L4 Breathing Systems, Scacvenging, and Intubation Supplies

What is the primary purpose of a breathing system?

To deliver oxygen and anesthetic gases to the patient and eliminate carbon dioxide

What are the two main types of breathing systems used in veterinary medicine?

Rebreathing systems and non-rebreathing systems

What is another name for a rebreathing system?

Circle system

What is the major difference between rebreathing and non-rebreathing systems?

Rebreathing systems chemically absorb CO₂, non-rebreathing systems eliminate CO₂ by high oxygen flow rates

What components are required for a rebreathing system?

Fresh gas source, unidirectional valves, breathing hoses, pressure gauge, CO₂ absorber, APL valve, and reservoir bag

How does gas flow in a rebreathing system?

In a one-way circular pattern through inspiratory and expiratory limbs

How is CO₂ prevented from being rebreathed in a circle system?

Chemical absorption using soda lime

What gases can be rebreathed in a circle system?

Oxygen and anesthetic gases, but not CO₂

What are advantages of a rebreathing system?

Lower oxygen flow rates, more economical, retains heat and humidity

What are disadvantages of a rebreathing system?

Increased resistance in small patients and more components that can malfunction

What oxygen flow rate range is used for a closed circle system?

4–11 mL/kg/min

What oxygen flow rate range is used for a low-flow circle system?

10–22 mL/kg/min

What oxygen flow rate range is used for a semi-closed circle system?

22–44 mL/kg/min

When should higher oxygen flow rates be used in a circle system?

During induction and recovery

What is a general minimum oxygen flow rate setting on a rebreathing system?

0.5 L/min

What size patient is appropriate for a rebreathing system?

Patients generally larger than 7–10 kg

What hose size is used for patients under 15 lb on a rebreathing system?

Pediatric breathing hose

What hose size is used for patients 15–300 lb on a rebreathing system?

Adult breathing hose

What is the function of the CO₂ absorption canister?

Removes carbon dioxide from exhaled gases

What happens if soda lime is exhausted?

CO₂ accumulates causing rebreathing and respiratory acidosis

How can soda lime exhaustion be detected?

Capnography changes, color change, lack of heat, hardness of granules, hours used, and patient signs

Why is soda lime color change unreliable?

Color may revert when not in use

What safety precautions should be taken when replacing soda lime?

Wear gloves and mask, avoid inhaling dust, prevent channeling

What is channeling in a CO₂ absorber?

Gas passing through gaps without contacting absorbent granules

How much space should be left when refilling soda lime?

1–2 cm to avoid tightly packing granules

What are the components of a non-rebreathing system?

Fresh gas source, expiratory limb or coaxial hose, open/close valve, and reservoir bag

What oxygen flow rates are used for non-rebreathing systems?

200–300 mL/kg/min

Which patients must always use a non-rebreathing system?

Patients under 3 kg

What patient weight range is considered a grey zone for breathing system choice?

3–7 kg

What are advantages of non-rebreathing systems?

Low resistance, minimal dead space, fewer components

What are disadvantages of non-rebreathing systems?

High oxygen flow rates, increased pollution, and risk of hypothermia

What is the most commonly used non-rebreathing system in veterinary medicine?

Mapleson D (Bain circuit)

What is a Bain circuit?

A modified Mapleson D system

What is a Mapleson F system also called?

Modified Jackson-Rees circuit

What is waste anesthetic gas (WAG)?

Escaped anesthetic gases released into the environment

Why is WAG exposure dangerous?

Chronic exposure poses health risks to personnel

What is the recommended maximum exposure to halogenated anesthetic gases?

Less than 2 ppm

What are the two types of scavenging systems?

Passive and active

How does a passive scavenging system work?

Charcoal absorption or venting to outside air

What gases are absorbed by charcoal scavenging systems?

Halogenated anesthetics like isoflurane and sevoflurane

What gases are NOT absorbed by charcoal scavengers?

Nitrous oxide and carbon dioxide

What is an advantage of passive scavenging systems?

Portable, low cost, easy to set up

What is a disadvantage of passive scavenging systems?

Must be replaced regularly and can become saturated

How does an active scavenging system work?

Central vacuum removes waste gas

What precautions reduce staff exposure to anesthetic gases?

Leak testing, cuffed ET tubes, low-flow anesthesia, avoiding mask induction

Why should vaporizers always be turned off before filling?

To prevent accidental anesthetic release

Why should cuffed endotracheal tubes be used?

To prevent anesthetic leaks and aspiration

What is the purpose of an endotracheal tube?

To maintain a patent airway and deliver anesthetic gases

Why is correct ET tube size important?

Prevents airway trauma and gas leakage

What equipment is needed for intubation?

Endotracheal tubes, laryngoscope, stylet if needed, syringe, lubricant

Why should cuff inflation be checked after intubation?

To ensure a seal without overinflation

How should an ET tube cuff be inflated?

Inflate until no leak is heard during positive pressure ventilation

What is the danger of overinflating the cuff?

Tracheal injury and ischemia