Oedema is the abnormal accumulation of fluid in the interstitial spaces or body cavities. It occurs when the normal homeostatic balance between fluid filtration and absorption is disrupted, leading to tissue swelling. While it is a clinical sign rather than a disease itself, oedema signals an underlying physiological imbalance that requires nursing investigation. The excess fluid mostly consists of water, electrolytes, and plasma proteins that have escaped the vascular network.
Fluid movement across the capillary wall is governed by Starling forces, which balance hydrostatic and oncotic pressures.
When capillary hydrostatic pressure rises or plasma oncotic pressure drops, fluid shifts overwhelmingly into the interstitium, causing swelling.
Oedema presents in different distributions depending on whether the trigger is a regional event or a systemic failure.
Recognising the distribution helps the nurse narrow down the diagnostic possibilities during the initial patient assessment.
Multiple medical conditions disrupt fluid dynamics. Heart failure increases venous pressure, forcing fluid into the lungs or lower limbs. Kidney diseases, such as glomerulonephritis, cause sodium and water retention while spilling vital proteins into the urine. Liver cirrhosis impairs the synthesis of albumin, dropping oncotic pressure. Additionally, malnutrition creates a protein deficit that mimics hepatic failure. Local blockages, such as filariasis or surgical removal of lymph nodes, prevent fluid return via the lymphatic system, resulting in firm, non-pitting swelling.
Assessing oedema requires systematic physical examination techniques. The nurse inspects the skin for tautness, shininess, and discolouration. To grade pitting oedema, firm pressure is applied with a thumb over a bony prominence, such as the tibia or medial malleus, for at least five seconds.
Documenting the depth and duration of the pit helps evaluate the effectiveness of ongoing diuretic therapy.
Laboratory and imaging tests help pinpoint the root cause of fluid accumulation. Urinalysis checks for proteinuria, which suggests glomerular damage. Serum electrolyte and blood urea nitrogen panels evaluate renal function. Liver function tests, including serum albumin and bilirubin levels, assess hepatic synthetic capacity. Electrocardiograms and echocardiograms reveal cardiac chamber enlargement or pump failure. Venous duplex ultrasound is ordered if deep vein thrombosis is suspected as the source of unilateral leg swelling.
Management strategies target both the underlying cause and the relief of fluid overload. Diuretics, such as furosemide, are commonly prescribed to promote renal excretion of excess water and sodium. Dietary sodium restriction prevents further water retention. Elevating swollen limbs above the level of the heart encourages venous and lymphatic return. Compression stockings help prevent fluid pooling in chronic venous insufficiency. Nurses must regularly monitor daily weights, strict fluid intake and output charts, and watch for electrolyte imbalances like hypokalaemia during diuretic therapy.
Unmanaged oedema creates significant tissue risks. Chronic swelling impairs local microcirculation, leading to skin breakdown, delayed wound healing, and ulcers. In severe cases, stagnant fluid increases the risk of local infections such as cellulitis. Patient education focuses on dietary modifications, proper skin care to prevent cracking, and recognizing danger signs. Patients must report sudden weight gain, worsening shortness of breath, or increased pain immediately, as these may signal worsening cardiac or renal function.