Fluid and Electrolyte Balance

Capillary hydrostatic pressure (CHP) ______ fluid ______. (favors filtration)

pushes, out.

Interstitial fluid osmotic pressure (IFOP) ______ fluid ____.

pulls, in. (favors filtration)

Blood colloid osmotic pressure (BCOP) ____ fluid ______.

pulls, in. (favors absorption)

Interstitial fluid hydrostatic pressure (IFHP) _____ fluid ___.

pushes, in. (favors absorption)

Capillary hydrostatic pressure (CHP) & Interstitial fluid osmotic pressure (IFOP)

Forces that filter fluid. Happens in the arterial end.

Blood colloid osmotic pressure (BCOP) & Interstitial fluid hydrostatic pressure (IFHP)

Forces that facilitate absorption within fluid through the venous end.

Edema

When fluid is trapped in the interstitial fluid. It is a failure of starling forces.

Edema can be caused by:

Increased CHP from heart failure, kidney disease, and pregnancy. Decreased BCOP from liver disease or nephrotic syndrome. Increased capillary permeability in inflammation or lymph blockage.

Pitting Edema from Right Heart Failure

Blood backs up to systemic veins since right ventricle cannot pump blood. Blood pooling in veins → venous pressure rises → rise in capillary hydrostatic pressure, more fluid pushes out → fluid accumulates in tissues → fluid seen in legs and feet

Edema from left heart failure

Left ventricle cannot pump blood to the rest of the body, blood backs up into pulmonary veins and thus into the capillaries of the lungs. Raises CHP in the pulmonary capillaries and pushes fluid into the lung tissue and alveoli. Causes hypoxia, air hunger, cyanosis, pink frothy sputum, crackles on auscultation.

Edema from Liver Disease

cannot produce albumin → BCOP falls → less water is reabsorbed back into blood and fluid stays in the tissue and body cavities → abdomen fills with fluid b/c of low CHP in abdomen and low BCOP from low albumin

Albumin

Produced by the liver and contributes to BCOP, the force that pulls water back into the capillaries.

Periorbital edema from kidney disease

Glomerular damage → plasma proteins leak out (albumin) into urine → decrease BCOP → less fluid absorption → eyes swell first because they fill the easiest

Exudative edema from inflammation

Histamine makes endothelial cells pull apart and make vessels more permeable. Proteins leak into interstitial fluid → IFOM increases (water follows the proteins) → swelling, heat, redness

Lymphedema and lymph blockage

If lymph system were to become blocked and not drain fluid (normally 2.4 L of blood) → fluid accumulate and become chronic, firm and non pitting mass like structure. (Seen after cancer surgery, radiation, or bad infection.)

Venous edema

Valves in veins fail → blood pooling → increase venous pressure → CHP increased → varicose veins form

Pitting Edema

When dent remains in skin after pressing. This indicates: fluid is free in the interstitial space and pressure forces fluid back into capillaries, space refills slowly. (Heart failure, kidney disease, liver disease)

Non-pitting edema

Pressing leaves no dent. Swelling is form tissue gel. Tissue gel is made of proteoglycans. Protein core of tissue gel is made of long carb chains that can bind to large amounts of water. (Seen in myxedema caused by hypothyroidism)

Brain Edema

Swelling dramatically raised intracranial pressure → compression of neurons and blood vessels → distortion of membranes and ion channels → disruption of synaptic activity. Can lead to confusion, loss of consciousness, herniation, and death

Water intoxication from hyponatremia

Drinking too much water can dilute sodium levels. Dangerous low levels cam cause water to move into brain cells and cause cerebral edema. Headaches, nausea, confusion, seizures and coma