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USMLE2 Surgery 4
Pre/Post Op
Question | Answer |
---|---|
What is the fractional excretion of sodium (FENa)? What does it tell you? | % of the sodium filtered by kidney which is excreted in the urine. Low --> Na retention --> non-kidney prob such as volume depletion or low output heart failure. Hi --> Na wasting due to acute tubular necrosis or other causes of intrinsic renal failure. |
What is the formula for the fractional excretion of sodium (FENa)? | (Na[ur] x Cr[pl])/(Na[pl] x Cr[ur]) x 100 |
Interpretation of FENa | <1% - prerenal (hypovolemia), >1 ATN or kidney damage |
dopamine - low dose | D1 receptors - dilating blood vessels, increasing blood flow to renal, mesenteric, and coronary arteries; and increasing overall renal perfusion. Dopamine therefore has a diuretic effect. |
dopamine - intermediate dose | positive inotropic and chronotropic effect through increased β1 receptor activation. It is used in patients with shock or heart failure to increase cardiac output and blood pressure. |
dopamine - high dose | "pressor" dose. vasoconstriction, increases systemic vascular resistance, and increases blood pressure through α1 receptor activation; but can cause the vessels in the kidneys to constrict to the point where they will become non-functional |
When is the cardiac risk for a non-cardiac operation too great? | when EF is less than 35% (nl is 55%) |
What is the worst finding that predicts high cardiac risk? What is the second worse? | JVD, MI within the last 6 months |
What to do if pre-op pt has elevated JVD? | Tx with ACE inhibitors, beta-blockers, dig, and diuretics BEFORE surg. |
Operative mortality within 3 months of an MI? Within 6 months? | 40%, down to 6% after 6 months |
what should be done if someone must go into surgery but had an MI in the last 6 months | admit to ICU a day before to optimize cardiac variables |
Pt needs noncardiac surg but is having severe progressive angina. What to do? | eval for coronary revascularization before the other operation. |
What is the most common cause of increased pulmonary risk in surg? | smoking (compromised ventilation) |
What should a smoker do before going into surgery? | quit smoking 8 months before, intensive respiratory therapy |
What is the risk of a peri-operative cardiac event if the Goldman's index is <5, <12, <25, >25? | 1, 5, 11, 22% risk |
Hepatic Risk - what is correlated with 40% mortality going into surgery? (bili, alb, PT, mental status) What if a pt has three of these variables? How about 4? | bili >2 OR albumin <3 OR PT > 16 or encephalopathy. If have three --> 80% mortality. If 4 --> 100% mortality. |
Hepatic Risk - what is correlated with 80% mortality going into surgery? (bili, alb, PT, mental status) | bili >4 OR albumin <2 OR blood ammonia > 150 |
What points to severe nutritional depletion? What to do before surg? | wt loss (by 20% in few months), alb <3, anergy to skin antigens, transferrin <200. 4 or 5 days preoperative nutritional support makes a big difference. |
What is an absolute contraindiation to surgery? What must you have before taking the pt to surgery in this case? | diabetic coma. Must have rehydration, return of UOP and at least partial correction of acidosis and hyperglycemia |
anesthetics implicated in development of malignant hyperthermia | halothane and succinyl choline |
Tx of malignant hyperthermia in surgery. What must you watch for? | IV dantrolene, 100% O2, correction of acidosis, and cooling blankets. Watch for development of myoglobinuria. |
How to tx wound infection? | If only cellulitis, then abx. If abscess, then open and drain. If you can't figure out which it is, use US. |
Treatment of Aspiration PNA | 1. BAL, 2. bronchoscopy (removal of acid and particulate matter), 3. broncho dilators, 4. respiratory support. NO steroids! |
Tx of delerium tremens | IV BZ's |
ogilvie syndrome. What is it? How to dx? How to tx? | elderly sedentery pts (Alzh, nursing hm) --> non-abd surg --> further immobilization post surg --> large abd, non tender, distension --> xrays show dilated colon. Colonoscopy to suck out gas, decompress colon, r/u colon CA. Leave long rectal tube in. |
Post op pt with large amounts of salmon colored fluid soaking the dressings. What is it and what do you do? | Wound dehiscence. Salmon fluid is peritoneal fluid. If not infected, tape it up and careful of pt moving or coughing. |
What would cause a GI tract fistula not to heal on its own? | FETIIID - forein body, epithelializaiton, tumor, infection, irradiated tissue, IBD, distal obstruction |
Looking at Na level, how do you know how much water a pt has lost? | Every 3 mEq/L above 140 represents 1L water lost |