Adjusting the Small Animal Bellows - Step-by-Step Guide


Step-by-Step Guide: Adjusting Small Animal Bellows

  1. Initial Setup:
    • Ensure you have a functional small animal ventilator setup with a flow control and bellows.
    • Set the flow control to a desired level, such as 5 liters per minute.
    • Adjust the bellows to approximately three-quarters of its full capacity.
  2. Check PEEP:
    • Observe the gauge reading for PEEP (Positive End-Expiratory Pressure) in centimeters of water.
    • The target PEEP range is usually between 5 and 7 centimeters of water.
  3. Check for Bellows Leak:
    • Turn the flow control knob all the way down to zero.
    • Monitor the bellows to ensure it stays steady and does not drop. This indicates a good seal without leaks.
  4. Adjusting the Bellows:
    • If you suspect a leak or need to adjust the bellows, follow these steps:
      • Loosen the four knobs on the back of the bellows and remove them.
      • Use a three-eighths-inch wrench to loosen the nut on the back of the bellows' adjustment rod.
      • Counterclockwise rotation loosens the nut, enabling adjustments.
  5. Determining Adjustment Direction:
    • Turn the adjustment rod clockwise to open the bellows more (increasing the leak).
    • Turn the adjustment rod counterclockwise to close the bellows (decreasing the leak).
  6. Adjustment Process:
    • Begin with small adjustments, as they can have a noticeable effect on the bellows' performance.
    • Make minor adjustments to the rod's position to achieve the desired level of sealing.
  7. Checking Bellows Suction:
    • While adjusting, test the bellows suction by gently pulling it up.
    • You should feel resistance indicating a proper seal; minimal resistance suggests a potential leak.
  8. Tightening the Nut:
    • Once the desired adjustment is reached, tighten the nut on the back of the adjustment rod.
    • Avoid overtightening to prevent damage.
  9. Reassembly:
    • Reattach the bellows onto the ventilator.
    • Tighten the four knobs on the back of the bellows evenly.
  10. Testing the Adjusted Bellows:
    • Reconnect the hose to the back of the bellows.
    • Fill the bag and the bellows to observe if the bellows drop when the flow control is turned down to zero.
    • Verify that there are no significant leaks and that the bellows maintain their position.
  11. PEEP Adjustment Verification:
    • Set the flow control to the desired level (e.g., 5 liters per minute).
    • Observe the gauge reading for PEEP.
    • Adjust the bellows' position if necessary to achieve the target PEEP range.
  12. Final Checks:
    • Ensure that the bellows don't drop with the flow control at zero.
    • Verify that the PEEP is within the desired range (5-7 centimeters of water).
  13. Completion:
    • You have successfully adjusted the small animal bellows to ensure a proper seal and achieve the desired PEEP level.

Note: Adjustments may require multiple iterations to achieve the desired outcome. Always prioritize safety and careful adjustments to prevent equipment damage.

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