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

Background
Variable costs account for resource use that
changes with respect to output. Drug and disposable
equipment are some examples of variable
costs associated with anaesthesia for a day procedure.
The empirical study required information
on these variable costs.
Method
The types of variable cost data collected were:
• anaesthetic use
• all drug use during anaesthesia
• PONV and adverse-event management
• anaesthetic room resource use
• theatre resource use
• recovery room resource use
• ward resource use
• postdischarge NHS resource use.
Drug and anaesthetic variable costs
Variable costs were collected prospectively. The
name, form, strength and quantity of all drugs,
including take-home drugs, given to each patient
throughout the day procedure were recorded. This
included drugs used in the management of PONV.
Changes in fresh gas (oxygen or N 2O) flows and
volatile anaesthetic concentrations, made by the
anaesthetist, to prevent or react to adverse events
were also recorded.
The quantity of volatile anaesthetic and fresh
gases given to each patient was calculated using
the Dion approximation. 24 This requires information
on the concentrations and flow rates used
throughout the induction and maintenance of
anaesthesia. Concentration and flow rate were
recorded at regular intervals: 1-minute intervals
in the anaesthetic room; 1-minute intervals for
the first 10 minutes, then 2-minute intervals for
a further 10 minutes and then 5-minute intervals
in the operating theatre.
Adverse-event management
variable costs
The variable costs associated with the management
of adverse events were collected for the anaesthetic
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Appendix 17
Calculating variable costs
Health Technology Assessment 2002; Vol. 6: No. 30
room, theatre, recovery and the ward. The type
of adverse event and the quantity of resources
used to manage each adverse event were recorded.
Only anaesthetic-related adverse events were
included, surgical adverse events being excluded.
Some examples of event-associated resource use
include: the insertion of a new laryngeal mask;
a visit from a senior anaesthetist to manage an
adverse event; and the patient vomited.
Posthospital resource use variable costs
Postdischarge NHS resource use data were
collected during the telephone interview with
the patient or the patient’s parent or guardian
at day 7 postdischarge. Three categories of
posthospital resource use were identified:
• over-the-counter medicines bought
• visit or contact with a GP and associated
prescribed drug costs
• visit or contact with the hospital.
Over-the-counter medicines bought
The over-the-counter medicines bought were
not consistent with the study perspective and were
not included in the total variable cost. However,
the type of over-the-counter medicines bought by
each patient was recorded to provide information
about the use of community-based healthcare
services (community pharmacies) following
a day procedure.
GP visit
A visit to a GP was categorised into one of
five types:
• the patient consulted with the GP
• the patient telephoned the GP
• the patient telephoned the surgery and
spoke to the receptionist
• the patient consulted with the practice nurse
• the patient had a home visit by a
district nurse.
Hospital visit
There were four categories of hospital ‘visit’:
• the patient attended the accident and
emergency department
• the patient was admitted for an overnight stay
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