Haemodynamic disorders Flashcards
Define Oedema.
Abnormal increase in interstitial fluid
What three forces determine the movement of fluid between blood vessels and the interstitial space?
Capillary hydrostatic pressure
Plasma hydrostatic pressure
Plasma oncotic pressure
What are the four broad causes of oedema?
Increased capillary hydrostatic pressure Decreased plasma oncotic pressure (e.g. nephrotic syndrome) Inflammation Lymphatic Obstruction
What is a common cause of pulmonary oedema?
Increased plasma hydrostatic pressure in the pulmonary capillary bed
Left Ventricular Failure – build up of pressure in left atrium leading to back pressure into the capillaries – this pushes water into the tissues
This is cardiogenic pulmonary oedema
What is non-cardiogenic pulmonary oedema?
Caused by increased permeability
ARDS – Acute Respiratory Distress Syndrome
Often caused by Sepsis, Shock and Trauma
What are the four types of cerebral oedema?
Vasogenic – physical breakdown of the blood-brain barrier – commonly due to trauma or tumours
Interstitial – breakdown of the CSF-brain barrier – commonly due to obstruction of the flow of CSF (Obstructive Hydrocephalus)
Cytotoxic – derangement of the sodium-potassium pumps leads to a build up of intracellular sodium causing intracellular oedema (common with ischaemic strokes)
Osmotic – increase in plasma osmolality – commonly caused by Syndrome of inappropriate ADH secretion (SIADH) that is commonly caused by small cell lung cancer
What are the possible serious consequences of cerebral oedema?
Rise in intracranial pressure, which could cause herniation
What are two common causes of generalised oedema?
Left Ventricular Failure Nephrotic Syndrome
What is a consequence of oedema in a peripheral setting?
Impaired wound healing
What are the three main factors affecting thrombus formation?
Hypercoagulability
Vessel Wall Injury
Stasis
What is cardiac thrombosis caused by and what is an important complication?
Stasis – e.g. atrial fibrillation
Complication – systemic embolisation
What is arterial thrombosis caused by?
Vessel wall injury
What is venous thrombosis caused by and what is an important complication?
Stasis and Hypercoagulability Complication – pulmonary embolism
What are the four fates of a thrombus?
Propagation– thrombus accumulates fibrin and grows
Embolisation– thrombus dislodges and moves somewhere else
Dissolution– thrombus is dissolved by fibrinolytics
Organisation and Recanalisation– thrombus becomes fibrotic and is remodelled, lumen appears again allowing blood flow
Where do most arterial thromboemboli originate?
Carotid arteries