A new level three Intensive  Care Unit has been built  in your hospital.   Patients  are going to be admitted next week.  The Director of Intensive Care Services gives you the job of testing that the gas supplies and suction that have been installed are appropriate and working satisfactorily.  How will you do this?

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College Answer

Testing should involve

a) Confirmation that the appropriate outlets are at each bed space, with correct labelling, colour coding, and sleeve index system. Bed spaces in a level three ICU are supplied with at least three O2, two air, and three suction outlets.

b) Testing that the correct gas is supplied, and that the gas is pure. Oxygen concentrations should be measured at all gas outlets. This will distinguish between oxygen, air, and another gas such as nitrous oxide or nitrogen. A sniff test assessing for objectionable odours should be performed at medical air outlets only. If a non-respirable gas is present, this testing must be performed by an anaesthetist.

c) Tests for flow rate and pressure. Tested using a device that fits the outlet, and incorporates a pressure manometer, a variable flow restrictor, and a flow meter. Static pressure is measured and should be 415 kPa (60 psi) on O2 and air outlets, and -60 kPa at suction outlets. The flow rate is then set to 40 L/min, and the change in pressure measured. The change in pressure should be <
10 kPa for air and O2, and < 15 kPa for suction.

d) Testing of alarms. Tested by turning off the isolating valve for each supplied gas in turn, and
ensuring that visible and audible alarms activate.

References: JFICM policy document IC-1; Australian Standard 2896 1998, Medical gas systems –
installation and testing of non-flammable medical gas pipeline systems.
Four out of forty-one candidates passed this question.

Discussion

Four out of forty-one candidates passed this question; this is a testament not to the quality of the candidates, but to the obscurity of the question.

The document referenced by the college answer is the Australian Standard 2896 1998, Medical gas systems – installation and testing of non-flammable medical gas pipeline systems. Its is not available online except for the steep price of $200 or so. The free sample of it looks like this.

The CICM policy document IC-1 (Minimum Standards for Intensive Care Units) is available for free, however. The following point from that document is relevant to this question:

  • There must be piped gas supply failure alarms.

The rest must come from the inaccesible Australian Standard. However, a helpful summary is available from this copper tubing company. Their document adds the following points:

  • The nominal design working pressure shall be 415 kPa for medical gas supply,
    -60 kPa for medical suction, and 1400 kPa for surgical tool gas supply.

Nowhere are there online guidelines as to how one must perform a sniff test assessing for objectionable odours.

In short, it is difficult to determine where the four passing candidates got their information from.

Presumably, these people had an intimate familiarity with Dorsch and Dorsch's Understanding Anaesthesia Equipment; specifically, Chapters 1 to 4 are dedicated exclusively to medical gas supply and distribution systems. Of course it is a textbooks which one has to pay for. For the freegan, the best I could come up with is this article from the Indian Journal of Anaesthesia.

In brief summary;

  • Make sure all the outlets have the right gases in them
  • Make sure the gases are at the correct static pressure (~ 400kPa)
  • Make sure the gas pressure does not drop when the flow is turned up
  • Make sure the low pressure alarms are working.

A more detailed Dorsch-and-Dorschian list of tests can be found in my brief point-form summary of medical gas supply and distribution system testing.

References

Das, Sabyasachi, Subhrajyoti Chattopadhyay, and Payel Bose. "The anaesthesia gas supply system." Indian journal of anaesthesia 57.5 (2013): 489.

 

Love-Jones, Sarah, and Patrick Magee. "Medical gases, their storage and delivery." Anaesthesia & Intensive Care Medicine 8.1 (2007): 2-6.

 

Westwood, Mei-Mei, and William Rieley. "Medical gases, their storage and delivery." Anaesthesia & Intensive Care Medicine 13.11 (2012): 533-538.