In oedema,excess tissue fluid accumulates,causing swelling. It may occur either in superficial tissues or deeper organs.
SITES OF OEDEMA.
When oedema is present in the superficial tissues,pitting of the surface may be observed,ie. an indentation in the skin remains after firm finger pressure has been applied.
The sites at which superficial oedema is observed are influenced by gravity and the position of the individual. When the individual is in the standing or sitting position the oedema is observed in the lower limbs,beginning in the feet and ankles. Patients on bed rest tend to develop oedema in the sacral area. This may be described as dependant oedema.
In pulmonary oedema, venous congestion in the lungs or increased pulmonary vessel permeability results in accumulation of fluid in the tissue spaces and in accumulation of fluid in the tissue spaces and in the alveoli. This reduces the area available for gaseous exchange and results in dyspnoea,cyanosis,and coughing up of frothy sputum. The most common causes of pulmonary oedema are cardiac failure,inflammation or irritation of the lungs and excessive infusion of intravenous fluids.
