How to manage severe hyponatremia in a diabetic patient scheduled for surgery tomorrow, who is currently being treated with half normal (1/2) saline (DNS) with 5 milliequivalents (meq) and 4 units of rapid-acting insulin?

Management of Severe Hyponatremia in a Diabetic Patient Scheduled for Surgery

Stop the 1/2 normal saline immediately and switch to 3% hypertonic saline with close monitoring, as your current regimen with hypotonic fluid is worsening the hyponatremia and poses significant perioperative risk. 1

Immediate Actions Required

Discontinue 1/2 DNS immediately - administering hypotonic saline (0.45% NaCl) to a patient with severe hyponatremia (Na 120 mEq/L) will worsen the sodium deficit and increase risk of cerebral edema. 1

Switch to 3% hypertonic saline for severe hyponatremia (<125 mEq/L), even if the patient is asymptomatic, given the urgent surgical need. 1, 2 Administer as:

• 100 mL boluses over 10 minutes, which can be repeated up to three times at 10-minute intervals if severe symptoms develop 1
• For continuous infusion, target correction of 6 mmol/L over the first 6 hours 1, 2

Transfer to ICU for close monitoring during active correction, with serum sodium checks every 2 hours initially. 2

Critical Correction Rate Guidelines

Maximum correction: 8 mmol/L in 24 hours - this is the absolute ceiling to prevent osmotic demyelination syndrome. 1, 2, 3 For diabetic patients, who may have additional risk factors (potential malnutrition, electrolyte disturbances), consider even more cautious rates of 4-6 mmol/L per day. 1

Target sodium for surgery: Aim for at least 125-130 mmol/L before proceeding to the operating room, as severe hyponatremia increases perioperative mortality 60-fold (11.2% vs 0.19% in normonatremic patients). 1

Insulin Management During Correction

Continue insulin therapy but adjust based on glucose monitoring - the 4 units of rapid-acting insulin you started is appropriate for glycemic control, but ensure you're monitoring glucose every 2-4 hours during hypertonic saline administration. 4 Hypertonic saline does not contain dextrose, so hypoglycemia risk increases.

Add dextrose if needed: If blood glucose drops below 150 mg/dL during correction, add D5W to prevent hypoglycemia while continuing sodium correction. 4

Volume Status Assessment

Determine if hypovolemic, euvolemic, or hypervolemic - this is critical for ongoing management: 1, 3

• Check urine sodium: <30 mmol/L suggests hypovolemia (71-100% positive predictive value for saline responsiveness) 1
• Assess volume status clinically: Look for orthostatic hypotension, dry mucous membranes, decreased skin turgor (hypovolemia) vs. edema, ascites, jugular venous distention (hypervolemia) 1
• If hypovolemic: After initial 3% saline correction, transition to 0.9% normal saline for volume repletion 1
• If euvolemic (SIADH): Implement fluid restriction to 1 L/day after acute correction 1, 2

Monitoring Protocol

Serum sodium every 2 hours during initial correction phase with 3% saline 2, 5

Switch to every 4 hours once severe symptoms resolve or after initial 6 mmol/L correction 5

Watch for overcorrection: If sodium rises >8 mmol/L in 24 hours, immediately stop hypertonic saline, switch to D5W, and consider desmopressin to reverse rapid correction. 1

Monitor for osmotic demyelination syndrome signs (typically 2-7 days post-correction): dysarthria, dysphagia, oculomotor dysfunction, quadriparesis. 1 Diabetic patients may have additional risk factors if malnourished or with chronic hyperglycemia.

Surgical Timing Considerations

Delay surgery if possible until sodium reaches at least 125 mmol/L, ideally 130 mmol/L. 1 If surgery is truly emergent and cannot be delayed:

• Continue 3% saline perioperatively with hourly sodium monitoring
• Coordinate closely with anesthesia regarding fluid management
• Avoid hypotonic fluids intraoperatively
• Use isotonic (0.9%) saline as maintenance fluid during surgery 1

Common Pitfalls to Avoid

Do not use hypotonic fluids (including 1/2 normal saline, D5W alone, or lactated Ringer's) in severe hyponatremia - this worsens the condition. 1, 3

Do not restrict fluids if the patient is hypovolemic - this is appropriate only for euvolemic hyponatremia (SIADH). 1, 2

Do not correct too rapidly - overcorrection exceeding 8 mmol/L in 24 hours significantly increases risk of permanent neurological damage from osmotic demyelination syndrome. 1, 2, 3

Do not ignore mild symptoms - nausea, headache, or confusion indicate the brain is already affected and require aggressive treatment. 3