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Porth - F and E
Porth - Essentials of Pathophysiology - Fluid and Electrolytes
| Question | Answer |
|---|---|
| Electrolytes | Substances that dissociate in a solution to form a charged particle |
| Ions | are the charged particles, Example: NaCl |
| Nonelectrolytes | substances that do not dissociate into charged particles, e.g. glucose |
| Sodium | 135-145 mEq/L |
| Potassium | 3.5-5.0 mEq/L |
| Chloride | 98-106 |
| Bicarbonate | 22-26 |
| Calcium | 8.5-10.5 mg/dL |
| Magnesium | 1.8-3.0 mg/dL |
| Hydrostatic pressure | Pushing force exerted by a fluid. Arterial capillary pressure is about 30 mm Hg and venous is 10. Interstitial fluid may have a negative hydrostatic pressure of about (-3 mm), which contributes to outward movement of fluid from the capillary. |
| Colloidal osmotic pressure | Pulling force of plasma proteins that cannot pass through the capillary membrane; assist the movement of fluid back into the capillary |
| Intracellular fluid (ICF) | contained in all body cells, including the blood cells |
| Extracellular fluid (ECF) | contained in the vascular system (blood plasma) and fluid contained in the interstitial spaces |
| Third spacing | -an abnormal clinical finding -3rd-spacing – fluid trapped in one of several possible transcellular spaces. -Examples: pleural effusion, pericardial effusion, ascites. -This fluid is not available for ECF or ICF uses, since it is trapped or “sequester |
| Ascites | accumulation of fluid in the peritoneal cavity, the space between the tissues lining the abdomen and abdominal organs (the peritoneal cavity) |
| Pleural effusion | another abnormal “third space” example |
| Osmosis | movement of water from an area of lower concentration to an area of greater concentration of solutes (electrolytes) |
| What happens to RBC's in a hypotonic solution | they lyse |
| What happens to RBC's in an isotonic solution | nothing they just go about there business |
| What happens to RBC's in a hypertonic solution | they shrivel up (crenation) |
| Crenation | is the contraction of a cell after exposure to a hypertonic solution, due to the loss of water through osmosis |
| Osmolarity of the blood plasma (serum) is determined | largely by the amount of Sodium (Na+) contained in the plasma. |
| A patient with an elevated serum Na+ will have serum hyperosmolarity, and this would cause what to happen? | this would tend to cause water to move out of the cells |
| What are the normal homeostatic mechanisms? | thirst, increased or decreased secretion of ADH, increased or decreased urine output |
| Obligatory urine output | 300-500ml /24 hrs for an adult (hourly urine output may need to be carefully assessed) |
| Normal water loss via skin is considered | normal perspiration (may be “insensible”), Lungs – normal breathing is another source of insensible water loss |
| Abnormal water loss via the skin is considered | diaphoresis (“drenched in sweat”) |
| Pulmonary edema | is fluid accumulation in the air spaces and parenchyma of the lungs. It leads to impaired gas exchange and may respiratory failure. Due to failure of left ventricle or an injury to the lung parenchyma or vasculature of the lung. |
| Hypodipsia | a disorder causing loss of ability to sense thirst |
| Posterior pituitary gland’s role in fluid balance | ADH - Antidiuretic Hormone |
| Isotonic | equal loss of water and sodium (common cases: vomiting, diarrhea, misuse of diuretics) |
| Rx for isotonic volume deficit (solute and water loss proportional, no change in plasma volume, serum sodium level is decreased to 125-150 mEq/L. The cause of the fluid loss is GI fluid loss, urine loss and decreased oral intake) | Intravenous (IV) Fluid replacement with Isotonic (0.9% Saline or NaCl) |
| Rx for Hypotonic Fluid Volume Deficit (More solute is lost than water. Plasma volume moves from the ECF to the ICF. Serum sodium levels are decreased below 125 mEq/L. The cause of the fluid loss is often a GI fluid loss with hypotonic oral intake) | Initially a bolus of 0.9% sodium chloride or Ringer's Lactate followed by 5% Dextrose in water and 0.9% sodium chloride. If the patient is severely symptomatic 3% sodium chloride at 4mL/kg should be given over 10 minutes with close monitoring. |
| Hypotonic fluid volume deficit possible causes? | excess renal losses of Na+, aldosterone deficiency (remember: aldosterone “saves“ or retains Na+) |
| Rx for Hypertonic Fluid Volume Deficit | =5% Dextrose or D5W in water and 0.225% or 0.45% sodium chloride. =Fluid replacement should be given slow and gradual over 48 hours. 2 to 3 mEq/kg of potassium should be given per 24 hours. |
| Fluid volume deficit: some key signs & symptoms | =Dry skin and mucous membranes, such as the tongue; also poor skin turgor =Decreased urine output; “concentrated” =In babies, depressed fontanel (soft spot on top of head); eyes may appear “sunken” =B.P. may be decreased, w/ heart rate (pulse) increas |
| Physiological consequences of severe fluid volume deficit | Inadequate kidney (renal) perfusion (blood flow to kidneys) --- can result in acute renal failure. |
| Physiological consequences of severe fluid volume deficit. What steps must be taken to prevent this serious complication? | First of all – RECOGNITION. Then treatment with IV fluids or blood (if blood was lost) |
| Fluid Volume Excess (fluid overload or volume expansion) - Causes? | Some causes: -Impaired kidney function – decreased output of urine -Heart failure or cardiac insufficiency -Excessive intake of water and sodium -Fluid retention related to (R/T) stress response |
| Clinical findings (signs and symptoms) – Fluid Volume Excess | =Acute weight gain =Increased blood pressure R/T increased vascular volume =Strong, “bounding” pulse =Possible shortness of breath (dyspnea) =Possible jugular venous distention (JVD) Edema |
| Hematocrit | The hematocrit (Hct) is a blood test that shows the % or proportion of red blood cells (RBC’s) to the plasma (fluid). |
| In a patient with dehydration (fluid volume deficit), the Hct. is increased. Why? | A decrease in the volume of plasma causes an increase in hematocrit, even though the RBC count has not inc. Example is a patient with burns, here plasma or fluid is lost from vascular space making blood more concentrated thus hct may increase to 60-65%. |
| Urine is measured by specific gravity | Specific gravity is a lab test that measures the density (weight) of urine, compared to the density of water, which is 1.000. Normal range for adults is 1.010-1.025 |
| When would you see a low or high specific gravity of urine? What would dehydration due to the specific gravity number? | A low specific gravity is seen in dilute urine, while a concentrated urine sample will show a high specific gravity. Dehydration results in a high specific gravity (more solutes per area of urine) |
| How does glucose or protein affect specific gravity? | If glucose or protein are in urine, the S.G. will be elevated, because these elements increase the density of urine |
| What is Urine Osmolality? | Reflects the kidney’s ability to produce a concentrated or dilute urine based on serum osmolality and the need for water conservation or excretion |
| What are 3 Drugs used to decrease fluid volume: All 3 are Diuretics | 1) Furosemide (Lasix) – a loop diuretic (works in the Loop of Henle in the kidneys) 2) Hydrochorothiazide (HCTZ) – a thiazide diuretic 3) Spironlactone (aldactone) |
| What is a sign of excess interstitial fluid? | Edema |
| Potential etiologies of edema | =Increased hydrostatic pressure =Lowered plasma oncotic pressure (due to decreased plasma proteins – albumin) =Increased capillary permeability =Lymphatic channel obstruction =Consider what might cause each of these… |
| Regulating Sodium and water when sodium level is low | =Serum sodium level decreases (water excess) =Then serum osmolality falls to < 280 mOsm/kg =Thirst diminishes, leading to decreased water intake =ADH release is suppressed =Renal water excretion increases =Serum osmolality normalizes!!! |
| Isotonic dehydration | is the situation in which sodium and water are lost in isotonic proportions. Causes include: severe vomiting & diarrhea, kidney disease, and overuse of diuretics. Use isotonic fluids to replace lost volume |
| Is tap water isotonic? | No |
| Are distilled water or salt water isotonic? | Distilled water is hypotonic and Salt water is hypertonic |
| Hyponatremia | Sodium <135 mEq/L |
| Hyponatremia Causes | =Excessive ADH =Gastrointestinal losses =Hypotonic irrigating solutions =Tap water enemas =Forced excessive water ingestion =Near-drowning in fresh water =Psychogenic Polydipsia |
| Hyponatremia Effects | =Muscle cramping and weakness =Abdominal cramping, N/V =Suppression of thirst =Headache =Confusion =Lethargy =Seizures =Coma =Death |
| Drugs which can cause hyponatremia | =Diuretics =Some antineoplastics =Some antipsychotics =Sedatives such as barbiturates and morphin |
| Diagnosis of Hyponatremia | =Lab values: Serum sodium level < 135 mEq/L =Patient’s volume status =Presence of signs & symptoms =Serum Osmolality < 280 mOsm/kg =Urine specific gravity < 1.010 =Increased urine SG and urine sodium in SIADH =Elevated hct and plasma protein |
| Treatment for Hyponatremia | =Treat cause =Water excess-treat w/ fluid restrict =Oral/IV admin NaCl sol. =Na deficiency, give Na supp. =Severe hyponatremia(<110mEq/L and seizures)-hypertonic(3%or5%) saline sol; =hypertonic solutions, can cause H2O flow out brain cells & brain dam |
| Hypernatremia | Sodium >145mEq/L |
| Hypernatremia causes | =Tube feeding =Watery diarrhea =IV infusion of hypertonic solution =Near-drowning in salt water =Overuse of salt tablets =Food intake with reduced fluid intake =Difficulty swallowing fluids =Inability to respond to thirst |
| Hypernatremia signs and symptoms | =Thirst =Oliguria (inability to form urine) =Decreased skin turgor =Decreased salivation =Headache =Agitation =Decreased reflexes =Seizures =Coma =Death |
| Assessment of hypernatremia - Drugs causing hypernatremia | =Antacids with sodium bicarb =Antibiotics such as ticarcillen di-sodium =Sodium bicarbonate =IV sodium chloride =Sodium polystryene sulfonate (kayexalate) |
| Assessment of hypernatremia - Nursing Functions | =Weigh patient daily =Check neurological status =Monitor for seizures =Safety precautions =Intake and output =Vital Signs =Teach to restrict sodium intake and foods that are high in sodium |
| Diagnosis of Hypernatremia | =History, physical exam, and lab results Serum sodium > 145 = Urine specific gravity >1.030 except in diabetes insipidus where it is low = Serum Osmolality > 300 m Osm/kg |
| Hypernatremia Treatment | =Address underlying problem =Careful replacement of fluids: Orally or intravenously =Fluids should be given gradually to avoid cerebral edema |
| Hypokalemia | Potassium < 3.5 mEq/L |
| Hypokalemia causes | =Anorexia =NPO (nothing by mouth) =Unbalanced diet =Potassium wasting diuretics =Diarrhea =Emesis =Gastric suction |
| Hypokalemia Signs and Symptoms | =Decreased urine specific gravity =Abdominal distention =Constipation =Diminished bowel sounds =Postural hypotension =Skeletal muscle weakness =Paralysis =Heart dysrhythmias =Polyuria =Confusion |
| Dietary Sources of Potassium | =Fruits, oranges, bananas, apricots, and cantaloupe =Meats =Vegetables, potatoes, mushrooms, tomatoes, and carrots =Dried fruit, nuts and seeds =Chocolate |
| Hypokalemia Diagnosis | =Lab results, =patient’s volume status, & =presence of symptoms |
| Treatment for Hypokalemia | =Replacement with potassium-containing foods when appropriate. =Replacement with oral supplements or intravenously |
| Hypokalemia Medications to Know | =K-Dur =Intravenous Potassium Chloride |
| Potassium | =NEVER push potassium IV, must be given by IV infusion =MUST be diluted when giving IV or will always cause death =Indications: Use for potassium def/replacement to prevent losses =Can be given IV & oral =Dilute liquid K+ in OJ or juice to disguise ta |
| Hyperkalemia | Potassium > 5.0mEq/L |
| Hyperkalemia causes | =Decreased renal function =Potassium IV fluid: too much or too fast =Crushing injury =Potassium sparing diuretics =Excessive oral ingestion |
| Hyperkalemia Signs & Symptoms | =Nausea =Vomiting =Intestinal cramps =Diarrhea =Heart dysrhythmias-cardiac conduction affected =Muscle weakness =Decreased neuromuscular excitability |
| Hyperkalemia Diagnosis | History, physical exam, lab results, and electrocardiogram (EKG) findings |
| Treatment for Hyperkalemia | Hold potassium-containing foods and potassium-sparing medications |
| Hyperkalemia Medications to know | =Sodium polystyrene (Kaexalate or Kalexate or Kayexalate) =Combination of glucose and insulin =Calcium gluconate |
| Hypocalcemia | Calcium < 8.0mg/dL |
| Hypocalcemia Causes | =Insufficient intake of calcium and vitamin D =Pancreatitis (calcium binds to free fatty acids) =Steatorrhea (presence of excess fat in feces) =Chronic diarrhea (including laxative abuse) =Hypoparathyroidism |
| Hypocalcemia Signs and Symptoms | =Neuromuscular irritability =Paresthesias =Muscle cramping =Hyperactive reflexes =Tetany =Hypotension =Cardiac dysrhythmias |
| Treatment for Hypocalcemia | =Calcium chloride =Calcium gluconate |
| Hypercalcemia | Calcium > 10.5 mg/dL |
| Hypercalcemia Causes | =Vitamin D overconsumption =Hyperparathyroidism =Bone tumors =Increased intestinal absorption of calcium secondary to large amounts of vitamin D |
| Hypercalcemia Signs and Symptoms | =Anorexia =Nausea =Emesis =Constipation =Fatigue =Muscle weakness =Decreased neuromuscular excitability =Headache =Stupor =Cardiac dysrhythmias (ventricular) |
| Treatment for Hypercalcemia | =Correct underlying cause of serum calcium excess =Promote urinary excretion of calcium |
| Hypercalcemia Medication to Know | Calcitonin |
| Hypomagnesemia | <1.8 mg/dL |
| Hypomagnesemia Causes | =Malabsorption of magnesium =Malnutrition =Chronic alcoholism =Diuretic therapy =Hyperparathyroidism =Diabetic ketoacidosis =Pancreatitis |
| Hypomagnesemia Signs and Symptoms | =Tetany =Personality changes =Nystagmus (eye twitch) =Choreiform movements (abnormal gait) =Trousseau signs (?hypocalcemia pg 188 in book?) =+ Babinski (plantar reflex where toes curl) |
| Hypomagnesemia Treatment | =Replacement with magnesium. =Medication/route of administration depends on severity of deficiency |
| Hypomagnesemia Medications to Know | =Magnesium hydroxide (Milk of Magnesia) =Magnesium Sulfate |
| Hypermagnesemia | Magnesium > 3.0mg/dL |
| Hypermagnesemia Causes | =Excessive intravenous (IV) administration of magnesium =Excessive oral intake of magnesium-containing medications (e.g. antacids) =Kidney disease |
| Hypermagnesemia Signs and Symptoms | =Lethargy =Hyporeflexia =Confusion =Drowsiness =Coma =Hypotension =Respiratory depression =Cardiac arrhythmias =Cardiac arrest |
| Hypermagnesemia Treatment | =Cessation of magnesium administration. =Administration of calcium. |
Created by:
rjjaramillo
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