Lactated Ringer's at 75 mL/hour: Clinical Appropriateness
Yes, you can administer Lactated Ringer's solution at 75 mL/hour, as this rate falls within the safe maintenance fluid range for most adult patients and is specifically supported for stroke patients and general medical care. 1
Standard Maintenance Rate
- Normal saline or LR at approximately 75-100 mL/hour is the recommended maintenance rate for stroke patients to maintain euvolemia. 1
- This rate provides adequate hydration without risking volume overload in most clinical scenarios. 1
- For a 70 kg adult, 75 mL/hour translates to approximately 1 mL/kg/hour, which is a conservative maintenance rate appropriate for most patients. 2
Clinical Context Matters
Sepsis/Shock Resuscitation:
- If your patient is in septic shock or requires acute resuscitation, 75 mL/hour is inadequate—you need bolus therapy instead. 1
- Initial sepsis resuscitation requires 250-1000 mL boluses over 15-30 minutes, not slow maintenance rates. 1
- WHO guidelines recommend 1000 mL immediately, then 20 mL/kg/hour (approximately 1400 mL/hour for a 70 kg patient) for ongoing sepsis management. 1
Elderly Patients:
- For elderly patients (>65 years), 75 mL/hour (approximately 1 mL/kg/hour for most adults) represents an appropriate conservative starting rate. 2
- This rate minimizes risk of volume overload while providing adequate maintenance hydration. 2
- Monitor closely for signs of fluid overload including jugular venous distention, peripheral edema, and pulmonary crackles. 2
Cardiac or Renal Disease:
- Patients with congestive heart failure or chronic renal disease require particularly cautious fluid administration, making 75 mL/hour a reasonable conservative choice. 1, 2
- Monitor for volume overload and adjust downward if signs develop. 2
LR vs Normal Saline Considerations
- LR is preferable to normal saline for most patients as it causes less hyperchloremic acidosis and may require less total volume for resuscitation. 3, 4
- In hemorrhagic shock models, LR required significantly less volume (125.7 mL/kg) compared to NS (256.3 mL/kg) to achieve the same endpoints. 3
- However, in elective surgical patients, both solutions perform similarly without clinically meaningful differences. 5
Critical Exception: Traumatic Brain Injury
If your patient has traumatic brain injury (TBI), reconsider using LR entirely. 6
- Pre-hospital LR was associated with 78% higher adjusted mortality compared to NS in TBI patients (HR = 1.78, p = 0.035). 6
- For TBI patients, normal saline is the preferred crystalloid, not LR. 6
When 75 mL/hour is NOT Appropriate
- Active hemorrhage or hypovolemic shock: Requires rapid bolus therapy, not maintenance rates. 1
- Hypotension requiring resuscitation: Need 250-500 mL boluses over 15-30 minutes. 1
- Septic shock: Requires initial 30 mL/kg (approximately 2100 mL for 70 kg patient) over 3 hours minimum. 1
- Severe dehydration: May require 3-5 mL/kg/hour with close monitoring. 2
In summary: 75 mL/hour LR is appropriate for maintenance fluid therapy in most stable adult patients, particularly those with stroke, but is inadequate for acute resuscitation scenarios requiring bolus therapy.