Table 4.
Minimum oxygen flow rates and reservoir (rebreathing) bag sizes for cats
| Non-rebreathing circuit (NRC)
Oxygen flow rate ⩾200 ml/kg/min |
Patient body weight | ||||
|---|---|---|---|---|---|
| kg | lb | Rebreathing bag size | Minimum oxygen flow rate | ||
| <1 | <2 | 0.5 l | 0.5 l/min | ||
| 1 | 2 | 0.5 l | 0.5 l/min | ||
| 2 | 4 | 0.5 l | 0.5 l/min | ||
| 3 | 7 | 0.5 l | 0.6 l/min | ||
| >3 kg | >7 lb | May use rebreathing circuit | |||
| 4 | 9 | 0.5 l | 0.8 l/min | ||
| 5 | 11 | 0.5 l | 1.0 l/min | ||
| 6 | 13 | 1 l | 1.2 l/min | ||
| 7 | 15 | 1 l | 1.5 l/min | ||
| 8 | 18 | 1 l | 1.6 l/min | ||
| 9 | 20 | 1 l | 1.8 l/min | ||
| 10 | 22 | 1 l | 2.0 l/min | ||
| Rebreathing circuit (circle system) | Patient body weight | ||||
| kg | lb | Rebreathing bag size | Oxygen flow rate – first 15 mins * | Minimum oxygen flow rate – maintenance † | |
| 0–3 | 0–7 | Use non-rebreathing circuit | |||
| 3–7 | 7–15 | 1 l | 2–3 l/min | 0.5 l/min | |
| 7–10 | 15–22 | 1 l | 2–3 l/min | 0.5 l/min | |
*
Higher oxygen flow rates in the first 15 mins accelerate the rate of change in inhalant concentration in the rebreathing anesthetic circuit
†
Monitor inspired CO2 to assess rebreathing of CO2 and the need for higher or lower oxygen flow rates. With an active scavenging system, higher oxygen flow rates may be needed (this will not harm patients)