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DU PA Surg Flui/elec

Duke PA Surgery Fluids and electrolytes

total body water accounts for __% or more of body weight 60
water is contained primarily in skeletal muscle
intrecellular water composes __ of total body water 2/3
extracellular water composes __ of total body water 1/3
interstitial water accounts for __% of extracellular water 75
intravascular water or plasma water, constitutes __% of extracellular water volume or 4-7% of body weight 25
in the intracellular compartment __ is the dominant cation potassium
in the interstitial and intravascular compartments __ is the dominant cation sodium
electrical neutrality is maintained by a balanced amount of chloride and bicarb ions
to maintain electrical neutrality, the negative charge on plasma albumin requires an increase in plasma cations, mostly sodium
the redistribution of ions across the semipermeable membrane is called the Donnan effect
refers to the number of particles dissolved in a solution olsmolarity
is calculated by considering only the concentration of impermeable solutes in solution tonicity
___ is an enzyme released by the juxtaglomerular cells of the afferent arteriole in response to a decrease in arterial blood pressure, hypovolemia, hyponatremia, and increased beta-adrenergic activity renin
Renin converts angiotensinogen to angiotensin I which is then converted to angiotensin II in the pulmonary circulation by Angiotensin-converting enzyme (ACE)
Angiotensin releases ___ from the renal cortex aldosterone
Aldosterone acts on the distal tubules and collecting ducts to increase sodium reabsorption and potassium excretion
angiotensin increases cardiac output and peripheral resistance
normally and adult ingests __L of water per day 2-3
___ mL/day is the minimal volume required to allow solute excretion 300
chronic volume depletion is manifested by oliguria, loss of skin turgor, orthostatic hypotension, low urine sodium concentration, BUN/creatinine ratio that exceeds 15:1.
Acute volume losses are manifested by hypotension, tachycardia, and tachypnea
normal dietary salt intake is __g/day 6-15
hypernatremia is defined as a serum sodium concentration that exceeds __ mEq/L 150
hypernatremia is always accompanied by hyperosmolarity
any net gain in sodium will increase the extracellular fluid and trigger transmembrane water shifts leading to cellular dehydration
hypernatremia may be due to excessive salt intake, excessive water loss, reduced salt excretion, reduced water intake
ordinarily the hyperosmolar state of hypernatremia will drive thirst and ADH release
in surgical patients, hypernatremia may result from the administration of __ which lead to free water depletion loop diuretics
neurologic symptoms of hypernatremia malaise, lethargy, vomiting, general seizures, and coma
rapid sodium increases will lead to cerebral dehydration
therapy for hypernatremia is directed first at restoring volume with isotonic saline solution
once intravascular volume is restored in hypernatremia, it is further corrected by administration of free water in the form of D5W
hyponatremia is defined as a serum sodium concentration that is less than __mEq/L 135
hyponatremia may be caused by excessive water intake, impaired renal water excretion, and loss of renal diluting capacity
symptoms of hyponatremia are mostly neurologic and are due to cellular swelling
cellular swelling in hyponatremia is induced by extracellular fluid hypo-osmolality
in hyponatremia cerebral swelling causes lethargy, confusion, vomiting, seizures, and coma
patients in this group often have edema hypervolemic hyponatremia
causes include renal failure, CHF, COPD, severe liver disease hypervolemic hyponatremia
the most common cause of normovolemic hyponatremia is the syndrome of inappropriate secretion of ADH (SIADH)
SIADH is seen in patients with central nervous system pathology such as stroke or injury, and in pulmonary conditions including tuberculosis and cancer
pateints with hypovolemic hyponatremia have renal or extrarenal losses of sodium that exceed water losses
in hypervolemic hyponatremic patients the treatment includes volume restriction and loop diuretics
patients with SIADH usually respond to fluid restriction
in hypovolemic hyponatremic patients treatment includes salt and water replacement
in asymptomatic patients, hyponatremia should be treated slowly
with symptomatic hyponatremia, current recommendations are to increase the serum sodium concentration no faster than __mEq/L/hr 0.5
in patients with stupor, coma, or other severe neurologic symptoms from hyponatremia __ is used hypertonic (3% NaCl) solution
most of the bodies potassium is found in skeletal muscle
the normal plasma potassium concentration is __ mEq/L 3.5-5
the usually dietary intake of potassium is __ mEq/kg 1-1.5
hyperkalemia is defined as a serum potassium concentration greater than __ mEq/L 5.5
hyperkalemia can result from renal or adrenal insufficiency, metabolic acidosis, or iatrogenic causes
the most common cause of metabolic alkalosis in surgical patients is nasogastric losses or vomiting
the peritoneal surfaces represent __% fo body surface area 50
during laparotomy, the expected evaporative fluid loss from exposed peritoneum is __ mL/kg/hr 10
hyperphosphatemia may result from rhabdomyolysis due to muscle ischemia or crush injury
the stress response to surgery results in the release of glucagon, aldosterone, cortisol, and antidiuretic hormone
hyperkalemia occurs with __ due to transcellular exchange of K+ and H+ metabolic acidosis
extrarenal causes of hyperkalemia intravascular hemolysis, rhabdomyolysis, seizures, and sever GI bleed
iatrogenic causes of hyperkalemia NSAIDs, ACEIs
the earliest EKG abnormality of hyperkalemia is peaking of T waves
as plasma potassium increases PR intervals become prolonged, and the RR interval increases
further increases in K+ concentration are associated with loss of P waves and widening of QRS
the final effect of hyperkalemia on the heart is complete heart block, v-tach, then asystole
extracardiac symptoms of hyperkalemia paresthesias, flaccid paralysis, ileus
to reverse cardiac toxicity in hyperkalemia __ should be administered calcium gluconate
in hyperkalemia the response to calcium salt therapy occurs in 1-5 minutes and lasts 30 minutes
in hyperkalemia concurrent treatment with __ moves K+ into cells insulin or sodium bicarbonate
potassium can be removed by treatment with the cation-exchange resin kayexalate (50-100 g as enema) or 40g orally with sorbitol
the most effective method of removing potassium is dialysis
when using ___ to treat hyperkalemia, the onset of action is slow, and the effects last 4-6 hours kayexalate
hypkalemia is defined as a serum potassium concentration that is less than __mEq/L 3.5
hypokalemia is a common problem in surgical patients and is usually caused by GI losses from vomiting, diarrhea, or fistula, and the use of diuretics
___ often coexists with hypokalemia metabolic alkalosis
metabolic acidosis decreases renal potassium conservation
EKG may show ___ in hypokalemia t-wave flattening/inversion, diminished QRS voltage, and U waves
in patients taking digoxin __ can provoke life threatening arrhythmias hypokalemia
potassium should be given __ unless the hypokalemia is severe (<2.5 mEq/L) orally
the serum ionized calcium concentration is maintained within a narrow range of ___ mg/dL 4.4-5.3
a reduction in serum calcium stimulates a release of parathyroid hormone
parathyroid hormone increases calcium reabsorption from bone
PTH enhances calcium reabsorption from the distal convoluted tubule
PTH stimulates formation of the active metabolite of vitamin D that increases gut absorption of elemental calcium
hypercalcemia is defined as ionized calcium concentration that exceeds __ mg/dL 5.3
although hypercalcemia is most frequently associated with hyperparathyroidism in surgical patients, it is also commonly associated with cancer
other causes of enhanced bone reabsorption Paget's disease, pheochromocytoma, hyperthyroidism, and use of thiazide diuretics
cardiovascular manifestations of hypercalcemia include arrhythmias and a shortened QT interval
GI effects of hypercalcemia anorexia, constipation, pancreatitis, and hyperacidity
the most common renal defect associated with hypercalcemia is polyuria
if hyperparathyroidism is the cause of hypercalcemia the best treatment is surgery
initial supportive therapy for hypercalcemia includes saline diuresis and furosamide
__ reduces bone reabsorption and has an immediate effect calcitonin
___ are highly effective inhibitors of osteoclast activity but have a delayed onset of 2-3 days biphosphonates
hypocalcemia is defined as an ionized calcium concentration of less than __ mg/dL 4.4
hypocalcemia is seen in parathyroid or thyroid surgery, sever pancreatitis, magnesium deficiency, and after massive blood transfusion
neuromuscular findings in hypocalcemia include paresthesias, muscular spasms, seizures, tetany, and weakness
cardiovascular symptoms of hypocalcemia include heart block, arrhythmias, bradycardia, and refractory hypotension
EKG findings with hypocalcemia prolongation of the QT interval and T-wave inversion
in patients with symptomatic or severe hypocalcemia ___ is indicated IV calcium therapy
fixed acids citric, pyruvic, sulfuric, phosphoric, acetoacetic
___ are the main buffers in the body bicarbonate and hemoglobin
in body fluids CO2 combines with water to form carbonic anhydrase
kidneys can compensate for the buffer lost during CO2 excretion by the lungs with bicarbonate reabsorption and ammonia production
metabolic acidosis is present when pH is less than 7.35 and plasma bicarbonate is less than __ mEq/L 22
in spontaneously breathing patients the increase in hydrogen ion concentration should stimulate __ thereby decreasing PCO2 compensatory increase in ventilatory rate
the presence or absence of an ___ helps to categorized metabolic acidoses anion gap
the anion gap is calculated as the difference between the concentrations of the major extracellular cation sodium and the major anions chloride plus bicarbonate
a normal anion gap is __mEq/L 8-12
the causes of anion gap acidosis can be remembered by the mnemonic Dr. Maples
Dr. Maples stands for Diabetic Ketoacidosis, Renal failure, methanol, alcohol, paraldehyde, lactic acidosis, ethylene glycol, salicylates
in trauma patients metabolic acidosis must be assumed to be due to blood loss (hypoperfusion and tissue hypoxia)
non-anion gap metabolic acidosis is characterized by loss of buffer base
common causes of non-anion gap metabolic acidosis GI tract loss, renal tubular acidosis, Addison's disease, total parenteral nutrition, and use of carbonic anhydrase inhibitors
therapy with ___ is reserved for those in severe metabolic acidosis (<7.2), and in those with life threatening ventricular arrhythmias, hemodynamic instability, inadequate compensatory response sodium bicarbonate
explained by the inability of the kidney to excrete excess bicarbonate or to retain hydrogen ion metabolic alkalosis
metabolic alkalosis is usually accompanied by respiratory compensation
respiratory acidosis is present when the pH is low and the PCO2 is elevated
respiratory acidosis is due to ineffective alveolar ventilation
treatment of respiratory acidosis may require intubation and mechanical ventilation
respiratory alkalosis is present when the pH is high and the PCO2 is low
caused by alveolar hyperventilation respiratory alkalosis
in the surgical pateint respiratory alkalosis may be caused by hypoxia, central nervous system lesion, pain, hepatic encephalopathy, and mechanical ventilation
in acute respiratory alkalosis renal compensation is minimal
in chronic respiratory alkalosis renal compensation is by a decrease in hydrogen ion excretion
most patients with respiratory alkalosis are asymptomatic
hyperventilation is particularly dangerous in patients with subarachnoid hemorrhage because it ecacerbates vasospasm
Created by: bwyche