3D360 first try

Apparently, other people thought this was a great idea too, so I got some funding from CEdICT at Flinders University to purchase some equipment to try this experiment.   I got 12 Hero4 Silver GoPros (and a remote), a 3DH3Pro12 holder from 360Heros.com and some software (PTGUI, Video-Stitch and 360CamMan).  I also got a couple 7-port USB3 hubs (for charging) and a couple microSD card readers.  The Hero4 doesn’t show up as a disk when connected via USB, so you can’t use 360CamMan to pull the videos off.  Have to either use the GoPro software or pull the SD cards and use the card readers.  I may also need some other software (Premiere Pro and a plugin called quicks3D), but I haven’t jumped on this yet.  So far, ffmpeg is serving my video rotation and combining needs.  I’ll post details in a later post once I’ve figured it out.

All set to go!  Wow, that’s a steep learning curve.  Talk about millions of settings all interacting. Hmmm, it’s not turning out like I anticipated.  I discovered this web page: http://elevr.com/elevrant-360-stereo-consumer-cameras/ which also references this page: http://elevr.com/stereo-polygons/ which implies that maybe this rig has some flaws.

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3D360 video?

Probably back in 2014, I attended an ‘Emerging Technologies Brainstorming’ session hosted by CEDICT at Flinders University.  One of the things we talked about was use of the Oculus Rift.  I had just ordered a DK2 a week or so prior – just because it was cool and not that expensive.  I was looking for something ‘official’ to do with it.

The idea was to create a procedures video library for health professional students (medicine, nursing, paramedics, etc).  This was largely inspired by the Moveo Foundation in France where they filmed a procedure (in stereo) from the surgeon’s PoV.  The idea was that when assisting as a student, you are sometimes given a job – e.g. hold a retractor.  You know that you have to do this job well and will get yelled at if you don’t, so you concentrate on doing a good job.  The result of this is that you miss out on the details of the procedure, and you certainly don’t have a view from the surgeon’s perspective.  Having a video from the surgeon’s perspective allows anyone to see what is done and review it at leisure.  A commentary by the surgeon, even after the fact could be added for further instructional value.

We thought that there might be many procedures that could be filmed in this way for students to view when learning how to do them.  The question is, how much effort is needed to produce these videos?  Options range from a single camera up to a spherical stereo video (11 or 12 GoPro cameras) best viewed with a VR rig (like the Oculus Rift).  Obviously the more cameras, the more complex and time consuming the post-production.

  • Single camera
  • Stereo pair (2)
  • Spherical (5 or 6)
  • Spherical stereo (11 or 12)

 

Qantum Ventilation

A question was raised recently regarding ventilation with Laerdal QCPR manikins.  Basically, the question was about required volumes (which is a physiological discussion) and how the manikins represent these volumes, as chest rise and as reported via software. These manikins use a lung bag placed between a plate and the chest skin to represent the lungs.  As this bag is inflated, it lifts the chest skin – separating the skin and the plate.  This is seen from the outside as visible chest rise.

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There is a clever little valve in the breathing circuit that allows flow only from the white side (input) to the branch (lung) and then only from the branch to the grey side (exhaust).  This is designed to direct gasses away from the rescurer to reduce potential cross-contamination between rescurers.  I don’t think this valve impacts on the volumes.

IMG_0744directional valve

Note that the Resus Anne Simulator with the intubation airway doesn’t use this valve, and exhausts gas back through the airway.  This manikin also has a check valve on the oesophagus to simulate the pressure needed to insufflate the stomach.

IMG_20150504_111251

There is a sensor that measures this inflation by measuring the distance that the centre of the chest skin has risen above (separated from) the plate. The sensor uses a pattern of lines and a photodetector to sense displacement.

IMG_0745IMG_0747

This implies that there are discreet values of displacement and thus reported volumes.  There are approximately 11 lines per centimeter, or 22 transitions per centimeter – giving a resolution of just under 0.5mm.  Which seems to be reported as about 14mL.  There is some inherent error in this apparatus.  The sticker with the lines is not always straight, and the sliding plastic piece that the sticker is on, can rotate slightly in the housing. The sensor that detects the displacement reports similar resolutions.

We measured the flow into a manikin using a Wright Respirometer Type P.M. Wright Respirometer

and compared those values with that reported by the Wireless Skillreporter software from Laerdal.  In a new QCPR Anne with unmodified lungs, the reported value is slightly (25%) higher than the measured flow.  (18% @ 400 mL to 15%  @ 700 mL)

QCPR measures vs reported volumes

Some years ago, we decreased the volume of the lung bag in one of our Resus Anne Simulators in an attempt to increase the amount of chest rise for a given ventilation volume.  This manikin was measured in the same way and the results are shown in the second graph.  In this case, the volumes reported by the software are slightly smaller than measured. (19% @ 400 mL to 7.5% @ 700 mL)

IMG_20150504_111122RASim volume measurements

Conclusions:

Neither lung matches the measured volumes exactly.  Shrinking the lung does move the curve in the right direction.  The volume used here (190mm lung width) was too small although it did give good chest rise.

I think it is possible to adjust the lung size to match the measured ventilation volumes and this will still give good chest rise.

An interesting side note is that the volumes reported from the software appear to be quantised with a volume of about 14ml.  This is not surprising given the nature of the sensor used to measure lung inflation.

The question of what volumes should be used is a physiological discussion. I will address some of the literature surrounding this topic in another post.

Handcuffs…er Manual Handling aid

We have recently started moving our manikins on and off beds and various shelves using a typical spinal board.  Nothing new here.  We often wrap them up in a sheet which works really well to keep everything contained and keeps the dust off for longer term storage.  For quicker moves – particularly for BLS practice on the floor where you don’t want a sheet (like you would on a bed), the manikins become a bit more awkward with their arms falling down.

The solution to this was a simple strap with loops in the ends like a set of handcuffs.  This is easy to store and use and prevents the arms from falling down while rolling on/off a backboard whether it’s onto the floor or a bed or shelf.

Once on the backboard, ANY trolley/cart will serve to help move them around.  Much more maneuverable than a bed or even an ambulance barouche.

The strap is about 600mm long with about 150mm ‘long’ (300-400mm circumference) loops in each end.  About 1 meter of simple webbing = $1.

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IMG_20140611_090522 IMG_20140611_090325

There has been a new requirement to label heavier manikins with warning signs indicating two-person handling was required.  We have added these signs to the handcuffs.

handcuffs and sign

Mobile LearningSpace cameras

We use CAE Healthcare’s Learning Space as a video capture and playback system.  Typically, recording is done in dedicated clinical simulation spaces with fixed cameras and microphones.  For a variety of reasons, we need some additional cameras that can be temporarily placed in one of several other teaching spaces on an infrequent, as-needed basis.

To do this requires a camera, audio encoder, microphone and some sort of stand to put it all on.  When we were first investigating use of IP cameras, we used an old IV pole as a temporary mount with a simple aluminum bracket on top.  For these mobile cameras, we acquired some additional IV poles from EvoCare in Brisbane, model EV3501C75H4 $215 ea incl GST & shipping.  This pole has a removable top section that holds the IV bag arms.  When this section is removed, the top of the pole is just a straight piece of tube (just under 20mm diameter) with a spring-loaded locking button to hold the top section in place.

overivew

 

On the top, I created a simple folded aluminum bracket with a piece of 20mm ID tubing tie wrapped under the ledge.  Conveniently, the bolt spacing for the camera and audio encoder were the same, so they could be mounted back to back using the same holes.

The camera is an Axis M3006 HD IP camera.  The audio encoder is an Axis P8221 and the microphone is an AudioTechnica Pro44.  A short adapter joins the microphone cable to the encoder.

audio encoder camera microphone

A nice hook from Ikea was attached to the middle of the stand using more tie wraps and some double-sided foam tape.  The IV stand manufacturer cautioned that this thin wall tubing was not suitable for mounting IV pumps, so we started with something lightweight.  The point of this hook was simply to hold the cables and microphone when not in use.  A plastic cup was used to hold the microphone and the cables (mic + 2x Ethernet) were coiled and hung on the hook.

A hole near the top edge of the bracket serves as a strain relief for the microphone cable.  The ethernet cables just hang.  The Microphone cable is nearly 8 meters long, so can go virtually anywhere in the room.  The Pro44 is a carotid pickup boundary mic, so sits on a flat surface like a table or the wall/ceiling.  If you really want to use the ceiling, the Pro44 can be mounted to a small piece of cardboard using double sided tape and slipped under the edge   of a ceiling tile.

ceiling mic

 

 

wrong fitting

We were having problems with my modification to the air leg on the ALS manikins.  I had put in what I thought was a check valve (SMC KCH06-00).  But whenever I disconnected the air source, the leg tank would drain.  Hmmm, not checking…

After a quick visit from Jason from SMC today, it turns out that I had the wrong fitting.  The KCH06-00 only checks flow when the tubing is removed.  The correct fitting is AKH06-00.  $13.50 ea.  I will modify the MCKelly – ALS post to reflect the proper part number.

Now we can fill the leg tank easily and disconnect from the wall to do mobile scenarios (i.e. between the operating theatre and recovery).