + more reabsorption
- Fluid shift from interstitial to plasma
= INCREASE IN PLASMA VOLUME
- Not sustainable for long term
Explain the long term responses for haemorrhage
Initial consequence= decrease in blood volume
Response= increase thirst
- Drink more fluids
- More fluid inside body
= INCREASE IN PLASMA VOLUME
- Increase in sympathetic activity
- Increase in arteriole vasoconstriction in kidney
- Decrease renal BF
= DECREASE IN URINARY OUTPUT - Conserve H2O
= INCREASE IN PLASMA VOLUME
= INCREASE IN CO - Decrease in plasma volume
- Stimulate release of vasopressin-> activates RAAS
- Aldosterone-> increases Na+ reabsorption = decrease in osmolarity of bodily fluids
- Vasopressin secreted -> for H2O reabsorption
- = DECREASE IN URUNARY OUTPUT + INCREASE IN PLASMA VOLUME
- Decrease in renal BF-> lower filtration
- Decrease O2 delivered to kidney-> erythropoietin released
= STIMULATE PRODUCTION OF RBC -> after a week of hemorrhage
List the classes where haemorrhage causes irreversible shock
- Class 3 + 4-> more than 30% blood vol. lost= irreversible shock
