Final answer:
Patients under 7 kilograms (15 pounds) should be connected to a non-rebreather anesthesia machine circuit, which is suited for small patients to prevent rebreathing of expired gases.
Step-by-step explanation:
Patients weighing less than 7 kilograms (approximately 15 pounds) should typically be connected to a non-rebreather anesthesia machine circuit. Non-rebreather systems are designed to prevent rebreathing of expired gases and are suited for small patients, such as neonates and infants, where minute ventilation is low. It is crucial for healthcare providers, particularly anesthesiologists and veterinary staff, to use the appropriate anesthesia delivery system based on the patient's weight to ensure the safety and effectiveness of the anesthesia.