Core Flashcards
Rhabdomylysis electrolyte effects
lysis of cells leads to hyperkalemia –> can lead to peaked T waves; hyperphosphatemia which binds to calcium resulting in hypocalcemia
cerebral salt wasting vs SIADH
Syndrome of inappropriate antidiuretic hormone (SIADH): pass urine with concentrated sodium but increased plama volume
Cerebral salt wasting occurs after intracranial injury. pass lots of urine with sodium and end up volume depleted. It responds to fluid and sodium replacement. It differs from syndrome of inappropriate antidiuretic hormone (SIADH) where you pass urine with concentrated sodium therefore also results in hyponatremia but increased plasma volume:
Curreri formula
25kcal/kg/day + 40 kcal/%TBSA/day
should also get 1-2 gm/kg/day of protein
Aspirin (acetylsalic acid)
inhibits cyclooxygenase which forms arachidonic acid compounds including thromboxane and prostacyclin. Thromboxane is a platelet aggregator and vasoconstrictor. Prostacyclin is a platelet aggregator.
Dextran
polysaccharide decreases platelet aggregation by altering electric charge of platelets and decreases blood viscosity. Also volume expander. Can cause renal injury and pulmonary edema.
Heparin
glycosaminoglycan that binds to antithrombin III and enhances its ability to inactivate thrombin (which converts fibrinogen to fibrin), as well as clotting factors IX, X, XI, and XII. May also cause NO-mediated vasodilation.
Hirudin
derived from leech Hirudo medicinalis and directly inhibits thrombin.
Streptokinase (first generation) and tissue plasminogen activator (second generation)
converts plasminogen to plasmin which breaks down fibrin within a clot
Glycoprotein IIb/IIIa inhibitors
antiplatelet agent like aspirin
vonWillebrand disease
treat with desmopressin (DDAVP). Can measure levels of von Willebrand factor ristocetin cofactor and coagulation factor VIII. Note DDAVP is a derivative of ADH so restrict fluid to avoid hyponatremia and seizures.
Factor V Leiden
most prevalent hypercoagulation disorder. Activated protein C cleaves factor V in three sites; a mutation in the first site is known as factor V Leiden. Factor Va is inactivated 10 times slower than normal.
Protein C and S deficiencies
Activated protein C with cofactor protein S inhibits coagulation cascade by inactivating factor V and factor VIIIa. May be associated with warfarin-related skin necrosis and purpura fulminans in neonatal period.
Antiphospholipid syndrome
most common acquired coagulation disorder. Autoimmune disorder with antibiodies to phospholipids including anticardiolipin, lupus anticoagulant, anti-beta-2-glycoprotein I.
Tetracyclines
contraindicated children under 8, effect growing teeth and bones
Quinolones
contraindicated children under 18, effect cartilage and joints
Third generation cephalosporins
cefotaxime, cephtriaxone
Antibiotic prophylaxis for leeches
aeromonas hydrophila so prophylaxes with fluoroquinolone or in children Bactrim (or ceftriaxone)
Fungal infections
- Coccidiomycosis (Southwest US)
- Histoplasmosis (Ohio-Mississippi river valley)
- Blastomycosis (Ohio-Mississippi river valley)
- Mucormycosis (rhizopus species)
- Crytococcus
- Chromomycosis (tropics)
Statistical error
- Type I: false positive; reject the null hypothesis and falsely conclude there is a treatment effect (guard against with low significance/alpha level of <0.05)
- Type II: false negative; failing to reject a null hypothesis that should be rejected due to inadequate sample size/power
- Type III: correctly reject the null hypothesis for the wrong reason
- Type IV: incorrect interpretation of a correctly rejected hypothesis
Levels of evidence
- High quality, multicentered or single-centered, randomized controlled trial with adequate power
- Lesser-quality, randomized controlled trial; prospective cohort study
- Retrospective comparative study; case control study
- Case series
- Expert opinion; case report
Autonomic dysreflexia
Uncontrolled sympathetic response (headache, hypertension, bradycardia, flushing, blotching, sweating) to stimulus (bladder distention, rectal distention, fractures, heterotopic ossification, dislocations, infections, pregnancy, labor). Patients with paralysis above T6. Treatment to remove stimulus (foley catheter), nifedipine.
Malignant hyperthermia
caused by inhalational agents like isoflurane and depolarizing muscle relaxants like succinylcholine. Results in skeletal muscle rigidity, tachycardia, fever, cardiac arrhythmias, acidosis, hypotension, hyperthermia, increase in end-expired CO2 concentration. Treat with dantrolene.
Succinylcholine side effects
only depolarizing muscle relaxant
can trigger malignant hyperthermia
can result in hyperkalemia in paralytics, burns, crush, rhabdomylitis, lower motor neuron injury due to upregulation of nicotinic acetylcholine receptors in denervated or traumatized muscle. Treat with sodium bicarbonate, glucose with insulin, calcium.
FENa
FENa = ((UNa x PCr)/(PNa x UCr)) x 100% calculates percent of filtered sodium excreted
FENa below 1% prerenal where appropriate reabsorption due to decreased renal perfusion
FENa above 2% inappropriate salt wasting indicating ATN or if intrinsic damage so less sodium reabsorbed. In postrenal disease the FENa is high initially then as there is renal damage the value increases. Diuretics and chronic renal failure alter reliability
BUN: serum creatinine ratio
BUN reabsorption is regulated whereas creatinine reabsorption is fixed. If prerenal than BUN absorption increased and creatinine stays the same so ratio above 20:1. If renal damage then BUN absorption decreased and ration less than 10:1. If post renal or normal then the ratio will be 10-20:1.
neurogenic diabetes insipidus
Closed head injury can lead to neurogenic diabetes insipidus. This is due to lack of vasopressin (ADH) production which is produced in the hypothalamus and released by the pituitary. It affects water retention in the collecting ducts and distal convoluted tubule so the patient makes dilute urine with low osmolality and develops hypernatremia.
free water deficit
free water deficit = normal body water x (1-(serum Na/140)).
Keloids
excess type III collagen compared to type I. Increased transforming growth factor beta (TGF-B).
Aprepitant
highly selective brain-penetrant, neurokinin-1 receptor antagonist. Block the binding of substance P at the neurokinin-1 receptor in brain stem emetic center and GI tract. Long half-life.
Ondanstron/Zofran
serotonin (5-HT3 receptor) antagonist effect chemoreceptor trigger zone and vagal afferents in GI tract
Droperidol
blocks dopamine receptors
Promethazine
central antidopaminergic mechanism
Metoclopramide
blocks dopamine receptors in central vomiting center and can block serotonin receptors in high doses
Preoperative guidelines for cardiac workup
Asymptomatic patient underoing elective, non-cardiac surgery who can perform moderate physical activity (4 mets like walking up two flights of stairs) then no further cardiac testing needed.
Treatment of MI
MOAN (morphine, oxygen, aspirin, nitroglycerin…and angiocath)
a. Can have asymptomatic ventricular premature beats and nonsustained ventricular tachycardia on monitoring but don’t treat of hemodynamically stable
b. If unstable or ventricular fibrillation or symptomatic sustained ventricular tachyarrhythmia then defibrillation and/or amiodarone
Bradycardia
treated with atropine, only if causing symptomatic hypotension
Narrow complex supraventricular tachycardia
treat with adenosine
tosades de pointes
treat with magnesium. Caused by digoxin toxicity or low magnesium
nerve fibers
alpha: large; proprioception, large motor
beta: small motor, touch pressure
gamma: muscle tone
delta: small; pain, temperature, touch
unmylenated: small; dull pain, temperature, touch
smaller nerves affected by blocks earlier
merkel cell
in epidermis, derived from neural crest
constant touch and pressure, static two-point discrimination
meissners corpuscle
in dermis
light touch, dynamic two-point discrimination
pacinian corpuscle
in dermis
vibration, deep pressure
bulb of Krause
in dermis
temperature (cold)
ruffini ending
in dermis
sustained pressure, temperature (hot)
Baux score
50% mortality if age + TBSA = 110
if inhalation injury then if =100
biobrane/trancyte
biobrane: nylon fabric coated with porcine dermal collagen with silicone membrane
trancyte: add neonate fibroblasts
