Common Faults in the Anesthesia Machine
Written by: Eng. Shayyan Khan
An anesthesia machine can develop many faults that may risk a patient’s life during surgery. Gas supply issues like leaks, empty cylinders, or wrong connections can stop proper oxygen flow. Flowmeter faults, broken tubes, or stuck bobbins may show wrong gas levels. If the oxygen failure alarm or cut-off system doesn’t work, the patient may receive harmful gases. Vaporizer problems such as wrong filling, leaks, or broken dials can cause over or underdose. Breathing system faults like leaks, blocked valves, or expired CO₂ absorbers affect the patient’s breathing. Ventilator errors, pressure imbalance, monitor failure, and human mistakes like not checking settings can all lead to serious problems. Regular checks and trained staff help avoid these risks and save lives.
1. Gas Pipeline Leak
A leak in the gas pipeline means oxygen or other gases can escape before reaching the machine. This reduces the amount of gas going to the patient. The leak can happen due to damaged pipes or loose connections. It’s dangerous because the patient may not get enough oxygen. Regular inspection can help find and fix this issue.
2. Cylinder Pressure Low or Empty
The cylinder stores gases like oxygen or nitrous oxide. If the pressure is low or the cylinder is empty, the machine won’t deliver the required gas. The pressure gauge shows how full the cylinder is. Doctors should always check it before surgery. A backup cylinder should also be available.
3. Incorrect Pipeline Gas Connection
Each gas (oxygen, air, nitrous oxide) has its own pipeline. If someone connects the wrong gas to the wrong port, the patient may receive a harmful gas. This mistake can cause serious problems during surgery. Color coding and safety connectors help avoid this. Always double-check connections.
4. Regulator Malfunction
A regulator controls the gas pressure coming from the cylinder. If it fails, the pressure might become too high or too low. This can lead to incorrect gas flow to the patient. It can also damage other parts of the machine. Regulators should be checked and calibrated regularly.
5. Flowmeter Tube Cracked or Broken
The flowmeter tube shows how much gas is flowing. If the tube is cracked, gas can leak from it. This means the patient won’t get the proper amount of gas. A broken tube can also show wrong readings. The tube must be clean and in good condition.
6. Stuck or Inaccurate Bobbin
The bobbin is a small part inside the flowmeter that moves with gas flow. If it gets stuck, it gives the wrong gas reading. This makes it hard for doctors to know the correct gas level. It can happen due to dirt or moisture. Clean and inspect the bobbin often.
7. Wrong Gas Flow Due to Valve Problem
Valves control how much gas goes to the patient. If a valve doesn’t open or close properly, too much or too little gas flows. This can affect the patient’s safety. A faulty valve may also cause a leak. Technicians should test valves regularly.
8. Oxygen Failure Alarm Not Working
This alarm warns doctors if oxygen supply stops. If it doesn’t work, the team won’t know there is a problem. This can be very risky for the patient. The alarm must be tested daily. It is a safety feature that should never be ignored.
9. Fail-Safe Valve Malfunction
A fail-safe valve stops the flow of other gases if oxygen fails. If it does not work, gases like nitrous oxide may still go to the patient. This can cause the patient to stop breathing. It’s a very serious problem. Maintenance is needed to keep this part working.
10. No Automatic Cut-Off of Nitrous Oxide on O₂ Failure
If oxygen stops, nitrous oxide must also stop. If it doesn’t, the patient may receive nitrous oxide alone, which is harmful. This system is called an automatic cut-off. If it fails, it puts the patient at risk. Always check this feature during machine testing.
11. Incorrect Agent Filling (Wrong Anesthetic)
Each vaporizer uses a specific anesthetic agent. If the wrong agent is used, it can cause harmful effects. The drug may act too fast or too slow. Labels and colors help avoid this mistake. Fill vaporizers carefully and double-check the agent name.
12. Vaporizer Leak
A vaporizer leak lets anesthetic gas escape into the room. This can be dangerous for the staff and cause underdosing for the patient. Leaks usually happen at the filler cap or seals. Always tighten the cap and check for smells. Use a leak detector if needed.
13. Vaporizer Overfilled or Underfilled
If the vaporizer is too full, it can overflow and cause a leak. If it’s too empty, it may not deliver enough anesthetic. Both situations are risky. Always fill it to the correct level. The level indicator should be checked before surgery.
14. Malfunctioning Concentration Control Dial
This dial sets how much anesthetic goes to the patient. If it doesn’t turn or is inaccurate, the patient may get too little or too much. This can cause slow anesthesia or overdose. Test the dial for smooth movement and accuracy. Calibration may be needed.
15. Circuit Leaks
The breathing circuit carries gas to and from the patient. If there’s a leak, gas escapes and the patient doesn’t get enough. Leaks can occur at joints, masks, or tubes. Use a leak test before surgery. Replace old or cracked tubing.
16. Disconnection or Loose Connections
If any tube is loose or disconnected, the gas flow stops. This is very dangerous as the patient may stop breathing. Connections must be tight and secure. Always check all parts before surgery begins.
17. Unidirectional Valves Stuck
These valves control the direction of airflow. If they get stuck, air may go the wrong way or not move at all. This can lead to high pressure or carbon dioxide build-up. Clean and check these valves regularly.
18. CO₂ Absorber Exhausted
The CO₂ absorber removes carbon dioxide from exhaled air. If it’s full or expired, CO₂ goes back to the patient. This causes breathing problems. The color of the absorber changes when it is exhausted. Change it on time.
19. Inaccurate Tidal Volume Delivery
The ventilator should deliver the right amount of air (tidal volume) to the lungs. If it gives too much or too little, the lungs may be harmed. This can happen due to sensor or setting faults. Test the volume output before use.
20. Bellows Not Filling Properly
Bellows help in pushing air into the patient’s lungs. If they don’t fill or move properly, the patient won’t get enough air. This could mean a leak or machine failure. Check for blockages or torn bellows.
21. Ventilator Controls Malfunctioning
The settings on the ventilator must work correctly. If the controls don’t respond, doctors cannot adjust airflow. This can be dangerous in an emergency. Regular machine service is important to prevent this.
22. Positive Pressure Too High or Low
Correct pressure is important for safe breathing. If pressure is too high, it can damage the lungs. If too low, the lungs won’t expand properly. Pressure settings should be tested before surgery.
23. Machine Leak During Leak Test
Before surgery, a leak test is done to check for gas loss. If gas leaks during this test, the machine is not safe. The source of the leak must be found and fixed. Never ignore a failed leak test.
24. APL Valve Stuck or Not Functioning
The APL valve controls pressure in manual mode. If it gets stuck, pressure may rise too much. This can harm the lungs. Always test the valve’s function before surgery starts.
25. Monitor Not Displaying Correctly
The monitor shows patient vital signs. If it’s not working, doctors can’t see the patient’s condition. This can delay treatment. Make sure the screen and sensors are working well.
26. Power Supply Failure
If power goes out and no backup is ready, the machine stops. This can be very risky during surgery. Always use a UPS or battery backup system. Keep the battery charged.
27. Alarm System Failure
The alarms alert staff if something is wrong. If alarms don’t sound, problems may go unnoticed. This can be deadly. Test all alarms before using the machine.
28. Blockage or Leak in Scavenging System
The scavenging system removes waste gases. If it’s blocked, gases may stay in the room and harm staff. Leaks may reduce suction power. Inspect the system often for safety.
29. Too Much Suction in Scavenging System
If the suction is too strong, it can remove fresh gas from the patient circuit. This causes under-ventilation. Adjust the suction to a safe level. Monitor the pressure often.
30. Improper Machine Check Before Use
Skipping the machine check before surgery is risky. Problems can go undetected. Always do a full machine test. Follow a checklist to avoid missing anything.
31. Wrong Settings
Wrong settings (like gas flow, pressure, volume) can harm the patient. Double-check all values before surgery. Never guess the settings. Always follow the surgical plan.
32. Inadequate Filling or Empty Cylinder Unnoticed
If the cylinder is empty or underfilled and no one notices, the machine may stop during surgery. Always check the gauge and fill level. Keep spare cylinders nearby.
