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to fentanyl overdose; as this problem could not yet be resolved, the system is currently not
available.
Equipment-related complications
In general, modern PCA pumps have a high degree of reliability. However, problems continue
to be reported as well as problems related to the disposable items required. Information
regarding complications due to equipment problems is mainly case‐based; examples from
a range of the cases reported are given.
While the number of reports of ‘run‐away’ pumps, where the PCA pump unexpectedly delivers
an unprescribed dose of drug (Notcutt & Morgan, 1990), has decreased following changes made
to pump design, they continue to occur, including a report of spontaneous triggering (Christie &
Cranfield, 1998) and of a frayed wire in the demand apparatus leading to triggering as a result of
an electrical short circuit (Doyle & Vicente, 2001).
Uncontrolled syphoning of syringe contents when the PCA machine was above patient level
has been reported following cracked glass PCA syringes (Thomas & Owen, 1988; ECRI, 1996),
failure of a damaged drive mechanism to retain the syringe plunger (Kwan, 1995), improperly
secured PCA cassettes (ECRI, 1995) and broken drug cartridge syringe (Doyle & Keebler, 2008).
To minimise the risk of syphoning, the use of antisyphon valves is recommended (ECRI, 1996).
Antireflux (one‐way) valves are essential if the PCA infusion is not connected to a dedicated
IV line. The non‐PCA infusion tubing should have an antireflux valve upstream from the
connection with the PCA line to prevent back‐flow up the non‐PCA line should distal
obstruction occur; otherwise, inappropriate dosing can occur (Paterson, 1998; Rutherford &
Patri, 2004).
7.1.7 Patient and staff factors
Patient factors
Patient factors play a role in the effectiveness of PCA as well as complications that can arise
from its use: much of the information regarding complications due to patient factors is case‐ CHAPTER 7
based — examples from a range of the cases reported are given below. Psychological factors
that may affect PCA use and efficacy are discussed in Section 1.2.
Education
Few controlled studies have evaluated the influence of information on PCA use. Of 200
patients surveyed who used PCA, approximately 20% were worried that they may become
addicted, and 20% and 30% respectively felt that the machine could give them too much drug
or that they could self‐administer too much opioid (Chumbley et al, 1998 Level IV). In a follow‐up
study, the same authors conducted focus groups with previous PCA users, developed a new
information leaflet and then undertook a randomised study comparing the old and new
leaflet. They found that patients wanted more information on the medication in the PCA,
the possible side effects and assurance that they would not become addicted (Chumbley et al,
2002 Level II).
Comparisons have been made between different forms of education given to patients about
PCA and results are inconsistent. In an assessment of patient information delivered using
structured preoperative interviews or leaflets compared with routine preoperative education,
patients given leaflets were better informed and less confused about PCA and became familiar
with using PCA more quickly, but there were no effects on pain relief, worries about addiction
and safety, or knowledge of side effects; the structured preoperative interview resulted in no
benefits (Chumbley et al, 2004 Level III‐2). Another comparison of structured education versus
routine information showed that overall analgesic efficacy, side effects, and recovery times
Acute pain management: scientific evidence 179
