Edema – excessive amount of fluid in the interstitial compartment -Causes swelling or enlargement of tissue -May be localized or throughout the body -May impair tissue perfusion -May trap drugs in ISF Causes of edema -Increased capillary hydrostatic pressure >Due to higher blood pressure or increased blood volume >Forces increased fluid out of capillaries into tissue >Cause of pulmonary edema -Loss of plasma proteins (“fluid leaves because blood is more diluted than ISF”) >Particularly albumin >Results in decreased plasma osmotic pressure >“Due to malnutrition” -Obstruction of lymphatic circulation >Causes localized edema *Excessive fluid and protein not returned to general circulation -Increased capillary permeability >Usually causes localized edema *May result from an inflammatory response or infection *Histamines and other chemical mediators increase capillary permeability >Can also result from some bacterial toxins or large burn wounds and result in widespread edema Effects of edema -Swelling >Pale or red in color -Pitting edema >Presence of excess interstitial fluid >Moves aside when pressure is applied by finger >Depression – “pit” remains when finger is removed -Increase in body weight >With generalized edema -Functional impairment >Restricts range of joint movement >Reduced vital capacity >Impaired diastole - fluid accumulates around heart -Pain >Edema exerts pressure on nerves locally >Headache with cerebral edema >Stretching of capsule in organs (kidney, liver) -Impaired arterial circulation (“aka impared perfusion”) >Ischemia leading to tissue breakdown >“Makes it harder for the blood to flow” Lymphatic filariasis (aka elephantiasis) -More common in tropics -Etiology - Lymphatic filariasis is caused by infection with nematodes (roundworms) of the family Filariodidea. There are three types of these thread-like filarial worms. -Wuchereria bancrofti, which is responsible for 90% of the cases Signs and symptoms -The majority of infections are asymptomatic, showing no external signs of infection. These asymptomatic infections still cause damage to the lymphatic system and the kidneys as well as alter the body's immune system. -Acute episodes of local inflammation involving skin, lymph nodes and lymphatic vessels -Are a result of bacterial skin infection where normal defenses have been partially lost due to underlying lymphatic damage. -When lymphatic filariasis develops into chronic conditions, it leads to lymphoedema (tissue swelling) or elephantiasis (skin/tissue thickening) of limbs and hydrocele (fluid accumulation). Involvement of breasts and genital organs is common. -Such body deformities lead to social stigma, as well as financial hardship from loss of income and increased medical expenses. The socioeconomic burdens of isolation and poverty are immense. Pathophysiology -Infection occurs when filarial parasites are transmitted to humans through mosquitoes. -Larvae migrate to the lymphatic vessels where they develop into adult worms in the human lymphatic system. -Worms and larvae block drainage of lymph vessels -Infection is usually acquired in childhood, but the painful and profoundly disfiguring visible manifestations of the disease occur later in life. -Whereas acute episodes of the disease cause temporary disability, lymphatic filariasis leads to permanent disability Diagnosis -Microscopic examination of blood samples Treatment -anti-worm medication (DEC) -compression clothing -surgery Fluid Deficit – Dehydration -Inadequate intake/excessive loss/both -Fluid loss often measured by change in body weight -More serious in infants and older adults -Water loss may be accompanied by loss of electrolytes and proteins, e.g., diarrhea. Causes of Dehydration -Vomiting and diarrhea -Excessive sweating with loss of sodium and water -Diabetic ketoacidosis >Loss of fluid, electrolytes, and glucose in the urine -Insufficient water intake in older adults or unconscious persons -Use of concentrated formula in infants Effects of Dehydration -Decreased skin turgor (“tension”) and dry mucous membranes -Sunken eyes -Sunken fontanelles in infant -Lower blood pressure, rapid weak pulse -Increased hematocrit -Decreasing level of consciousness -Urine: low volume and high specific gravity Attempts to Compensate for Fluid Loss -Increasing thirst -Increasing heart rate -Constriction of cutaneous blood vessels -Concentrating urine Fluid excess 1.Volume excess – both sodium and water are retained >Caused by renal failure or aldosterone hypersecretion (“more sodium in blood”) 2.Hypotonic hydration -more water than sodium is retained or ingested >Can happen when both water and salt are lost in urine or sweat and is replaced by just plain water >Extra water dilutes the ECF and causes cellular swelling >ADH hypersecretion can also cause through excessive water retention as sodium continues to be excreted -Pulmonary and cerebral edema are serious complications of fluid excess Third-Spacing of Fluid Fluid shifts out of the blood into a body cavity or tissue and can no longer reenter vascular compartment Causes: High osmotic pressure of ISF as in burns Increased capillary permeability as in some gram-negative infections Malnutrition, low osmolarity of blood Sodium Imbalance Review of sodium -Primary cation (“positively charged ion”) in ECF -Sodium diffuses between vascular and interstitial fluids -Transport into and out of cells by sodiumpotassium pump -Actively secreted into mucus and other secretions Hyponatremia -Low concentration of sodium in blood Causes of Hyponatremia -Losses from excessive sweating, vomiting, diarrhea -Use of certain diuretic drugs combined with lowsalt diets -Hormonal imbalances >Insufficient aldosterone >Adrenal insufficiency >Excess ADH secretion -Diuresis -Excessive water intake Effects of Hyponatremia -Low sodium levels >Cause fluid imbalance in compartments >Fatigue, muscle cramps, abdominal discomfort or cramps, nausea, vomiting -Decreased osmotic pressure in ECF compartment >Fluid shift into cells *Hypovolemia (“blood that is dilute; lower blood volume”) and decreased blood pressure -Cerebral edema >Confusion, headache, weakness, seizures Hypernatremia -Too much sodium in blood Causes of Hypernatremia -Imbalance in sodium and water -Insufficient ADH (diabetes insipidus) >Results in large volume of dilute urine -Loss of the thirst mechanism -Watery diarrhea -Prolonged periods of rapid respiration -Ingestion of large amounts of sodium without enough water Effects of Hypernatremia -Weakness, agitation -Dry, rough mucous membranes -Edema -Increased thirst (if thirst mechanism is functional) -Increased blood pressure Potassium Imbalance Review of potassium -Ingested in foods -Excreted primarily in urine -Insulin promotes movement of potassium into cells Hypokalemia -Too little potassium in the blood Causes of Hypokalemia (serum K+ <3.5 mEq/L) -Excessive losses due to diarrhea -Diuresis associated with some diuretic drugs -Excessive aldosterone (“too much potassium out of blood”) or glucocorticoids >i.e., Cushing syndrome -Decreased dietary intake >May occur with alcoholism, eating disorders, starvation -Treatment of diabetic ketoacidosis with insulin >Insulin stimulates Na-K ATPase (“pump”) activity and facilitates K entry into cells Effects of Hypokalemia -Cardiac dysrhythmias >Due to impaired repolarization > cardiac arrest -Interference with neuromuscular function >Muscles less responsive to stimuli -Paresthesias – “pins and needles” Hyperkalemia -Too much potassium in the blood Causes of Hyperkalemia (serum K + >5 mEq/L) -Renal failure -Deficit of aldosterone -“Potassium-sparing” diuretics -Leakage of intracellular potassium into the extracellular fluids >In patients with extensive tissue damage Effects of Hyperkalemia -Cardiac dysrhythmias -May progress to cardiac arrest - too much potassium in the interstitial fluid shortens repolarization and widens QRS complex (“depolarization of ventricles”) -Muscle weakness common >Progresses to paralysis >May cause respiratory arrest >Impairs neuromuscular activity -Fatigue, nausea, paresthesias Calcium Imbalance Review of calcium -Ingested in food and stored in bone -Excreted in urine and feces -Balance controlled by parathyroid hormone (PTH) and calcitonin -Vitamin D promotes calcium absorption from intestine >Ingested or synthesized in skin in the presence of ultraviolet rays >Activated in kidneys -Functions of Calcium >Provides structural strength for bones and teeth >Maintenance of the stability of nerve membranes >Required for muscle contractions Hypocalcemia -Too little calcium in the blood Causes of Hypocalcemia -Hypoparathyroidism -Malabsorption syndrome -Deficient serum albumin -Increased serum pH -Renal failure Effects of Hypocalcemia -Increase in the permeability and excitability of nerve membranes >Spontaneous stimulation of skeletal muscle *Muscle twitching *Carpopedal spasm >Tetany -Weak heart contractions >Delayed conduction >Leads to dysrhythmias and decreased blood pressure Hypercalcemia -Too much calcium in the blood Causes of Hypercalcemia -Uncontrolled release of calcium ions from bones >Neoplasms; malignant bone tumors -Hyperparathyroidism -Demineralization due to immobility >Decrease stress on bone -Increased calcium intake >Excessive vitamin D >Excess dietary calcium -Milk-alkali syndrome - hypercalcemia, various degrees of renal failure, and metabolic alkalosis as a result of ingestion of large amounts of calcium (usually milk) and absorbable alkali (sodium bicarb). -MAS is now believed to be the third most common cause of in-hospital hypercalcemia Effects of Hypercalcemia -Depressed neuromuscular activity >Muscle weakness, loss of muscle tone >Stupor (“disoriented”), personality changes -Interference with ADH function >Less absorption of water >Decrease in renal function -Increased strength in cardiac contractions >Dysrhythmias may occur Phosphate Imbalance Review of phosphate -Bone and tooth mineralization -Important in metabolism – ATP -Integral part of the cell membrane Hypophosphatemia -Malabsorption syndromes, diarrhea, excessive antacids Hyperphosphatemia -From renal failure Chloride Imbalance Review of chloride -Chloride levels related to sodium levels -Chloride and bicarbonate ions can shift in response to acid-base imbalances Hypochloremia -Usually associated with alkalosis -Early stages of vomiting – loss of hydrochloric acid Hyperchloremia -Excessive sodium chloride intake Acid-Base Imbalance -Acidosis >Excess hydrogen ions >Decrease in serum pH -Alkalosis >Deficit of hydrogen ions >Increase in serum pH Respiratory Acidosis -Acute problems >Pneumonia, airway obstruction, chest injuries >Drugs that depress the respiratory control center -Chronic respiratory acidosis >Common with chronic obstructive pulmonary disease Metabolic Acidosis -Excessive loss of bicarbonate ions to buffer hydrogen >Diarrhea – loss of bicarbonate from intestines -Renal disease or failure >Decreased excretion of acids >Decreased production of bicarbonate ions Effects of Acidosis -Impaired nervous system function -Headache -Lethargy -Weakness -Confusion -Coma and death Compensation -Deep rapid breathing -Secretion of urine with a low pH Respiratory alkalosis -Hyperventilation -Caused by anxiety, high fever, overdose of aspirin -Head injuries -Brainstem tumors Metabolic alkalosis -Increase in serum bicarbonate ion (“too many bicarbonate ions in blood”) -Loss of hydrochloric acid from stomach -Hypokalemia -Excessive ingestion of antacids Effects of Alkalosis -Increased irritability of the nervous system -Causing restlessness -Muscle twitching -Tingling and numbness of the fingers -Tetany (“sustained traction”) -Seizures -Coma
