Patient-controlled analgesia (PCA) is a technique allowing patients to self-administer parenteral analgesics. It is an effective, safe, and well-accepted treatment for post-operative pain, sickle cell crisis pain, and cancer pain.

Advantages
• PCA shortens the interval from the time of patient-defined need to the time of actual analgesic administration, thereby providing more immediate relief of incident (breakthrough) pain
• The same degree of analgesia is achieved compared to other delivery systems with the less/same total amount of medication.
• It provides patients with a greater sense of personal control over their pain

PCA devices
Most devices have a drug reservoir and infusion system whereby PCA administration can occur with or without a background continuous infusion. Thus, PCA devices need the following orders:
1. PCA dose in mg or mcg (patient initiated dose, patient demand dose, or bolus dose);
2. Delay interval ("lockout") in minutes (period during which the patient cannot obtain additional demand medication);
3. Continuous infusion (CI) rate in mg/hr or mcg/hr (if CI is used); and
4. Hour limit — maximum amount of drug to be dispensed in a defined period of time. Often the 1-hour limit is set to deliver 3-5 times the estimated required hourly dose. (Note: due to the need for frequent dose adjustments, the hour limit is often omitted in palliative care.)

Indications
• The primary indication for PCA is the patient who requires parenteral analgesia (e.g., severe pain and/or oral/transdermal/rectal route not useable) and has incident pain or other pain patterns that are not predictable.
• PCA is also indicated for use in acute, severe pain as a method of rapid dose titration and dose finding.

Relative contraindications include patients who :
• do not have the cognitive ability to understand how to use a PCA device, or
• the anticipated need for parenteral opioids is less than 24 hours.

Opioids used in PCA devices include morphine, hydromorphone, fentanyl, and methadone.

Routes of administration. IV or SQ are the most common routes of administration; it may also be used with epidural or intrathecal opioid administration.

Risk of overdose. The patient who is pushing his or her own PCA button will fall asleep before serious signs of overdose occur as long as only the patient pushes the button.

See more information at the reference.

Adapted from Prommer E. Palliative Care Network of Wisconsin. Fast facts and concepts #92. Patient controlled analgesia in palliative care. Internet. Accessed on June 21, 2016.