Patient-controlled analgesia

Patient-controlled analgesia
Intervention
A patient-controlled analgesia infusion pump, configured for epidural administration of fentanyl and bupivacaine for postoperative analgesia
MeSH	D016058

Patient-controlled analgesia (PCA^[1]) is any method of allowing a person in pain to administer their own pain relief.^[2] The infusion is programmable by the prescriber. If it is programmed and functioning as intended, the machine is unlikely to deliver an overdose of medication.^[3]

Routes of administration

Oral

The most common form of patient-controlled analgesia is self-administration of oral over-the-counter or prescription painkillers. For example, if a headache does not resolve with a small dose of an oral analgesic, more may be taken. As pain is a combination of tissue damage and emotional state, being in control means reducing the emotional component of pain.^{[citation needed]}

Intravenous

A patient-controlled analgesia infusion pump, configured for intravenous administration of morphine for postoperative analgesia

In a hospital setting, a PCA refers to an electronically controlled infusion pump that delivers an amount of intravenous analgesic (usually an opioid) that is set by the patient.^[4] PCA can be used for both acute and chronic pain patients. It is commonly used for post-operative pain management, and for end-stage cancer patients.^[5]

Narcotics are the most common analgesics administered through PCAs.^[6][7] It is important for caregivers to monitor patients for the first two to twenty four hours to ensure they are using the device properly.^[8]

Epidural

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 can be used by women in labour, terminally ill cancer patients or to manage post-operative pain.^[5]

Inhaled

In 1968, Robert Wexler of Abbott Laboratories developed the Analgizer, a disposable inhaler that allowed the self-administration of methoxyflurane vapor in air for analgesia.^[9] The Analgizer consisted of a polyethylene cylinder 5 inches long and 1 inch in diameter with a 1 inch long mouthpiece. The device contained a rolled wick of polypropylene felt which held 15 milliliters of methoxyflurane. Because of the simplicity of the Analgizer and the pharmacological characteristics of methoxyflurane, it was easy for patients to self-administer the drug and rapidly achieve a level of conscious analgesia which could be maintained and adjusted as necessary over a period of time lasting from a few minutes to several hours. The 15 milliliter supply of methoxyflurane would typically last for two to three hours, during which time the user would often be partly amnesic to the sense of pain; the device could be refilled if necessary.^[10] The Analgizer was found to be safe, effective, and simple to administer in obstetric patients during childbirth, as well as for patients with bone fractures and joint dislocations,^[10] and for dressing changes on burn patients.^[11] When used for labor analgesia, the Analgizer allows labor to progress normally and with no apparent adverse effect on Apgar scores.^[10] All vital signs remain normal in obstetric patients, newborns, and injured patients.^[10] The Analgizer was widely utilized for analgesia and sedation until the early 1970s, in a manner that foreshadowed the patient-controlled analgesia infusion pumps of today.^{[12][13][14][15]} The Analgizer inhaler was withdrawn in 1974, but use of methoxyflurane as a sedative and analgesic continues in Australia and New Zealand in the form of the Penthrox inhaler.^{[16][17][18][19][20][21]}

Transcutaneous

Transcutaneous delivery systems, including iontophoretic systems, are available. These are popular for administration of opioids such as fentanyl, or local anesthetics such as lidocaine. Iontocaine is one example of such a system.

Advantages and disadvantages

Advantages of the use of Patient Controlled Analgesia include the lack of waiting time for patients requiring pain medication before a caregiver can increase the dosage of medication. In this way, the patient spends less time in pain and as a corollary to this, patients tend to use less medication than in cases in which medication is given according to a set schedule.^[5] Disadvantages include the possibility that the button can accidentally pressed, delivering an unneeded increase in the dosage of the medication. Many newer systems have mechanisms to prevent this. Also, if a PCA device is not programed properly for a patient it can result in an under-dose or overdose in a medicine.^[22] The system may also be inappropriate for certain individuals, for example patients who present with learning difficulties or confused patients. Patients with poor manual dexterity may be unable to press the buttons as would those who are critically ill. Furthermore, PCA may not be appropriate for younger patients.

History

The PCA pump was developed and introduced by Philip H. Sechzer in the late 1960s and described in 1971.^[23]

References

Further reading

• Crombie, JM (1876). "On the self-administration of chloroform". The Practitioner 16 (2): 97–101. ISSN 0032-6518. http://books.google.com/?id=H2UCAAAAYAAJ&pg=PA97&lpg=PA97&dq=self-administration+chloroform#v=onepage&q=self-administration%20chloroform&f=false. Retrieved 2010-11-23. 
• Klieman RL, Lipman AG, Hare BD, MacDonald SD: A comparison of morphine administered by patient-controlled analgesia and regularly scheduled intramuscular injection in severe, postoperative pain. J Pain Sympt Manag 1988;3:15-22
• Sechzer, PH (1971). "Studies in pain with the analgesic-demand system". Anesthesia and Analgesia 50 (1): 1–10. doi:10.1213/00000539-197101000-00001. ISSN 0003-2999. PMID 5100236. 
• Fast Fact and Concept #085: Epidural Analgesia, End of Life/Palliative Education Resource Center, Medical College of Wisconsin
• White PF: use of patient-controlled analgesia for the treatment of acute pain. JAMA 1988;259:242-247