L21: Hypertension, Hypotension, Shock

Question 1

When does venous hypertension develop

Answer 1

Impaired outflow of venous blood a.k.a passive congestion

Question 2

Give examples of conditions that may lead to venous hypertension pls

Answer 2

Congenital/ acquired arteriovenous anastomosis e.g. congenital hepatic arterioportal fistula

Question 3

What is a consequence of venous hypertension

Answer 3

INC plasma hydrostatic pressure in tributary veins, venues, capillary beds upstream –> oedema and diapedesis of erythrocytes

Question 4

What is pulmonary hypertension

Answer 4

sustained increase in systolic BP in pulmonary artery

>30mm Hg dog/cat

Question 5

What is cor pulmonale

Answer 5

R heart disease caused by pulmonary hypertension

Question 6

Why does cor pulmonale develop

Answer 6

pressure overload on right ventricle during systole –> R sided congestive heart failure or chronic compensatory concentric hypertrophy of right ventricle

Question 7

In which circumstances does pulmonary hypertension develop

Answer 7

Congenital anomalies –> L to R shunting blood E.g.
Patent ductus arteriosus
Atrial septal defect
Ventricular septal defect

Inc resistance in pulmonary blood flow E.g.
heart worm
pulmonary neoplasia
Severe chronic diffuse interstitial fibrosis

Question 8

Whats systemic hypertension

Answer 8

sustained increased in systemic arterial BP

Question 9

Which diseases can predispose animals to the development of systemic hypertension

Answer 9

Diabetes 
liver disease 
glomerular disease 
renal disease 
endocrinopathies 
NSAIDS

Question 10

Describe how some endocrinopathies can lead to systemic hypertension in animals

Answer 10

middle aged cats can develop nodular hyperplasia of their thyroid gland, generating too much T3, T4

Low thyroid function & obesity in older dogs

Cushing’s (high adrenocortical cortisol)

Question 11

Why can systemic hypertension be self-perpetuating if not adequately treated

Answer 11

related to underlying disease process –> must treat this to reduce hypertension

Question 12

Which organs are most susceptible to systemic hypertension

Answer 12

eyes
brian
kiddys

Question 13

What are some clinical signs that can develop subsequent of systemic hypertension

Answer 13

PU/PD –> reflects both diuresis and underlying primary disease process (E.g. renal failure, diabetes mellitus, hyperthoiridism, hyperadrenocorticism)

Cardiac murmur +/- galloping heart

epistaxis

strokes

Question 14

What is systemic hypotension

Answer 14

sustained decrease in systemic arterial blood pressure (<60mm cats, dogs or <80mm Hg systolic pressure)

Question 15

What overall cardiovascular changes can cause systemic hypotension

Answer 15

dec in CO and TPR

Question 16

What does persistent systemic hypotension lead to

Answer 16

shock

Question 17

Define shock

Answer 17

generalised phenomenon peripheral circulatory failure, characterised by systemic hypo perfusion and systemic hypotension

Question 18

What are the types of shock

Answer 18

Cardiogenic shock 
Hypovolaemic shock 
Distributive 
Neurogenic 
Anaphylactic 
Septic

Question 19

What is cardiogenic shock

Answer 19

rapid decrease in systolic CO despite adequate blood volume

Question 20

what causes cariogenic shock

Answer 20

Severe dilated cardiomyopathy*
Myocardial infarction 
Cardiomyopathy 
Atrial fibrillation
Tachyarrhythmias 
Rupture chordae tendinae 
Rapid pericardial effusion 
Pulmonary hypertension/ severe systemic hypertension 
Heart worm

Question 21

What is hypovolaemic chock

Answer 21

significant reduction in circulating blood volume (>20-25%)

Question 22

what are some causes of hypovolaemic shock

Answer 22

haemorrhage
severe fluid loss (vomiting/ diarrhoea)
or fluid loss through increased vascular permeability
sequestration fluid (e.g. grain overload)

Question 23

What is distributive shock

Answer 23

inappropriate vasodilation arterioles, pooling of blood in capillary beds & venous channels
(total reduced peripheral vascular resistance, decreased effective circulating blood volume)

Question 24

What are the 4x types of distributive shock

Answer 24

neurogenic shock
anaphylaxis
sepsis
heat stroke

Question 25

Describe neurogenic shock

Answer 25

fear/ pain --> brain signals affect vasomotor centre of medulla --> inappropriate peripheral vasodilation/ bradycardia

Question 26

Describe anaphylactic shock

Answer 26

mass mast & basophil degranulation= mass release vasoactive amines e.g. histamine

Question 27

What is septic shock

Answer 27

e.g. endotoxin release --> endothelial release vasodilators -> systemic arteriolar vasodilation --> hypotension & decreased effective circulating blood volume High LPS doses cause also activate platelets, activate cascade, cause widespread vascular injury & thus widespread DIC

Question 28

What are the 3 stages of shock

Answer 28

1. Initial non-progressive stage 2. Progressive stage of tissue hypo perfusion 3. Irreversible stage

Question 29

Describe the initial, non progressive stage of shock

Answer 29

COMPENSATED HYPOTENSION baroreceptors detect hypotension chemoreceptors detect hypercapnia Stimulation sympathetic NS Activation RAAS

Question 30

What is the outcome of initial non progressive/ compensated shock?

Answer 30

Vasoconstriction of arterioles and venules Maintenance of blood pressure Conservation of fluid

Question 31

In which case is the bodies attempt to compensate for initial non-progressive shock essentially useless?

Answer 31

In cases of distributive shock, where peripheral vasoconstriction is a characteristic, therefore value of compensatory response is diminished

Question 32

Describe the progressive stage of tissue hypoperfusion as part of shock

Answer 32

sustained vasoconstriction in nonessential organs= hypoxia --> lactic acid --> reversal of vasoconstriction --> pooling of blood in microcirculation Hypoxic injury can trigger DIC Oliguria

Question 33

Describe the irreversible stage of shock

Answer 33

shock will eventually lead to widespread hypoxic ell necrosis, multiple organ failure +/- DIC Death can't be prevented in this stage, only in 2nd stage with correction of underlying haemodynamic abnormalities

Question 34

What are the clinical signs of hypovolaemic and cardiogenic shock

Answer 34

``` hypotension tachycardia thready pulse tachypnoea MM pallor inc CRT decreased mentation ```

Question 35

What are the clinical signs of cardiogenic shock

Answer 35

arrhythmia, murmur muffled heart sounds

Question 36

What are the clinical sings of distributive shock

Answer 36

dark red (injected) MM, rapid CRT