The tidal volume for most laboratory animals is ____ ml/kg.

• A. 2-5
• B. 10-12
• C. 15-20
• D. 25-30

Answer: (C)

Tidal volume per kilogram is the amount of air moved with each breath, scaled to body weight, to achieve adequate alveolar ventilation without causing lung injury. In most laboratory animals, dead space relative to body size is relatively large and metabolic demands are high, so a larger tidal volume per kilogram helps ensure enough fresh gas reaches the alveoli for proper gas exchange during anesthesia. That’s why a range of about 15–20 ml/kg is commonly used as a standard to maintain normocapnia and effective ventilation. Values much lower, like 2–5 ml/kg, would under-ventilate and raise CO2 levels; values much higher, like 25–30 ml/kg, increase the risk of lung overdistension and injury. Some species or situations may use around 10–12 ml/kg, but 15–20 ml/kg fits the typical needs of most lab animals.