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were not affected by the education program (Lam et al, 2001 Level II). Patients who were shown
a video on PCA prior to surgery had better knowledge about the technique and reported
better pain control after surgery (Knoerl et al, 1999 Level III‐2; Chen, Yeh et al, 2005 Level III‐2).
Inappropriate use of PCA
The safety of PCA depends on an adequate understanding of the technique by the patient and
the fact that unauthorised persons do not press the demand button.
Oversedation with PCA has followed the patient mistaking the PCA handset for the nurse‐call
button and family or unauthorised nurse‐activated demands (‘PCA by proxy’) (Wakerlin &
Larson, 1990; Fleming & Coombs, 1992; Chisakuta, 1993; Ashburn et al, 1994; Sidebotham et al, 1997;
Tsui et al, 1997).
There have been case reports expressing concerns that patients can use PCA to treat
increasing pain and therefore mask problems such as compartment syndrome (Harrington et al,
2000; Richards et al, 2004), urinary retention (Hodsman et al, 1988), pulmonary embolism (Meyer &
Eagle, 1992) and myocardial infarction (Finger & McLeod, 1995). However, appropriate routine
patient monitoring should detect changes in pain scores and analgesic consumption enabling
identification of such complications.
Nursing and medical staff
Much of the information regarding complications due to nursing and medical staff factors is
case‐based — examples from a range of the cases reported are given.
As noted above in Section 7.1.5, operator error is a common safety problem related to PCA
use (Ashburn et al, 1994; Looi‐Lyons et al, 1996; US Pharmacopeia, 2004). Misprogramming of PCA
pumps is thought to account for around 30% of PCA errors, be twice as likely to result in injury
or death than errors involving general‐purpose infusion pumps, and lead to more harm than
errors in other types of medication administration (ECRI, 2006). Mortality from programming
CHAPTER 7 (Vicente et al, 2003).
errors has been estimated to range from 1 in 33 000 to 1 in 338 800 patients prescribed PCA

A number of reports involve the programming of drug concentrations that were lower than
the concentration ordered, with the resultant delivery of an excessive amount of opioid
leading to respiratory depression and sometimes death (ECRI, 1997; ECRI, 2002). The use of an
incorrect prefilled ‘standard syringe’ for PCA (morphine 5 mg/mL instead of the prescribed
1 mg/mL) also had a fatal outcome (Vicente et al, 2003). It has been suggested that drug
concentrations should be standardised within institutions to reduce the chance of
administration and programming errors (ECRI, 2002).
Some PCA pumps now incorporate dose‐error reduction systems that use internal software to
guide manual programming by checking programmed doses against preset limits and alerting
the programmer to inappropriate dose or continuous infusion settings; preset dosing
protocols can also be used, so that ‘standard’ settings can be programmed for each of the
opioids administered (ECRI, 2006).
Inappropriate prescriptions of supplementary opioids (by other routes) and sedative drugs
(including some antihistamines) can lead to oversedation and respiratory depression (Ashburn
et al, 1994; Tsui et al, 1997; Lotsch et al, 2002).

7.1.8 PCA in specific patient groups
For PCA in the paediatric patient, the elderly patient, the patient with obstructive sleep
apnoea and the opioid‐tolerant patient, see Sections 10.6, 11.2, 11.5 and 11.7 respectively.

180 Acute Pain Management: Scientific Evidence