Patient-controlled analgesia
Patient-controlled analgesia (PCA) is any method of allowing a person in pain to administer their own pain relief.

# Etymology
PCA was introduced by Dr. Philip H. Sechzer in the later 1960s and described in 1971.

# General use
The most common form of this is the paracetamol that many keep in their bathroom cabinet. If a complaint, e.g. a headache, does not resolve with a small dose of painkiller then more may be taken up to a maximum dose. This situation has the patient in control, and is in fact the most common patient-controlled analgesia. As pain is a combination of tissue damage and emotional state, being in control means reducing the emotional component of pain.

# Hospital use
PCA has passed into medical jargon to mean the electronically controlled infusion pump that delivers a prescribed amount of intravenous or epidural analgesic to the patient when he or she activates a button.
Opioids are the medication most often administered through PCAs.

## Benefits
Among the benefits of this device are:
- It saves time between when the patient feels pain and/or the need to receive analgesia and when it is administered (activation automatically pumps the dose into a pre- existing IV line into the patient).
- It reduces workload of the nursing staff (an amount of the prescribed analgesic is pre-loaded into the PCA, enough for multiple doses).
- It reduces the chances for medication errors (the PCA is programmed per the physician's order for amount and interval between doses and "locks out" the patient if he or she attempts to self- administer too often.)
- Patients can receive medicine when they need it, instead of having to wait for nursing staff, and tend to use less.
- Patients who use PCAs report better analgesia and lower pain scores than those patients who have to request analgesia from the nursing staff when they are in pain.
- PCA provides a measurement of how much pain an individual patient is experiencing from one day to the next.
- It involves patients in their own care, giving them control and ultimately rendering better patient outcomes

## Disadvantages
Disadvantages are:
- Patients may be unwilling to use the PCA or be physically or mentally unable to. (in a lot of cases physical inability can be mitigated through use of an eye gaze, sip-puff or alternative switch access method). PCA pumps are rated among the worlds most accessible pieces of equipment since all manufacturers must have alternative switch access built into their PCA pumps. Most companies will use a TASH apporoved switch interface connection as TASH is one of the industry standards in accessibility switches.
- The pumps are often expensive and may malfunction. (Malfunctions are usually limited, and many malfunctions result from an inproperly maintained/charged battery.)
- More importantly, the dosing regimen may be set so that the patient does not receive enough analgesia (bolus doses set too small, lock-out too long). When the patient sleeps, the analgesic wears off so they wake in pain. This is sometimes countered by setting a background continuous infusion of the analgesia.

# Patient-controlled epidural analgesia (PCEA)
Patient-controlled epidural analgesia (PCEA) is a related term describing the patient-controlled administration of analgesic medicine in the epidural space, by way of intermittent boluses or infusion pumps. This is most commonly used by terminally ill  cancer patients.