Patient-controlled analgesia (PCA) is a widely used method for controlling pain in settings ranging from surgical floors to obstetrical units and intensive care. As PCA therapy becomes more commonplace the possibility of decreased vigilance on the part of the caregivers to monitor for complications becomes possible. Patient-controlled analgesia is viewed as a safe and effective method for administering medication for short-term relief of pain. However, there are complications associated with its use. These range from programming errors to nausea and vomiting to respiratory depression. Now may be an appropriate time to revisit monitoring guidelines for the use of PCA devices.

Patient-controlled analgesia is usually administered by IV or epidural routes. Pain medication is given as a small continuous (basal) rate with bolus infusions when the patient pushes a button. This allows the patient to have nearly continuous pain control without the peak and valley effects associated with IM and oral administration. Patient-controlled analgesia works well to control short-term pain such as that experienced after surgery and during painful procedures. It has gained popularity with patients, because they have a feeling of control over their pain relief. In fact, many patients are asking their doctors to prescribe it.

The setup for IV or epidural administration of PCA is the same. A special syringe is filled with a pre-determined concentration of medication, usually morphine or Demerol. The syringe is inserted into a special PCA pump that controls the rate of the infusion and calculates the amount of time between patient-requested doses. The PCA pump can be set to prevent an overdose by controlling the number of doses, and hence the amount of medication. Pain medication requirements differ among patients, therefore the nurse and doctor must determine the optimal dose for each patient and program it into the pump.

PCA pumps are designed to accept a variety of medications and drug concentrations. Complications can occur due to errors in programming the PCA pump. Therefore, the nurse initiating therapy must program the pump to deliver the prescribed dosage based on the drug concentration. Incorrect drug concentrations, incorrect rates, and calculation errors can lead to inaccurate drug delivery. Factors associated with programming errors include inexperienced or poorly trained nurses, mathematical errors, and a user interface that is difficult to use (Eade, D.M., 1997). Better training with competency reviews could help reduce errors from training deficiency.

Pain management centers often use larger doses of narcotics to treat pain. In fact, some experts believe that there is no upper limit on the dosage of morphine sulfate in the patient with intractable pain. In addition, many practitioners are using high dose narcotics along with potentiating agents, such as Phenergan or combination therapy with non-narcotic pain medicines, such as Toradol.

Giving pain medications can lead to unwanted complications. The more severe complications are respiratory depression, respiratory arrest, and allergic reaction. These can be life threatening and require a high level of observation to prevent. Less severe complications include nausea, vomiting, constipation, and increased somnolence. The combination of respiratory depression and neurological depression can make the patient at risk for atelectasis, pulmonary edema, and acute respiratory distress syndrome (ARDS).

Some strategies to prevent complications include closely monitoring the patient's response to changes in dosage. Respiratory depression can be a fatal complication of narcotic administration, and is caused by narcotic depression of the central nervous system. Sedation from narcotics can lead to decreased respiratory effort and cause atelectasis. Respiratory or neurological depression should be monitored closely in any patient receiving PCA. Pulmonary interventions such as coughing, deep breathing, forced expiration, and incentive spirometry should be implemented hourly to prevent respiratory complications. An interface or connection to an apnea monitor or pulse oximetry monitor could alert the nurse of impending respiratory depression.

The narcotics used in PCA pumps can cause nausea and vomiting. One study (Snell, et al.) found that patients taking intramuscular pain medications used three times as much antiemetics as the PCA group. However, this may be due to arbitrary pre-mixture with narcotics by nurses. Complaints of nausea should be taken seriously, especially in post-operative patients who are at risk for aspiration due to the residual effects of anesthesia. Aspiration of stomach acid can cause pneumonitis and acute respiratory distress syndrome.

Hourly monitoring of patient status may be necessary if the patient's response to narcotic is unknown, and after changing the type of medication or dosage. Increased observation should be exercised with patients receiving multiple pain medications. Lastly, reversing agents such as Narcan for narcotics, and Rumazican for benzodiazepam should be readily available for use if oversedation or respiratory depression occurs.

In conclusion, PCA pumps provide valuable relief for short-term pain. However, their use can be associated with respiratory depression and other complications, especially at higher doses. Individualized therapy and close monitoring are essential to provide for patient safety. Hospitals should have clearly defined protocols for the administration of PCA and monitoring for side effects to prevent untoward patient outcomes.

Resources:

Intravenous Nurses Society
Pain dot com

Nursing Continuing Education