IV Fluid Therapy Calculations

Overview

• Year Group: BVSc3 +
• Focuses on individualized assessment and adjustment of fluid therapy plans for animals.

Equipment Needed

• Calculator
• Pen
• Paper

Key Concepts in Fluid Therapy

Maintenance Fluid Rate

• Adult Dogs/Cats:
  • 2 mL/kg/hr OR 50 mL/kg/24 hours
  • Example: A 35kg dog requires 70mL/hour or 1750mL/24 hours
• Puppies/Kittens:
  • 3-4 mL/kg/hr
• Guidelines: 2013 AAHA/AAFP Fluid Therapy Guidelines for Dogs and Cats

Fluid Deficit Calculation

• Estimate the percentage dehydration (e.g., a 35kg dog at 8% dehydration)
  • Calculation: 35kg x 0.08 = 2.8kg (equivalent to 2800mL fluid deficit)
• Fluid replacement over 24 hours combines maintenance and deficit
  • Example: 1750mL maintenance + 2800mL deficit = 4550mL/24 hours
• Severe Dehydration: Front-loading
  • Possibly replace 30% in the first 3 hours, adjust per case response
• Shock Treatment:
  • Bolus fluids for rapid deficit replacement

Ongoing Losses

• Adjust fluid rates for ongoing losses (e.g., vomiting, diarrhea, hemorrhage)
• Estimate volume loss and adjust fluid therapy

Overall Fluid Rate Calculation

• Take into account maintenance, deficit, and ongoing loss
• Input into infusion pump or calculate drip rate (mL/min)
  • Example: 116mL/hour = 1.93mL/min; 1.93mL/min x 20 drops/mL = 38 drops/min

Fluid Administration During Anaesthesia

• Standard rate: 2-4 mL/kg/hr (for healthy animals)
• Adjust for individual cases

Scenarios and Calculations

1. 6-year-old DSH Cat for Dental Surgery
   • Weight: 3.4kg; Drip Rate: ~ 1 drop every 5 seconds
2. 15-week Old Puppy with Vomiting/Diarrhea
   • Weight: 6.8kg; 6% dehydration
   • Total Fluids: 897.6mL over 24 hours
   • Drip Rate: ~ 12.5 drops/min
3. Dog in Hypovolemic Shock Post RTA
   • Weight: 35kg; Bolus: 30mL/kg over 20 minutes
   • Drip Rate: 700 drops/min
4. 9-year-old MN DSH Cat with Urethral Obstruction
   • Weight: 4.7kg; Dehydration: 10%
   • Infusion Pump: 117.5mL over 30 minutes (rate: 235mL/hr)
   • Suitable Fluids: 0.9% NaCl or Hartmann's

Practical Considerations

• Adjust for small body size to prevent excessive fluid administration.
• Monitor fluid status to avoid overdose.

Infusion Pump Abbreviations

• VTBI: Volume to be infused
• RATE: Fluid administration rate (e.g., 2mL/kg/hr)
• VI: Total volume infused

Key Research

• Study by Drobatz et al. (2008) on crystalloid type effects on acid-base and electrolyte status in cats with urethral obstruction.

Additional Notes

• Regularly assess and adjust fluid therapy based on current animal condition and response.