Week 7 Lesson 53 In Class Fluids 4 Fluids for Dehydration

Systems Overview

Urinary Tract and Water Balance: Vital for maintaining body fluid levels and effective waste elimination, the urinary system plays a significant role in homeostasis, regulating electrolyte balance, blood pressure, and the acid-base equilibrium of the body.

By the end of this session, students will be able to:

Calculate maintenance fluid therapy for small and large animals receiving intravenous (IV) fluids in a hospital scenario, taking into account specific species requirements and health conditions.
Accurately calculate fluid therapy for dehydration in small and large animals, incorporating clinical signs of dehydration and the duration of fluid therapy needed in a hospital setting.
Evaluate and select an appropriate type of fluid (category) for maintenance therapy in various clinical contexts, recognizing isotonic, hypotonic, and hypertonic solutions, and their respective indications.
Review key parameters for monitoring fluid therapy, including hydration status, vital signs, and laboratory values to ensure effective treatment and avoid complications.

MDO Acronym: What does the "D" stand for?

Daily requirement for most mammalian species (excluding cats):
- A. 10 ml/kg/day
- B. 20 ml/kg/day
- C. 40 ml/kg/day
- D. 60 ml/kg/day
- E. 100 ml/kg/day

Maintenance (M): Refers to fluids that replenish normal intake if the patient is not eating or drinking. Known as maintenance fluids, these are critical for sustaining basic physiological functions.
Deficit (D): Represents the fluid deficit to be replenished for dehydrated patients, calculated based on physical examination findings and lab results indicating the level of dehydration.
Ongoing Losses (O): Pertains to replacing excessive fluid losses incurred through various routes (e.g., vomiting, diarrhea, excessive urination). Addressing ongoing losses is vital to prevent further dehydration and associated complications.

Example 1: Maintenance Rate for Cat
- What is the maintenance fluid requirement per day for a 4 kg cat?
  - Answers vary: Typically around 40 ml/day is commonly accepted, leading to various calculations depending on the approach used.
Example 2: Maintenance Rate per Hour
- What is the maintenance fluid requirement per hour for a 4 kg cat?
  - Answers vary: Range from approximately 1.67 ml/hr to 2.67 ml/hr based on various factors including activity level.

Definition: Fluid deficit refers to the volume of fluid missing from the interstitial and intravascular compartments in dehydrated patients. This deficit significantly affects physiological functions and must be addressed promptly.
- Calculation Example: A goat weighing 20 kg is assumed to be 5% dehydrated:
  - Fluid Deficit (L) = Body Weight (kg) x % Dehydration (as a decimal) = 20 kg x 0.05 = 1 L.

Oral fluids: Often the first line of treatment, especially in mild cases.
Subcutaneous fluids: Useful for moderate dehydration, typically employed in patients that can tolerate fluids via the subcutaneous route.
Intravenous fluids: Essential for severe dehydration or in cases where rapid fluid replacement is needed, such as severe gastroenteritis.

Medical need: Assessing the severity of dehydration and patient condition.
Cost: Evaluating the financial implications of each treatment option.
Available supplies: Confirming what fluids and tools are available in the clinical setting.
Patient demeanor: Consideration of how the patient responds to treatment options in real-time.

Example: A goat weighing 100 kg is 5% dehydrated.
- Convert to decimal (0.05), then calculate fluid deficit (5 L).
- Determine the hourly rate for rehydration (over a period of 12 or 24 hours).

For a goat weighing 100 kg at 5% dehydration:
- Maintenance: Based on common guidelines, assume 60 ml/kg/day to achieve a total of 6000 ml/day.
- Divide by 24 hours to find the hourly rate (250 ml/hr).
- Combine Maintenance (M) and Deficit (D) to establish the total fluid rate.

Estimation of ongoing excessive fluid loss, critical for patients with gastrointestinal losses (e.g., Parvo puppy with vomiting/diarrhea).
- Total Calculation: Compiling M + D + O implementations, rounding as necessary, and adjusting based on patient assessments to ensure safety and effectiveness of fluid management.

Emphasizes the importance of monitoring parameters including:
- Hydration parameters (e.g., skin turgor, mucous membranes)
- Perfusion parameters (e.g., heart rate, blood pressure)
- Signs of fluid excess: Notable risks if fluid returns have not been balanced properly, which could lead to complications such as pulmonary edema.

Case examples for M D O calculations (e.g., Frenchie, Bella, Sally, Beau, Ramon) allow students to apply principles through practical scenarios and calculate based on specific signalment and fluid needs.

Total daily MDO requires conversion of ongoing losses into a per-day amount to accommodate the larger size and varying physiological needs of large animals, ensuring adequate assessment of hydration needs over time.

Reviewed components of a comprehensive fluid plan encompassing maintenance, deficit, and ongoing losses. Practiced calculating maintenance therapy, deficit replenishment, and continuously monitoring parameters to optimize patient outcomes.