CR Revision 6 Flashcards
What are the 4 classifications of shock? [4]
Obstructive shock
Distributive shock
Cardiogenic shock
Hypovolaemic shock
How does obstructive shock ?
Explain three examples that could cause obstructive shock xx [2]
PE
Tension pneuomothorax air gets trapped in pleural space: compresses against vena cava and heart: stops blood flow into right side of heart: reduced preload: reduced CO
Cardiac tamponade :accumulation of pericardial fluid: causes increas in intrapericardial pressure which reduceds cardiac filling
Describe how disitributive shock works xx
Results from excessive vasodilation and the impaired distribution of blood flow
Characterized by a significant drop in peripheral vascular resistance and, as a result, hypotension
Explain 3 examples of distributive shock x
Sepsis: dysregulated host response to infection where bacteria in blood release chemicals causing uncontrolled hypotension
Anaphylactic shock: allergic response to antigen: IgE mediated mass degranulation releasing histamines: vasodilation and capillary leaking
Neurogenic shock: loss of sympathetic tone and thus unopposed parasympathetic response driven by the vagus nerve. Consequently, patients suffer from instability in blood pressure,
What is cardiogenic shock?
Name 4 causes of cardiogenic shock xx [4]
Failure of the heart to pump blood
Occurs as a result of ventricular dysfunction (esp. LV)
Causes:
* Acute myocardial infarction leading to ventricular dysfunction
* Arrhythmias
* Valvular rupture
* Decompensated heart failure
What is hypovolaemic shock?
Reduced circulating volume leads to reduced venous return and therefore preload
Explain 4 causes of hypovolaemic shock xx
- Haemorrhage
- GI losses: severe diarrhoea and vomiting
- Surgery: exposure of internal structures to heat
- Burns: fluid shift into extravasuclar space due to inflam response
Explain the compensatory mechanisms for haemorrhagic shock [3]
Baroreceptors detect drop in arterial pressure
Activates sympathetic stimulation:
- Constriction of small arterioles increasing total peripheral resistance thereby maintaining BP
- Veins and venous reservoirs constrict, maintaining venous return
- Increased heart rate and contractility to maintain cardiac output
CNS ischaemia results in increased noradrenaline and adrenaline secretion from adrenal medulla
How does RAAS system work to compensate shock? [3]
- Water retention and salt reabsorption
- Vasomotor centre in the medulla signals to the hypothalamus to release vasopressin (ADH)
- Urine flow and sodium excretion decrease
Name 3 long term compensatory mechanisms of shock [3]
- There is (by an unknown mechanism) stimulation of albumin and other plasma protein synthesis in the liver.
- Increased fluid absorption from GI tract
- Fibroblasts surrounding the kidney tubules are sensitive to hypoxia and release increased amounts of erythropoietin: Red cell production
CO = [] X []?
BP = [] x []?
CO = HR X SV
BP = CO x Systemic vascular resistance
Vasodilation is mediated by the activation of which two compounds? [1]
Explain their basic mechanism [1]
Nitric oxide and prostacyclin [1]
MoA: Through cGMP and cAMP respectively, secondary messengers cause decrease in calcium and smooth muscle relaxation
Vasoconstriction is predominately activated by which molecule on which receptors? [2]
Name two alternative compounds that can cause vasoconstriction [2]
Vasoconstriction is predominately activated by which molecule on which receptors? [2]
Noradrenaline on alpha 2 recptors
Name two alternative compounds that can cause vasoconstriction [2]
Angiotensin
Vasopressin
What are the overall physiological consequences of shock ? [3]
- Increased afterload
- Reduced systemic vascular resistance (Failure to maintain peripheral vasoconstriction)
-
Decreased CO
i) reduced preload
ii) reduced contactility
Describe the effects to cells of hypoxia and hypoperfusion
- Cells switch from aerobic to anaerobic metabolism
- Lactic acid production
- Cell function ceases & swells
- Membrane becomes more permeable
- Electrolytes & fluids seep in and out of cell
- Na+/K+ pump impaired
- Cells swell causing mitochondria damage
- Cell death
Name and describe the 4 stages of shock
What are the signs of shock?
- Pulse is weak and rapid
- Pulse pressure reduced - mean arterial pressure (MAP) may be maintained - NOTE; ARTERIAL BP is NOT A GOOD INDICATOR OF SHOCK since it will be maintained until a very large amount of blood loss
- Reduced urine output
- Reduced pH
- Confusion, weakness, collapse and coma
Explain the mechanism of septic shock xx
Pathogens have unique cell wall molecules called pathogen associated molecular patterns (PAMPS) that bind to pattern recognition receptors (TLRs) on immune cells
Causes pro-inflam cytokines: activates the adaptive immune, which causes direct and indirect host injury
Causes release of NO: vasodilation and drop in BP
Cytokine release causes the endothelial lining of blood vessels to become more permeable. This causes fluid to leak out of the blood and in to the extracellular space leading to oedem, a reduction in intravascular volume, and therefore amount of oxygen reaching tissues
Activation of the coagulation system leads to deposition of fibrin throughout the circulation further compromising organ and tissue perfusion. It also leads to consumption of platelets and clotting factorsas they are being used up to form the clots within the circulatory system.
Explain the MoA of anaphylactic shock
pathological allergic response:
- an antigen (usually inhaled or swallowed) reacts with IgE on mast cells & basophils; This is called Type 1 hypersensitivity.
- The cells degranulate and release inflammatory mediators including histamine.
- Histamine reacts on capillaries and arterioles to cause endothelial cells to lose their tight junctions and separate. This allows water to leak out into tissues.
- Causing swelling and vasodilation leading to uncontrolled hypotension and anaphylactic shock
Describe the 4 classes of haemorrhagic shock
x
Explain which of HR or BP falls first in major haemorrhage stroke :)
Cardiac output can accommodate c. 10% blood loss before change in CO
Between 10-20% fall in blood loss, arterial pressure compensates by vasoconstriction
SO you see a raise in HR to compensate fall in SV BEFORE you see a fall in BP
Whats the A-E of shock management?
Airway: probs ok unless they have analphylaxis
Breathing: usually ok, may have compensatory increase in RR to compensate hypoxia in tissues. OR might have tension pneumothorax. Later stages: hypoxic
Circulation: give IV access: increase fluids to increase BP
Disability: Low: cant respond bc of lack of 02
Exposure: look at skin – rash / burns / pale
What is chylothorax? [1]
Why may it occur? [1]
Chylothorax: leakage of lymph into the pleural cavities
Can cccur due thoracic duct damage
What are the paths for the deep and superficial cervical lymph nodes?
Superficial cervical lymph nodes run down external jugular vein.
Drain to the deep cervical lymph nodes: run down internal jugual vein
Label A & B xx
A: Thoracic duct
B: Left venous angle
Name the superficial cervical nodes [6]
Parotid
Buccal
Submental
Submandibular
Retroauricular
Occipital
Label A-F
A: Parotid
B: Buccal
C: Submental
D: Submandibular
E; Retroauricular
F: Occipital
Lymph from the internal and external iliac nodes drains into the [] nodes and then the [] nodes.
Lymph from the GI tract drains into the [] lymph nodes ([], [] and [] nodes)
Intestinal + right and left lumbar trunks drain to []
Lymph from the internal and external iliac nodes drains into the common iliac nodes and then the lumbar nodes.
Lymph from the GI tract drains into the pre-aortic lymph nodes (celiac, superior mesenteric and inferior mesenteric nodes)
Intestinal + right and left lumbar trunks drain to cisterna chyli (beginning of thoracic duct)
Where do you find each of the following tonsils?
Palatine [1]
Lingual [1]
Pharyngeal [1]
Tubal [1]
Palatine: between palatoglossal & palatopharyngeal
Lingual: back of tongue
Pharyngeal adenoids if enlarged: top of nasopharynx
Tubal tonsils: opening of eustachian tube
Label A-D
A: Pharyngeal
B: Lingual
C: Palatine
D: Tubal tonsils
From the breast:
- 75% drains into [] nodes
- 25% goes to [] nodes
Clinically important because of relationship to breast
75% of lymph drains into axillary node from breast
25% goes to parasternal nodes
What are the axillary lymph nodes? [3]
Where do they drain lymph from? [3]
Ddescribe their path to to L / R venous angle [2]
Humeral lymph nodes drain from upper limb
Pectoral lymph nodes drain from anterior chest wall (majority drains into here)
Subscapular lymph nodes drain from posterior chest wall (rotator cuffs etc)
Together: go to central –> apical –> supraclavicular –> left / right venous angle
Describe the path of deep drainage of the thorax lymphatics
Sub pleural plexus –> interlobal lymph vessels –> interpulmnarry lobes –> inferior trachea bronchiol nodes –> superior trachea bronchiole lobes –> bronchomediastinal trunks –> L / R venous angle
What is the most common site for atherosclerotic plaque build up? [1]
Which area is most common for coronary artery athersclerotic plaque build up? [1]
Acceptable responses: Bifurcations, Bifurcation points, Points of bifurcation, Bifurcation
the anterior interventricular/left anterior descending branch being most commonly affected.
Label 1-3
1: LCA
2: LAD
3: Left circumflex
Which valves close during S1?
Which valves close during S2?
Where do each of the following correspond to on an ECG?
S1: closure of mitral and tricuspid valves: QRS
S2: close of aortic and pulmonary valves: After T wave
An 18 year-old pregnant patient has her 19 week ultrasound. A defect in the foetal heart is picked up.
The foetal heart is shown in the image. On the right is the Doppler image showing blood flow.
Based on your knowledge of congenital heart defects, which defect do you think the doppler image is demonstrating?
Transposition of the great vessels
Ventricular septal defect
Patent ductus arteriosus
Coarctation of the aorta
An 18 year-old pregnant patient has her 19 week ultrasound. A defect in the foetal heart is picked up.
The foetal heart is shown in the image. On the right is the Doppler image showing blood flow.
Based on your knowledge of congenital heart defects, which defect do you think the doppler image is demonstrating?
Transposition of the great vessels
Ventricular septal defect
Patent ductus arteriosus
Coarctation of the aorta
This image here shows the ventricles of the heart, and the mixing of blood between the ventricles indicates a ventricular septal defect (VSD)
Label the vert. layers of A-D
The laryngeal prominence occurs at which vertebral level
C3
C4
C5
C6
C7
The laryngeal prominence occurs at which vertebral level
C3
C4
C5
C6
C7
