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(Manjushree et al, 2002 Level II). PCINA pethidine is as effective as IV pethidine, although larger
doses are needed (Striebel, Malewicz et al, 1993 Level II), and more effective than SC injections
of pethidine (Striebel et al, 1995 Level II). Diamorphine PCINA (bolus doses of 0.5mg) was less
effective than PCA IV morphine (higher bolus doses of 1 mg were used) after joint replacement
surgery (Ward et al, 2002 Level II) but provided better pain relief in doses of 0.1 mg/kg
compared with 0.2 mg/kg IM morphine in children with fractures (Kendall & Latter, 2003).
Transdermal PCA
A number of studies have reported that the iontophoretic fentanyl patient‐controlled
transdermal system (PCTS) is comparable with standard IV PCA morphine regimens in terms
of pain relief and incidence of side effects (Viscusi et al, 2004 Level II; Hartrick et al, 2006 Level II;
Ahmad et al, 2007 Level II; Grond et al, 2007 Level II; Minkowitz et al, 2007 Level II; Viscusi et al, 2007
Level II). However, a meta‐analysis showed that while fentanyl PCTS provided good pain relief,
it may not be as effective as IV morphine PCA. While there was no difference in Patient Global
Assessment, significantly more patients in the PCTS group withdrew because of inadequate
analgesia (Poon et al, 2009 Level I).
Comparison of ease‐of‐care and satisfaction measures of the two techniques showed that
patients, nurses and physiotherapists found the iontophoretic fentanyl PCTS system easier
to use than IV PCA and they were more satisfied with PCTS (Hartrick et al, 2006 Level II; Gan et al,
2007 Level IV; Grond et al, 2007 Level II; Minkowitz et al, 2007 Level II).
Maximum blood concentrations of fentanyl were the same if the fentanyl PCTS patch was
placed on the chest, or upper outer arm, but less if placed on the lower inner arm; the
pharmacokinetics were not affected by gender, ethnicity, age or weight (Gupta et al, 2005
Level II).

7.1.5 Complications related to PCA
Complications related to the use of PCA can be divided into operator or patient‐related errors,
and problems due to the equipment or the opioid used.
An early prospective study of 4000 patients given PCA postoperatively found nine cases CHAPTER 7
of respiratory depression. These were associated with drug interactions, continuous
(background) infusions, nurse‐ or physician‐controlled analgesia, and inappropriate use
of PCA by patients (Looi‐Lyons et al, 1996 Level IV). A similar sized prospective survey of
3785 patients showed that use of PCA was associated with 14 critical events: 8 programming
errors (all associated with the setting of a continuous infusion); 3 family members activating
PCA; 1 patient tampering; and 3 errors in clinical judgment (Ashburn et al, 1994 Level IV).
The most common of the 5377 PCA‐related errors reported from September 1998 to August
2003 and examined by the United States Pharmacopeia (USP) were improper dose/quantity
38.9%, unauthorised drug 18.4%, omission error 17.6% and prescribing error 9.2%. Other
errors included wrong administration technique, wrong drug preparation, wrong patient and
wrong route (US Pharmacopeia, 2004 Level IV).
A much later retrospective analysis of information (from July 2000 to June 2005) reported to a
national voluntary medication error‐reporting database, showed that PCA‐related medication
errors continue. Of 919 241 medication errors reported, 9571 (only 1%) were associated with
PCA and of these, just 624 were associated with patient harm; the majority of errors occurred
during drug administration (Hicks et al, 2008). Of these, 38% were errors in dose or quantity,
17.4% involved an omission, and 17.3% were related to an unauthorised or wrong drug;
human factors were the main cause of errors; distractions (37.8%) and inexperienced staff
(26.3%) were the leading contributing factors (Hicks et al, 2008).

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