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Old 17 April 2017, 16:07   #1
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AED DEFIBRILLATOR. What's the current thought?

What is current first aid training thoughts on whether AED can be used aboard RIBs?
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Old 17 April 2017, 16:32   #2
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This is going to depend on the conditions in the RIB. If everything is swimming in salt water I could see issues with the unit not being able to analyse a "shock-able wave pattern" in which case it won't fire but more concerning is the risk of shocking someone else standing in a connected pool of water. The 150 joules that an AED delivers is in the form of around 1600 volts at about 30 amps. If everything is dry I don't see it being any different from using it in any other exposed location.
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Old 17 April 2017, 16:33   #3
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What is current first aid training thoughts on whether AED can be used aboard RIBs?
There's a bit of debate going. The obvious concern is the salt water! The other that I recall is the amount of *stray* current around that may interfere with the sensor on the AED. I can offer no advice. RNLI don't currently (see what I did there?) carry them - and it's not the money that's holding them back!!!
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Old 17 April 2017, 16:53   #4
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The other that I recall is the amount of *stray* current around that may interfere with the sensor on the AED.
The units use differential analysis from the diffib pads to establish the ECG waveform and the filtering is very good. It's unlikely that it would shock someone who didn't need shocked as it has to see a recognisable VF waveform before it will charge & fire, and it's not going to mistake that with "noise" from stray currents. They are looking for around 50 ohms to establish the pads are properly connected to prevent burning so the ECG is generally well defined. However, I wouldn't use one if the patient is lying on a soaked deck, pretty dangerous.
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Old 17 April 2017, 17:33   #5
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Something makes me think Tower RNLI does have a defib, but possibly not intended for use afloat just as a convenient way to get it en scene without traffic.

It does surprise me that ALBs don't carry them. But perhaps they rarely have someone that critically ill inside in the dry on an ALB. If you go on a yacht and are doing CPR you are not going to transfer them back to the ALB as you'll want them helo'd off. shocking them on a yacht with confined space, wet gear etc will be a challenge.

Waterproofing the unit will also be an issue.

My sailing club has a defib. In the event of an incident (only been used once and wasn't actually a CPR job "just" a head injury with LOC) the casualty is brought to the slipway where the defib meets the casualty.

You are going to need to consider what your options might be...
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Old 17 April 2017, 17:45   #6
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By way of background I'm a current A&E and pre-hospital doctor. This questions comes up a fair bit in water rescue scenarios. There are several issues regarding AED use in open boats and for those who don't want the war-and-peace version my advice would be there are FAR better things to spend that kind of money on. I own 2 defibs for my pre-hospital work, and neither ever comes on a RIB with me!

Issues as I see them:

1) Safety - if there is lots of water around is it fairly likely someone unintended will get a shock? Answer - yes, it's pretty likely. If there is a cardiac arrest in the boat I would suggest keeping the deck dry is going to be the lowest priority. Equally space will be extremely limited, and there are lots of bits of metal to provide other conduction pathways even without the water. Having said that if you read this:

https://www.ncbi.nlm.nih.gov/pubmed/18458166

you might well reach the conclusion that you likely won't feel the shock anyway, since these researchers connected themselves to a simulated patient by a metal return wire, and then shocked the simulator with their hand on the "patients" chest. Do not ask who they got to volunteer for the study...

2) Defib use - will an AED work reliably on a RIB? Answer - it will not be put off at all by the electronics on board. In my resus we have lights, mobile phones, PCs, tablets, other monitors, electric beds, pumps, etc. The only thing I can think of that might cause an issue is radar near the device. As already mentioned the filters are very good, and sophisticated. If they aren't sure what the rhythm is they will fail-safe to "No Shock". HOWEVER - Will the AED survive living in a RIB - I would imagine not! None of the devices I know of are anywhere near waterproof, and the designers clearly don't intend them to be stored anywhere near salt water. Down below on a boat with a dry cabin would probably be fine, but if you think it's going to live in the same locker as your flare pack and then work when you need it think again.

3) By far the biggest issue - are you ever going to use it effectively? Likely not. If you come across a cardiac arrest in an open power-boat of any kind the most likely causes are 1) drowning 2) hypothermia related to immersion and 3) trauma. I'd suggest that asthma and anaphylaxis are also a good bit more likely than a cardiac arrest caused by ischaemic heart disease. Generally all of the above (trauma, drowning, etc) other than heart disease will give a non-shockable rhythm - meaning the defib won't shock (correctly) and won't be of any use.

My boat's medical kit (when I finish building it) is going to fill a decent sized pelican case, and won't include a defib despite the fact I probably will put in a small portable cardiac monitor.

Just my opinion.

p.s. GMC number available on request.
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Old 17 April 2017, 18:35   #7
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It does surprise me that ALBs don't carry them. But perhaps they rarely have someone that critically ill inside in the dry on an ALB.
If they know they are going to an "ill" patient or doing a medical transfer (e.g. from an island) they will usually take a local paramedic or doctor along, who comes with their own kit.

I am sure I recall seeing a "return on investment" calculation* of when it was worth putting in AED's. There were three criteria: (i) the ambulance would take longer than 5 minutes; (ii) the AED could be on scene in less than 5 minutes; (iii) it would be used at least once every 5 yrs. It will be exceptional that any lifeboat arrived within 5 minutes of the incident.

* they don't call it that - but its what they mean!

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3) By far the biggest issue - are you ever going to use it effectively? Likely not. If you come across a cardiac arrest in an open power-boat of any kind the most likely causes are 1) drowning 2) hypothermia related to immersion and 3) trauma. I'd suggest that asthma and anaphylaxis are also a good bit more likely than a cardiac arrest caused by ischaemic heart disease. Generally all of the above (trauma, drowning, etc) other than heart disease will give a non-shockable rhythm - meaning the defib won't shock (correctly) and won't be of any use.
Andy - my gut feel was this was exactly the issue; but its nice to see some substance behind it.

I see a reasonable number of media reports of divers who are taken "unwell" (and sadly usually don't make it). I'm not a diver, and have always wondered if that was a simple "bend" [which as an outsider seems odd as divers know about such risks and issues] or if it was an underlying issue like a heart problem - perhaps exacerbated by exercise, pressure, temperature etc.? Not sure if you'd have a feel for that? Do you think there is any more sense for a club full of tubby middle aged divers than normal people?

I also have wondered with the increased emphasis on "Cold Shock" in recent years whether that actually brings about a "Heart Attack" as is sometimes suggested (and if they mean an MI - is it likely to result in a shockable rhythm if the casualty is recovered quickly).

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Down below on a boat with a dry cabin would probably be fine,
ignoring the waterproofing I think the issue on a rib is the vibration/shock. Whilst obviously some AED's get thrown around by paramedics they are also regularly tested and faults will be picked up. On board a boat I can imagine they will be easily neglected.

There's been some work on AED's in poolside environments: https://www.ncbi.nlm.nih.gov/pubmed/12879378 http://r.think-safe.com/documents/De...al_surface.pdf which suggests the wet is not too much of an issue for rescuers/bystanders.
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Old 17 April 2017, 19:04   #8
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I see a reasonable number of media reports of divers who are taken "unwell" (and sadly usually don't make it). I'm not a diver, and have always wondered if that was a simple "bend" [which as an outsider seems odd as divers know about such risks and issues] or if it was an underlying issue like a heart problem - perhaps exacerbated by exercise, pressure, temperature etc.? Not sure if you'd have a feel for that? Do you think there is any more sense for a club full of tubby middle aged divers than normal people?

I also have wondered with the increased emphasis on "Cold Shock" in recent years whether that actually brings about a "Heart Attack" as is sometimes suggested (and if they mean an MI - is it likely to result in a shockable rhythm if the casualty is recovered quickly).
I think a lot of the diving incidents genuinely are bends - often caused by loss of buoyancy control and uncontrolled ascent, although there are the unlucky few who get bent diving within the tables/computer limits.

I would guess that medical cardiac arrests (as in - ischaemic heart disease type) are more common in the diving community due to average age, weight, diet and cold water immersion. Having said that if you go into VF at depth by the time you are recovered to the boat you will likely no longer be in a shockable rhythm, and if you ever return to one it will be after a hefty dose of IV adrenaline. Either way your chances are slim. As you said, you would have to recover the casualty quickly for them still to be shockable, and that is most likely in a casualty already on the surface (such as an MOB with a lifejacket).

Cold water immersion can certainly precipitate a shockable-rhythm (VF or VT) cardiac arrest. Sudden immersion in cold water increases heart rate, breathing rate and releases a lot of stress related chemicals (adrenaline, cortisol, etc). Coupled with that all your peripheral blood vessels constrict to preserve heat. This means you heart is trying to pump a lot harder against a suddenly increased resistance. If your heart is already a bit dodgy (technical term) then that can precipitate something bad... That badness is likely to be shockable initially (for a few minutes) so this is perhaps the only time I can think of that an AED might come in handy.

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ignoring the waterproofing I think the issue on a rib is the vibration/shock. Whilst obviously some AED's get thrown around by paramedics they are also regularly tested and faults will be picked up. On board a boat I can imagine they will be easily neglected.
Yep - the ones we use on ambulances get checked twice a day by the paramedics, and regularly by the support staff. They still break. I can't think of one that would like being in a RIB. Wrapped in bubble wrap inside a pelican case would be OK I imagine, but who's going to give up that much storage space for something you will use on average once every 28 lifetimes.
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Old 18 April 2017, 02:24   #9
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Really don't think there is much I can add other than to say the RNLI have been pushing ( certainly at dive conferences ) for divers to consider getting their health checked professionally before diving. Commercially they must have a yearly medical but not for sports diving. If it drops the numbers of divers 'not making it' by one then it is worth it. Personally , if I have recovered a diver to a rib , they will be dripping wet with large puddles of water before having to cut off a dry suit and set up a defib ... the risk of shocking somebody else through the water is far too great.
Carry a really good first aid kit and know how to use it would be my advice to all.
( For what it's worth , I am a commercial diver and rib operator , have completed dive related first aid training including defibrillator stuff and my company never take our defibs on a boat )
Hope that helps
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Old 18 April 2017, 02:34   #10
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Carry a really good first aid kit
I'm always a bit sceptical about anyone with a really "good" first aid kit. There is very little in a first aid kit you will actually use for anything serious, and even less that can't be improvised. I tend to focus on the stuff that makes or breaks a day with the kids... plasters, paracetemol/calpol, etc.
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and know how to use it would be my advice
That I would agree with - and understand the principles of what you are trying to achieve as learning rote fashion the correct treatment probably isn't going to apply well outside the comfort of a classroom.
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