Pain at the Pump

The Hospitalist. 2007 September;2007(09):

September 1, 2007 | The Hospitalist

Hospitalists at UW, including Rob Hoffman, MD, often order the PCA. “It’s very well-liked by patients, who are not dependent on a busy nurse to get their analgesics administered,” Dr. Hoffman says. “The biggest concern, involving overdosing patients who are opioid-naïve, may be somewhat overblown. I haven’t experienced problems with my patients being over narcotized, but I start with a low dose and monitor them frequently.”

PCA technology can tabulate how much analgesic the patient has received during the previous 24 hours, Dr. Hoffman notes. “You know that’s a safe dose for the patient, and you can use it to make the transition to oral medications,” he says.

“Most of the patients I have on PCAs are palliative care patients,” says Rachelle Bernacki, MD, MS, a hospitalist, palliative care physician, and geriatrician at the University of California-San Francisco Medical Center. “I use it somewhat differently for the patients in my hospitalist practice—for example, for those who are experiencing intermittent, unpredictable episodes of abdominal pain. It’s also useful for patients with a need to feel in control of their situation. For constant, predictable pain, it’s better to use an around-the-clock schedule. I also send certain patients home on PCAs, especially if they are going to hospice care.”

Dr. Bernacki notes that some of her patients kiss the PCA button as if it were a long-lost friend, including one she recalls who had a bowel obstruction and had not found relief prior to starting on the PCA. But she also recalls a patient for whom the PCA was not a solution. “He was Cantonese-speaking,” she says. “Despite the presence of an interpreter and several attempts at education, he was never able to understand the connection between the PCA button and relief for his pain. We just couldn’t cross the cultural and language barriers.”

Hospitalists probably underuse the PCA, says Mahmood Shahlapour, MD, hospitalist and palliative care consultant at Chandler Regional Hospital in Chandler, Ariz. “Some hospitalists may feel uncomfortable with it,” he says. “I think it’s important for hospitalists to try to get more experience and comfort to be able to use it for the right patient and the right setting.”

What Is the PCA?

PCA technology as we know it today was pioneered in the early 1970s. Now it’s routine for post-surgical pain management. It is used for patients who have trouble taking oral medications or who need rapid response to acute pain crises. Increasingly, it is also used for patients with moderate to severe chronic pain related to cancer or who are being followed by hospice or palliative care services.

PCA refers both to the process of patient self-administration of parenteral analgesics and to the computerized infusion pump that makes this control possible. Recent advances in pain management also include patient-controlled epidural and transdermal analgesia systems—and other new pain modalities continue to be developed.3 Patients unable to operate the equipment themselves—for example, neonates or infants—may receive nurse-controlled analgesia, but experts say this should only be done within carefully defined parameters.

Considerations for PCA Use

Patient selection: The first requirement of the PCA is a patient able to exercise choice and control. Patients who have physical, psychological, or cognitive impairments or are fearful, demented, confused, unresponsive, paralyzed, or very young (under age 7) are not good candidates. Pain in cognitively impaired patients generally is controlled more effectively with scheduled doses or continuous infusions. Post-operative patients are the most common PCA candidates in the hospital, along with those who have sickle cell, cancer, pancreatitis, or other moderate-to-severe acute pain syndromes. Hospitals may consider developing patient selection criteria as part of their PCA policies.

Drug choice: The most common drug used in PCAs is morphine, considered the gold standard in opioid analgesic treatment. Hydromorphone (Dilaudid) is a second choice, especially for patients who are morphine-intolerant or have kidney failure. Fentanyl is another option, but because it is short acting and more potent, fentanyl (or other nonstandard PCA orders) is often reserved for pain or palliative care services. Meperidine is also used in PCAs, but generally is not recommended as an analgesic by pain experts.

Dosing: Standard equianalgesic conversion ratios between opioids and oral and intravenous routes of administration are foundational tools for hospitalists working with PCAs.7 Typical demand doses of morphine in PCAs for opioid-naïve patients are 0.5, 1.0, or 2.0 mg., although a 1989 study suggested that the lower number may be too little and the higher number too high for effective pain management.8 Another consideration when the initial dosage proves insufficient to manage the patient’s pain is to titrate up the demand dose rather than the basal rate. This approach allows a quick response to immediate pain without “stacking” opioids in the bloodstream. Then, based on the patient’s experience over the previous 24 hours, it will be clearer if the basal rate needs titrating upward—and what is a safe basal rate. “Ideally, what you want is to see the patient taking three to five demand doses per day,” Dr. Bernacki says. “If there are 20 or more, you may have undershot the dosing need—but if there are none, you may have overshot it.”

Safety monitoring: Given that opioids are used with PCAs, it is important to monitor the patient for respiratory depression or inadequate analgesia. Special caution is urged for the opioid-naïve, the very young or old, and patients with high opioid requirements or who have pulmonary conditions, asthma, obesity, or sleep apnea. Orders for PCAs can include monitoring expectations for nurses and instructions to decrease the dose if oversedation is detected. Pain experts emphasize the importance of monitoring respiration quality or depth—not just frequency—and of observing the level of consciousness before rousing the patient; being able to rouse an over-sedated patient may be misleading. Pulse oximetry is a standard monitoring technique, but hospitalists may also consider using capnography (carbon dioxide monitoring), especially for patients considered at higher risk.

Other safety concerns: Two July 2003 alerts by the Institute for Safe Medication Practices included recommendations such as testing PCA equipment before purchasing it. Prescribers must undergo a privileging process, providing ongoing information about PCA safety hazards to clinicians, establishing patient selection criteria for the facility, and developing PCA standard orders. Safety concerns include human error and machine error.9 Approaches such as bar coding recognition devices for medication and double-checking PCA inputs by nurses are recommended. Having oxygen and naloxone (Narcan) readily available is another precaution for using opioids. Standard recommendations for any opioid prescribing include watching out for drug interactions and ordering a stool softener to prevent constipation. —LB