General Surgery Flashcards
What happens to intestinal blood flow during shock?
Large arteriolar vasoconstriction and small arteriolar vasodilatation which provides preservation of flow the mucosa but decrease flow the muscularis propria.
What happens to intestinal perfusion after initial resuscitation after shock?
Intestinal perfusion is still diminished
What is the order of highest to lowerst potassium secreting organs?
Colon > Saliva > Gastric > Bile
What patient medical history would make you not want to use succinylcholine for fear of hyperkalemia?
Burns, Trauma, spinal cord injury, and neurogenic disorders
How much potassium is in the body?
50meq/kg which equals about 3500meq.
How much potassium loss occurs when there are only 3meq/L on labs? 2meq/L?
Deficit of 100-200 meq/L for K of 3, and 300-600 meq/L for K of 2
What are the clinical manifestations of metabolic acidosis?
Oxygen dissociation curve shift to the right, increased catecholamine release, decreased cardiac contractility, peripheral arterial dilatation
What are the ECG changes for hypokalemia?
ST depression, flattening T waves, U waves
When do ECG changes occur for hypokalemia?
Under 3meq/L
What is the concentration of NA, K and Bicarb in the pancreas?
140, 5, and 100 because it has the same concentration of Na and K as there is in plasma and its alkalotic due to the centroacinar and intercalated duct cells
Can you get hyperkalemia in a patient with normal kidney function?
No because 90% of ingested potassium is excreted in urine
What muscles are affected by potassium changes?
Cardiac, skeletal and smooth muscle
What does hyper and hypokalemia interfere with?
membrane depolarization and repolarization
What ECG changes can you see with mild hyperkalemia?
Peaked T waves and shortened QT interval
What ECG changes can you see with severe hyperkalemia?
Flattened P waves, prolongation of QRS complex, deep S waves
What is the feared complication of hyperkalemia?
Ventricular fibrillation and cardiac arrest
What can you do to treat hyperkalemia temporarily?
10-20% calcium gluconate, glucose and insulin, or Sodium bicarbonate
What is the dosing for calcium gluconate and calcium chloride for hyperkalemia?
1000mg over 2-3minutes with cardiac monitoring. Lasts for 60 minutes
Which calcium can go in the periphery and which in central vein for hyperkalemia?
Calcium chloride goes in the central vein and calcium gluconate goes in the periphery
How do u dose the insulin and glucose for hyperkalemia?
10U regular insulin and 25g of glucose (50amps of D50) or 10U in 500ml of 10% dextrose
What is considered hypophosphatemia?
0.8 mmol/L
What conditions are at risk for hypophosphatemia?
DKA, alcoholism, Sepsis, malnutrition with carbohydrate feeding
How does hypophosphatemia manifest?
Affects diaphragm contractility leading to respiratory failure
Who should you evaluate for hypophosphatemia?
Patients you are weaning from vent and those with COPD
What is the formula for FeNA?
(UNa x Pcr/Pna x Ucr) x 100
What value of UNa suggests hypovolemia?
Una of 10-15 mEq/L
What value of UNa suggests ATN?
UNa of 20meq/L
What FeNa is considered for prerenal azotemia?
What is the physiological response of renal hypoperfusion
Renin secretion from juxtaglomerular cells on afferent arterioles which produces angiotensin II, which promotes Na and H2o resorption and aldosterone secretion, and arteriolar vasoconstriction
What fluid is best for hemorrhagic shock?
isotonic crystalloid solution
What are the main symptoms of hyperkalemia of 7 or 8 meq/L
muscle weakness and cardiac arrhythmias
What are the primary causes for decreased urinary excretion of potassium?
hypovolemia, hypoaldosteronism, renal failure, and drugs like spironolactone and NSAIDs
Why do you get peaked T waves with hyperkalemia?
The increase potassium concentration causes a faster repolarization
Why do you get flattened P waves with hyperkalemia?
Hyperkalemia prevents the Na channels from opening to get depolarization by decreasing the membrane potential
What are the three things that will counterbalance hyperkalemia?
hypercalcemia, hypernatremia, and alkalosis
How long does it take for IV sodium bicarb work to antagonize hyperkalemia?
30-60 minutes to raise pH
How long does it take for IV insulin and glucose to work? and how much does it bring the potassium down?
1 hour for 0.5-1meq/L decrease
How long does kayexalate take to work and how much does it decrease the potassium?
2-4 hours and by 0.5 - 1 meq/L with 50g of kayexalate.
How does the kidney compensate for acid load? and how long does it take?
secreting ammonia and 2-4 days
How long does ventilatory compensation for metabolic acidosis occur?
12 to 24 hours
What should you do while treating a DKA patient with insulin and fluids?
Replace potassium
How much albumin ends up in the interstitial space?
50%
Why is dextrose added to hypotonic solutions?
to increase their tonicity and prevent red blood cell lysis
How many meq of Sodium is in lactated ringers?
130meq/L
