Leaks in the anaesthesia circuit are relatively commonplace. For this reason we run through specific tests of the machine and ventilator to check for any faults at the start of every day. Even so, leaks still occur.
The most common culprits in my experience are a faulty ETT cuff, or inadvertent disconnection of a pipe from the machine. These are the easiest to identify, and therefore the quickest to correct. If the situation arises that the leak persists even after these have been checked, it can lead to a bit of anxiety for the anaesthesist with a sleeping, non-breathing patient in your care.
For situations such as this, we all have a specific routine to search for, and identify a circuit leak ingrained into our subconscious. There is no time for panic, the leak must be found and plugged (so to speak) as soon as possible to keep the patient breathing.
I recently had to deal with one of these unpleasant situations.
I had checked my machine at the start of the day. Nothing roused any suspicion. I had already used the machine without incident for a couple of patients. I induced the next patient, and hooked him up to the ventilator. It gave the first breath, and then failed to re-fill as expected, and so had no gas for the next breath! This tells me that there is a leak, and it's a big one. I checked the ETT cuff, no problem there. I checked the circuit, no obvious disconnection there either. I increased the amount of gas delivered to the circuit. Thankfully this gave my patient an acceptable short term tidal volume, and bought me some extra time to identify the problem.
I ran through my usual routine. I checked the pipes and bag for holes, no problem. I checked the ventilator housing box, no leak there. I checked the sodalime canister was fitted correctly, it was. I checked that the switch on the front was set to the circuit and not the auxillary gas outlet, it wasn't. I still couldn't find the leak.
I ran through the checks for a second time. When checking the sodalime canister again, I felt a breeze against my arm, and then after a few seconds, again. I followed this intermittent draught, and found a crack in the bottom of the sodalime canister! Of all the places! No wonder I had had difficulty finding it!
I plugged it with my finger and sent a nurse to fetch a new canister. I replaced it, and everything returned to normal. Crisis averted.
I think someone once said: "Always expect the unexpected".
As it turns out, the nurse I had sent to fetch a new sodalime canister was surprised when I asked her, as she had only just replaced it, before this case.