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Week 3
Fluid Homeostasis and Imbalances
Question | Answer |
---|---|
Who has more extracellular fluid than intracellular fluid? | Infants |
Who has more intracellular fluid than extracellular fluid? | Adults |
Who has the most water of body mass? | Males. Females typically less bc of more body fat |
Who has the lowest amount of water in body mass? | Older adults |
Which group is most vulnerable to fluid imbalances? | Neonates and infants and older adults |
Liver produces_______ | Angiotensinogen |
Angiotensinogen is converted to angiotensin I by ______ | Renin |
Renin is released by kidney in response to... | Low BP, or low fluid volume |
Angiotensin I gets converted to angiotensin II by _____ | ACE |
ACE is | angiotensin-converting enzyme, produced in the lungs |
Angiotensin II acts on __________, causing it to release ______ | Adrenal gland; aldosterone |
Aldosterone acts on __________ | collecting ducts of kidney |
What does aldosterone do? | Make nephrons reabsorb water (retention of Na+Cl-) |
What does aldosterone induced retention of water do to BP? | Increases BP |
Fluid homeostasis involves what 4 factors? | Fluid intake, distribution, excretion and loss |
How can one intake fluid? | Orally, rectally |
How is fluid distributed? | Between vascular and interstitial fluid, or between interstitial and intracellular |
How does fluid move between vascular and interstitial fluid? | Via capillary filtration, hydrostatic and oncotic forces |
How does fluid move between interstitial and intracellular? | Osmosis |
What is the hormone that increases fluid into the vascular system, as well as produces less, more concentrated urine? | ADH. Anti-diuretic hormone |
What triggers ADH release? | Increased plasma osmolality activates osmoreceptors, in the hypothalamus. Stimulates ADH release from posterior pituitary |
ADH is released from the ______. | Posterior pituitary gland |
ADH acts on the _____ to do what? | Kidney tubules to reabsorb water. Water moves from kidney tubules back into blood |
Osmoreceptors in the hypothalamus that trigger release of ADH, also triggers _____. | Thirst, to increase fluid intake and reduce blood osmolarity to set point |
What does aldosterone do? | Think “volume”. Increases fluid volume |
What triggers aldosterone? | Decreased volume to renal artery |
Aldosterone is released by _____ | Adrenal cortex |
How does aldosterone work? | Acts on kidney by increasing Na+ reabsorption from distal tubule into plasma. Where sodium goes, water follows |
Where sodium goes, ______ follows | Water |
Elevated serum levels of what electrolyte directly triggers aldosterone? | K+. To maintain ion balance, potassium is moved from plasma and excreted |
BP and volume are also regulated by _____ which inhibits ADH release. | Atrial Naturetic Peptide |
What kind of IV fluid goes to extracellular fluid only? | Isotonic!! |
What does NS in isotonic IV solutions mean? | Normal saline: 0.9% NaCl |
Which type of IV solution is used to make up for loss of water? | Hypotonic |
Which type of IV solution should you give with low BP, or volume issue? | Isotonic solution |
What type of IV solution should you give with longer term IV fluid with no other input? | Hypotonic solution, NS is not enough water. |
Which type of IV solution allows movement of fluid into cells? | Hypotonic |
What is ECV excess? | Normal concentration, too much volume |
What is ECV deficit? | Normal concentration, not enough volume |
What is hypernatremia? | Too high of concentration |
What is hyponatremia? | Too low of concentration |
What is clinical dehydration? | ECV deficit, plus hypernatremia |
What is lost during insensible perspiration? | Just water |
What is lost during respiratory loss? | Just water |
What is lost during sweating? | Salt and water |
What is lost during diarrhea? | Lots of salt and water |
What is lost during urination? | Dilute salt and water |
Normal saline (NS) IV moves 1/3 into vascular, which ______ hydrostatic pressure | Increases |
Which fluid imbalance has normal serum sodium, and extracellular fluid overload? | ECV excess |
What are some risk factors in ECV excess? | Risk factors such as excessive intake of sodium and water, renal retention of saline due to excessive aldosterone |
What can cause renal retention of saline (ECV excess)? | Oliguria due to acute kidney failure; end-stage renal disease (ESRD), CHF (excessive aldosterone), cirrhosis, hyperaldosteronism, excessive ingestion of black licorice, Cushing’s syndrome, medications that cause renal retention of saline |
Renal retention of saline causes which fluid imbalance? | ECV excess |
What 3 conditions cause excessive aldosterone? | Hyperaldosteronism, CHF, cirrhosis |
Excessive ingestion of black licorice can cause ____ | ECV excess. Black licorice has aldosterone-like effect |
What are some clinical assessments of ECV excess? | Rapid weight gain, edema in dependent areas, bounding pulse, distended neck veins when partially upright, bulgin fontanel in infants, crackles/rales in lungs, dyspnea, orthopnea, short of breath lying down |
Crackles/rales can be a sign of which fluid imbalance? | ECV excess |
Bounding pulse can be a sign of which fluid imbalance? | ECV excess |
Distended neck veins when partially upright can be a sign of which fluid imbalance? | ECV excess |
Edema in dependent areas can be a sign of which fluid imbalance? | ECV excess |
A bulging fontanel in infants can be a sign of which fluid imbalance? | ECV excess |
Dyspnea, orthopnea and shortness of breath while lying down can be a sign of which fluid imbalance? | ECV excess |
Excess fluid retention results from excessive salt intake because... | Water follows salt |
What are important teachings for patients with ECV excess? | Sodium restriction, taking daily weight, non-food sources of sodium, indications of ECV excess if sleeping upright |
What is ECV deficit? | Loss of sodium-containing fluid |
What are some causes of ECV? | Adrenal cortex is not secreting aldosterone, 4+ days of bed rest, emesis, diarrhea, burns, rapid 3rd space accumulation (acites), fistula drainage, nasogastric suction, intestinal decompression, blood loss |
What is third space accumulation? | Accumulation of fluid that is not part of normal fluid distribution |
What are ascites? | Fluid accumulation in the peritoneal cavity. Rapid ascites fluid accumulation can cause ECV to decrease/cause deficit |
Liver issues and lack of protein in the blood can cause | 3rd space accumulation |
An acute GI obstruction can cause _____ | ECV deficit, due to fluid collection in the GI. So much fluid can be moved rapidly into the GI that ECV is decreased |
Why might excessive bed rest cause ECV deficit? | Because lying down causes more blood to pool centrally due to gravity. Kidneys are well-perfused, and excrete fluid |
Not enough aldosterone secretion may cause which fluid imbalance? | ECV deficit |
Diarrhea, burns, emesis may cause which fluid imbalance? | ECV deficit |
What are some clinical sign of ECV deficit? | Hypotension, weak, rapid pulse, dizziness with change in position, oliguria, prolonged capillary refill time, poor skin turgor, dry mucous membranes, absence of tears and sweat, longitudinal furrows in tongue |
ECV deficit can lead to ____ | Hypovolemic shock |
Low blood pressure can be a sign of which fluid imbalance? | ECV deficit |
A weak, rapid pulse can be a sign of which fluid imbalance? | ECV deficit |
Oliguria can be a sign of which fluid imbalance? | ECV deficit |
Poor skin turgor can be a sign of which fluid imbalance? | ECV deficit |
Absence of tears and sweat can be a sign of which fluid imbalance? | ECV deficit |
Soft sunken eyeballs can be a sign of which fluid imbalance? | ECV deficit |
Longitudinal furrows in the tongue can be a sign of which fluid imbalance? | ECV deficit |
Prolonged capillary time can be a sign of which fluid imbalance? | ECV deficit |
Important teachings for patients with ECV deficit? | Replace body fluid losses with both salt and water |
What IV solution is used to treat ECV deficit? | Normal saline/ isotonic colution |
What is clinical dehydration? | Combination of ECV deficit and hypernatremia |
What is important to teach a patient with diarrhea, excessive sweating, or emesis? | To replace with fluids containing both salt and water. Electrolyte containing fluids |
What is hypernatremia? | Excess salt relative to water in the blood |
What can cause hypernatremia? | Loss of more water than salt; gain of more salt than water |
Hypernatremia: loss of more water than salt can be caused by...? (2) | Diabetes insipidus: not enough ADH; diarrhea without fluid replacement (clinical dehydration); excessive sweating without fluid replacement |
Gain of relatively more salt than water (hypernatremia) can be caused by... | Decreased thirst sensation with aging; inability to respond to thirst; limited or no access to water, difficulty swallowing, self-limited water intake, high solute intake without adequate water (tube feedings), hypertonic saline |
What is diabetes insipidus? | Not enough ADH is produced, causing excessive dilute urine. Salt remains in the body. |
What can cause diabetes insipidus? | Brain surgery, brain trauma, infection, tumor |
Craving for cold/ice water is common in ____ | Diabetes insipidus |
In diabetes insipidus, an alert patient can drink enough to remain safe. If the patient is not alert, ____ is given. | vasopressin (desmopressin) (ADH) |
How is DI monitored? | Serum sodium checks every 4 hrs, urine specific gravity every 6 hr, record intakes and outputs, monitor LOC for any confusion |
What is hyponatremia? | Blood contains excess water relative to salt |
What can cause hyponatremia? | Excessive ADH release stimulated with stressors, nausea, anesthesia, pain and increased osmolarity |
What are some clinical signs of hyponatremia? | Nausea, emesis, malaise/lethargy, confusion, serum sodium of < 130 mEq/L |
Why could hyponatremia cause confusion? | Because of the low osmolarity of the blood, water moves into cells (water moves toward higher concentrations). Water moving into the cells can cause neuronal cell swelling, resulting in confusion. Can progress to seizure or coma |
In hyponatremia, what can cause gain of relatively more water than salt? | Excessive D5W, excessive tap water enemas, rapid/excessive/forced water drinking, excessive ADH (SIADH), ibuprofen/other nonselective NSAIDs |
In hyponatremia, what can cause loss of relatively more salt than water? | Diuretics, sweating/emesis/diarrhea with excessive replacement of water but not electrolytes |
What is important to teach to patients with hyponatremia? | Alternatives to tap water enemas, replace body fluids losses with fruit juices or boullion instead of tap water, why prescribed fluid retention is used to treat hyponatremia |
What is SIADH? | Syndrome of inappropriate (excessive) ADH. ADH acts on kidneys to pull water back into blood, causing hyponatremia, or ECV excess |
What can cause SIDH? | Meningitis/other infections, head injury, pituitary tumor or surgery, cancers (small-cell lung cancer) can secrete ADH, ecstasy |
What are some SIDH interventions? | Prescribed fluid restriction (may need to shut off water in room), monitoring for confusion, salt tablets may be prescribed, soft moist foods may help tolerate fluid restriction |
What 2 hormones aid in retention of fluid? | ADH, aldosterone |
What type of IV solution has fluid distribution that is 1/2 saline (extracellular), and 1/2 water (1/3 extracellular, 2/3 into cells)? | Hypotonic fluid that contains sodium |
Which IV solution has fluid distribution that is aprox. 1/3 extracellular (vascular and interstitial) and 2/3 intracellular? | Hypotonic fluid with no sodium |
Which hormone affects volume? | Aldosterone |
Which hormone affects concentration? | ADH |
Which should you treat first: ECV deficit or hyponatremia? | Volume deficit with isotonic IV solution |