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Patient controlled analgesia (PCA)

Created: 29/6/2004
Updated: 22/7/2021

Graseby 3300 pump

The Graseby 3300 pump

Graseby 9300 Ambulatory PCA

The Graseby 9300 Ambulatory PCA

PCA is a technique whereby small doses of analgesic drugs, usually opioids, are administered (usually IV, although can be subcutaneous) by patients themselves. It is mostly used for the control of postoperative pain. The PCA system allows on-demand bolus injections with the option of a background infusion. Overdosage is avoided by limiting the size of the bolus and the total dose administered within a set period of time. A lock-out interval is also set. PCA has been shown to provide more consistent plasma drug levels when compared with standard intramuscular techniques, and less sedation. Drugs with (relatively) short half lives are usually used.

Dose regimens for PCA

Bolus dose (mg)
Lock-out (minutes)

Nausea and vomiting may be a problem if regular anti-emetics are not prescribed. PCA may also be used in conjunction with epidural analgesia (using plain bupivacaine infusions to avoid opioid overdosage).

Safety aspects of PCA

A one-way valve should be incorporated into any system which is linked via a Y-connector to a fluid infusion. Backflow can occur into the tubing of the fluid infusion, which may then deliver a large bolus. Alternatively, PCA may be delivered by a separate IV line. The pumps should be lockable and contain alarms which warn of excessive doses. Patients should be observed for their level of sedation and respiratory rate. Nursing staff should be allowed to administer naloxone in cases of suspected overdosage.


i] Postoperative patient-controlled analgesia: meta-analyses of initial randomized control trials.
Ballantyne JC et al.
J Clin Anesth 1993; 5: 182-93.

ii]  Efficacy and safety of patient-controlled opioid analgesia for acute postoperative pain.
Walder B et al.
Acta Anaesthesiol Scand 2001; 45: 795-804.

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