Patient controlled analgesia (PCA) is a pain control system that allows patients to manage their own pain rather than wait for a nurse or other healthcare professional to give more medication. PCA uses a computerized pump that is hooked up to the patient’s intravenous line (IV) and lets the patient safely self-administer small doses of a prescribed opioid as needed for pain control. Several safety features exist with PCA to make certain patients do not receive too much analgesia. The portable device delivers a preset dosage with an adjustable “lock-out” that controls the frequency of dose administration and the maximum allowable amount during a specified time interval.
As the name implies, it is intended for the patient to control. The patient can receive the pain medication by pressing a button, allowing that individual greater control in managing the pain he or she is experiencing. The device provides a built-in safety check because an over-sedated patient is not able to push the button to cause a harmful or even fatal overdose. Patient-controlled analgesia bypasses the delays inherent in traditional analgesia administration (the demand cycle). Medication administered by IV produces a rapid pain response and greater consistency in patient response.
PCA is an effective and efficient method of controlling pain. When it is used as prescribed and intended the risk of over-sedation is significantly reduced; however, when a family member or healthcare professional administers PCA, serious adverse events can result. When family members, caregivers, or clinicians, who are not authorized, become involved in administering the analgesia for the patient it is called “PCA by proxy.”
According to a warning issued by the Joint Commission on Accreditation of Healthcare Organizations (JCAHO), well-intended family members and caregivers who want to keep the patient from suffering may actually be putting them at risk by becoming involved in administering PCA. Over the past several years the Institute for Safe Medical Practices (ISMP) has issued a number of warnings and reports alerting healthcare organizations and practitioners to safety issues related to PCA by proxy. With PCA, the patient provides a measure of safety because the analgesia is delivered at doses lower than what is needed for sedation because an over sedated patient will not push the button to give additional opiate. Bypassing this built-in safety feature by proxy is potentially dangerous. PCA by proxy errors are readily preventable and can be virtually eliminated through appropriate education and training of staff and family members.
Nurse-controlled analgesia using a PCA infusion device may be useful in some critical care settings and offers advantages over traditional medication administration for pain management; but, protocols and appropriate assessment tools must be in place to gauge:
Take the case of a 45 year old who was hospitalized for major abdominal surgery. One of her daughters that had some medical training, but not specific to post operative medications, did not want her mother to suffer and began pushing the PCA button whenever her mother moaned or seemed uncomfortable. The well-intentioned daughter over sedated her mother so much that respiratory depression began to set in as evidenced by decreased oxygen saturation levels. While decisions were being made as to the need for intubation, it was identified that the daughter was pushing the PCA button rather than the patient. The patient was properly educated prior to surgery but family members were not warned of the risks of PCA by proxy.
Information from an ISMP safety alert describes a 72-year old woman who underwent cancer surgery and her surgeon prescribed PCA with a 2 mg morphine loading dose and 1 mg every 10 minutes as needed (6 mg maximum dose per hour). Initially, the patient was restless and agitated in the post anesthesia care unit, but she remained obtunded after surgery. Despite the patient’s ability to verbalize pain, nurses pushed the PCA button and delivered frequent doses of morphine over the next 48 hours. Subsequently, the patient suffered a cardiorespiratory arrest and seizure, leading to hypoxic encephalopathy. She died several months later without ever regaining consciousness.
Nurse-controlled analgesia was not appropriate in this case. The patient was not an appropriate candidate for PCA and proper assessment tools were not used as guides for nurse-controlled analgesia. The patient was at risk for toxicity because she was obtunded, obese, and had compromised lung capacity (COPD). Although vital signs were recorded periodically, oxygen saturation monitoring was not used. The nurses did not recognize the signs of morphine toxicity and they continued to administer the analgesic despite serious hypotension and very shallow respirations.
The most common PCA errors are usually the direct result of family members or healthcare professionals administering doses for the patient with the intent of keeping them comfortable. This well-intentioned effort can result in over-sedation, respiratory depression, and even death. The United States Pharmacopia (USP) and the Institute for Safe Medication Practices (ISMP) medication errors database revealed a combined total of 6,069 PCA errors. Of this number:
The root-cause issues related to PCA errors are:
Since an important safety feature with PCA is that the patient delivers each dose, candidates for PCA should have the mental alertness and cognitive, physical, and psychological ability to manage their own pain. PCA criteria based selection should include the following:
When assessing patients for nurse-controlled analgesia, identify risk factors that may suggest increased monitoring such as age, weight, and pre-existing conditions including allergies and current medication use.
PCA would not be indicated for patients with cognitive impairment, hemodynamic impairment, or respiratory impairment. Infants and young children under 10 years of age are not candidates for PCA; however, a PCA pump may be used. Over the past 5 years the Departments of Anesthesiology and Critical Care Medicine and Pediatrics at Johns Hopkins Hospital, Baltimore, treated non-surgical and postoperative pain in children less than 6 years of age using a PCA pump to deliver small doses of continuous IV opioid infusions supplemented by parent and nurse controlled opioid bolus dosing. This method provided effective pain relief in most children experiencing non-surgical or postoperative pain. The observed incidence of vomiting and pruritis was similar to that seen in older patients treated with patient-controlled analgesia. However, significant respiratory depression did occur, thus reinforcing the need for close patient monitoring of all patients receiving continuous and bolus doses of IV analgesia.
Even at therapeutic doses, opiates can suppress respiration, heart rate, and blood pressure. The ISMP recommends using appropriate sedation and pain assessment tools to monitor the patient’s response to PCA. Monitor the patient more frequently in the first 24 hours, when the effects of opioids on intellectual functioning are less predictable, and at night, when nocturnal hypoxia can cause serious problems. Assessment includes:
Assessment should be done:
Most patients who are suitable candidates for PCA can be taught how to use the device successfully; however, patients who have been taught to use the device during the immediate postoperative period have often been too groggy to fully understand its use. These patients often report poor pain control during the first 12 hours after surgery. PCA education should be included as part of the pre-operative teaching with reinforcement of teaching in the immediate pre-operative period.
Alert, intelligent patients also have misunderstood the directions for use. The most often misunderstanding is that they must press the button every 6 minutes or so, even when they are sleepy and comfortable. At times, family members have awakened patients so that they can press the button frequently. Family members may press the button for the patient if they have not been alerted to avoid PCA by proxy.
Some of the opiates used for PCA have similar names and packaging, which has led to drug selection errors. Pre-filled syringes of meperidine and morphine have been packaged in similar-looking boxes. Morphine is available in pre-filled syringes in two concentrations, but the packaging may not help to quickly differentiate the two strengths. Differentiation between opiates with and without preservatives is not prominent on labels. All pharmacy-applied labels may look similar on prepared syringes or bags. Name similarities have led to inadvertent mix-ups between morphine and hydromorphone or the mistaken belief that hydromorphone is the generic name for morphine.
Programming errors when setting up the PCA pump is, by far, the most frequently reported practice-related issue. Incorrect transcription of the prescription into pharmacy computers or medication administration records have occurred, this is often related to look alike product names. Calculation errors have been made when determining dose or rate of infusion. IV admixture errors, unavailability of hydromorphone in pre-filled syringes, or premixed bags necessitates IV admixture of this opiate. Drug shortages, most notably with Fentanyl, also have required the use of less familiar products such as sufentanil, which has led to serious dosing errors.
Programming a PCA pump requires multiple steps, but the pump’s design is often far from intuitive. Most programming errors have resulted because concentration settings for opiates such as morphine default to 0.1 mg/ml or 1 mg/ml, but a higher concentration may be used. Other design flaws that have facilitated programming errors include:
Inadequate training of staff may contribute to PCA errors. Staff may not always receive adequate training in pump programming and may not retain their proficiency once trained if multiple pumps are in use. PCA therapy may be encountered infrequently. Prescribers may not undergo a credentialing process designed to verify proficiency with this form of pain management.
The PCA order itself can be a source of errors. Physicians may make mistakes in converting an oral opiate to the IV dose route. The most problematic conversion is hydromorphone, which has an oral to IV conversion range of 3:1 to 5:1. Physicians have prescribed a drug to which the patient is allergic or have selected an opiate that is not appropriate for the patient. Like meperidine for patients with renal impairment. The dosage may be wrong. Clinicians have been known to misunderstand verbal or written orders. Concurrent orders for other opiates (oral or parenteral) can overlap while the PCA is in use and can resulted in opiate toxicity.
The Joint Commission offers the following safe practice recommendations:
1. Develop criteria for selecting appropriate patients to receive PCA and nurse controlled analgesia.
2. Carefully monitor patients. Even at therapeutic doses, opiates can suppress respiration, heart rate and blood pressure. Oximetry and/or capnography monitoring may be appropriate in some cases.
3. Teach patients and families about proper use of PCA. Provide written instructions to family members that instruct them NOT to administer PCA doses.
4. Alert staff to the dangers of administering a dose for the patient outside of a nurse controlled analgesia protocol.
ISMP Tips for prescribing PCA:
PCA is an effective and efficient method of controlling pain, and when used as prescribed and intended, the risk of over sedation is significantly reduced. Some patients are not appropriate candidates for PCA because of age, mental state, level of consciousness, intellectual capacity, or other factors that require close monitoring of the delivery of pain medications. PCA by Proxy errors are usually the direct result of family members or healthcare professionals administering doses for the patient with the intent of keeping them comfortable. PCA by Proxy errors are readily preventable and can be virtually eliminated through timely and appropriated education for patients, family members, and staff caring for patients with PCA. The dangers of having others pressing the medication button needs to be understood by all involved in the care of the patient.
Hill, Charlene D. Joint Commission Issues Alert on Dangers of Family Members, Caregivers Delivering Patient Controlled Analgesia; JCAHO News Release (2004)
ISMP Medication Safety Alert! May 29, 2002, Institute for Safe Medication Practices
ISMP Medication Safety Alert! July 10, 2003, Institute for Safe Medication Practices
ISMP Medication Safety Alert! July 24, 2003, Institute for Safe Medication Practices
Joint Commission on Accreditation of Healthcare Organizations Sentinel Event Alert – Issue 33 – December 20, 2004
Maddox, R.R.; Williams, C.K.; Fields, M. Respiratory Monitoring in Patient-Controlled Analgesia, AM J Health-Sys Pharm 2004; 2628-9
Monitto, GL.; Greenberg, RS; Kost-Byerly, S.; Wentzel, R.; Billett, C.; Lebet, RM.; The Safety and efficacy of parent-/nurse-controlled analgesia in patients less than six years of age; Abstract Entrez PubMed – Clinical Trials (2005)
Murhammer, Joan; Ross, Mary; Bebout, Kevin; Patient-Controlled Analgesia: Review of Safety Issues: Rx Update: August 2003
Nettina, Sandra M. Lippincott Manual of Nursing Practice, 7th Ed. Lippincott, Philadelphia (2001)