Hyperaemia Flashcards
What is colloid osmotic pressure the same as?
Oncotic pressure
What is hyperaemia?
Accumulation of RBCs inside blood vessels
Can be physiological or pathological
Hyperaemia can be active or passive. What are these also known as? Do they take place in arteries or veins?
Active hyperaemia = inflammation. Accumulation of arterial blood in arteries, arterioles and arteriolar capillary bed
Passive hyperaemia = congestion. Accumulation of blood in veins and venular capillary bed
Is active hyperaemia local or generalised? Is it acute or chronic? What about passive hyperaemia?
Active - local, acute
Passive - local or generalised, acute or chronic
What colour are the tissues affected by active hyperaemia and passive hyperaemia
Active - bright red
Passive - dark red/blue and swollen
What is ischaemia? What are the different types?
Inadequate blood supply to a tissue or organ
Can be complete or partial
Can be local or general
What causes ischaemia? (3 ways)
Heart failure (general ischaemia) Obstruction of an artery (local) Venous obstruction (local)
What is obstruction of artery/arteriole related ischaemia associated with?
Idiopathic cardiac hypertrophy
Venous obstruction causes stagnation, hypoxia and ischaemia. What is stagnation?
No blood flow/movement
Local passive hyperaemia is an increase in RBCs due to obstruction of venous return from an organ. What can cause this?
Organ misalignment
Venous thrombosis or embolism
Compression of vessel
What are the different types of organ misalignment?
Intussusception (invagination) Volvulus Torsion Twist Herniation with strangulation
How does organ misalignment cause necrosis and haemorrhagic infarction?
Veins occluded
Persistence of arterial blood supply
Increased blood pressure and congestion
Blood extravasation
What is infarction?
Tissue death to inadequate blood supply (ischaemia leads to infarction)
What is intussusception or invagination? Where is this most likely to occur?
Trapping of mesentery and vessels causes intestine to fold into the section ahead of it
Small intestine
What is volvulus?
Loop of intestine twists 180 degrees around its axis
or 360 degrees if gastric volvulus
What is gastric dilation?
Stomach rotates from its long axis to one paralleling the abdomen
What does gastric volvulus cause in terms of other GI organs?
Oesophagus completely occluded
Spleen, pylorus and duodenum moved
What type of dogs are associated with gastric volvulus? What behaviour is it associated with?
Deep chested breeds
Aerophagia and fast eating
What are predisposing factors to gastric volvulus?
Increased laxity of hepatogastric ligament
Small particle diet
Recent kennelling
Raised food bowl
What is the difference between gastric volvulus, torsion and dilation?
Volvulus - 360 degrees around itself
Torsion - rotates from long axis to axis parallel to abdomen
Dilation - rotates around its long axis
What is torsion? What organs can experience this?
Twisting around its long axis
Lung lobe, stomach, uterus
What organs can undergo twist?
Spermatic cord
What is herniation with strangulation? Give examples of where this can occur
Displacement of organ through tear or aperture of membrane
E.g. inguinal ring, diaphragm
What is a thrombosis?
Thrombus (blood clot) reduces blood flow through a vessel
What is an embolism?
A thrombus or other substance becomes stuck in a vessel and obstructs blood flow
Give examples of how compression can lead to local passive hyperaemia
Fibrosis - fibrous tissue obstructs blood vessels
Tumours
Abcesses
What can cause generalised passive hyperaemia?
Heart failure
Impeded venous return
Increased pulmonary resistance
What does heart failure cause?
Oedema, tissue hypoxia, RAAS activation, chronic congestion of lungs and liver, ascites and hydrothorax, cardiac hypertrophy
What are the 2 types of cardiac hypertrophy? What are these due to?
Concentric - due to pressure overload
Eccentric - due to volume overload
What is forward and backwards heart failure?
Forwards - systolic failure (reduced CO and perfusion)
Backwards - inability to cope with preload, due to increased venous pressure
What organs does left sided heart failure impact? What does this cause?
Lungs - pulmonary congestion and oedema
Kidneys - hypo perfusion (decreased GFR and urine)
What organs does right sided heart failure impact?
Liver, body cavities and subcutaneous tissues
Results in LSHF
Increased resistance in pulmonary circulation due to right ventricle pressure overload
How are arterial pressure and perfusion of vital organs maintained during heart failure?
Increased preload - increasing contractility
Myocardial hypertrophy and chamber dilation
Activation of RAAS, release of noradrenaline, ANPs
Impeded venous return is a cause of generalised active hyperaemia. What can cause impeded venous return?
Caval thrombosis
Hydropericardium
Exudative pericarditis
Increased pulmonary resistance causes generalised active hyperaemia. What causes increased pulmonary resistance?
Thoracic fluids
Pulmonary fibrosis
Pulmonary emphysema (don’t confuse with empyema!)
What is pulmonary emphysema?
Damage to lung bronchioles
and alveoli
A type of chronic obstructive pulmonary disease (COPD)
