Author Topic: Question for the medical personnel  (Read 677 times)

Offline Gadget

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Re: Question for the medical personnel
« Reply #9 on: Wednesday 25 March 20 10:28 GMT (UK) »

Added, and it is referring to the N95 masks,  not the regular every day surgical masks.

The ordinary surgical masks are not really suitable for this virus. That's why I referred to ffp3 masks in my earlier post. The N95(US) are similar.

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Re: Question for the medical personnel
« Reply #10 on: Wednesday 25 March 20 10:32 GMT (UK) »
Medical personnel will more than likely know diddly squat about the process of sterilisation of instruments, material, pads, masks.

Sterilisation lecture.

To sterilise any surgical instrument, gauzes, etc requires a specialist machine with a steam supply and an accurate control system.  An autoclave is typically 600mm in diameter and a meter long, it is mounted horizontally with a hinged door at one end, the hinged doors and controls will be within a sterile area.  A bank of autoclaves will be fixed and sealed in a wall where the rear of the machines are in the service area where the trained maintenance staff will perform the tests and inspections necessary.

With the items loaded correctly into the body of the machine, and initially I will explain about surgical instruments, the sterilisation cycle will begin.  Steam will be admitted into the machine and the temperature will rise.  The control system will seek to maintain a minimum of 134 degrees C and a maximum of 136 degrees C for four minutes. When the sterilisation cycle has completed and the temperature and time criteria have been met the machine will go into cool down mode and at the end a pass / fail  light will illuminate, a fail will also initiate a warning tone as well.

Now surgical pads, dressings, masks etc are more problematic to sterilise since they contain a lot of air which might not be removed by the steam.  To achieve air removal the machine is pressurised and then evacuated a few times (Daltonís Laws of partial pressures applies).  Then the sterilisation process begins, and as above the cool down mode will remove moisture from the goods inside the machine.

Typically Steam will be at 60 lbs per sq inch in pressure and it will be reduced in pressure as it enters the machine since a property of steam is that it can essentially be wet or dry and anywhere in between.  The moisture content in the steam is important as it helps with breaking down the contaminants structure (bacteria, virus, matter etc).

Lecture over

I am or rather was a Hospital Engineer and my staff maintained the autoclaves and every quarter I would set up a test system, load up each autoclave and run it through its cycle and making adjustments as necessary.

I would also train the Theatre Staff in how to correctly load up an autoclave since if it is not done correctly then items could fail to be sterile even if the cycle has been completed correctly.  If any were doubters I would incorrectly load items and put our temperature measuring thermocouples within the instruments and then watch on the trace as they showed that the temperature was not reached.

They learned, do as Colin says.

Offline wee Hugh

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Re: Question for the medical personnel
« Reply #11 on: Thursday 26 March 20 15:53 GMT (UK) »
I take it that was in the 19th century, Colin.

Unitil recently the unit of pressure was the bar. 
Now we're supposed to use the kilopascal.
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