Friday, January 29, 2010

TIPS

Transjugular Intrahepatic Portosystemic Shunt
  • Treatment for patients who bleed from portal hypertension
  • Limited by high incidence of stent stenosis or thrombosis in first year
  • Effective in reduction of refractory ascites, but associated with increased hepatic encephalopathy (vs serial paracentesis)

Thursday, January 28, 2010

LVH EKG criteria

1: R aVL + SV3 >25 (men) or >20 (women)
2: SV1 + R V5 or 6 > 35, RV5 or 6 > 25
3: R aVL > 8
4: RV6 > 18
5: VAT > 0.05s

These criteria have high specificity (in the 90s) but low sensitivity (10-25%)

Cheyne-Stoke Respiration

Periodic respiration/cyclic respiration: hyperventilation and hypocapnea followed by recurrence of apnea
  • common in advanced heart failure
  • associated with low cardiac output
  • decreased sensitivity of respiratory center to arterial CO2

Wednesday, January 27, 2010

Diuretics

Loop Diuretics (Furosemide)
  • acts in thick ascending limb of loop of Henle to block the Na+/K+/2Cl- co-transporter, preventing reabsortion of Na, K, Cl
  • increase fractional excretion of Ca++ up to 30%, increase fractional excretion of Mg++ up to 60%
  • used to tx hypercalcemia, edematous states ie CHF
Thiazides and Thiazide-like Diuretics (chlorothiazide)
  • acts in distal convoluted tubule to block coupled Na and Cl reabsorption
  • increase excretion of Na, K, Cl but less potently than loop diuretics
  • reduce Ca++ excretion
  • used in uncomplicated hypertension, less useful in edematous states
Distal Potassium-Sparing Diuretics (spironolactone, amiloride)
  • acts in cortical collecting duct prinicpal cells on aldosterone-sensitive Na+ channel
  • reduced excretion of K+, Ca++, Mg++
  • first line for cirrhotic ascites, also can be used in heart failure w/ systolic dysfunction, weak diuresis so commonly used in combination with a loop/thiazide diuretic to decrease K+ loss, increase diuresis in refractory edema

Carbonic Anhydrase Inhibitors (acetazolamide)

  • act in proximal tubule to inhibit bicarbonate absorption
  • transient, brisk alkaline diuresis
  • useful in edema w/ metabolic alkalosis to help restore acid-base balance

Osmotic Diuretics (Mannitol)

  • freely filtered but poorly reabsorbed
  • acts in proximal nephron and thin loops of Henle to prevent urinary concentration

Monday, January 25, 2010

Adrenal Insufficiency

Primary Adrenal Insufficiency (Addison's)
  • caused by autoimmune, infectious (TB, cryptococcus, CMV, pneumocystis), iatrogenic (bilateral adrenalectomy), or metastatic (lung, breast) etiologies
  • clinical features related to lack of cortisol: GI symptoms (anorexia, nausea/vomitting, abdominal pain), hypoglycemia, hypotension, hyperpigmentation, intolerance to physiologic stress
  • clinical features related to lack of aldosterone: hyponatremia and hypovolemia-->decreased cardiac output and renal perfusion, syncope, shock, hyperkalemia
  • tx in acute crisis: several liters of IV fluids (D5NS), IV hydrocortisone, tx underlying condition
  • chronic tx: daily oral glucocorticoid, daily mineralocorticoid
Secondary Adrenal Insufficiency
  • Causes: long term steroid therapy + illness/trauma
  • clinical features: same as above except that hyperpigmentation and hyperkalemia are not seen because ACTH is low, and aldosterone is normal
  • tx: same as above except that only glucocorticoid supplementation is necessary

Friday, January 22, 2010

Heart sounds--gallops

Order of heart sounds: S4-->S1-->S2-->S3

S3
Occasionally heard in healthy children or adults, esp athletes
Occurs in dilated ventricles, for ex:
large VSD
CHF
volume overload

S4
Usually pathologic
Occurs with decreased ventricular compliance , for ex:
Normal (especially athletes)
Hypertensive
Coronary artery disease
Aortic stenosis
Restrictive cardiomyopathy

Thursday, January 21, 2010

Chronic Pain Treatment

Chronic pain treatment optimally involves a combined pharmaceutical and non-pharmaceutical approach. Pharmaceutical options include a range of classes:
  • Opioids, side effect: sedation, constipation, respiratory depression, abuse potential
  • NSAIDS: GI ulcers, bleeding, renal impairment
  • Serotonin agonists: MI, stroke, peripheral vascular occlusion
  • Antiepileptics: sedation, dizziness, cognitive impairment
  • Antidepressants: Cardiac arrhythmia, sedation, nausea, dry mouth, constipation, sleep disturbance
Some commonly used pharmaceuticals include:
  • Tramadol (ultram): 250-300 microgm q 6hr, binds mu-opioid receptors and inhibits the noradrenaline reuptake inhibitor, has addictive/abuse potential
  • Toradol (Ketorolac): 10 mg q 6hr, NSAID, risk of gastritis after 5-7 days
  • Vicodin: 5/500 or 7.5/750, hydrocodone and acetaminophen, formulations which use NSAID instead of acetaminophen are also available (Vicoprofen)