Intended for healthcare professionals

Editorials

Use of mobile phones in hospitals

BMJ 2006; 333 doi: https://doi.org/10.1136/bmj.38995.599769.80 (Published 12 October 2006) Cite this as: BMJ 2006;333:767

Distance Criterion Required

I conducted a hospital vox pop of attitudes to mobile phone use and
found a large variation. What everyone had in common was a self-confessed
ignorance of the peer-reviewed literature on the subject. I was shocked to
find these authors behaving likewise. This articles is tiresome. As
Richard Brady has pointed out – it contains no systematic reference to the
literature, but a string of anecdote, hearsay and opinion.
Consider the null hypothesis. “Mobile phones can safely be used anywhere,
at any time in any part of any hospital, regardless of proximity to
therapeutic or life support equipment”. Let’s demand p < 0.05. i.e.
less than a 5% chance of an adverse event. The MDA bulletin would force us
to reject the null hypothesis. And contrary to myth, the phones tested in
the MDA bulletin included GSM i.e. current handsets. Modern handsets may
be dinky and appear to have long battery lives but the power required to
reach the nearest base station is governed by Maxwell’s equations and they
haven’t changed since the MDA bulletin. Furthermore, adaptive power
control makes it difficult to generalise the results of testing. A phone
in an operating theatre is probably broadcasting at maximum power in order
to penetrate the x-ray hardened walls.

To date, although mysteriously un-referenced by Derbyshire and
Burgess, the most comprehensive treatment of the subject of mobile phone
EMI and medical devices is by Lawrentschuk and Bolton(1). I shall not try
to summarise this paper but they likewise reject the null hypothesis in
favour of some form of proximity criterion – probably between one and two
metres.

The survey of the AAA alluded to was widely quoted in the media at
the time but involved one of the least scientific questionnaires ever
produced; yet even these highly biased respondents admitted to a total of
incidents that took them half way to rejecting the above null hypothesis.

It would be interesting to perform an experiment where an NHS
hospital offered the following deal. Staff may carry a mobile phone and
use it freely on the campus. But they would make no ingoing or outgoing
personal calls nor browse the web. This would of course include calls
related to the private medical sector. On the other hand how would
judicious use of low power DECT phones, wireless networks and paging
systems compromise communication ?

references
1.Lawrentschuk N, Bolton DM. (2004). "Mobile phone interference with
medical equipment and its clinical relevance: a systematic review.". Med J
Aust. 181: 145-9.

Competing interests:
None declared

Competing interests: No competing interests

05 November 2006
douglas r small
Clinical Scientist, Dept of Clinical Physics
Southern General Hospital, Glasgow, G51 4TF