Patient controlled analgesia:
PCA is a unique way of administering pain medications. The medication is administered with the help of a pump. Patient has the freedom to control the amount and dose of the pain medication. The response time is minimal compared to intermittent administration by a nurse. Pain relief is achieved faster and satisfaction rates are higher. Any patient with basic understanding skills can benefit from the use of PCA. It has been used successfully in pediatric as well as geriatric populations. It has been used for hospital inpatients as well as ambulatory and home/ hospice use.
Common indications for PCA:
Routes: I.V. PCA and epidural (PCEA). Other routes are intrathecal / transdermal (E-Trans) / surgical incisional (On-Q pumps) / intra-articular (On-Q pumps) etc.
Drugs commonly used:
The PCA is used for as long as it is practical and tolerated. At the time of transition to other routes of use (most commonly oral medications) patients should be re-assessed and needs for analgesics reviewed. The last 12- or 24- hour requirements are noted and equiv.-analgesic conversions made for the alternate drugs and alternate routes.
Example: If administration of long-acting opioids is appropriate for a patient, the last 12 or 24 hour requirements is prescribed as a long-acting opioid. Ten to 15% of the 24 hour dose is provided as breakthrough. Using morphine, if a patient required 300mg of IV morphine over the past 24 hours: 300 mg IV morphine X 3 = 900 mg po morphine. Divide by 2 to equal 450 mg po q 12 hours with 10-15% of the 24 hour dose (90mg-135mg) immediate release morphine prescribed as breakthrough q 4 hours PRN
For your reference, another less commonly used method to transition from IV analgesia to oral: 2/3rds of the total dose is given in a sustained release form for basal analgesia and 1/3rds as rescue medication for breakthrough pain. For example if the last 24-hour dose was 15 mg of morphine i.v, then oral morphine requirements would be 45 mg. Morphine ER (extended release) 15 mg po bid and Morphine IR (immediate release) 15 mg po prn q 4 hourly would be appropriate.
If the patient needs too frequent rescue doses then the dose of the sustained release form should be increased. Rest pain is better controlled with sustained release forms and incidental pain is better controlled with immediate release forms.
Opioids should be combined with NSAIDs, pain adjuvants and modalities whenever possible. Rapid tapering of the opioids (25% less every day) is essential once the pain condition improves.
Complications and side effects of PCA:
NOTE: Patients, family, staff should all be informed that only the patient should press the PCA button.
Please refer to pain management guidelines in the clinical protocols of Loyola EMR for further details.