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Patient-Controlled Analgesia

A Guide For Doctors

Matthew G. Beckwith, M.D.

What Is Patient-Controlled Analgesia?
Patient-controlled Analgesia (PCA) is intravenously administered pain medicine under the patient's control. The patient has a button on the end of a cord which she can push at will whenever more pain medicine is desired. This button will only deliver more pain medicine at pre-determined intervals, as programmed by the doctor's order.

Rationale
The modern approach to pain control is to give the patient control over the administration of the analgesia so that she doesn't have to wait for the nurse to draw up the medicine and come down the hall to administer it.

Disadvantages of the Old Approach to Pain Control
There are several drawbacks to the old on-demand approach to pain control:

Safety
Patient-controlled Analgesia (PCA) is quite safe. This is because the patient doesn't get the analgesia unless she pushes the button. If the patient gets too much narcotic, she falls asleep and can no longer push the button. Thus, respiratory depression is extremely unlikely. The only way respiratory depression is a possibility is if the basal rate is set too high. So, if you want to completely avoid this possibility, always set the basal rate to zero.

Method
Patient-controlled Analgesia (PCA) orders are quite simple. They comprise the name of the medication (Morphine, Demerol, Dilaudid, et cetera), 3 required parameters, plus a few optional parameters, as follows:

Required Parameters
  1. Basal Rate: This is the amount of medication that continually runs without the patient requesting it. In other words, this is an automatic drip rate, and is not patient-controlled at all. You can set this to zero if you want, which would effectively make all of the analgesia patient-controlled.
  2. Demand Amount: This is the amount of medication delivered whenever the patient pushes the button.
  3. Lockout Interval: This is the number of minutes for which the button is inactivated after it is pushed. In other words, once the patient pushes the button for medication, the button is inactivated for this number of minutes. For example, if the lockout interval is 10 minutes, the patient can only push the button once every 10 minutes.
Optional Parameters
  1. Bolus Amount. You can specify a bolus amount. This is a one-time amount of analgesic to be given at the beginning of the treatment, to get the patient started on the pain medicine. In some institutions, and on some wards, bolus amounts are not allowed.
  2. One-hour Maximum, Four-hour Maximum: Depending on the institution, one- and four-hour maxima can be specified. This is just a safeguard. If at your institution this is a standard, you just add together the basal rate and the demand amounts for one or four hours.
  3. Medications for itching: Narcotics can cause itching, so some canned PCA orders specify antihistamines for itching. However, I don't recommend this. After all, this would be an allergic reaction, and why would you want to continue to give a medication to which a patient is allergic?
  4. Narcan: You can prescribe Narcan for excessive sedation if you like. In fact, there are canned PCA orders at most institutions, and you may want to use these, with some modification, rather than just free-hand your PCA orders anyway.
  5. Call MD for inadequate or excessive analgesia. This is a phrase I like to add to all of my PCA orders.

Examples
Here are some examples: