I had my 17th surgery yesterday so it's fair to say I've been around the "hospital" block quite a few times and know what to expect on the patient side of things.

Everything went as expected up until I was on the operating table and they were administering the general anesthesia to put me to sleep, and they put a breathing mask full of oxygen covering my mouth and face. (This was as expected too as I recall this happening prior to all my other surgeries). But this time, as soon as they put the oxygen over my nose and mouth, I felt like I couldn't breathe. I had a hard time breathing, and wanted to rip the mask off because I started panicking that I actually was not breathing (even though I logically knew there was an oxygen mask over me). But the mask made me hyperventilate instead, and my lungs started to hurt. Thankfully, this experience was only 30-40 seconds of panic before I drifted off to sleep.

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So my questions:

Why a mask of oxygen over mouth & nose while general anesthesia is administered to knock one out for surgery? Common to feel like you can't breathe when it's placed over the mouth and nose?

  • Is it because some patients may have trouble breathing during the first few moments of the induction of anesthesia? (Like the sensation of not feeling able to breathe was not the oxygen mask, but the general anesthesia entering the body, impacting breathing system).

  • Or do the oxygen masks contain so much oxygen that the body has a hard time breathing it. (Like the amount/% of oxygen being pumped in a LOT of oxygen in the lungs all at once, and the lungs start to hurt?)

  • Or... simply that mini panic attacks can ensue as instinct doesn't appreciate something over the nose and mouth and wants to throw the mask off. And this causes one to get anxious and hyperventilate?

Basically, why the need for the breathing mask at first? And is it common to find it harder to breathe?

  • 3
    This is actually a good question and I look forward to seeing a good answer, but here's a hint: it's not just oxygen the mask is providing.
    – Carey Gregory
    Sep 29, 2018 at 0:43
  • @CareyGregory, thank you!! I was wondering that myself. I thought the anesthesia was in my IV, but maybe the oxygen mask also had some sedatives in it too? Just wondering if my fear of not breathing was typical behavior (I hadn't experienced before), and where that comes from -- I had no fear going into surgery. Sep 29, 2018 at 6:26
  • 1
    @CareyGregory Not necessarily. For a general anaesthesia via IV lines with propofol or fentanyl, pre-oxygenation is still a common procedure because then you have a bit more time for the intubation before oxygen levels get low. For Children, there is the option of using inhalational anaesthesia like sevoflurane as an induction and then continue with propofol for the intubation.
    – Narusan
    Sep 29, 2018 at 7:37
  • Either possibilities won't explain the panic, sevoflurane or N2O or other inhalational agents are usually administered along with oxygen or normal air or N2O + oxygen. An oxygen mask for pre-oxygenation wouldn't make you experience trouble breathing either. It might have been a psychological reason, i.e. you didn't like something being put right over your mouth and nouse.
    – Narusan
    Sep 29, 2018 at 7:42
  • @Narusan I've undergone general with propofol a number of times and it's always been accompanied with a sevoflurane/N2O gaseous agent. If it was just pre-oxygenation there wouldn't be a need for two tubes connected to the mask. I think the experience was most likely psychological, but it could possibly have been her airway reacting to the dry O2.
    – Carey Gregory
    Sep 29, 2018 at 14:59