Outline of Lecture
CAPILLARY CIRCULATION
Movement Of Fluid Across Capillaries
Capillary (hydrostatic) pressure
Interstitial fluid (hydrostatic) pressure
Plasma oncotic pressure
Interstitial fluid oncotic pressure
OEDEMA
Definition
An increased volume of interstitial fluid (ISF) in a tissue or organ.
May be localised or generalised (systemic)
Causes of Oedema
Raised capillary pressure
Reduced oncotic pressure
Increased capillary permeability
(Endothelial damage)
Impaired lymphatic drainage
I- Increased Venous Pressure
Raised Capillary Pressure
Cardiac failure
right ventricular failure – systemic oedema
left ventricular failure – pulmonary oedema
congestive cardiac failure – both
Local venous obstruction
deep vein thrombosis
external compression
SVC obstruction
Pregnancy
Right Ventricular Failure
Raised jugular venous pressure also seen
Enlarged liver also common due to congestion (nutmeg liver)
Pulmonary Oedema
Usually caused by LVF
Raised pressure across pulmonary capillaries
Causes shortness of breath
Due to ischemic heart disease or hypertension
Pulmonary Oedema
Congestive Heart Failure
Combination of left and right ventricular failure
Common in ischemic heart disease
Causes systemic and pulmonary oedema
Pregnancy Oedema
Commonly occurs in the lower limbs due to pressure on Pelvic nerve
II- Reduced Oncotic Pressure
(Decreased Plasma Proteins)
Renal disease
loss of albumin across glomerulus
Hepatic disease
inadequate albumin synthesis
Malnutrition
inadequate albumin intake in dite
III- Increased Capillary Permeability
Allergia (histamine increases capillary permeability).
Insects bite.
Severe hot.
Frost bite: (severe cold)
Bacterial toxins
IV- Lymphatic Obstruction
Tumours
Elephantiasis (Filariasis)
Inflammation
Surgery
Congenital abnormality
Generalised Oedema
Congestive cardiac failure
Right ventricular failure
Renal disease
Liver disease
Cerebral Oedema
Causes: increased intracranial pressure
Fatal if left untreated
Generalised in hypoxia, injury
Surrounding other lesions eg tumour, abscess
Fluid in Body Cavities
Pleural effusion
heart failure, inflammation, tumour
Pericardial effusion
inflammation, tumour
Ascites (peritoneal effusion)
cirrhosis, heart failure, tumour
Pleural Effusion
Pericardial Effusion
Ascites
Most severe cases associated with
cirrhosis of the liver
intra-abdominal malignancy
