2 - Haemodynamic disorders Flashcards
What causes pulmonary oedema?
What causes this?
raised hydrostatic pressure in the pulmonary capillary bed
this is caused by left ventricular failure
(increased pressure in the left atrium—> back pressure-volume in the capillaries—> pushes fluid into the interstitial space
What is cardiogenic pulmonary oedema?
fluid accumulated in the interstitial space and spills over into the alveolar walls
What is non-cardiogenic pulmonary oedema caused by?
increased permeability
What is ARDS?
What are the most common causes?
What is the main symptom?
acute respiratory distress syndrome
causes: sepsis, shock, trauma
main symtom is dyspnea
List the 4 types of cerebral oedema
- vasogenic
- cytotoxic
- osmotic
- interstitial
What is a vasogenic cerebral oedema?
What are the causes?
physical breakdown of the blood-brain barrier
causes: trauma and tumours
What is a cytotoxic cerebral oedema?
derangement of the sodium-potassium pump leads t o a build of intracellular sodium, causing intracellular oedema
common in ischaemic strokes
What is an osmotic cerebral oedema?
What is the cause?
reduction in plasma osmolality
cause: SIADH (syndrome of inappropriate ADH secretion), which is commonly caused by small cell carcinoma
What is an interstitial cerebral oedema?
What is the cause?
breakdown of the CSF-brain barrier
cause: obstructive hydrocephalus
CSF moves into the interstitial space
What is anasarca?
sever generalised oedema
Define generalised oedema?
the widespread accumulation of fluid in subcutaneous tissue and serous cavities
Define thrombosis
an abnormal blood clot formation in the circulatory system
What often causes vessel war injury?
atherosclerotic plaques
What is a stenosis?
What does it cause?
narrowing of an artery by the thrombus
causes ischaemia
What is an occlusion?
What does it cause?
complete blockage of an artery by a thrombus
causes infarction of the tissue supplied by the artery
Define embolism
a detached intravascular solid, liquid or gaseous mass that is carried by the blood to a site distant form its point of origin
most are thromboemboli (fragments of dislodged thrombus)
What are the other types of embolic material?
- fat
- air
- amniotic fluid
- tumour
Where do venous thromboemboli originate from and what is the major consequence?
most originate from the deep veins (DVT)
major consequence is pulmonary (thrombosis)embolism
Why is there a range of consequences of pulmonary thromboemboli?
consequence depends on the size and where it becomes lodged
e.g. emboli lodging in a major pulmonary artery will cause instantaneous death
What is a saddle embolus?
one that becomes lodged at the bifurcation of the pulmonary trunk
What are the symptoms when a pulmonary embolism lodges in a middle sized artery?
breathlessness
Where do arterial thromboemboli originate from and what can it cause?
originate from carotid arteries
most likely to affect cerebral arteries and cause stroke
Where do cardia thromboemboli originate from?
Where can it lodge and what are the consequences?
originate from the left side of the heart
can lodge in:
- cerebral artery= stroke
- mesenteric artery= bowel infarction
- lower limb artery= acute lower limb infarction
Define haemorrhage
extravasation of blood due to vessel rupture
can be external or enclosed within a tissue
What are the causes of haemorrhage?
trauma
intrinsic disease of the vessel
How are haemorrhages classified?
based on their size
What can be the result or a solid haematoma within the cranial cavity?
can be fatal
causes a rise in ICP and (tonsillar) herniation
When does shock occur?
when tissue perfusion is insufficient to meet the metabolic demand
Give the equation for mean arterial pressure
MAP = CO x SVR
Mean arterial pressure = cardiac output x systemic vascular resistance (total peripheral resistance)
