Chapter 09 - Fluids and Electrolytes Flashcards
What fraction of body weight is water for men?
Fractionally, 2/3 of body weight is water for men.
What fraction of body weight is water for infants?
In infants, more than 2/3 of their body weight is water.
What fraction of body weight is water for women?
In women, less than 2/3 of their body weight is water.
What fraction of water weight is intracellular?
2/3 of water weight is intracellular.
What fraction of water weight is extracellular?
1/3 of water weight is extracellular.
What fraction of extracellular water weight is interstitial?
Of the 1/3 of extracellular water weight, 2/3 is interstitial and 1/3 is plasma.
What fraction of extracellular water weight is plasma?
1/3 of extracellular water weight is plasma.
What fraction of extracellular water weight is interstitial fluid?
2/3 of extracellular water weight is interstitial fluid.
Where is most intracellular fluid stored?
Most intracellular fluid is stored in muscle.
What is the equation for plasma osmolarity?
Plasma osmolarity = (2 x Na) + (glucose/18) + (BUN/2.8)
What is the normal range for plasma osmolarity?
Normal plasma osmolarity is 280-295.
What is the main fluid used during surgery and the first 24 hours after?
The main fluid used is LR (Lactated Ringer’s).
What should be started 24 hours after surgery?
24 hours after surgery, stop LR and start D5 1/2 NS with 20 mEq K+.
What should be started 24 hours after surgery?
Start D5 1/2 NS with 20 mEq K+.
What is the fluid loss rate during open-abdominal surgery?
Fluid loss is 0.5-1.0 L/hour.
What is the rate of insensible fluid loss?
Insensible fluid loss happens at a rate of 10 cc/kg/day.
What percentage of insensible fluid loss is from the skin?
75% of insensible fluid loss is from the skin.
What percentage of insensible fluid loss is from the respiratory system?
25% of insensible fluid loss is from the respiratory system.
What fluid is used for gastric outlet obstruction fluid replacement?
Fluid replacement is done with NS.
What should be replaced first in fluid management?
Replace volume/chloride status first, then supplement potassium.
What is the daily dextrose intake from D5 1/2 NS at 125 mL/h?
Roughly 150 g of dextrose per day.
What is the daily caloric intake from D5 1/2 NS at 125 mL/h?
Roughly 525 kcal/day.
What is the fluid replacement for gastric outlet obstruction?
Fluid replacement is done with NS.
How should volume/chloride status be managed in gastric outlet obstruction?
Replace volume/chloride status first, then supplement potassium.
What is the fluid replacement for pancreatic fluid loss?
Pancreatic fluid loss is replaced with LR.
What is the fluid replacement for small bowel fluid loss?
Small bowel fluid loss is replaced with LR.
What is the fluid replacement for large bowel fluid loss (diarrhea)?
Large bowel fluid loss (diarrhea) is replaced with LR.
What is the fluid of choice for dehydration from exercise?
The fluid of choice is NS.
Which organ in the GI tract secretes the most fluid?
The organ that secretes the most fluid is the stomach at 1-2 L/day.
What is the daily fluid secretion range for the duodenum, pancreas, and biliary system?
They secrete 500-1,000 mL of fluid per day.
Which bodily fluid secretion has the highest concentration of potassium?
The bodily fluid secretion with the highest concentration of potassium is saliva.
What is the normal K+ requirement for the body?
The normal K+ requirement is 0.5-1.0 mEq/kg/day.
What is the normal Na+ requirement for the body?
The normal Na+ requirement is 1-2 mEq/kg/day.
What is the treatment for hyperkalemia?
Treatment involves immediate administration of calcium gluconate, followed by sodium bicarbonate and insulin.
What is the immediate treatment for kalemia?
Immediate administration of calcium gluconate, followed by sodium bicarbonate and insulin.
What is the role of calcium gluconate in hyperkalemia treatment?
Calcium gluconate acts as a membrane stabilizer for the heart.
How does sodium bicarbonate affect potassium levels?
Sodium bicarbonate causes more potassium to enter the cell because of the alkalotic environment.
What is the mechanism of action of insulin in hyperkalemia?
Insulin activates Na/K ATPase, causing potassium to enter the cell with glucose.
What is the recommended dosage of insulin for treating hyperkalemia?
10 U of insulin with 1 amp of 50% dextrose (D50).
This is equivalent to 25g of glucose and roughly 100 calories.
What is the mechanism of action of Kayexalate?
Kayexalate binds K+ in the GI tract and excretes it through the feces.
What is the generic name for Kayexalate?
The generic name is polystyrene sulfonate.
How does Kayexalate lower potassium levels?
It releases sodium or calcium ions in the stomach in exchange for hydrogen ions, and in the large intestine, hydrogen ions are exchanged for free potassium ions.
What should be checked before replacing potassium in hypokalemia?
Check magnesium (Mg+) levels and replace prior to IV potassium.
How can pseudohyponatremia in DKA/HHS be estimated?
By adding 2 points to Na+ value for every 100 over the normal glucose.
What is the correction factor for albumin in calcium levels?
For every 1 g decrease in albumin, add 0.8 to calcium.
What is the most common cause of iatrogenic hypocalcemia?
Thyroidectomy.
What is the most common cause of iatrogenic hypocalcemia?
The most common cause of iatrogenic hypocalcemia is thyroidectomy.
What should be avoided in hypocalcemia patients?
In hypocalcemia patients, LR (Lactated Ringer’s) should be avoided because it contains calcium.
What is the most common cause of hypomagnesemia?
The most common cause of hypomagnesemia is diuretics, chronic TPN, and ETOH abuse.
What is the most common cause of hypophosphatemia?
Hypophosphatemia is most commonly caused by renal failure; it is treated with sevelamer, a low phosphate diet, and dialysis.
What is renal failure treated with?
Renal failure is treated with sevelamer, a low phosphate diet, and dialysis.
How does sevelamer work?
Sevelamer binds phosphate in the gut so that it can’t be absorbed.
What is hypophosphatemia most commonly caused by?
Hypophosphatemia is most commonly caused by renal failure.
What is the treatment for hypophosphatemia?
Hypophosphatemia is treated with sevelamer, a low phosphate diet, and dialysis.
What causes hypo-phosphatemia?
Hypophosphatemia is most commonly caused by refeeding syndrome.
How is hypo-phosphatemia treated?
Hypophosphatemia is treated with potassium phosphate.
What symptoms can patients with refeeding syndrome develop?
Patients with refeeding syndrome can develop hypophosphatemia, which presents as muscle weakness and failure to wean from the ventilator.
What conditions can cause normal anion gap acidosis?
Ileostomies, small bowel fistulas, and lactulose can all cause normal anion gap acidosis.
What is the reason for normal anion gap acidosis in these conditions?
Normal anion gap acidosis is due to the loss of bicarbonate.
What can cause normal anion gap acidosis?
Ileostomies, small bowel fistulas, and lactulose can all cause normal anion gap acidosis.
Due to loss of bicarb.
What is the management of metabolic acidosis?
The management of metabolic acidosis involves treating the underlying cause and maintaining the pH > 7.2 with bicarb.
What is the most severe complication of having a pH < 7.2?
The most severe complication of having a pH < 7.2 is dysfunctional myocardial contractility.
What can metabolic alkalosis cause?
Metabolic alkalosis can have paradoxical aciduria due to increased activity of Na+/H+ exchanger to reabsorb water.
How is FENa calculated?
FENa is calculated by (urine Na/Cr)/(plasma Na/Cr).
or = (urine Na x plasma Cr) / (urine Cr x plasma Na) - cross multiply and divide.
What characterizes pre-renal azotemia?
Pre-renal azotemia is characterized by FENa less than 1.
What is Pre renal azotemia?
A condition characterized by specific laboratory findings related to kidney function.
What is the FENa value in Pre renal azotemia?
FENa is less than 1%.
What is the Urine Na level in Pre renal azotemia?
Urine Na is less than 20.
What is the Bun/Cr ratio in Pre renal azotemia?
Bun/Cr ratio is greater than 20.
What is the Urine osmolality in Pre renal azotemia?
Urine osmolality is greater than 500 mOsm.
What is the FENa value in pre-renal azotemia?
FENa is less than 1%.
What is the Urine Na level in pre-renal azotemia?
Urine Na is less than 20.
What is the Bun/Cr ratio in pre-renal azotemia?
Bun/Cr ratio is greater than 20.
What is the Urine osmolality in pre-renal azotemia?
Urine osmolality is greater than 500 mOsm.
Why is myoglobin toxic to renal tubule cells?
Myoglobin is toxic to renal tubule cells because it gets converted to ferrihemate.
What is the first step in the Vitamin D pathway?
Sunlight converts 7-dehydrocholesterol to cholecalciferol.
What happens to cholecalciferol in the liver?
It is converted to 25-OH.
What happens to 25-OH in the kidney?
It is converted to 1-OH, which is the active form of vitamin D.
What effect does vitamin D have on calcium-binding protein?
It increases levels of calcium-binding protein, leading to more absorption of Ca in the GI tract.
What is the active form of vitamin D?
1-OH, which is produced in the kidney after conversion from 25-OH in the liver.
How does vitamin D affect calcium absorption?
It increases levels of calcium-binding protein and leads to more absorption of Ca in the GI tract.
What converts 7-dehydrocholesterol to cholecalciferol?
Sunlight.
What happens in acute renal failure regarding BUN or creatinine levels?
There is not an increase in BUN or creatinine until 70% of the renal tissue is damaged.
What do patients with chronic renal failure typically present with?
Decreased Na+.
What is the rate of insensible fluid loss?
10 cc/kg/day, mostly from the skin (75%) followed by the respiratory system (25%).
What is the sodium content in 0.9% normal saline?
154.
What is the chloride content in 0.9% normal saline?
154.
What is the chloride content in 3% normal saline?
513.
What is the sodium content in 3% normal saline?
513.
What is the sodium content in Lactated Ringer’s?
130.
What is the potassium content in Lactated Ringer’s?
4.
What is the calcium content in Lactated Ringer’s?
2.7.
What is the chloride content in Lactated Ringer’s?
109.
What is the lactate content in Lactated Ringer’s?
28.
What does lactate in Lactated Ringer’s get converted to in the body?
HCO₃⁻.
What is Lactated Ringer’s converted to in the body?
Lactated Ringer’s is converted to HCO₃⁻ in the body.
What does the liver do with lactate from Lactated Ringer’s?
The liver metabolizes the lactate to glycogen.
What happens to glycogen in the body?
Glycogen is converted to carbon dioxide and water by oxidative metabolism.
What is the result of the metabolism of lactate?
The metabolism results in bicarbonate (HCO₃⁻).
What is the lactate content in Lactated Ringer’s?
The content of lactate in Lactated Ringer’s is 28.
Why is it okay to give Lactated Ringer’s to a patient in lactic acidosis?
The conversion of lactate to bicarbonate helps to counteract acidosis.
