BIOMEDS AND INFECTION CONTROL

        In the Biomed shop, we are trying to be multi-taskers. We are often pulled away from tasks as priorities shift. It is easy to understand how universal precautions can be circumvented in the name of productivity.
      The concern is our own health risk and being part of hospital aquired, infections (HAI) of patients that we are there to serve. This site is worth the time for us to refresh http://www.osha.gov/SLTC/etools/hospital/hazards/univprec/univ.html

Biomed studies about the ICU

This website is full of interesting info on ICU procedures and technologies. Thanks to . http://www.icufaqs.orgGreat study material for a Biomedical Equipment technician.

http://www.icufaqs.org, By Mark Hammerschmidt, RN

Medical suction safe practices

Fellow Biomeds,
A very good discussion on medical suction safe practices.http://www.ohiomedical.com/
Click on "Clinical Products then choose Nasogastric or Tracheal training.

Microcontroller project

      This is my first microcontroller project. An AT89C52 microcontroller with the MCS BASIC-52 located in internal  8K of ROM. 8K of STATIC RAM and 8K of NVRAM are used for program execution and program storage
       A 82C55 peripheral interface feeds the LCD display. A AD558 an 8-bit digital-to-analog converter was added and has yet to be used.The Microcontroller idea book by jan Axelson provides pretty much all of the circuitry that I used.
     The MCS BASIC-52 Language was made public domain by Microsoft a while ago. BASIC-52 was loaded into the 89C52 ROM using an Iquana labs PG302 interface and a ADT87 zif adapter.
     All of this software and a lot more info is on the web. I Have the BASIC-52 instruction manual as a Word file and a small number of programmed/ unprogrammed 89C52 chips available for the cost of shipping. My email address is cbet@aol.com. She ain't pretty, but she works.

Anesthetic gases and workplace exposures

This .gov article just might convince you to do trace gas testing at your Hospital.
http://www.osha.gov/dts/osta/anestheticgases/index.html#C1

Hyfrecator safety issues

The Conmed 2000 Hyfrecator

                This little rascal  deserves some study. I was recently reminded that potential shock or burn hazards can exist. It is most commonly  used as a monopolar, ground referenced ESU with about 30 watts output.  The ground reference is made through the green wire in the power cord. The patient’s body is capacitive coupled through the air to ground, completing the circuit.

            The operators manual describes the necessary precautions to be taken.

I found the operators manual at :

http://www.promed.ie/shop/assets/catalog/parts/Hyfrecator%20200%20Manual1.pdf

Solar powered LA battery charger

 Solar powered battery charger

                  This solar charger circuit is used to charge a twelve-volt, lead acid battery. The battery in turn, can supply any device within its power capacity.

This circuit will charge a variety of SLA batteries up to about 3 Ah. The circuit will reduce the charge current as the battery reaches its Vmax, and the comparator shuts off the MOSFET. You will need the Vmax spec for the battery you are using.

Adjust the potentiometer until the point where battery voltage equals Vmax and current no longer flows. Placing the circuit and solar panel in a reflective, hinged box will boost output and protect the panel when not in use.

The original  design is from the web, by Oscar den Uijl,  odu@xs4all.nl at http://www.electronics-lab.com/projects/power/031/. I eliminated some parts and added a charging current meter.

    

Medtronic education site

So I am looking for education opportunities to help with my CBET certification and visit https://wwwp.medtronic.com/mdtConnectPortal/registration/index.jsp. Just create a log in and on the CONNECT PAGE there are lots of cool education videos and powerpoint presentations. I looked under "Therapies and Procedures and selected "Temporary pacing". We use Medtronic 5388 dual chamber external pacemakers. I think the tutorials are great.

Static hazards in Biomed world

It has been my personal experience to learn some things the hard way, several times.
      All our work stations in our Biomed shop have anti static pads and wrist straps. Just a reminder that these pads and straps wear out pretty quickly. We replace our anti static gear every two years.
We all wear our wrist straps during any equipment disassembly . Up in patient areas, "Yes, our shop is in the basement"remember that static can damage equipment modules that are carried from place to place. Ask nursing staff to avoid touching the metal connections  Wikapedia says  http://en.wikipedia.org/wiki/Antistatic_wrist_strap

Isolated Power Systems

This site rocks for describing Isolated power from all sides. I think that this subject is often misunderstood and may be under served as a topic for preventive maintenance.
http://stevenengineering.com/tech_support/PDFs/45HIPS.pdf

Strain gauges are used in all sorts of medical equipment. Invasive blood pressure monitoring, patient weighing scales etc. Here is a simple, no frills strain gauge amplifier hobby project.

 Strain Gauge Amplifier project

Parts list

IC1= 78L05                            C1= 3.3uf Tantalum, 35v                     R1= 22k

IC2= AMP04                         C2= .22uf Tantalum, 35v                     R2= 250, 1%

IC3= LM385-1.2                    C3= .22uf, 50v                                       D1= 1N4001

J1= Mouser 154-UL623K4                                                 

J2= 1/8 inch mono phone jack, R/S 274-248A                  T1 = tywrap

Chassis= Mouser # 616-62006                                                           SG1 =  Transpac strain gauge

        IC1 provides a regulated five volts for the strain gauge exciter voltage. IC3 is used as a low impedance source for the IC2 reference input of 1.2 volts. This provides +/- pressure readings using a single ended power source. D1 provides reverse voltage protection.

Tie the IC2 reference input to ground if you want a single ended positive pressure amplifier. Tie the reference input to five volts if you want to measure only negative pressures.

R2 sets the gain of IC2 at 400. This gain provides a one milli-volt output per mmHg input pressure input. The typical disposable blood pressure transducer produces 5.0uV/V/mmHg.. C3 is an eight-Hertz low pass noise filter. The completed unit draws approx. five milli-amps. This should allow for greater then ten hours operation using a Duracell nine-volt alkaline battery.

Typical output voltage of the circuit in the schematic:

100mmHg / 2.20 volts

0 mmHg / 1.20 volts

Minus 100 mmHg / 0.20 volts

Construction notes for the strain gauge amplifier.

1.                    The modular jack is a Mouser P/N 154-UL623K4. Leads are Red = in-, Green = in+, Yellow = 5volts, Black = ground.