Monitoring the Critically Ill Small Animal Using The Rule of 20

The core philosophy is anticipation rather than reaction, aiming to detect and prevent organ compromise before failure occurs through methodical daily evaluation of 20 parameters.

1. Metabolic and Fluid Status

• Fluid Balance: Ensures adequate perfusion (intravascular) and hydration (interstitial). Assessment includes heart rate, pulse quality, body weight, and urine output.

• Oncotic Pull/Albumin: Albumin provides major oncotic pressure; levels < 2 g/dL indicate a poor prognosis. Treatment involves natural (plasma/albumin) or synthetic colloids.

• Glucose: The goal is 80–120 mg/dL. Supplementation is required for hypoglycemia (often caused by sepsis or heat stroke); continuous monitors (CGMs) are recommended for precise tracking.

• Electrolytes: Monitor potassium (hypokalemia causes weakness/ileus; hyperkalemia is life-threatening), sodium, calcium, magnesium, and chloride.

• Acid-Base Balance: Focuses on identifying lactic acidosis (from poor perfusion) or unmeasured anions via Anion Gap (AG).

2. Cardiopulmonary Function

• Oxygenation and Ventilation: Gold standard is arterial blood gas. Supplement oxygen if SpO2 < 96%; mechanical ventilation is required if PaO2 < 60 mmHg or work of breathing is too high.

• Blood Pressure: Maintain Mean Arterial Pressure (MAP) > 60 mmHg (systolic > 90). Hypotension is treated with volume, oxygen, and potentially vasopressors like dopamine or norepinephrine.

• Heart Rate, Rhythm, and Contractility: Use ECG to identify arrhythmias (e.g., V-tach > 160 bpm) and echocardiograms to assess contractility for inotropic support.

3. Systemic and Organ Health

• Neurologic Status: Screen for metabolic causes of altered mentation; manage cerebral edema with head elevation (15°) and medications (mannitol/furosemide).

• Coagulation: Detect DIC early (hypercoagulable stage) before it progresses to hemorrhage; thromboelastography is a useful diagnostic tool.

• Red Blood Cell/Hemoglobin: Maintain a minimum PCV of 20% or Hgb of 7 g/dL to ensure oxygen delivery.

• Renal Function: Monitor urine output (1–2 mL/kg/hour) and serial BUN/creatinine to detect acute tubular injury.

• Infection Control: Use aseptic techniques and isolation; select empirical antibiotics based on site but narrow the spectrum (de-escalate) once cultures return.

4. GI and Supportive Care

• GI Motility/Mucosal Integrity: Prevent atony and ulcers using motility modifiers (metoclopramide), antiemetics (maropitant), and nasogastric tubes for decompression.

• Nutrition: Enteral nutrition is always preferred to maintain the GI barrier; start at 25%–33% of caloric needs to avoid refeeding syndrome.

• Pain Control: Use validated scoring tools; opioids (titrated to effect) are the primary treatment, with adjuncts like ketamine or lidocaine for refractory pain.

• Wound and Bandage Care: Covers traumatic, surgical, and iatrogenic (IV site) wounds; bandages must be changed if soiled or wet.

• Drug Dosages/Metabolism: Daily review of the medication list for interactions and adjustments based on current renal/hepatic function.

5. Nursing Care and TLC

• Patient Advocacy: Skilled staff recognize subtle changes before clinicians.

• Mobility/Recumbency: Turn patients every 4 hours to prevent atelectasis and decubital ulcers; encourage activity for GI health.

• Stress Reduction: Encourage owner visits and provide familiar items (toys/blankets).