When the repertoire of rules is exhausted, then new solutions
have to be devised. This is cognitively intense work
and especially in situations where the operator is under time
pressure, the brain’s tendency is to select a rule that approximates
to the situation facing the operator.16 These are
known as fixation errors because the tendency is to go down
one path and ignore evidence to the contrary. An example
from anaesthetic practice is a clinical situation where an
anaesthetist is presented with unexpectedly high airway
pressure and a slight fall in oxygen saturation levels in an intubated
anaesthetist patient. If this is due to a foreign body in the
catheter mount connecting the tracheal tube to the breathing
system but interpreted by the anaesthetist as bronchospasm
then that fixation error may result in harm to the patient as
more powerful bronchodilators are administered. Knowledgebased
errors often cause problems not due to lack of specific
facts or concepts but due to misapplication of existing knowledge
during the management of fixation errors. The GMC
study8 highlighted the lack of knowledge of not only pharmacology,
especially drug interactions, but also lack of knowledge
of prescribing systems and how to use them. As with rulebased
mistakes, this is much less likely with experienced
anaesthetists but the administration of ‘wrong drugs’ during
the management of a crisis as part of a fixation error could
result in serious patient harm.