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

to being ready for discharge from the recovery
room to the ward, the pain levels experienced in
hospital, the rates of postoperative nausea and
vomiting (PONV), indicators of fatigue and the
time to reach the criteria for discharge home. 14
Longer term clinical indicators that have been
used to assess the effectiveness of anaesthesia
include: the rate of unplanned postoperative
admission, the rate of readmission, contact
with a general practitioner (GP) in the first
24 hours after discharge, contact with the hospital
in the first 24 hours after discharge, pain after
discharge, PONV after discharge and the time
to return to normal activity.
PONV is the most commonly investigated sideeffect
in day-case anaesthesia and surgery, with a
reported average incidence of 36% in the UK. 15
Factors that influence PONV include the type
of surgery, the duration of surgery, the gender
of patient, the age group of patient and the use
of certain drugs (N 2O, opioids, anti-emetics,
premeditation). However, published reports
show a wide range of PONV rates, even for the
same procedure (e.g. studies of gynaecological
laparoscopy patients show a range of 0–96%). 16
Guidelines have been published that recommended
the reduction of PONV to 10%. 17 PONV
is an important cause of unscheduled hospital
stays in day surgery. Meaden and co-workers 18
from Norfolk and Norwich Hospital reported
that 3.6% of day-surgery patients were admitted
overnight in 1992 and 2.7% in 1993. Of these,
42.6% and 20.9% of admissions, respectively,
were due to PONV.
Patient acceptability
Patients who undergo day surgery are generally
healthy and in hospital for a minimum period of
time. Issues concerning their care can be expected
to be different from those for other patient groups.
Common side-effects after day surgery are PONV,
pain, drowsiness and fatigue. These side-effects
are generally transitory and do not persist beyond
4 days after surgery. A British survey of adult
day-surgery patients showed that pain worsens
following discharge, increasing on the journey
home and persisting for several days. It took up to
72 hours for mean pain scores to decrease to the
levels reported at discharge. The incidence of
nausea increased three-fold during the journey
home and took 48 hours to return to discharge
levels. Most patients (70%) felt that pain was a
problem and 44% felt that nausea was a problem. 19
Admissions to hospital are usually for medical or
surgical reasons, such as pain. Anaesthetic-related
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Health Technology Assessment 2002; Vol. 6: No. 30
admissions may be due to PONV, somnolence
or aspiration. 20 Preliminary studies have shown
that patients place value on avoiding these
transitory but unpleasant sequelae. Hawksworth 21
reported that patients were willing to pay for
the improved outcomes associated with propofol
and ondansetron, as compared to thiopentone
or metoclopramide.
Economic evidence
The cost of anaesthesia has historically been
combined with the costs of surgery. Indeed, there
are some sources of cost that can be difficult to
attribute solely to anaesthesia or solely to surgery.
However, there are increasingly robust anaesthesia
costing methods available. 22,23 The use of patientbased
(bottom-up) costs, rather than average
(top-down) costs or charges is required if differences
between anaesthetic techniques are to
be identified.
Anaesthesia-costing studies show that the cost of
drugs is a small proportion of the total anaesthetic
cost, being as low at 4% in day surgery 23 and
sometimes less than 1% in inpatient surgery. 22
Organisational and operational factors within
institutions are likely to have a much more significant
effect on costs. A 30-minute delay in the
start of an operating session can be equivalent
to the cost of 2 hours of anaesthesia using a
propofol infusion. 23
Anaesthetic agents vary widely in terms of
acquisition and administration costs. At induction,
for example, propofol can cost £4 per patient,
compared with £1 per patient for thiopentone.
During maintenance anaesthesia, the hourly cost
for an adult is around £12 for propofol, £1.50 for
halothane, £6 for enflurane, £12 for isoflurane and
£12 for sevoflurane. 22,24
There were 2.2 million reported day-case
admissions for surgical procedures in England
for the year 1994–95. 23 Although drug costs are
dwarfed by other costs, the aggregated cost of
drugs is considerable. If all these operations had
used the cheapest possible agents, the annual
cost would have been £2.2 million. A policy
switch to use the most expensive option available
would have cost around £26.4 million.
The newer anaesthetic agents are perceived to be
the more costly. However, since the costs (usually
unmeasured) of healthcare resources, the time to
recovery and side-effects also differ, the higher
price of the more expensive agents may be offset
by reductions in recovery and discharge time, and
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