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over the previous 24 hours was a reasonable indicator of average pain experienced by the
patient during that time (Jensen et al, 2008 Level III‐2).
Patients asked to rate their pain using a VNRS prior to and after morphine administration were
also asked to rate their pain relief on a 5‐point standard Likert scale as 0 = no pain relief,
1 = a little pain relief, 2 = moderate pain relief, 3 = a lot of pain relief and 4 = complete pain
relief. The VNRS reductions associated with these pain relief ratings were 9.0, 7.5, 3.9, 2.1 and
–0.1 respectively (Bernstein et al, 2006 Level III‐2).
2.2.2 Functional impact of acute pain

Analgesia should be titrated to achieve both decreased pain intensity and the ability to
undertake appropriate functional activity (Breivik et al, 2008). This will enable analgesia to
optimise recovery. Most tools for measuring the functional impact of pain are based on
chronic pain assessment, and therefore are not routinely applicable to the acute pain
environment.
CHAPTER 2 Measurement of pain intensity scores on movement or with coughing is a useful guide,
however this reflects the subjective pain experience and not the capacity to undertake the
specific activity. The Functional Activity Scale score (FAS score) is a simple three‐level ranked
categorical score designed to be applied at the point of care (Scott & McDonald, 2008). Its
fundamental purpose is to assess whether the patient can undertake appropriate activity at
their current level of pain control and to act as a trigger for intervention should this not be the
case. The patient is asked to perform the activity, or is taken through the activity in the case of
structured physiotherapy (joint mobilisation) or nurse‐assisted care (eg ambulation, turned in
bed). The ability to complete the activity is then assessed using the FAS as:
A — no limitation the patient is able to undertake the activity without
limitation due to pain (pain intensity score is typically
0 to 3);
B — mild limitation the patient is able to undertake the activity but
experiences moderate to severe pain (pain intensity
score is typically 4 to 10); and
C — significant limitation the patient is unable to complete the activity due to
pain, or pain treatment‐related side effects,
independent of pain intensity scores.
This score is then used to track effectiveness of analgesia on function and trigger interventions
if required. Disadvantages of the FAS score are that it has not been independently validated
and clinical staff need to be educated in its application.

2.2.3 Multidimensional measures of pain
Rather than assessing only pain intensity, multidimensional tools provide further information
about the characteristics of the pain and its impact on the individual. Examples include the
Brief Pain Inventory, which assesses pain intensity and associated disability (Daut et al, 1983)
and the McGill Pain Questionnaire, which assesses the sensory, affective and evaluative
dimensions of pain (Melzack, 1987).
Unidimensional tools such as the VAS are inadequate when it comes to quantifying
neuropathic pain. Specific scales have been developed that identify (and/or quantify)
descriptive factors specific for neuropathic pain (Bouhassira et al, 2004 Level IV; Cruccu et al, 2004
Level IV; Bouhassira et al, 2005 Level IV; Dworkin et al, 2007 Level III‐2) and that may also include

38 Acute Pain Management: Scientific Evidence