Dr M B Dobson,
Consultant Anaesthetist, John Radcliffe Hospital, Oxford OX3 9DU.

Introduction		The EMO vaporiser
Routine care		The OMV vaporiser
Special attention for vaporisers		Technical queries

If you work in a district hospital it is unlikely that you will have the help of a skilled technician to look after your apparatus, and the responsibility is therefore yours. No apparatus will work reliably unless it is properly and regularly inspected and cared for. Draw-over apparatus is not difficult to understand, and many simple procedures will prevent or correct breakdown. The first rule is not to interfere with apparatus which is working well! If you do have to make a repair, obtain a copy of the service manual, and make sure you have all the necessary spare parts and any special tools before you start.

 
Routine Care

Like all machines, your draw-over system requires regular attention to keep it in good, reliable working order. One of the main advantages of draw-over apparatus is that it is relatively simple to carry out these regular checks and simple repairs yourself - but remember that vaporis ers and valves are precision instruments, and need to be handled carefully. Never use excessive force.

Make sure your apparatus is stored in a clean, dry place, away from dusty environments. Wipe it over regularly with a soft, moist cloth and a little detergent. Close off open ends with corks or plastic caps to prevent dust and insects getting inside.

Regularly inspect your Ambu (or other universal breathing) valves, and clean them when necessary. The inlet and exhaust ports can be unscrewed by hand, and the valve rubbers removed by gentle pulling. Wash the inside and outside of the valve with warm soapy water, and allow the parts to dry thoroughly before carefully re-assembling the valve. Most Ambu valves can be sterilised, either with antiseptics or by autoclaving, but sterilisation is only necessary if the valve has been contaminated by use on an infected patient - for example one with tuberculosis.

When using the Oxford inflating bellows with an AMBU (or other universal breathing valve) ensure that you disable the flap valve nearest the patient using the magnet provided. This will prevent the valves from jamming during intermittent positive pressure ventilation.

If your anaesthetic facemasks have an inflatable margin check the state of the rubber, as it is likely to perish in time. If the small bung used to retain the air is missing it should be replaced with a suitable substitute - do not inflate the mask and tie a knot in the inflating tube!

Check your stock of endotracheal tubes regularly. Red rubber tubes are liable to deteriorate in hot and humid conditions. The inflatable cuff is especially vulnerable and should be tested before use.

 
Special Attention for Vaporisers

Drain and discard the contents of your vaporisers once a week, to avoid the build-up of deposits inside.

Vaporisers are precision instruments and must be treated with care. When complicated repairs are needed, the machine must be sent to a competent medical engineer or service centre, but there are a number of simple problems which you can deal with yourself. First of all, write to the manufacturers to obtain a service manual and any replacement parts you will need. When these have arrived, set aside a time when the vaporiser will not be needed for clinical use, and you have time to work on it. Below are brief descriptions of some of the operations you should be able to manage on Penlon vaporisers (EMO & OMV - the address is:)

Penlon Ltd,
Radley Road,
Abingdon OX14 3PH.
Telephone 44 235 554222
Fax 44 235 555252.

Other brands of draw-over vaporisers generally need the attention of a service engineer.

 
The EMO Vaporiser - Common Faults

1. The pointer sticks and is difficult or impossible to move

   Cause: build up of sticky deposits around the internal rotor drum.

   Remedy: remove the drum and clean it; re-assemble the vaporiser.

   You will need: Maintenance manual, screwdrivers, artery forceps, penetrating oil, ether, brass polish, vaseline and possibly a new main gasket.

2. The thermocompensator breaks - only the metal disc is visible in the window on top of the vaporiser.

   Cause: metal fatigue after 5-10 years use.

   Remedy order a replacement unit from the manufacturer. This is very simple to exchange for the broken unit - only a screwdriver needed to loosen 3 screws.

   You will need: Screwdriver, replacement part.

3. Broken window of the filler gauge. Warning : you must not use an EMO with a broken filler gauge - it will give a dangerously high concentration of ether

   Cause: accidental breakage.

   Remedy: order and fit a replacement from the manufacturer. Fitting is simple - loosen 3 screws, remove the old unit and slot in the replacement.

   You will need: screwdriver, replacement part.

(Continued...)

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