Aanesthetic Agents for Day Surgery - NIHR Health Technology ...

nurses to have an in-depth knowledge of the local
procedures for notifying patients and parents/
guardians about the forthcoming day-surgery
procedure and admitting the patients on the
day of surgery. The research nurses developed a
standardised approach to patient recruitment for
the adult and paediatric studies. The pilot study
and liaison with the relevant ward and theatre
staff played an important role in developing
this approach to recruitment.
Generally the recruitment procedure worked
well once the patient was approached, and around
three-quarters of all patients approached agreed to
take part. However, it was not possible to approach
all patients who came in for day procedures, for a
number of reasons. One particular problem was
that there were not enough research nurses to
recruit from all available lists. Day-patient lists may
have been run in parallel and the number of study
sites used meant that nurses sometimes had to be
in more than one place at a time. At the time of
the study, one of the trusts was undertaking a
waiting-list-reduction initiative, and this led to a
reduction in the numbers of paediatric patients
available for recruitment.
The majority of patients received written
information about the study prior to the day of
their operation. However, it was not always possible
to approach the patient on the morning of their
operation before they were called for theatre.
The study aimed to use consultant anaesthetists
who were experienced in all four anaesthetic
techniques for adults and the two techniques for
paediatrics. Not all consultant anaesthetists who
were approached were comfortable with all the
techniques, and in particular some expressed
concern with using propofol TIVA. These anaesthetists
were either trained to use the technique or
were not recruited into the study. This limited the
number of patient lists that could be used with
recruited anaesthetists. In some instances, on the
morning of the theatre list, a junior anaesthetist
took over the place of the recruited anaesthetist
and no patients could therefore be approached.
Recruitment at one site was facilitated by having a
research registrar anaesthetist who was dedicated
to the project for 2 days per week and could
take over anaesthetising the patients as required
(e.g. if a non-recruited anaesthetist or a junior
anaesthetist was doing the list).
Patients’ willingness to participate
An appreciable number of patients (226 adults
and 59 parents) refused to take part in the study
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Health Technology Assessment 2002; Vol. 6: No. 30
because they did not want inhalational induction,
either for themselves or for their children (compared
with five and six, respectively, for intravenous
induction). This reluctance contributed
markedly to a smaller sample size than originally
anticipated. However, only seven adults and two
parents withdrew from the study once they were
randomised to inhalational induction.
Follow-up of patients
Patients were followed up by telephone 7 days after
discharge from hospital to obtain CVs and data on
postdischarge resource use. It was expected that
some patients would be lost to follow-up, particularly
because the patient population for this study
was generally healthy and working, and so often
not at home. This was the situation that was
commonly found. Overall, 85.3% of adults and
80.7% of parents were contacted for follow-up.
There was no difference in follow-up rates between
randomisation arms. This follow-up rate was facilitated
by the use of research nurses for interview,
who concentrated their efforts in the early evening.
Sample size
The original power calculations (using the change
in the rate of PONV) required that 440 children
and 1320 adults be recruited to the study. It was considered
that a PONV rate of less than 20% to 10%
would not be clinically significant, and the study was
powered on this basis. The problems noted above
meant that these recruitment targets were not
achieved. However, statistically significant changes
in PONV were found in both the adult and the
paediatric component of the CESA RCT, indicating
that the study had reached sufficient power to detect
a difference in the primary outcome variable.
Adherence to protocol
The protocol was designed to reflect practice
closely. This was made possible by the six anaesthetists
in the project team. However, the protocol
also was designed to reflect practice as defined in
the literature and in the national surveys, which
meant that this would not necessarily concur with
local practice patterns in the clinical sites. This
was expected to be an issue with the use of TIVA,
sevoflurane induction and the lack of use of
perioperative morphine and prophylactic antiemetics.
However, in practice, with the support
of the CESA research nurses, project coordinator
and anaesthetists, the participating anaesthetists at
both clinical sites observed the protocol conditions
extremely rigorously. There were very few patients
withdrawn due to protocol violations (12 children
and 15 adults), a fact that supports the selection
of a practice-based design for the study.
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