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)

Severely elevated transaminases

Severely elevated ALT/AST (>10000) indicates extensive hepatic necrosis. Common causes include:
  • ischemia, shock (prolonged hypotension/circulatory collapse)
  • acute toxic insult (acetaminophen toxicity, mushrooms: Amanita phalloides)
  • Severe viral hepatitis
This is in contrast to:
  • moderately elevated ALT/AST (high hundreds to thousands): acute viral hepatitis
  • mildly elevated ALT/AST (low hundreds): chronic viral hepatitis, acute alcoholic hepatitis.

Monday, January 18, 2010

Leukopenia

Leukopenia: WBC<4-4.5X10^3/mm3
Neutropenia: most common cause of leukopenia, classified based on risk of overwhelming infection as
  • mild: 1000-1500 cell/mm3
  • moderate: 500-1000 cell/mm3
  • severe: <500>

Mild/moderate neutropenia can be tx on outpatient basis if a clear, reversible source is identified and no clinical findings are seen. Severe neutropenia with fever should be admitted with panculture and panimaging.

Mechanisms of leukopenia

1. bone marrow injury: drugs, radiation, toxins, infections (mumps, measles, malaria, influenza, parvo, TB, typhoid, tularemia, HIV, EBV) , infiltrative disease of bone marrow (lymphoma, leukemia, and mets from lung, breast, prostate, stomach CA)

2. maturation defect : folic acid/B12 deficiency, neoplasm (ie acute myeloblastic leukemia)

3. sequestration: hypersplenism

4. destruction: autoimmune (ie Systemic lupus erythematosus)

Lymphopenia

lymphocyte count <2x10^3>

Common causes: HIV, corticosteroids, Hodgekin's lymphoma, multiple myeloma, protein-calorie malnutrition

Wernicke Encephalopathy

  • Sx: confusion, ataxia, opthalmoplegia
  • Mechanism: thiamine deficiency
  • Affected population: alcoholism, AIDS, hyperemesis, bowel resection/gastric bypass
  • Tx: thiamine c/ dextrose, often given as banana bag with folic acid and Mg sulf
  • can be worsened by glucose, so glucose should not be given prior to thiamine

Friday, January 15, 2010

Myasthenia vs. Lambert-Eaton

Myasthenia Gravis
Sx: fluctuating weakness of commonly used voluntary muscles, weakness increased by activity
  • diplopia
  • ptosis
  • difficulty swallowing
  • respiratory and limb muscles may be involved

Dx: Tensilon test (edrophonium chloride test): short acting (min) anticholinesterase, transiently improves symptoms of Myasthenia gravis

Associated conditions: thymic tumor, thyrotoxicosis, rheumatoid arthritis, lupus erythematosus

Mechanism: anti-Ach-R antibodies made

Tx: 1st line: anticholinesterases (symptomatic), recommended if pt <60>

Admit indications: acute exacerbation, plasmaphoresis, thymectomy, starting corticosteroids

Interactions: aminoglycosides worsen symptoms

Lambert-Eaton

sx: variable weakness, improved with activity

  • dysautonomic symptoms present

associated conditions: h/o malignant disease (small cell carcinoma)

Mechanims: antibodies against voltage gated Ca++ channel

Tx: combined plasmaphoresis and immunosuppressive therapy (prednisone, azathioprine), tx underlying malignancy, response to anticholinesterases is variable