nida
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Harrison's Q
A 36-year-old male undergoes knee surgery to repair torn ligaments. Postoperatively he is prescribed acetaminophen for pain. One day later he reports worsening pain. Physical examination reveals blood pressure 120/75 mmHg, heart rate 80/min, respiratory rate 14/min, and temperature 37°C (98.6°F). He has severe pain at the knee but no redness or signs of infection. Serum electrolytes are as follows:
Sodium 128 meq/L
Potassium 4.0 meq/L
Chloride 95 meq/L
Bicarbonate 25 meq/L
BUN 12 mg/dL
Creatinine 1.0 mg/dL
Which of the following therapies is most appropriate at this time?
A. Hypertonic saline
B. Furosemide
C. Morphine
D. Normal saline
E. Vancomycin
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| cyra
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Hmmm....low sodium...but there aren't really any symptoms one could attribute to it.Morphine for the pain?
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| drk1980
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all of these Qs seem to be going over my head 
abt this Q...just speculating, maybe he is overhydrated from after the surgery...and hypertonic saline cud help?? cant attribute tht to the pain though.....again, these Qs are going over...
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| msyamp
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C
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| drk1980
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how low do we let ASxtic sodium levels go until we treat it?
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| cyra
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drk...you have a point here.Low sodium levels warrant treatment...be it a mild,moderate or severe hyponatremia.Here there is a mild decrease(levels between 120-130 meq/L) and as far as I can remember...you treat that with water restriction.Moderate hyponatremia(levels ~ 110-120 meq/L) needs normal saline and a loop diuretic(furosemide).A severe decrease(<100 meq/L) would be treated with hypertonic saline.That said...I just went for morphine cos nothing else fit and I thought the patient did need soemthing for the severe pain.On a hunch I just googled pain and SIADH!Apparently pain is a stimulus for ADH release...so once you relieve the patent of the pain the hyponatremia would get corrected too!Thats the only plausible explaination I could come up with...however...while emedicine states that pain is a cause of SIADH it also cites morphine in post op patients as a cause for it....which makes me wonder if this could actually worsen the hyponatremia...and leaves me confused.Anyways...I sould prob stop playing sherlock and get back to studying!
heres the emedicine link if anyone is interested:
http://www.emedicine.com/ped/topic1124.htm
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| docofthebigapple
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I had a similar question previously and the answer basically proved to me that we can use furosemide to increase serum sodium levels. It may semm redundant at first thought but the explaination said the body looses more water than sodium in furosemide use.
SO my answer here B. Give furosemide.
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| MAZI
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iwill go for c
i think that this is SIADH due to pain and if you correct this, the level of Na will be correct???
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| drk1980
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thanks for the info sherlock cyra;o)
i think i too am beginning to see the need to address his pain first.
looking forward to the explanation of this Q
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| msyamp
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D
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| frank100
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(c)
SIADH due to pain?, this is new stuff (thanks).
I wouldn´t give rehydration therapy, because hyponatremia is asymptomatic in this case.
Furosemide will make it worst.
and vancomycin is out...
so morphine will relief pain, won´t interfere with sodium levels.
*with a little experience, you will notice nothing wrong or harmful is going on here, so morphine and observation would be enough.
sorry if i´m wrong
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| nida
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The answer is C.
Many nonosmotic factors may increase AVP secretion from the pituitary or its effect at the collecting duct. Pain, nausea, any intracranial event (e.g., stroke, hemorrhage, seizure, or infection), a pulmonary infection or an infiltrative process, stress, hypoglycemia, pregnancy, or drugs may cause hyponatremia with a normal intravascular volume. Recent reports have implicated selective serotonin reuptake inhibitors as a cause of the syndrome of inappropriate antidiuretic hormone secretion (SIADH). Postoperative patients may have increased secretion of AVP for "appropriate" (e.g., hyperosmolality, hypovolemia) or "inappropriate" (nonosmotic) reasons. Pain and nausea are among the most potent stimuli for AVP secretion. This patient has no evidence of intravascular volume depletion requiring normal or hypertonic saline or infection requiring antibiotics. Furosemide probably would worsen the hyponatremia and precipitate volume depletion. Improved pain control with free water restriction probably will correct the serum sodium. Ethanol inhibits the secretion of AVP from the pituitary and its effect at the collecting duct.
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