One Liners issue 67 - May 2009

A survey was undertaken by the Critical Care Outreach Team (CCOT) of Nottingham University Hospital following the observation that episodes of desaturation were occasionally noted during patient transfers. On a number of these occasions, the portable oxygen cylinder was found to be empty or at such a low pressure to result in a reduced flow.

Take a breather!
In this survey, 60% of relevant staff:

• ...wrongly estimated oxygen cylinder content and could not or would not change an empty cylinder for a full one.

Tube little, tube late!
Do you know how long the oxygen would last in a size D (340 litres) and PD (300 litres) cylinder when on nasal “specs” at 4 litres a minute?

• The answer is:
  85 minutes for a D sized cylinder.
  75 minutes for a PD sized cylinder.

Silly 'N' der
Do you know how long a D size oxygen cylinder would last on a “Venturi” mask at 40%?

• A facemask at 40% via this system would require 10 litres per minute flow rate, lasting for 34 minutes or 30 minutes for a PD cylinder.

Don't mask the danger
How long would the oxygen in the cylinder last when used with a non-re-breathe mask and set at its maximum flow rate?

• The answer is:
  23 minutes for a P size, 20 minutes for a PD cylinder. A non-re-breathing or “trauma” mask at maximum delivery rate uses 15 litres per minute.

The final countdown
As a result of this CCOT survey, key recommendations for hospital staff include:

• production of an education poster containing the oxygen contents and times to depletion at each size cylinder at common slow rates,
• appropriate competency based training,
• the need to risk assess oxygen requirements on the most oxygen dependent patients.

Smooth operator
Further advice can be found in “Oxygen Cylinders and their Regulators: Top Tips for Care and Handling” published by MHRA in April 2008.

• These MHRA publications can be downloaded from the MHRA website at www.mhra.gov.uk.

The One Liners Editions are published by the MHRA, an executive agency of the Department of Health.
Adverse incidents should be reported at the earliest opportunity. We prefer to receive reports via the online reporting system on our website www.mhra.gov.uk
You may also use this online system to send an e-mail copy of your report to your medical device liaison officer.
We also have an adverse incident hotline: 020 7084 3080. You can find detailed reporting guidance on our website.