Maintenance IV Fluid Rate for a 70kg Male
For a 70kg adult male, the maintenance IV fluid rate is 110 mL/hour (2,640 mL/24 hours) using the Holliday-Segar formula. 1
Calculation Method
The Holliday-Segar formula remains the standard approach for calculating maintenance fluid requirements: 2, 1
- First 10 kg: 4 mL/kg/hour = 40 mL/hour 2, 1
- Next 10 kg (10-20 kg): 2 mL/kg/hour = 20 mL/hour 2, 1
- Remaining 50 kg (above 20 kg): 1 mL/kg/hour = 50 mL/hour 2, 1
- Total: 40 + 20 + 50 = 110 mL/hour 2, 1
Alternatively expressed as 2,640 mL per 24 hours. 2
Fluid Composition
Use isotonic crystalloid solutions (0.9% normal saline or balanced crystalloid) as the standard maintenance fluid. 2
- Isotonic fluids (sodium 140 mEq/L) significantly reduce the risk of hospital-acquired hyponatremia compared to hypotonic solutions 2
- Balanced solutions (such as Plasma-Lyte or lactated Ringer's) are preferred over normal saline to reduce length of stay and avoid hyperchloremic acidosis 2
- Add 5% dextrose to prevent hypoglycemia, with blood glucose monitoring at least daily 2
- Include potassium 20-30 mEq/L once adequate renal function and urine output are confirmed 2
Critical Adjustments for Specific Clinical Scenarios
Reduce the calculated rate to 65-80% (72-88 mL/hour) if the patient has conditions causing increased antidiuretic hormone (ADH) secretion: 2, 1
- Post-operative state 2
- Pain, nausea, or stress 2
- Pneumonia or CNS disorders 2
- Any acute illness requiring hospitalization 2
Further restrict to 50-60% of calculated rate (55-66 mL/hour) for patients with: 2, 1
Monitoring Requirements
Reassess fluid balance and clinical status at least daily, with regular electrolyte monitoring (especially sodium). 2, 1
- Total daily fluid intake must include all IV fluids, medications, line flushes, blood products, and enteral intake 2, 1
- Avoid fluid overload and cumulative positive fluid balance, as this prolongs mechanical ventilation and increases length of stay 2, 1
- Monitor for signs of fluid overload: weight gain >2.5 kg, peripheral edema, pulmonary congestion 2
Common Pitfalls to Avoid
- Do not use hypotonic fluids (0.45% saline or lower) as maintenance therapy in hospitalized adults, as this significantly increases hyponatremia risk 2
- Do not continue maintenance fluids at full calculated rates in patients with SIAD or SIAD-like states without clinical reassessment 2
- Do not add potassium until adequate urine output is established and serum potassium is known to be <5.5 mEq/L 2
- Avoid "fluid creep" by accounting for all sources of fluid administration, not just the maintenance infusion 2, 1