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PEDIATRIC ANESTHESIA

The Safety of Patient-Controlled Analgesia by Proxy in Pediatric Oncology Patients

Doralina L. Anghelescu, MD^*, Laura L. Burgoyne, BM, BS, FANZCA^*, Linda L. Oakes, RN, MSN, CCNS, and Debora A. Wallace, RN, BSN^*

Division of *Anesthesia and Nursing Research and Patient Care Services, St. Jude Children’s Research Hospital, Memphis, Tennessee

Address correspondence and reprint requests to Doralina L. Anghelescu, MD, Division of Anesthesia, Mail Stop 130, St. Jude Children’s Research Hospital, 332 North Lauderdale St., Memphis, TN 38105-2794. Address e-mail to doralina.anghelescu{at}stjude.org.

	Abstract

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Between February 1999 and December 2003, we studied the use of patient-controlled analgesia (PCA) to control pain in 1011 children and young adults with cancer, by evaluating 4972 24-h periods of PCA usage, 576 of which involved PCA by proxy. Selection of patients for PCA by proxy was based on younger age group, neuromuscular limitation, expectation of repeated painful procedures, and terminal disease. We measured the incidence of respiratory and neurological complications related to the use of PCA. Major complications were observed during 70 of the 4972 24-h observations, with 28 of 4972, or 0.56%, involving respiratory complications, 35 of 4972, or 0.7%, involving neurological complications, and 7 of 4972 24-h observations, or 0.14%, involving both respiratory and neurological complications. In the PCA by proxy group, two respiratory complications and two neurological complications were observed. Reversal of opioid-related respiratory or neurological effects with naloxone was required in three instances, two in the standard PCA group and one in the PCA by proxy group. Recommendations to ensure continuing safety include careful patient selection, education of proxy users, appropriate documentation, and institutional guidelines.

	Introduction

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Since its introduction more than 20 years ago as a method of postoperative analgesia, patient-controlled analgesia (PCA) has become widely accepted as a convenient, safe, and effective modality for pain control. PCA can be used to deliver self-managed boluses of medication with or without the use of a background infusion. PCA has found a broad spectrum of applications in children with moderate to severe pain, including pain related to surgery, burns, mucositis, bone marrow transplantation, and sickle-cell disease (1–7).

PCA by proxy describes activation of the PCA device by someone other than the patient. The administration of PCA by proxy has been described in adults and children (8,9) but is controversial because of concerns about respiratory depression. We evaluated the prevalence and safety of PCA by proxy at our pediatric cancer center and determined the incidence of respiratory and neurological complications associated with standard (self-managed) PCA and PCA by proxy. We then developed guidelines and an education program for PCA by proxy at our institution.

	Methods

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Complications experienced by patients receiving PCA at our institution are audited by the Pain Clinical Nurse Specialist as a part of the quality assurance program of the Pain Management Service; these data were used in our study. Approval to use this information was obtained from the St. Jude Children’s Research Hospital (St. Jude) IRB. We analyzed data obtained between February 1999 and December 2003. Data collection days occurred on weekdays when the Pain Clinical Nurse Specialist was able to spare time from other duties. During the study period, this was possible on 702 of 1780 days, which was an average of 2.8 days per week. On data collection days, every patient who had received PCA in the previous 24 h was identified by pharmacy records, and their medical case notes were examined for the previous 24-h period. St. Jude is a tertiary-care pediatric facility whose main focus is patient care and research on pediatric cancer and related hematological and infectious diseases. The institution has 56 inpatient beds: 34 for hematology and oncology, 8 for intensive care, and 14 for bone marrow transplantation. Patients range in age from newborns to young adults.

PCA can be initiated by St. Jude physicians without consultation with the Pain Management Service. PCA is administered by using a CADD-Prizm® Variable Infusion Profile Ambulatory Infusion Pump, Model 6101 (Smiths Medical MD Inc., St. Paul, MN). The opioids used for PCA are morphine, fentanyl, and hydromorphone, and guidelines for starting doses are available on the hospital intranet site. The recommended starting bolus doses are: morphine 0.02 mg/kg, hydromorphone 0.004 mg/kg, and fentanyl 0.5 µg/kg, with a 15-min lockout interval. A background infusion can be added, and the recommended starting dose per hour is equal to the bolus dose. These doses are titrated as required, without a defined maximum dose, until adequate analgesia is achieved or dose escalation is limited by uncontrollable side effects.

Vital signs (blood pressure, heart rate, respiratory rate, and temperature) were monitored every 4 h on the floor and every 2 h in the intensive care unit (ICU). Pulse oximetry was performed as appropriate for the clinical condition at the discretion of the clinicians. PCA-specific monitoring consisted of assessing pain intensity and level of consciousness every 4 h. Pain intensity was assessed by using the Faces, Legs, Activity, Cry, Consolability (FLACC) scale, the Wong-Baker FACES scale, or the numerical rating scale, depending on the patient’s age and clinical condition. The patient’s level of consciousness was categorized as alert, asleep, drowsy, confused, or unarousable.

The drugs, doses, equipment, and procedures used for standard PCA and PCA by proxy were identical. This study did not determine the identity of the proxy (i.e., the parent or the nurse).

The medical and nursing records (including the specific PCA record sheet) for each 24-h period were examined by one Pain Clinical Nurse Specialist seeking any indication of a change in respiratory and neurological status. A change in respiratory status included, but was not limited to, any record of decrease in respiratory rate and amplitude or pulse oximetry values. Whether the change was significant was left to the clinical judgment of the caregiver. Neurological change included, but was not limited to, any record of confusion, difficulty in arousing the patient, major personality change, hallucinations, or seizures. Naloxone use was recorded.

	Results

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There were 702 data collection days in the study period, during which we examined 4972 24-h periods of PCA use by 1011 patients. In 576 (11.6%) of these 24-h periods, PCA by proxy was used. Major complications were observed during 70 of 4972 24-h observations, with 28 of 4972, or 0.56%, involving respiratory complications, 35 of 4,972, or 0.7%, involving neurological complications, and 7 of 4972 24-h observations, or 0.14%, involving both respiratory and neurological complications (patient diagnosis and age are shown in Tables 1 and 2). Four-thousand-nine-hundred-two (98.59%) periods of PCA use were free of major adverse events. PCA was self-managed during 26 of the 28 periods in which respiratory status was altered and during 33 of the 35 periods in which neurological changes were reported. Therefore, serious side effects occurred in only 4 of 576 (0.87%) periods of PCA by proxy. Naloxone was required because of altered respiratory status in two periods (one each in the standard and PCA by proxy group) and because of both altered respiratory and neurological status during one period (in the standard PCA group) (Table 3). One of the periods requiring naloxone occurred in a patient also receiving epidural fentanyl and benzodiazepines and antihistamines. In the other two periods, the patients were receiving benzodiazepines in addition to PCA. To place these events in context, there were 4 patients (4 of 1011) in the study who were receiving epidural opioids in addition to parenteral opioids by PCA. The use of other central nervous system depressants (such as antiemetics and antihistamines with central nervous system depressant side effects) in our population is almost universal.

	Discussion

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At our institution, PCA was given by proxy a substantial proportion of the time (11.6% of 24-hour PCA periods), but the frequency of serious side effects was less during PCA by proxy (0.87%) than during periods of standard PCA use (1.48%). The largest study of pediatric patients treated with PCA by proxy found that 9 of the 240 patients (3.7%) required naloxone for complications (10). The difference between this finding and ours may be explained by several unique characteristics of our patients and their families. Our patients are rarely opioid naïve, and their families are very involved in their care, including the management of computerized infusion pumps. Parents become skilled at detecting changes in their child’s medical status or symptoms. This difference is likely to account for the greater safety of PCA by proxy at our institution, but it also limits the generalizability of our study.

PCA administration by proxy is highly controversial because of concerns about respiratory depression. In our institution, the proxy may be a nurse or a parent, but in other institutions, the practice is limited to nurses (8,11). In July 2003, The Institute for Safe Medication Practices (ISMP) issued a warning against the proxy administration of PCA because of the risk of oversedation and death. Previously, the ISMP had described the case of an adult who died after a hypoxic event related to proxy administration of PCA (ISMP, May 29, 2002). Facilities that provide PCA by proxy or nurse-controlled analgesia were advised to establish protocols to identify suitable patients and to educate staff and family members. In December 2004, the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) issued a sentinel event alert regarding unauthorized administration of PCA by proxy. Although the alert specifically stated that it did not address situations of authorized usage, it recommended identifying patients who may need enhanced monitoring when receiving PCA by proxy.

PCA by proxy has been described for cancer pain in children with advanced malignancy (8). The 4 patients in that series were not opioid-naïve, and all received proxy boosts by a nurse, with no reported episodes of hypoxemia. PCA by proxy has also been described in the management of postoperative pain in children undergoing scoliosis surgery who were unable to use standard PCA because of their developmental level or upper extremity weakness (11). There were no significant adverse outcomes, but the number of patients was small, and the study was conducted in an ICU. The patients who received PCA by proxy were found to have received less morphine per kilogram than a comparison group of patients who received standard PCA, although pain scores and patient satisfaction scores were similar. Monitto et al. (10) published an observational study of 240 episodes of PCA by proxy in 212 children less than six years of age. Nine patients required naloxone: 5 (1.7%) for PCA-related apnea or oxygen desaturation, 3 for sedation, and 1 to facilitate tracheal extubation. In adults, PCA by proxy has been studied only in tracheally intubated patients in an ICU (12,13). Analgesia was found to be as effective as standard PCA, and no major respiratory events were noted.

A recent adult meta-analysis, based on a wide definition of respiratory depression, reported a rate of respiratory depression of 0.3%–17% (14). The use of a background infusion, advanced age, concomitant sedative/hypnotic use, and proxy boosts by family and health care workers were cited as contributing factors (15–17). Studies in children include a series of 100 adolescent patients undergoing spinal fusion who received morphine PCA; seven cases (7%) of respiratory depression were reported (18). An Italian study of 62 patients aged 4–17 years, who received morphine PCA with background infusion for chronic or postoperative pain, reported mild sedation in 2 children (3.2%) and transient respiratory depression in 1 (1.6%) (19). A study of 59 pediatric patients who received morphine PCA alone (n = 32) or PCA plus background infusion (n = 27) after major orthopedic surgery reported no episodes of clinically significant respiratory depression (20). Our overall rate of respiratory depression associated with the use of PCA (0.56%) compares favorably to the lower end of the reported range in adults and is somewhat less than that of the smaller pediatric studies.

After reviewing the clinical experience of our institution, the available reports, and the recommendations of the ISMP, (ISMP Medication Safety Alert, May 29, 2002) and JCAHO (JCAHO Sentinel Event Alert, Issue 33, December 20, 2004), we developed hospital guidelines for the management of PCA by proxy. These guidelines cover patient selection, the use of background infusions, the need for a physician’s order for proxy use, education of parents who will be proxies, and appropriate documentation.

Our guidelines consider four categories of patients to be candidates for PCA by proxy. First are those who are not able to operate a PCA because of age or cognitive ability and are frequently <5 years of age. Second are those who have neuromuscular impairment (e.g., post-bone marrow transplant neuropathy) that prevents their operation of a PCA pump. Third are patients who must undergo painful procedures such as dressing changes, and fourth are patients receiving end-of-life care. Such patients may be unable to administer PCA for various reasons, including physical weakness, intermittent confusion, and sedation caused by other drugs.

Our next step was to implement an education program for parents on the administration of PCA by proxy. The program incorporates written materials and an instructional video and emphasizes that the device must be activated only when the child indicates that he or she is in pain, not when the child is asleep. Nursing education comprises training on pain assessment during orientation, yearly pain competency testing, and various educational sessions throughout the year. Documentation will be standardized to include physician orders specifying whether the child, the parent, or the nurse is to operate the PCA. The responsible health care professional must document the completion of appropriate parent education (Table 4).

Our study did not evaluate the efficacy of pain control. We noted the range of pain scores over each 24-hour period, but their extreme variability made it difficult to interpret their significance. Therefore, we cannot exclude the under treatment of pain. We do, however, have an institutional policy that immediate intervention is to be considered when a pain score is more than 5 of 10, and the patient is to be reassessed within one hour to assure that the score decreases to less than 5 of 10. Another limitation of our study is that the doses we used were not standardized. Despite institutional guidelines for initiation of therapy, the nature of our patient population often requires upward titration, particularly during end-of-life care. Therefore, our results were obtained from patients receiving many different dose regimens.

There are limitations to the design of the study, in particular, to it being retrospective. We relied on the medical records made by nursing and medical staff who were not given specific instructions as to what to report over and more than the education given regarding PCA record keeping. However, we did not limit our adverse incidents to a specific list, which may have made it more inclusive. In cases where the nurse keeping records was also the proxy, it is possible that under reporting occurred. We did not have a standardized measure of respiratory depression or hypoxemia. In particular, pulse oximetry and capnography are not a routine part of our monitoring for patients on PCA. We did, however, have naloxone usage as a definitive end-point, which has been used in other studies (10,14). The choice of days was not made in a random fashion, and audits were not conducted on weekends. However, patient data occurring on Sundays were captured by audits on Mondays, but data occurring on Saturdays were not covered in our study.

In conclusion, PCA was administered by proxy during 11.6% of the 4972 24-hour periods for 1011 patients. During the 576 days of PCA by proxy in 131 patients, 5 complications were found. This infrequent occurrence of serious respiratory and neurological complications supports PCA by proxy as being safe in our practice. Our results should not be extrapolated to the general pediatric practice because of the uniqueness of the pediatric cancer population and the lack of separation of parents and health care providers as proxy users in our study. Our results are preliminary, and further studies are required to evaluate efficacy and safety before recommending this modality in other patient populations. In particular, capnography and pulse oximetry would strengthen the safety data provided by the clinical end-points used in our study.

	Footnotes

 
Supported, in part, by The American Lebanese Syrian Associated Charities®

Accepted for publication June 10, 2005.

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