Category Archives: Inventions

New ideas or ways of doing things

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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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

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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

 

 

DRE skill trainer

This is a custom skill trainer for doing digital rectal exams.  It was created by the staff at the CSSU at Flinders School of Medicine before my time, but I rebuilt it a few years ago with some various improvements.

The idea is to practice the finger sweep necessary for a DRE and to be able to describe what is felt in a standardised way.

Construction is based around some PVC plumbing parts (gutter downspout and 1″ pvc pipe) with various objects at different places to be found and described.  A balloon is placed over the mouth of the pipe and extended down into the pipe.  A lubricated, gloved finger into the balloon provides a surprisingly good analogue to the real thing.

We have two sets of two gutters with three practice holes each (total of 6 different holes).  The gutter is ~750mm long with the tubes spaced ~230mm apart (one in the centre).  These are not critical dimensions.  Do what suits you for storage, portability and student access.

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Each tube is 25mm (1″) nominal size.  This means an OD of ~33.5mm and varying ID depending on the pressure rating or schedule.  This can range from 30.45 to 28.05mm ID  The thinnest pipe is fine for this application.  The tube lengths are about 115-120mm.  Again, this dimension is not critical.  Ours extend past the gutter by a centimeter or two.  An oversized hole (~35mm) is drilled into one side of the gutter.  The tube is held in by a bolt (1/4″ x 60mm) cross drilled through both parts near the bottom.  The bolt size was driven by the availability of the dome nuts.  I got bolts to fit the nuts.  You don’t have to use dome (acorn) nuts, but I think they make a neat finish.

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Previously, these tubes were glued to the gutter section, but this made maintenance very difficult.  The drawback to using bolts and nuts to hold the tubes in is a compromise on horizontal use and stacking for storage.

Inside each tube, there is a different arrangement of things to feel.  The first two are single 3/16″ dome nuts (with short bolt) at two different angles and depths (65mm and 75mm from the top of the tube).

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The third hole/tube simulates a fistula with a hole off to the side using a 1″ PVC Tee piece.  Construction of this one requires a slightly larger hole in the top to accommodate the Tee fitting OD and another hole in the bottom to allow for assembly.  Place the Tee in the gutter sticking through the upper hole.  Then insert the length of tubing through the bottom hole and secure with the bolt.  I recommend placing this one near the end of the gutter section for ease of assembly.  No glue is required.

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The next tube has two nuts at different angles and depths. 40mm deep at 45º and 70mm deep at 135º.

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The next tube has a lady bug decoration glued into the tube at a random angle.  This provides a different shape to describe, and has a groove along the top edge to simulate a prostate.  Something about this size with a groove – be creative!

IMG_20140128_084250  IMG_20140128_084626

The final tube is lined with some anesthetic corrugated hose to provide yet another texture to describe.  We often put a lump of bluetack in the balloon in either this one or the one with the ladybug to simulate some poo.  Being in the balloon, the bluetack is mobile and can be easily replaced.  All the balloons do have to be replaced regularly when they break (every ~8-16 students).

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The following text is placed on the table as “answers” by each tube that students can uncover to check their description.

Station 1:
There is an object that protrudes <1cm from the side of the pipe.
It is 9mm wide and the tip is rounded and firm for the first 5mm.  Then the sides are sharp and angulated.    It is mobile.
It starts 5.5cm from the opening (it was screwed in at the 6cm mark)
It is a “dome” nut.
Clearly it is important to know the length of your index finger.  Measure your finger.
Check it out again and get a feel of how far 5.5 and 6cms are.

Station 2:
It is very important to be able to accurately describe the location of an abnormality.  The current practice in Australia is to use the clockface and the distance from the anal margin.
If the back of the patient is 6 o’clock, then their front is 12 o’clock, their right is 9 and their left is 3.
Please see whiteboard.
There is an object that protrudes <1cm from the side of the pipe.
It is 9mm wide and the tip is rounded and firm for the first 5mm.  Then the sides are sharp and angulated.    It is mobile.
It starts 6.5cm from the opening (it was screwed in at the 7cm mark)
It is also a “dome” nut.
The end of the nut is at 9 o’clock, 7cm from the opening.
In station 1, the end of the nut was at 12 o’clock

Station 3:
The pipe has an opening at 3 o’clock, 3cm from the opening.
The opening is about 2.5 cm wide, circular in shape and has a firm edge.
It goes from about 1 o’clock to 5 o’clock.

Station 4:
There is a lump on the side of the pipe at the 12 o’clock position (in D4 but about 11 o’clock in C4).
It starts at about 2cm from the opening.
Closest to the opening, there are two lobes separated by a groove in the centre. The lobes are symmetrical and increase in width from where they start to about 1cm wide each at the widest (3cm from the opening) with a total width of 2.2cm.
These lobes end in a groove running across the lump followed by a lobe 1cm by 1.5cm. This lobe finishes with a knob of 7mm by 5mm.
Total length of 5cm
It has the same consistency in all lobes: firm, hard with a smooth surface but rougher at the top. It is not mobile.

Station 5:
There are two lesions
Finding one lesion doesn’t mean the end of the examination, you must complete a thorough examination.
The two lesions are at:
4cm at 7o’clock
7cm at 11 o’clock

Chest Drains

Recently, I received a request to develop a simulation involving a chest drain on SimMan Classic.  I thought I had seen some posts somewhere on how others had done this.  Here’s one post from the SimGhosts 2012 DIY Video contest.

I also referred to some excellent material from SimCentral.  Their SuperAnnie 3 product seems really good, and there’s some good chest tube info there.  However, as usual, I needed a solution that was really cheap and available instantly.

The scenario being planned needed to show swinging in the drain and ideally some bubbling.  Chest tube insertion wasn’t an issue, it was already in place.  We have the Ocean 2002 UWSD from Atrium.  Much to my delight, it still had blue dye in the chambers.  Not sure if this one had ever been used.  Hooking up to suction caused bubbling in chamber A (suction control).  Blocking off the drain line brought the bubbling under control and I could adjust the suction to get just a trickle of bubbles.  Attaching a 60 mL syringe to the end of the drain line provided enough volume change to move the ‘bubble & swing’ ball in chamber B throughout its range.  The beige irrigation tubing I mentioned in the IV Setup post fits nicely on luer fittings.  I used a whole roll (10m) on the end of the drain and the 60 mL syringe worked fine.  This will let me put the syringe in the control room for remote activation.

A dual size adapter I found in the cupboard made a very neat connection between the drain and the long irrigation tube.

Adding a Y connector and an IV roller clamp as suggested by the SimGhosts video allows for a variable air leak.  Put the roller clamp near the free end of the tubing so you can cut off bits as the tubing gets crushed over time.

I visited ICU this afternoon to get some personal experience with chest drain swinging and bubbling – not something I normally see as a paramedic.  In a drain setup without suction, spontaneous inhalation will cause, the ball and water column in chamber B to rise.  This will be more pronounced the larger the breath and the larger the pleural space.  Generally, this swing can be around 10 – 15 cm up the column (negative pressure).  Apparently, patients with asthma can draw 50-60 cm water – hence the long drain tube and the low placement of the drain below the patient.  Remember, these are pleural pressures, not lung pressures, although they are related.

In patients who are externally ventilated, the pressures are generally positive (i.e. positive pressure ventilation).  This is particularly true of patients who have a PEEP (positive end expiratory pressure) set on their ventilators.  This keeps the pressure in the lungs always positive.  But what is happening in the pleural space depends on its volume.  Gas (a compressible fluid) in the pleural space will transmit pressures from the lungs.  As the pneumothorax is resolved and the volume of the pleural space approaches zero, the pressure transmitted into the chest tube will decrease to zero on positive pressure ventilation.  The pleural space pressure is limited by a relief valve in the drain and the height of the water in the bubble chamber C.  Large positive pressures in the pleural space are bad (tension pneumothorax).

With suction applied to the drain apparatus, the reference point is decreased to the level of vacuum being applied.  Thus the pressure in the pleural space (relative to atmospheric) is -20 cm H2O + whatever is shown in column B (negative for spontaneous ventilation and generally slightly positive for external ventilation).

What this all means is that the changes I can make to the drain display with my big syringe and variable leak from the control room will closely mimic what actually happens.

Operation of this system involves moving the syringe plunger with each spontaneous breath or setting a slightly positive pressure when externally ventilated. It would be nice to integrate this somehow with the SimMan pneumatics to operate automatically.  I’ll post an update if/when I work this feature out.

Air fittings for manikins

We frequently move our manikins from place to place and were having a problem with the push-on fittings used by the Laerdal manikins.  Over time, the tube would get damaged and not release properly.  I fixed this by replacing the push-on fittings in the regulator box with a proper quick disconnect – a KK3 from SMC Pneumatics.

The KK3S (socket/female) has an internal check valve.  I have set this up on the hose that comes from the wall.

SMC KK part numbers

The corresponding male/plug bulkhead fitting (KK3P-06E) was used on the regulator box and other manikin connections throughout our centre to allow consistent connection of air.

Inside the regulator box, a short tube stub connects to a 6mm push-on tee to replicate the original configuration.

qd

This is a sample of the hose that connects from our piped wall air.  There is a short section of reinforced hose crimped with appropriate fittings.  This is adapted to 6mm polyurethane “push-on” compatible air tube which finishes with the KK3S for connection to various manikins.

ResusAnne Simulator and the ALS Simulator will take the 55psi (380 kPa) nominal wall pressure easily.  Their relief valves are set to 10 bar (145 psi = 1000 kPa).

Replication of the regulator box was accomplished using an SMC AR20-02H-01 regulator (0.2MPa spring) with appropriate fittings and pressure gauge.  The output is set to 110-120 kpa per the Laerdal regulator box spec (1.1 Bar +- 10% = 15.95psi (109 kPa)).  The double lumen tube that connects to the manikins connects to a bulkhead fitting from Colder (PTC16020) with 1/8″ hose barbs.  These will take a 6mm OD push-on hose with a bit of heat and persuasion.

This arrangement could use a relief valve to protect the manikin in the event of a regulator fault.  I have this setup on our SimBaby and SimNewB cots.

KK3P-06E

IV setup for medical simulation

We use a simple setup with an IV ‘bung’ on the end of a piece of hose to simulate an IV site on our manikins and simulated patients (actors).  The hose assembly is held onto the patient with a piece of ‘tubigrip’ elastic stocking.   If we don’t want an IV in-situ at the beginning of the scenario, the bung is covered by the tubigrip and only uncovered by a confederate when an IV has been established.

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It is also possible to attach an IV cannula to the bung and put the tubing over this.  This adds the visual indicator of cannula size (via hub colour) as well as restricting the flow somewhat to give more accurate (i.e. lower) flow rates.

The hose passes under the arm and over the top of the bed to a bucket (5 litre spring water dispenser with a hole in the top) or urine collection bag.  This allows participants to infuse anything (drugs or fluid) during scenarios.

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[Edit 18 June 2013]

A suggestion was made at a recent NHET-Sim workshop to include the plastic cannula between the bung and the tubing to restrict the flow to more reasonable rates.  You may have to cut off any protruding bits to leave a nice round section for the tube to grip.  It’s a tight fit, glue and/or clamps are not necessary.

bung

The Sims team at the Women’s and Children’s Hospital in Adelaide suggested an improvement to this by using ‘skin’ colored irrigation tubing from the local hardware store (Bunnings).  Various other tubing does work, but silicone is very expensive.  This was about $7.50 AUD for 10 meters.  The adapters can be used to connect the tubing to the collection bucket, but just putting the tube through a hole down into the bottom of the bucket works quite well and you don’t hear the tinkling of water falling into the bucket.

MegaCode Kelly

With the introduction of the SimPad by Laerdal, their mid-technology manikins have gotten a huge functionality boost.  The ALS simulator introduced a couple years ago provides some quality features that approach those of SimMan Classic such as spontaneous chest rise as well as using the same body and parts.  We have two aging SimMan Classics and two largely unused MegaCode Kellys.

MC Kelly

The quest is to potentially upgrade the MC Kellys to ALS or ‘nearly ALS’ status. The primary features I wanted to add to our MC Kellys are: spontaneous chest rise, comprression sensor, and possibly the jaw sensors.  The pneumatic adjustments to the airway are not available at this level, but are very seldom used outside of anaesthesia.  We primarily use mask ventilation.

The parts that need to be replaced include:

  • main board (FST-1975)
  • right thigh with air tank and regulators (205-00350)
  • chest plug & chest rise bladder (205-00150, 200-00250)
  • jaw and neck sensors (205-01350, 205-01450)
  • torso cable assy (205-00650)
  • airway obstruction servo ass’ys (205-00850)
  • new style lungs (205-03750)
  • compression sensor (380350)

These parts cost about $6000+GST.  A new ALS simulator is a bit over $17k + GST