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Patient-controlled analgesia
A number of studies have looked specifically at the relationship between pain relief and
psychological factors in patients using patient‐controlled analgesia (PCA) in the postoperative
period.
In general, anxiety seems to be the most important psychological variable that affects PCA use.
Preoperative anxiety correlated with increased postoperative pain intensity, the number of
PCA demands made by the patient (often ‘unsuccessful’, that is, during the lockout interval),
degree of dissatisfaction with PCA and lower self‐reports of quality of analgesia (Jamison et al,
1993 Level IV; Perry et al, 1994 Level IV; Thomas et al, 1995 Level III‐1; Brandner et al, 2002 Level IV;
Ozalp et al, 2003 Level IV; Hsu et al, 2005 Level IV; De Cosmo et al, 2008 Level IV). Another study
designed to look at predictors of PCA demands made during the lockout interval also found
that anxiety and negative affect positively predicted PCA lockout interval demands and
postoperative pain, as did preoperative intrusive thoughts and avoidant behaviours about the
impending surgery (Katz et al, 2008 Level IV).
Evidence regarding PCA opioid consumption is contradictory; both no change (Gil et al, 1990 CHAPTER 1
Level IV; Gil et al, 1992 Level IV; Jamison et al, 1993 Level IV) and an increase (Ozalp et al, 2003
Level IV; De Cosmo et al, 2008 Level IV; Katz et al, 2008 Level IV) have been reported.
In a study looking at the effect of a number of psychological factors on both pain and PCA
morphine use in the immediate postoperative period and on pain 4 weeks after surgery,
preoperative self‐distraction coping positively predicted postoperative pain levels and
morphine consumption; emotional support and religious‐based coping positively predicted
PCA morphine consumption; and preoperative distress, behavioural disengagement,
emotional support, and religious‐based coping also positively predicted pain levels 4 weeks
after surgery (Cohen et al, 2005 Level IV).
There was no relationship between locus of control and postoperative pain intensity,
satisfaction with PCA or PCA dose‐demand ratio (Brandner et al, 2002 Level IV). However,
preoperative depression was associated with increased pain intensity, opioid requirements,
PCA demands and degree of dissatisfaction (Ozalp et al, 2003 Level IV; De Cosmo et al, 2008
Level IV).
Key messages
1. Preoperative anxiety, catastrophising, neuroticism and depression are associated with
higher postoperative pain intensity (U) (Level IV).
2. Preoperative anxiety and depression are associated with an increased number of PCA
demands and dissatisfaction with PCA (U) (Level IV).
The following tick box represents conclusions based on clinical experience and expert
opinion.
Pain is an individual, multifactorial experience influenced by culture, previous pain events,
beliefs, mood and ability to cope (U).
1.3 PROGRESSION OF ACUTE TO CHRONIC PAIN
The importance of addressing the link between acute and chronic pain has been emphasised
by recent studies. To highlight this link, chronic pain is increasingly referred to as persistent
pain. A survey of the incidence of chronic pain‐related disability in the community concluded
Acute pain management: scientific evidence 9
