Non-Rebreathing Systems for Small Animal Anesthesia

Non-rebreathing systems, also known as Mapleson systems, are ideal for small animal anesthesia in patients weighing 7 kilograms (15.4 pounds) or less. These systems offer a simplified design compared to rebreathing circuits, bypassing the soda lime canister, pop-off valve, and manometer found in circle systems. In a non-rebreathing system, the fresh gas tube connects directly to the fresh gas flow from the anesthesia machine, located after the vaporizer.

The system includes another tube that attaches to an F/air canister or an active waste gas evacuation system. This setup effectively removes carbon dioxide and waste anesthetic gases from the patient’s breathing circuit, ensuring proper ventilation and reducing exposure to harmful gases.

Types of Non-Rebreathing Systems: Bain Coaxial and Modified Jackson Rees

The two most commonly used non-rebreathing systems today are the Bain Coaxial System and the Modified Jackson Rees System.

• Bain Coaxial System: This system features a unique design with a tube within a tube. The inner tube delivers fresh gas and anesthetic to the patient, while the outer tube carries waste gas away from the patient, improving efficiency and minimizing dead space.
• Modified Jackson Rees System: This system includes a fresh gas tube that connects to an elbow adapter, which is then attached to the patient. A separate corrugated tube connects to the pop-off valve of the anesthetic circuit, removing waste gases.

Vetamac’s SafeSigh Non-Rebreathing System

Vetamac manufactures its own version of the Modified Jackson Rees system, called the SafeSigh Non-Rebreathing System. The SafeSigh system enhances patient safety by incorporating our patented “One Touch” valve stem, which ensures that the valve cannot be left in the closed position, preventing potential harm or even fatal consequences for the patient due to improper ventilation.

Why Choose Non-Rebreathing Systems?

Non-rebreathing systems are crucial for smaller patients, providing a more efficient and safer anesthesia experience. Their simple design, along with advanced features like the SafeSigh valve in Vetamac’s system, improves ventilation and minimizes risks. When choosing between non-rebreathing circuits, the Bain Coaxial and Modified Jackson Rees systems are popular options, with each offering unique advantages for different clinical needs.

By understanding these systems and their benefits, veterinarians can ensure optimal care and safer anesthesia management for small animal patients.

Non-Rebreathing Systems: Considerations for Flow Rate, Anesthetic Depth, and Safety

When using a non-rebreathing system in small animal anesthesia, it is important to note that a higher flow rate is required. We recommend an oxygen flow rate of 100 ml to 300 ml/min, with a minimum of 500 ml/min. This higher flow rate is essential for proper ventilation and the efficient removal of waste gases. One key benefit of non-rebreathing systems is that they reduce dead space and do not add significant resistance to ventilation, allowing for easier airflow compared to rebreathing circuits.

Faster Anesthetic Depth Changes with Non-Rebreathing Systems
Non-rebreathing systems enable faster changes in anesthetic depth compared to circle systems, allowing for quicker adjustments during procedures. However, this can be a double-edged sword, as the patient can transition from lighter to deeper anesthesia (or vice versa) more rapidly. Careful monitoring is necessary to avoid over- or under-sedation, which could lead to complications.

Increased Oxygen Usage and Potential Risks
While non-rebreathing systems are more efficient in some ways, the higher oxygen flow rates required mean more oxygen is consumed. This can lead to hypothermia and respiratory tract dryness in the patient due to the increased flow of gas. These factors must be carefully managed, especially during longer procedures.

The Importance of Using a Manometer
Most non-rebreathing systems in veterinary clinics today do not feature a manometer, unless a Bain block is used. Without a manometer, it can be difficult to gauge the tidal volume delivered during ventilation. This lack of accurate pressure measurement can result in inaccurate ventilation, which may cause serious and even fatal complications.

Introducing the SafeSigh Non-Rebreather Manometer

To address this issue, Vetamac now offers the SafeSigh Non-Rebreather Manometer. This device is designed to attach between the bag and valve or between the patient and elbow adapter in the non-rebreathing system. The SafeSigh Manometer allows clinicians to safely ventilate the patient while knowing exactly how much pressure is being delivered with each breath, reducing the risk of complications and improving the accuracy of ventilation.

By incorporating the SafeSigh Non-Rebreather Manometer into your practice, you can enhance patient safety during anesthesia, ensuring that pressure levels are correctly monitored and that your patients receive optimal care.