Miscellany
From WickedSim
This page is for odd bits and bobs which might not fit well elsewhere, at least at present!
Contents |
Staying alive
In resuscitation scenarios, it is common for the participant who is compressing the chest to slow down from the recommended 100 compressions per minute, especially after a minute or so as they tire. One effective strategy that prevents such slowing is to have background music with a beat of around 100/minute. The obvious candidate is of course the Bee Gees' "Stayin' Alive", which has a beat very close to this frequency. Interestingly enough, the reason for the monotonously unchanging 100 BMP drum beats throughout the song is that the group's sound engineer Albhy Galuten simply pulled out two bars of drum beats from a previous song and repeated these throughout Stayin' Alive, as the group couldn't get a drummer in France where they were recording for tax reasons, and the drum machine they tried gave a lousy result.
Another piece of music with a similar beat rate is sadly enough Queen's "Another One Bites the Dust"; of course this particular piece of music may not translate well from simulation to resuscitating granny in the clinical environment. If you encounter a piece of music with a similar tempo to the pieces mentioned, please feel free to enter it below. (Musicians usually express tempo as the number of quarter notes in a minute).
For disco music, this is an unusual tempo, but check out:
- Love To Love You Baby - Donna Summer (97 BPM)
- More, More, More - Andrea True Connection (106 BMP)
- Dancing Queen - Abba (100 BPM)
- Fly Robin, Fly - Silver Convention (101 BPM)
You might wish to explore other genres! (Meanspeed will help).
Nobody has yet described a similar method of keeping the frequency at which resuscitators bag patients to the required 10 breaths per minute (or less). Whenever a resuscitator is the least bit distracted, they will automatically revert to 20--30 BPM, causing hypocapnia and putting the patient at risk due to the consequent cerebral vasoconstriction. Any candidate music with a loud bass belch every 10 beats will be welcome!
Scenario Writing
This is the bane of the average simulator's existence. One consideration is to use computerised tools to facilitate writing scenarios, an example being CELTX. If you know of similar open source tools, you might wish to add them here!
Thoracentesis simulators
There are several options. They include:
- Simulab TraumaMan
- The Medisim thoracentesis model
- (We also hear that Immersion Medical is working on a thoracentesis needle simulator).
Glass Ampoules
Have you ever thought about how pervasive glass ampoules are in Medicine (and consequently in Medical simulation)? Hermetically sealed glass ampoules were invented in the 1800s by the retail pharmacist Stanislas Limousin (1831-1887. He also invented the medicine dropper, a system for colouring poisons, 'wafer cachets' for minimising the nasty taste of certain drugs, and apparatus for therapeutic administration of oxygen). Empty ampoules are filled from the top and then heat-sealed using an open flame. Apart from being durable and sterile, ampoules are the ultimate tamper-evident storage mechanism!
The problem of course in medical simulation is that not only are real ampoules expensive, but the drugs we use are often powerful and have the potential for misuse and abuse. Accounting for their use in the simulation setting can be a pain in the bottom (especially scheduled drugs), but using unadorned bottles of sterile water and pretending that they're propofol (or whatever) doesn't fit well with the philosophy of high fidelity simulation!
Each sim center must consider the level of realism needed to get a point across. Do you make your students start IVs? Do you use real drugs? If you do these things, do you need to do them on your main mannequin or can you use a partial task trainer? Can you handle (or do you want to start handling) the maintenance required to use these things, such as regular flushing with sterile water and regular replacement of IV veins? How realistic is the rest of your simulation? Do you use flexible rooms that can be easily converted, but don't provide an especially realistic backdrop? Do you use a room so similar to your ED/OR/ICU/etc. that most people couldn't tell the difference? If you want to completely immerse your students in the environment, glass ampoules are a good choice. Otherwise, it may not be worth your time and money. Consider your needs, and then consider the pros and cons of glass ampoules in that context.
Here are a few facts about ampoules to pique your interest.
What glass is used?
Ampoules are usually made of USP (United States Pharmacopoeia) type I glass (best), or occasionally type III glass. Type I is borosilicate glass (silicon dioxide 70% + boric oxide 10%, with relatively low levels of other oxides). The boron content favourably modifies the glass properties as it is 'network forming' --- the glass is consequently chemically resistant, has a low thermal coefficient of expansion, and has low leachability. Type III is soda lime glass, with a lot of sodium oxide and calcium oxide, more easily molded but less chemically stable when compared with Type I glass. Borosilicate glasses are crown glasses with low dispersion and low refractive indices. Here's a practical example showing why borosilicate glass is better than USP type III glass. (Glasses are amorphous solids which behave like supercooled liquids. They are made up of network forming oxides such as silicon dioxide, network stabilisers like calcium and magnesium oxides, and fluxes like sodium oxide which modifies the melting point of the silica).
Borosilicate glass was invented by Otto Schott and sold under the name 'Duran' from 1893, but from 1915 it became known as 'Pyrex' in many countries (also Endural, Bomex). Confusingly enough, 'Pyrex' products now made by World Kitchen are made from soda-lime glass!
What are the pros and cons of glass ampoules?
The advantages of glass (particularly borosilicate glass) are that it is impermeable to gas, non-reactive with most substances (and where the reactions occur they are almost always predictable and can be taken into account), doesn't adsorb many drugs, and is tamper-proof. The downside is small --- glass fragments, breakages and cuts.
Who makes them?
Oddly enough manufacturers seem relatively coy, at least on the Web. It may well be that the client-supplier networks are relatively well established, and who is interested in a simulation centre wanting a few thousand ampoules of sterile water, anyway?
FWIW, here are some manufacturers of unfilled ampoules:
- Schott Germany
- Thueringer Pharmaglas Germany
- Adelphi UK
- BD Accu glass USA
- Aegis India
- Kapoor India
- Klasspack India
- Birgi Mefar Turkey
Haptic technology and haptics
Haptic refers to the touch and feel of an object. Clearly faithful haptic technology is rather important in achieving high-fidelity simulation. Haptics is the study of haptic technology, although some would have us restrict use of the word 'haptics' to refer to the touching behaviour of people as they interact!
Medical haptics is still in its infancy. An experienced operator who has used current 'state of the art' simulators representing IV cannula insertion, bronchoscopy, or laparoscopic surgery will likely describe substantial differences from 'the real thing'.
- Here's the website of the IEEE Technical committee on haptics.
- The best exploration of non-medical haptic technology we know of is summarised at the Haptic Museum on the University of Southern California website. Museum visitors explore works of art by touching them in a virtual space!
- The Shadow Robot Company's 'Dextrous Hand' is well worth a visit; other groups such as Utah/MIT 'dextrous hand' and teams at Yale, Vanderbilt and NASA are said to be working on similar projects.
A good Google search for technical papers relevant to haptic technology is ["god object" "surface contact point"]!
Sound card gems
Okay, your sound card is giving you problems, most notably under MS Windows. The most likely problem is simply 'no sound', (it was working) and, unless somebody has done something really silly like delete the drivers, the cause of this is likely to be that somewhere a 'mute the sound' box has been ticked, or somewhere a volume control is turned down very low. This sounds obvious, but there are many possible points at which programs can interfere. You will have great fun hunting them down, no doubt! (If there are specific problems with only some applications, research that application or the associated codecs; if sound is skipping or burbling then there may be a problem with DMA --- Windows irreversibly forces PIO and disables DMA after six DMA failures, so you have to re-install the device if this has happened).
If this isn't the problem, then it's not a bad idea to go back to basics:
- Are the speakers plugged in and turned on and (where there's a volume control) up? (If you think it's a speaker problem you could do worse that to try the speakers on another system, or try other speakers on yours).
- Is the sound card enabled, with a functional driver? Check out the device manager (Start|Run|devmgmt.msc) and look for 'Sound, video and game controllers'. Select your sound card, and do the dastardly double click to pull up the properties etc.
- The problem may now be obvious: for example, a defective driver which you might be able to download and update off the web.
- Looking at the Windows registry is a thought (brave person), but this is more likely to be a problem on installation (for example, some versions of Windows XP service pack 2 set the key HKEY_LOCAL_MACHINE\ SYSTEM\ CurrentControlSet\Enum\PCI to only allow the System full rights, preventing even an administrator from installing new PCI devices!). There's a variety of registry cleaners available, many of them free, and it's even possible that some of them will not give your registry a terminal experience. Back it up before you fiddle.
Otherwise, go really back to basics. Remember that a 'sound-blaster-style' card needs just three things to run properly:
- An appropriate IRQ (without any conflicts) --- IRQ stands for 'interrupt request'
- Direct Memory Access (DMA)
- An address in memory.
If there's trouble (especially after adding a new hardware device) the a possible problem is an IRQ conflict, although under Windows XP this is less likely due to the use of ACPI (Advanced Configuration and Power Interface) which permits IRQ sharing. Do not fiddle with ACPI. Fiddling with IRQs is tricky. Just to whet your appetite, the IRQ priority is 0, 1, 8, 9, 10, 11, 12, 13, 14, 15, 3, 4, 5, 6, 7, working from highest to lowest!
Finally, if you're really desperate and running XP, you might try a 'System Restore' or even try individually restoring your sound card to its default settings using a registry tweak. If you do this, always back up your registry first, and if you don't know how to back up your registry, don't go any further --- first ask somebody who does. Here's the tweak: http://www.5starsupport.com/faq/sound.htm#1-1
