Acute Postoperative Pain

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By Joseph W. Galassi, M.D. 

How Pain Medication is Administered 
When Developing a Pain Medication Plan

How Pain Medication is Administered
In the acute postoperative setting, patients will experience pain to varying degrees depending on the surgery, the patient’s co-morbidities, and type of anesthesia. For example, a patient may arrive in the Post Anesthesia Care Unit (PACU) and have no pain at all due to the use of a regional anesthetic intraoperatively.

An individual patient’s pain management regimen is best individualized based in part on the above mentioned issues. Pain medications take the form of acetaminophen, aspirin, NSAIDS, opioids, local anesthetics, and anti-seizure and anti-depressant medications. They can be administered in a variety of manners including, but not limited to:

PO
If the surgical procedure is relatively minor and a patient is able to take oral meds, this route of administration is most commonly used. Acetaminophen, aspirin, NSAIDS, and/or opioids are often used orally for this level of pain. Sometimes adjuvant analgesics such as anti-seizure medications like gabapentin are added as well.

PR
This route of pain medication administration is sometimes used for those who cannot take PO meds. The downside of rectal administration is the inconsistency of absorption and, therefore, is not often used.

IV
This is the most frequently used route of administration for opioids in the postoperative setting where the pain is moderate to severe and/or the patient cannot take PO medication.

This can be further subdivided into Patient Controlled Analgesia (PCA) or as needed (prn) nurse administered dosing. There are benefits to the former in that patients can titrate their medication to their need and they don’t have to wait for an RN to administer the dose.

Further, it has been shown that they can avoid excessive sedation and other side effects through PCA use.

IM
This route of administration is sometimes used in patients with moderate pain that would require the use of opioids. Typically, the opioid is administered on a prn basis.
Advantages of this route include:
  • Familiarity to physicians and nursing staff that make it relatively safe in terms of avoiding excessive morbidity and mortality 
  • Potentially more cost effective in that no special equipment is needed for this route (may be offset by labor costs or morbidity/mortality) 
  • Gradual onset of analgesia allows for more time to monitor the patient should side effects develop
  • Disadvantages of this route include: 
  • Variability of individual analgesic requirements leads to over and under medication 
  • Fluctuation in blood levels leads to similar patterns of sedation and inadequate analgesia 
  • Pain is enhanced by the delay between patient request and actual time of administration 
  • Worry over side effects and potential for addiction can lead to under medication (this can apply to any route of opioid administration)
IT
This route of administration is typically used for opioids when given concomitantly with a local anesthetic for spinal anesthesia. The advantage of spinally administered morphine is that it’s relatively long duration of action, which can be as much as 24 hours.

As a consequence, patients receiving morphine by this route will generally need less supplemental analgesics via other routes that first day postoperatively. The patient must be monitored for all the usual side effects of opioids during those 24 hours.

Epidural
Similar to intrathecal administration, this can be used for postoperative pain management for surgeries anywhere from the thorax distally to the feet. The advantage of epidural administration is that it generally is administered through a catheter placed in the thoracic or lumbar epidural space (as opposed to the usual single shot intrathecal route) that can be left in for several days or longer in certain clinical circumstances.

The biggest advantage of epidurally administered analgesia is the lower dose of opioids that are used to produce analgesia compared to IV/IM dosing. As a consequence, patients generally have less sedation than IV/IM dosing.

Epidurals usually have a very high satisfaction rate with patients. The disadvantages of epidural catheters are the risk for bleeding upon removal in the anticoagulated postop patient (DVT prophylaxis included) and the increased incidence of urinary retention and need for indwelling foley catheters while receiving epidural opioids.

SQ
Local anesthetics can be administered by the surgeon or anesthesiologist in the area of surgery. For many operations, this is the anesthetic in conjunction with IV sedation. At the very least, wound infiltration using local anesthetics provides some postop analgesia and may incidentally decrease the incidence of postop wound infections.

Topical
Analgesics applied topically in the acute postoperative setting provide limited relief, likely being effective for only small or minor procedures. They are not a good choice in most clinical settings.

Perineural
The application of peripheral nerve blocks using local anesthetics can be accomplished with a single injection or with the placement of an infusion catheter.

Single shot peripheral nerve blocks using a local anesthetic that are commonly performed include upper extremity brachial plexus blocks at one of several locations along the path of the plexus, lumbar plexus blocks or blocks of an individual nerve of the upper or lower extremity. The latter includes blockade of the median, radial, ulnar, femoral and sciatic nerves.

More anesthesiologists are incorporating the addition of a peripheral nerve catheter for more prolonged analgesia. These catheters have the benefit of providing good analgesic effect using local anesthetics only – that is, without the addition of an opioid – for a period of several days.

With the exception of the lumbar plexus and sciatic nerve catheter locations, the issue of bleeding with catheter removal is minimal. Patients may need to supplement their analgesia regimen with oral pain medications, but to a lesser degree than without the local anesthetic.

There are several manufacturers of pain management systems for ambulatory use. They include I-Flo and Stryker.

These companies provide support, education and training in the use of their devices for physicians, nursing, support staff and patients. 

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When Developing a Pain Medication Plan
Choices for pain medications must be individualized to the patient. A number of factors come into play when making decisions about a specific person’s analgesic regimen.

These factors include the patient’s: 
  • Co-morbidities, 
  • Allergies, 
  • Substance use/abuse history, 
  • Prior history of effective/ineffective pain management, 
  • Home support system, 
  • Level of understanding regarding pain management, 
  • Degree of tissue disruption due to the surgical procedure and/or injury requiring the surgical procedure
For example, take a morbidly obese patient with a history of obstructive sleep apnea who requires the use of a CPAP mask at night but doesn’t use it on a regular basis. He or she would not be the best person to give a large amount of opioids to and send home the same day after a large ventral hernia repair.

Anesthesiologists and/or pain medicine physicians are the physician best trained to provide consultative services regarding postoperative analgesic regimens, especially for the more complicated patients. They can be contacted perioperatively to help best prepare an analgesic plan for any given patient. 

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