| Sodium | |
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The Problem: Problems with sodium are very common on the neurosurgery floor. Many of the post-injury and post-op patients will have SIADH or diabetes incipidus (DI). There is also a condition called cerebral salt wasting (CSW) that should be mentioned. Often sodium changes are the inciting factor causing a change in the level of consciousness of a patient, so don't forget to check it. Hyponatremia with hypoosmolality contributes to cerebral edema. When sodium levels change quickly, they can be corrected quickly with less fear of central pontine myelinosis. Treatment with 3% NaCl is common with our patients. SIADH... look for a euvolemic patient with low serum sodium and low urinary sodium. DH... hypovolemic with high serum sodium and very dilute urine ..output often grater than 200 cc/hr. CSW... very rare ... low serum sodium, hypovolemic and normal to high urinary sodium |
What We Do: Treatment of SIADH.... Just like in all of the books, fluid restriction works well but if the drop in Na+ was rapid you can start some 3% NaCl at 30 cc/hr and recheck in 6 hours. If you start 3% check the lytes at least BID and make appropriate adjustments. NEVER fluid restrict patients with SAH as dehydration worsens vasospasm. Treat SAH patients with risk of vasospasm with 3% NS. Treatment of DI... this is most common with our post op pituitary cases and after some cerbral aneurysm cases. It can be a bit tricky to treat. Often the endocrine service gives us a hand with the long term management of these patients. All post op patients will have to mobilise fluid given intraoperatively and this tends to happen POD#2 or #3. An increase in urine output alone does not make the diagnosis of DI. The best strategy with these patients is to let them drink (if they are awake). Put a jug of water in front of them and tell them to drink when they are thirsty. Ask the nurses to follow the ins and outs regularly... q1h if necessary.... if they are sedated... deep up with urinary losses wiht IV fluids. First with NS or 1/2NS. Follow the serium and urinary lytes closely and only treat the DI with DDAVP if the sodium starts to go up with urinary losses and the sodium begins to climb...try 1 microgram of DDAVP IV and follow. The DDAVP will last for about 6 hours. If it needs to be given regularly keep an eye on the sodium because the DI may also resovle quickly. Treatment of CSW... the big trick here is making the diagnosis and convincing the endocrine team not to fluid restrict the patient. 3% NS will work but the patient will become hypovolemic and hyponatremic wihtout it. Initially adding more salt to the diet can be tried i.e. 4 - 6 packets of salt per meal... easier if they are on feeds. Mineralocorticoids also have arole in the treatment of CSW. Florinef works well but again the sodium needs to be followed as CSW can resolve quickly. Another point on sodium is patients with head injuries or post-op patients often are unable to keep up with daily fluid intake. We often write DC IV when drinking well...this is hard to assess and the IV often comes out too early. For all of the chronic patients...be sure to follow their fluid status...i.e. do weekly lytes and renal functions.
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| Authorship: Dr Valerie Taylor | Last Revised: 29 May 2002 |