Pretest_1 Flashcards
Loss of the ileum (eg jejunoileal bypass, or functional loss as in Crohn’s) predisposes to what?
hyperoxaluria and calcium oxalate stones!
Normally, calcium and oxalate bind in the bowel and are excreted. Unabsorbed fatty acids and bile acids combine with calcium, enabling the uptake of oxalate. The oxalate is then secreted in the kidney, where it can combine with calcium to form stones.
How do you calculate FENa?
(urine sodium x serum creatinine) / (urine creatinine x serum sodium)
Which values support a prerenal etiology for oliguria?
- FENa
- Urine sodium
- Urine osmolality
- BUN/Cr
- Urine Cr / Serum Cr
- FENa < 1% –> (UrNaxSCr)/(UrCrxSNa)
- Urine sodium < 20mEq/L
- Urine oxmolality > 500 mOsm/kg
- BUN/Cr > 20
- Urine/Serum (Cr) >20
Since both hypomagnesemia and hypocalcemia have similar neurological effects (paresthesias, hyperreflexia, muscle spasm, tetatny), how can you differentiate between them?
EKG! Hypocalcemia leads to prolonged QT and TWI; Hypomagnesemia more like hypercalcemia cardiac wise (ST segment depression, flattening of p waves)
According to Goldman’s criteria, an MI within ___ months of surgery is considered to increase a patient’s risk for cardiac complication after surgery.
6
A history of tinnitus in conjunction with mixed metabolic acidosis-respiratory alkalosis is pathognomonic for
salicyclate intoxication
Heparin-induced thrombocyotpenia (HIT) is mediated by antibodies to complexes formed by binding heparin to ______________
platelet factor 4
How is HIT treated?
Use of a non-heparin anticoagulant (like lepirudin or ragatroban, which are both direct thrombin inhibitors) with conversion to oral warfarin when platelet count back above 100K
When do most perioperative infarcts occur?
Around the third postoperative day, when the third-space fluids return to the circulation, which increases the preload and myocardial oxygen consumption.
What is the treatment of mesenteric ischemia?
Initially: increase cardiac output and blood pressure. Celiotomy (aka laparotomy) is required once diagnosis of arterial occlusion or bowel infarction has been made or if peritoneal signs develop.
What is von willebrand factor?
a stimulus for platelet aggregation and a carrier protein for circulating factor VIII
How is von Willebrand disease treated?
Do not generally require treatment unless need surgery or are severely injured.
1) DDAVP which results in normalization of factor VIII activities by boosting the release of vWF
2) Cryoprecipitate (provides vWF)
Why does DDAVP only help with Type I and Type II vWD?
DDAVP, a synthetic analogue of vasopressin, activates receptors that result in release of vWF from storage sites and increases levels of factor 8 as well. (helps with Type I and Type II, which is marked by decreased and defective vWF; Type III is absent).
A diagnosis of SIRS involves 2 or more of which 4 criteria?
1) T>38C or T< 36
2) HR > 90
3) RR>20 or PaCO2 < 32
4) WBC >12, WBC < 4, or >10% bands (immature neutrophils)
Why do large amount of banked blood transfusions lead to coagulopathy?
What is the treatment?
Dilutional thrombocytopenia and deficiencies in factors V and VIII.
Treatment = FFP and platelets
When do the components of the GI system start to function again following surgery?
1) stomach
2) small bowel
3) colon
1) stomach: 24 hrs
2) small bowel: within hrs
3) colon: 3-4 days
What is refeeding syndrome? What electrolytes are affected?
Hypokalemia, hypomagnesemia, hypophosphatemia, resulting from reshift of electrolytes BCK into the intracellular space (after being shifted extracellularly during periods of starvation)
What are early complications of TPN? (x4)
1) hyperglycemia
2) refeeding syndrome (hypokalemia, hypomagnesemia, hypophosphatemia)
3) hyperchloremic acidosis
4) volume overload with resultant heart failure
Severe stress, infection, trauma, or abrupt cessation/too rapid tapering of chronic glucocorticoid therapy can lead to _________, which is classically manifested by which symptoms?
How can it be distinguished from sepsis?
acute adrenal insufficiency:
1) changing mental status
2) increased temperature
3) cardiovascular collapse
4) hypoglycemia
5) hyperkalemia
Sepsis usually has hyperglycemia and no change in potassium
When should FFP be transfused to minimize bleeding due to surgery?
WHen the patient is called to the operating room (half life is 4 to 6 hours; should cover surgery and post op)
Factors that predispose to fistula formation and may prevent closure include:
FRIENDS foreign body radiation inflammation epithelialization of the tract neoplasm distal obstruction steroids
A high output fistula puts out more than ____ cc per day
500
What is used to prevent or treat bleeding complications in severe hemophilia A?
Hemophilia A (Factor VIII defiency)
1) desmopressin with aminocaproic acid (ddAVP boosts factor VIII, amicar prevent fibrinolysis)
2) cryoprecipitate
3) factor VIII concentrates
(though FFP does include factor VIII, it doesn’t have enough to treat hemophiliacs)
When should a patient stop taking NSAIDs before surgery? Aspirin?
NSAIDs: 3-4 days; reversible defect in cyclooxygenase
aspirin: 7 days before surgery, because aspirin permanently acetylates cycloxygenase and leaves affect platelets dysfunctional throughout their 7 day lifespan
Where is calcium ingested?
Proximal small intestine: duodenum and jejunum
What is the cause of postthyroidectomy hypocalcemia?
Transient ischemia of the parathyroid glands (tingling, cramps). Usually self limited and resolves in a couple of days; supplement w/ IV calcium gluconate for severe, oral for mild
Hpocalcemia is a associated with a prolonged QT and is exacerbated by (hypo/hyper)magnesemia and (acidosis/alkalosis).
Hypocalcemia is exacerbated by HYPOmagnesemia and ALKALOSIS
alkalosis causes calcium to bind more closely to albumin
Why is massive transfusion associated with hypocalcemia?
Secondary to chelation with citrate in banked blood
A normal QT interval is < or equal to ___msec
440
How do you calculate corrected calcium based on albumin?
serum calcium + 0.8 (4 - serum albumin)
Hypocalcemia can occur with (hyper/hypo)proteinemia, even though the serum calcium fraction remains normal.
HYPOproteinemia
Fluid loss in the duodenum, jejunum, ileum should be replaced with
Ringers lactate
What counteracts the myocardial effects of hyperkalemia without affecting the K level?
calcium gluconate!
What are methods to reduce serum K?
1) kayexalate
2) beta agonists
3) insulin + glucose
4) sodium bicarbonate (increase in serum pH drives K intracellularly in exchange for H+)
Alopecia, poor wound healing, night blindness/photophobia, anosmia, neuritis, skin rashes are all characteristic of ____ deficiency, often resulting in the setting of diarrhea.
Zinc deficiency!
Normal saline and Ringers lactate can be used to replace the volume of blood lost in a ratio of __:__
3:1
What are the earliest signs of sepsis? (x3)
1) Changing mental status
2) tachypnea leading to respiratory alkalosis
3) flushed skin
Sepsis causes a decreased peripheral utilization of oxygen, yielding a(n) (increased/decreased) peripheral utilization of oxygen, yielding an (increased/decreased) arteriovenous oxygen difference.
decreased peripheral utilization of oxygen
decreased arteriovenous oxygen difference
Because small-bowel fluid has high sodium, potassium, chloride, and bicarbonate, patients with large ileostomy outputs are at risk for
dehydration with accompanying hyponatremia, hypokalemia, and normal anion-gap metabolic acidosis.
How do you treat a hemolytic transfusion reaction?
1) aggressive fluid resuscitation (with fluids and mannitol, to clear hemolyzed red cell membranes)
2) alkalinization of urine ( IV sodium bicarb; prevents hemoglobin clumping in kidney)
What ais the surgical treatment of C difficile colitis and what are its indications?
Subtotal colectomy with end ileostomy
Indications: intractable disease, failure of medical therapy (metronidazole, vancomycin as second-tier agent), toxic megacolon, colonic perforation
What are the calorie requirements for:
1) starvation?
2) routine op?
3) multiple organ failure/severe injury?
4) body surface area burns > 50%?
1) starvation 0.8 (1800 calories)
2) routine op: 1.1 (2200 calories)
3) multiple organ failure: 1.5 (3000 calories)
4) BSA burns >50% 2 (4000 calories)
What are estimated daily insensible losses for:
1) feces
2) lungs
3) skin
Faeces approximately 100 ml/ day
Lungs approximately 400 ml/ day
Skin approximately 600 ml/ day
What is “severe sepsis”?
sepsis + organ dysfunction or hypoperfusion (lactic acidosis, altered mental status, oliguria)
Where is the majority of iron absorbed?
duodenum (and jejunum)
While crystalloid is used for fluid repletion in a ratio to blood loss of 3:1, colloid is replaced in what ratio?
1:1
Lactated ringers have a pH that is (</ > / =) to 7.
<7 (but still not as acidic as NS)
LR is (hypo/iso/hyper)osmotic to serum.
HYPOosmotic
What is type 4 RTA?
deficiency of aldosterone, or a resistance to its effects. Associated with hyperkalemia.
What is the difference between type 1 and type 2 RTA?
Type 1 is in the distal tubules and is Failure of H+ secretion by the α intercalated cells. PH of urine cannot be <5.3
Type 2 is in the proximal tubules and is Failed HCO3− reabsorption from the urine by the proximal tubular cells
