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Comment by lostlogin | Hacker News Reader

> Once the patient was anesthetized and the heavy door to the MRI machine room was closed and locked, I could only monitor my unconscious patient through a darkened heavy glass window.

Why was the door locked?

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There's some sort of latching mechanism to seal the faraday cage. Sometimes it's a latch, sometimes it's pneumatic or a bladder that inflates.

The doors can also lock (I'm pretty sure they are required to be locked when qualified personnel are not present) but usually they are not locked when the scanner is staffed and in use.

Faraday cage makes sense considering the RF sensitivities involved with MRI.

I do wonder if someone being in the room is enough to distort a scan? As there's no ionising radiation danger, it always seemed odd that you were left alone in there.

No, people in the room won't interfere unless they are doing things inside the scanner during the scan. MRI generally operate at radiowave frequencies (the faraday cages mostly keep radio stations out). There's other stuff they're blocking but radio stations are the strongest interference.

In that case, why (in the above example) does the anaesthetist have to monitor from, or a nurse or family member have to wait outside?

I understand there's magnet safety worries, but if the anaesthetist is knocking someone out on the scanner bed, doesn't that prove them magnet safe?

I don't understand your question. The anesthesiologist was describing equipment that was not safe to have in the room and was positioned outside the room to be viewed through the observation window.

Many sites screen individuals to accompany patients. It's fairly common in pediatrics.

If by "the above case" you are talking about the accident that happened, it has nothing whatsoever to do with anesthesia in the first place. It was an outpatient knee MRI performed without anesthesia at a free standing clinic (not a hospital). Based on the wife's description of what happened, the technologist brought her husband into the room at her request to help her up after the scan had finished and the technologist failed to screen him.

Sorry, I completely misunderstood what they said. My mental picture was the equipment being _in_ the room attached to the patient (and safe to be so), but the person being stuck outside unable to easily intervene. My experience with MRIs is always being alone in a room which backed that up.

I'm not even thinking of this incident. My base query is why MRI patients seem to always be alone in the room. Ignore all the anaesthetics too; I've seen them refuse to let a nervous patients family member stand in the room during the scan even though it could completely calm the patient... that's what seems odd to me. This is based on UK hospital experiences; I'm not sure if it's universal.

The incident in question is sad and seems avoidable, but I hadn't even got that far yet; I got stuck on the top(ish) comment of "(Once the patient was anesthetized and the heavy door to the MRI machine room was closed and locked,) - I could only monitor my unconscious patient through a darkened heavy glass window". My thinking went "surely being in the room would be better" -> "they never seem to let anyone in the room" -> "why not?" - and then I confused you and we ended up here :)

> I've seen them refuse to let a nervous patients family member stand in the room during the scan even though it could completely calm the patient... that's what seems odd to me. This is based on UK hospital experiences; I'm not sure if it's universal.

We do let family members in, we just try to avoid it. Having extra people there is extra problems, extra safety issues and makes everything slow. ‘It completely calms’, is rarely true. We are good at getting patients through scans - we do it 50x a day.

MR also causes issues outside the facility if you scan with the door open.

I worked somewhere that had a lot of MR scanner in the area and the coast guard sent a letter as someone was routinely leaving the door open and messing with the airwaves.

MRs have powerful transmitter - which is why you heat up during imaging.

Sort of?

It should be lockable when no staff are present and no one is in there.

It just needs to close when in use.

So no one can accidentally walk into the room while wearing metal while it is on, to prevent injuries like the post we're commenting on, from happening.

No, that's wrong. The locks are because the magnet is always on but the scanner is not always staffed. The scanner door is never locked when the scanner is staffed or a patient is inside.

interesting!

The door shouldn’t be locked when staff are present.

It certainly shouldn’t with people inside.

I work in MRI.

We have ear defenders and staff inside and monitoring visible in both locations -- anaesthetic machine in the control room. There's not much you can safely do in the fringe field but you can do CPR and rapidly get someone out of the room (and before my spinal injury I used to practice both of those regularly, particularly when part of a team scanning patients with inotropes)

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