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sensory testing (QST) may show changes in pain thresholds and tolerability (Chang et al, 2007).
In the experimental setting, patients with opioid‐managed (morphine or methadone) chronic
non‐cancer pain (Hay et al, 2009) and those in methadone maintenance programs (Compton et
al, 2000 Level III‐2; Doverty et al, 2001 Level III‐2; Athanasos et al, 2006 Level III‐2; Hay et al, 2009
Level III‐2) have been shown, to be hyperalgesic when assessed with cold pressor testing but
not with electrical pain stimuli. However, such testing is uncommon in the clinical setting.
The challenge faced by the clinician is that if inadequate pain relief is due to OIH, a reduction
in opioid dose may help; if it is due to opioid tolerance, increased doses may provide better
pain relief (Mao, 2008). There are case reports of patients with cancer and chronic non‐cancer
pain, taking high doses of opioid and who had developed OIH, whose pain relief improved
following reduction of their opioid dose (Angst & Clark, 2006; Chang et al, 2007); there have been
no such trials performed in the acute pain setting.
When a patient who has been taking opioids for a while (either legally prescribed or illicitly
obtained) has new and ongoing tissue injury with resultant acute pain, a reasonable initial
response to inadequate opioid analgesia, after an evaluation of the patient and in the absence
of evidence to the contrary, is a trial of higher opioid doses (Chang et al, 2007). If the pain
improves this would suggest that the inadequate analgesia resulted from tolerance; if pain
worsens, or fails to respond to dose escalation, it could be a result of OIH (Chang et al, 2007).
Fortunately, some of the strategies that may be tried in an attempt to attenuate opioid‐
tolerance in the acute pain setting may also moderate OIH (see below).
Other reasons for increased pain and/or increased opioid requirements should also be
considered. These include acute neuropathic pain, pain due to other causes including
postoperative complications, major psychological distress, and aberrant drug‐seeking
behaviours (see Section 11.8) (Macintyre & Schug, 2007).

11.7.2 Patient groups

Three main groups of opioid‐tolerant patients/patients with OIH are encountered in surgical
and other acute pain settings:
• patients with chronic cancer or non‐cancer pain being treated with opioids, some of
whom may exhibit features opioid addiction (see Section 11.8);
• patients with a substance abuse disorder either using illicit opioids or on an opioid
maintenance treatment program (see Section 11.8); and
• patients who have developed acute opioid tolerance or OIH due to perioperative opioid
administration, particularly opioids of high potency.
Recognition of the presence of opioid tolerance or OIH may not be possible if the patient’s
history is not available or accurate. If a patient is requiring much larger than expected opioid CHAPTER 11
doses and other factors that might be leading to the high requirements have been excluded,
opioid tolerance or OIH should be considered.
11.7.3 Management of acute pain

While the discussion below will focus on management of the opioid‐tolerant patient, it is
recognised that these patients may also have OIH.
Since 2004, a number of articles and chapters have been published outlining suggested
strategies for the management of acute pain in the patient taking long‐term opioids for both
chronic non‐cancer pain or because they have an addiction disorder and are in a drug
treatment program (Carroll et al, 2004; Mitra & Sinatra, 2004; Kopf et al, 2005; Peng et al, 2005;
Roberts & Meyer‐Witting, 2005; Alford et al, 2006; Hadi et al, 2006; Mehta & Langford, 2006; Rozen &

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