Is D5 (5% Dextrose in Normal Saline) NS (Normal Saline) with potassium okay for patients after a Low Anterior Resection (LAR)?

D5 NS with Potassium for Patients After Low Anterior Resection

For patients after low anterior resection (LAR), D5 NS with potassium is not recommended as the preferred intravenous fluid; instead, a hypotonic crystalloid solution with appropriate potassium supplementation should be used if IV fluids are necessary beyond postoperative day 1. 1

Optimal Postoperative Fluid Management After LAR

Immediate Postoperative Period

• Intravenous fluids should be discontinued as early as possible, ideally by postoperative day 1 1
• Patients should be encouraged to drink when fully recovered and offered an oral diet within 4 hours after surgery 1
• Early transition to oral intake is a key component of Enhanced Recovery After Surgery (ERAS) protocols 1

If IV Fluids Are Required Beyond POD 1

If intravenous fluids must be continued postoperatively (which should be avoided if possible):

• Recommended fluid: Hypotonic crystalloid solution 1
• Sodium content: 70-100 mmol/day 1
• Potassium supplementation: Up to 1 mmol/kg/day 1
• Rate: 25-30 ml/kg/day as maintenance 1

Why Not D5 NS?

D5 NS (5% Dextrose in Normal Saline) should be avoided for several reasons:

1. High sodium content: Normal saline (0.9% NaCl) contains 154 mmol/L of sodium, which exceeds the recommended 70-100 mmol/day 1

2. Risk of hyperchloremic acidosis: 0.9% saline causes hyperosmolar states and hyperchloremic acidosis 1

3. Impaired renal function: Saline can decrease renal blood flow and glomerular filtration rate 1

4. Gastrointestinal effects: Hyperchloremic acidosis reduces gastric blood flow and can impair gastric motility, which is particularly concerning after colorectal surgery 1

5. Risk of fluid overload: Saline can lead to sodium retention and edema, which may compromise anastomotic healing 1

6. Transient hyperglycemia: The dextrose component can cause significant hyperglycemia even in non-diabetic patients 2

Balanced Solutions Are Preferred

• Balanced crystalloids (e.g., Ringer's lactate) are recommended over 0.9% saline for any ongoing fluid replacement 1
• These solutions have electrolyte compositions closer to plasma and avoid the complications associated with normal saline 1

Monitoring and Management

• Maintain near-zero fluid balance postoperatively 1
• Replace any ongoing losses (e.g., vomiting, high stoma output) on a like-for-like basis with balanced solutions 1
• Monitor electrolytes regularly, especially in patients with preoperative electrolyte disturbances 1
• For patients with hypotension receiving epidural analgesia, use vasopressors rather than indiscriminate fluid boluses after ensuring normovolemia 1

Special Considerations

• Avoid fluid overload: Even 2.5L of excess fluid can cause adverse effects including increased complications, prolonged hospital stay, and higher costs 1
• Avoid fluid restriction: Inadequate fluid can lead to decreased tissue perfusion and oxygen delivery, potentially compromising anastomotic healing 1
• Glucose monitoring: Regular monitoring is important, especially if dextrose-containing solutions are used 1, 2

In conclusion, while D5 NS with potassium has traditionally been used in postoperative settings, current evidence strongly supports the use of more physiologic, balanced solutions with appropriate potassium supplementation when IV fluids are necessary after LAR. The goal should be early discontinuation of IV fluids and transition to oral intake whenever possible.