Page 219 Acute Pain Management

7. PCA, REGIONAL AND OTHER LOCAL

ANALGESIA TECHNIQUES

7.1 PATIENT-CONTROLLED ANALGESIA

Patient‐controlled analgesia (PCA) refers to methods of pain relief that allow a patient to self‐
administer small doses of an analgesic agent as required. Most often, however, the term PCA
is associated with programmable infusion pumps that deliver opioid medications
intravenously, although a variety of other methods and routes of delivery (systemic and
regional) using opioids as well as other analgesic agents have been described. For epidural PCA
see Section 7.2.3; for regional PCA techniques see Section 7.5.1.
7.1.1 Efficacy of intravenous PCA

Analgesia, patient preference and outcomes
IV opioid PCA provides better analgesia than conventional (IM, SC) opioid regimens, although
the magnitude of the difference in analgesia is small (8.012 on a pain scale of 0 to 100); opioid
consumption is greater; there are no differences in duration of hospital stay or opioid‐related
adverse effects other than pruritus, which is increased, and patient satisfaction is higher
(Hudcova et al, 2006 Level I).

Note: reversal of conclusions
This partly reverses the Level I conclusion in the previous edition
of this document; earlier meta‐analyses had reported no
difference in opioid consumption or opioid‐related adverse effects

Other information obtained from published cohort studies, case‐controlled studies and audit CHAPTER 7
reports only (ie not RCTs) (Dolin & Cashman, 2002 Level IV) suggests that IV PCA may be
appreciably more effective than intermittent IM opioid analgesia in a ‘real life’ clinical setting;
patients given IM opioid analgesia were more than twice as likely to experience moderate‐to‐
severe pain and severe pain as those given PCA.
In settings where there are high nurse:patient ratios and where it might be easier to provide
analgesia truly on‐demand, conventional forms of opioid administration may be as effective
as IV PCA. A comparison of PCA versus nurse‐administered analgesia following cardiac surgery
found no difference in analgesia at 24 hours (a period when nursing attention is likely to be
higher) but significantly better pain relief with PCA at 48 hours (Bainbridge et al, 2006 Level I).
In an emergency department setting, IV PCA was as effective as nurse‐administered IV bolus
doses of opioid (Evans et al, 2005 Level II).
The enormous variability in PCA parameters (bolus doses, lockout intervals and maximum
permitted cumulative doses) used in many studies indicates uncertainty as to the ideal PCA
program and may limit the flexibility, and thus the efficacy, of the technique. Individual PCA
prescriptions may need to be adjusted if patients are to receive maximal benefit (Macintyre,
2005; Macintyre & Schug, 2007; Macintyre & Coldrey, 2008).
A number of studies have shown that PCA provides less effective pain relief compared with
epidural analgesia (see Section 7.2).

Acute pain management: scientific evidence 171