Patient-controlled analgesic administration. A comparison of steady-state morphine infusions with bolus doses

Pharmacological Treatment of Cancer Pain: Alternative Routes of Opioid Administration

Cancer-related pain is present in 51% of patients at various stages of the disease, and the incidence increases up to 74% in advanced and terminal stages. The World Health Organization proposed and issued very simple guidelines for the pharmacologic treatment of cancer-related pain. According to the guidelines, opioid analgesics are the mainstay of analgesic therapy, and the first choice for drug administration is considered to be the oral route. However, in some clinical situations, the oral route is not feasible, and analgesic drugs consequently have to be administered via an alternative route. For example, this is the case when the patient presents vomiting, bowel obstruction, severe dysphagia, mental confusion and when the opioid dose has to be increased drastically in order to achieve adequate pain control. This review of the literature is aimed at describing the indications, the limits and the main aspects of the pharmacokinetics and pharmacodynamics relative to the alternative routes of administration of opioids most commonly used in clinical practice. Sublingual, rectal, subcutaneous, intravenous, transdermal and spinal administration routes are examined.

Systematic review of antimicrobials, mucosal coating agents, anesthetics, and analgesics for the management of oral mucositis in cancer patients

PURPOSE

The aim of this project was to develop clinical practice guidelines on the use of antimicrobials, mucosal coating agents, anesthetics, and analgesics for the prevention and management of oral mucositis (OM) in cancer patients.

METHODS

A systematic review of the available literature was conducted. The body of evidence for the use of each agent, in each setting, was assigned a level of evidence. Based on the evidence level, one of the following three guideline determinations was possible: recommendation, suggestion, or no guideline possible.

RESULTS

A recommendation was developed in favor of patient-controlled analgesia with morphine in hematopoietic stem cell transplant (HSCT) patients. Suggestions were developed in favor of transdermal fentanyl in standard dose chemotherapy and HSCT patients and morphine mouth rinse and doxepin rinse in head and neck radiation therapy (H&N RT) patients. Recommendations were developed against the use of topical antimicrobial agents for the prevention of mucositis. These included recommendations against the use of iseganan for mucositis prevention in HSCT and H&N RT and against the use of antimicrobial lozenges (polymyxin-tobramycin-amphotericin B lozenges/paste and bacitracin-clotrimazole-gentamicin lozenges) for mucositis prevention in H&N RT. Recommendations were developed against the use of the mucosal coating agent sucralfate for the prevention or treatment of chemotherapy-induced or radiation-induced OM. No guidelines were possible for any other agent due to insufficient and/or conflicting evidence.

CONCLUSION

Additional well-designed research is needed on prevention and management approaches for OM.

Interventions for treating oral mucositis for patients with cancer receiving treatment

BACKGROUND

Treatment of cancer is increasingly effective but associated with short and long term side effects. Oral side effects, including oral mucositis (mouth ulceration), remain a major source of illness despite the use of a variety of agents to treat them.

OBJECTIVES

To assess the effectiveness of interventions for treating oral mucositis or its associated pain in patients with cancer receiving chemotherapy or radiotherapy or both.

SEARCH STRATEGY

Electronic searches of Cochrane Oral Health Group and PaPaS Trials Registers (to 1 June 2010), CENTRAL via The Cochrane Library (to Issue 2, 2010), MEDLINE via OVID (1950 to 1 June 2010), EMBASE via OVID (1980 to 1 June 2010), CINAHL via EBSCO (1980 to 1 June 2010), CANCERLIT via PubMed (1950 to 1 June 2010), OpenSIGLE (1980 to 1 June 2010) and LILACS via the Virtual Health Library (1980 to 1 June 2010) were undertaken. Reference lists from relevant articles were searched and the authors of eligible trials were contacted to identify trials and obtain additional information.

SELECTION CRITERIA

All randomised controlled trials comparing agents prescribed to treat oral mucositis in people receiving chemotherapy or radiotherapy or both. Outcomes were oral mucositis, time to heal mucositis, oral pain, duration of pain control, dysphagia, systemic infection, amount of analgesia, length of hospitalisation, cost and quality of life.

DATA COLLECTION AND ANALYSIS

Data were independently extracted, in duplicate, by two review authors. Authors were contacted for details of randomisation, blindness and withdrawals. Risk of bias assessment was carried out on six domains. The Cochrane Collaboration statistical guidelines were followed and risk ratio (RR) values calculated using fixed-effect models (less than 3 trials in each meta-analysis).

MAIN RESULTS

Thirty-two trials involving 1505 patients satisfied the inclusion criteria. Three comparisons for mucositis treatment including two or more trials were: benzydamine HCl versus placebo, sucralfate versus placebo and low level laser versus sham procedure. Only the low level laser showed a reduction in severe mucositis when compared with the sham procedure, RR 5.28 (95% confidence interval (CI) 2.30 to 12.13).Only 3 comparisons included more than one trial for pain control: patient controlled analgesia (PCA) compared to the continuous infusion method, therapist versus control, cognitive behaviour therapy versus control. There was no evidence of a difference in mean pain score between PCA and continuous infusion, however, less opiate was used per hour for PCA, mean difference 0.65 mg/hour (95% CI 0.09 to 1.20), and the duration of pain was less 1.9 days (95% CI 0.3 to 3.5).

AUTHORS' CONCLUSIONS

There is weak and unreliable evidence that low level laser treatment reduces the severity of the mucositis. Less opiate is used for PCA versus continuous infusion. Further, well designed, placebo or no treatment controlled trials assessing the effectiveness of interventions investigated in this review and new interventions for treating mucositis are needed.

Orofacial pain in cancer: part II--clinical perspectives and management

Cancer-associated pain is extremely common and is associated with significant physical and psychological suffering. Unfortunately, pain associated with cancer or its treatment is frequently under-treated, probably due to several factors, including phobia of opioids, under-reporting by patients, and under-diagnosis by healthcare workers. The most common etiology of cancer pain is local tumor invasion (primary or metastatic), involving inflammatory and neuropathic mechanisms; these have been reviewed in Part I. As malignant disease advances, pain usually becomes more frequent and more intense. Additional expressions of orofacial cancer pain include distant tumor effects, involving paraneoplastic mechanisms. Pain secondary to cancer therapy varies with the treatment modalities used: Chemo-radiotherapy protocols are typically associated with painful mucositis and neurotoxicity. Surgical therapies often result in nerve and tissue damage, leading, in the long term, to myofascial and neuropathic pain syndromes. In the present article, we review the clinical presentation of cancer-associated orofacial pain at various stages: initial diagnosis, during therapy (chemo-, radiotherapy, surgery), and in the post-therapy period. As a presenting symptom of orofacial cancer, pain is often of low intensity and diagnostically unreliable. Diagnosis, treatment, and prevention of pain in cancer require knowledge of the presenting characteristics, factors, and mechanisms involved.

Interventions for treating oral mucositis for patients with cancer receiving treatment

BACKGROUND

Treatment of cancer is increasingly effective but associated with short and long term side effects. Oral side effects, including oral mucositis (mouth ulceration), remain a major source of illness despite the use of a variety of agents to treat them.

OBJECTIVES

To assess the effectiveness of interventions for treating oral mucositis or its associated pain in patients with cancer receiving chemotherapy or radiotherapy or both.

SEARCH STRATEGY

Computerised searches of Cochrane Oral Health Group's Trials Register; Cochrane Pain, Palliative and Supportive Care Group's Trials Register; CENTRAL; MEDLINE and EMBASE were undertaken. Reference lists from relevant articles were searched and the authors of eligible trials were contacted to identify trials and obtain additional information. Date of the most recent searches June 2006: CENTRAL (The Cochrane Library 2006, Issue 2).

SELECTION CRITERIA

All randomised controlled trials comparing agents prescribed to treat oral mucositis in people receiving chemotherapy or radiotherapy or both. Outcomes were oral mucositis, time to heal mucositis, oral pain, duration of pain control, dysphagia, systemic infection, amount of analgesia, length of hospitalisation, cost and quality of life.

DATA COLLECTION AND ANALYSIS

Data were independently extracted, in duplicate, by two review authors. Authors were contacted for details of randomisation, blindness and withdrawals. Quality assessment was carried out on these three criteria. The Cochrane Oral Health Group statistical guidelines were followed and risk ratio (RR) values calculated using fixed effect models.

MAIN RESULTS

Twenty-six trials involving 1353 patients satisfied the inclusion criteria. Four agents, each in single trials, were found to be effective for improving (allopurinol RR 3.33, 95% confidence interval (CI) 1.06 to 10.49; granulocyte macrophage-colony stimulating factor RR 4.23, 95% CI 1.35 to 13.24; immunoglobulin RR 1.81, 95% CI 1.24 to 2.65; human placentral extract RR 4.50, 95% CI 2.29 to 8.86) or eradicating mucositis (allopurinol RR 19.00, 95% CI 1.17 to 307.63). Three of these trials were rated as at moderate risk of bias and one as at high risk of bias. The following agents were not found to be effective: benzydamine HCl, sucralfate, tetrachlorodecaoxide, chlorhexidine and 'magic' (lidocaine solution, diphenhydramine hydrochloride and aluminum hydroxide suspension). Six trials compared the time to heal and mucositis was found to heal more quickly with two interventions: granulocyte macrophage-colony stimulating factor when compared to povidone iodine, with mean difference -3.5 days (95% CI -4.1 to -2.9) and allopurinol compared to placebo, with mean difference -4.5 days (95% CI -5.8 to -3.2). Three trials compared patient controlled analgesia (PCA) to the continuous infusion method for controlling pain. There was no evidence of a difference, however, less opiate was used per hour for PCA, and the duration of pain was shorter. One trial demonstrated that pharmacokinetically based analgesia (PKPCA) reduced pain compared with PCA: however, more opiate was used with PKPCA.

AUTHORS' CONCLUSIONS

There is weak and unreliable evidence that allopurinol mouthwash, granulocyte macrophage-colony stimulating factor, immunoglobulin or human placental extract improve or eradicate mucositis. There is no evidence that patient controlled analgesia (PCA) is better than continuous infusion method for controlling pain, however, less opiate was used per hour, and duration of pain was shorter, for PCA. Further, well designed, placebo-controlled trials assessing the effectiveness of allopurinol mouthwash, granulocyte macrophage-colony stimulating factor, immunoglobulin, human placental extract, other interventions investigated in this review and new interventions for treating mucositis are needed.

Postoperative morphine consumption in children with sickle-cell disease

BACKGROUND

Effective pain control is a primary goal in the perioperative management of patients with sickle-cell disease. To understand analgesic requirements better, the authors compared postoperative morphine consumption and pain scores in sickle and non-sickle children who had undergone laparoscopic cholecystectomy.

METHODS

We reviewed the medical records of all sickle and non-sickle children referred to the Acute Pain Service of a tertiary care teaching hospital for patient-controlled analgesia (PCA) following laparoscopic cholecystectomy from 1996 to 2003. Data collected included postoperative morphine consumption, visual analogue pain scores, and perioperative outcome.

RESULTS

Total postoperative morphine consumption in sickle children (n = 12) (1.58 +/- 0.78 mg.kg(-1)) was more than double when compared with non-sickle children (n = 10) (0.65 +/- 0.32 mg.kg(-1)) (P < 0.005). Duration of PCA use among sickle children (51 +/- 25 h) was more than double when compared with non-sickle children (21 +/- 11 h) (P < 0.005). Sickle patients had greater pain scores in the initial 24 h after surgery (P < 0.05) and used more adjuvant analgesics (P < 0.05). Duration of postoperative hospital stay was 3.4 +/- 1.6 days and 1.5 +/- 0.5 days for sickle and non-sickle children, respectively (P < 0.005).

CONCLUSIONS

Sickle children self-administered more than double the amount of morphine, reported more intense pain, and remained hospitalized for more than twice as long as nonsickle children undergoing the same surgical procedure. These findings probably have a multifactorial origin, and might be attributable in part to alterations in pain perception, opioid pharmacokinetics, opioid tolerance, and psychosocial variables.

The role of opioid receptor internalization and beta-arrestins in the development of opioid tolerance

Opioid tolerance, a phenomenon characterized by decreased analgesic effects obtained by the same dose of opioids after repeated use of the opioids, is a significant clinical problem. Traditional theory attributes receptor desensitization and internalization and post-receptor adaptation to the development of opioid tolerance. However, morphine, a commonly used opioid, induces tolerance but is not an effective drug to induce opioid receptor desensitization and internalization. Recent studies found that internalized opioid receptors can become competent receptors and recycle back to the cell surface membrane after dephosphorylation. Thus, receptor internalization may be a way to reduce opioid tolerance. Multiple studies have suggested a key role of beta-arrestins in opioid receptor desensitization and internalization and opioid tolerance. Although beta-arrestin 1 and beta-arrestin 2 are important for these effects induced by opioids with high intrinsic efficacy such as etorphine and fentanyl, morphine tolerance may be mediated mainly via beta-arrestin 2. Modification of opioid receptor internalization by affecting the interaction between opioid receptors and beta-arrestins may be a therapeutic target for reducing opioid tolerance.

Recent developments in patient-controlled analgesia

Patient-controlled analgesia (PCA) has become the gold standard for acute pain management since it was first introduced 20 years ago, and its merits have been discussed in quite a large number of publications. This review summarizes the more recent developments, such as new application devices and strategies, including intranasal, spinal, and regional PCA; patient-controlled sedation; experience with children and elderly people; and some data from chronic pain situations. Analyzing PCA literature from 2001 onwards confirms the author's long belief that the PCA principle ("WYNIWYG": what you need is what you get) was the most important aspect of a patient-controlled strategy, more or less independent of the type of drug or machine. Discovering this principle has changed the understanding of pain and suffering.

Clinical practice guidelines for the prevention and treatment of cancer therapy-induced oral and gastrointestinal mucositis

BACKGROUND

Oral and gastrointestinal (GI) mucositis can affect up to 100% of patients undergoing high-dose chemotherapy and hematopoietic stem cell transplantation, 80% of patients with malignancies of the head and neck receiving radiotherapy, and a wide range of patients receiving chemotherapy. Alimentary track mucositis increases mortality and morbidity and contributes to rising health care costs. Consequently, the Multinational Association of Supportive Care in Cancer and the International Society for Oral Oncology assembled an expert panel to evaluate the literature and to create evidence-based guidelines for preventing, evaluating, and treating mucositis.

METHODS

Thirty-six panelists reviewed literature published between January 1966 and May 2002. An initial meeting in January 2002 produced a preliminary draft of guidelines that was reviewed at a second meeting the same year. Thereafter, a writing committee produced a report on mucositis pathogenesis, epidemiology, and scoring (also included in this issue), as well as clinical practice guidelines.

RESULTS

Panelists created recommendations from higher levels of evidence and suggestions when evidence was of a lower level and there was a consensus regarding the interpretation of the evidence by the panel. Panelists identified gaps in evidence that made it impossible to recommend or not recommend use of specific agents.

CONCLUSIONS

Oral/GI mucositis is a common side effect of many anticancer therapies. Evidence-based clinical practice guidelines are presented as a benchmark for clinicians to use for routine care of appropriate patients and as a springboard to challenge clinical investigators to conduct high-quality trials geared toward areas in which data are either lacking or conflicting.

Managing pain in mucositis

OBJECTIVE

To discuss pharmacologic and nonpharmacologic approaches available to manage pain.

DATA SOURCE

Published journal articles, book chapters, clinical experience.

CONCLUSION

Pain management requires treatment directed at the various factors involved in the pain experience.

IMPLICATIONS FOR NURSING PRACTICE

Nurses need to assess pain daily and follow patients closely until mucositis resolves. Management targeted to specific dimensions of pain can improve the effectiveness of pain control.

Interventions for treating oral mucositis for patients with cancer receiving treatment

BACKGROUND

Treatment of cancer is increasingly effective but associated with short and long-term side effects. Oral side effects, including oral mucositis (mouth ulceration), remain a major source of illness despite the use of a variety of agents to treat them.

OBJECTIVES

To assess the effectiveness of interventions for treating oral mucositis or its associated pain in patients with cancer receiving chemotherapy and/or radiotherapy.

SEARCH STRATEGY

Computerised searches of Cochrane Oral Health Group's Trials Register, CENTRAL, MEDLINE and EMBASE were undertaken. Reference lists from relevant articles were searched and the authors of eligible trials were contacted to identify trials and obtain additional information. Date of the most recent searches August 2003: (CENTRAL) (The Cochrane Library Issue 3, 2003).

SELECTION CRITERIA

All randomised controlled trials comparing agents prescribed to treat oral mucositis in people receiving chemotherapy and/or radiotherapy. Outcomes were oral mucositis, time to heal mucositis, oral pain, duration of pain control, dysphagia, systemic infection, amount of analgesia, length of hospitalisation, cost and quality of life.

DATA COLLECTION AND ANALYSIS

Data were independently extracted, in duplicate, by two reviewers. Authors were contacted for details of randomisation, blindness and withdrawals. Quality assessment was carried out on these three criteria. The Cochrane Oral Health Group statistical guidelines were followed and relative risk values calculated using fixed effect models.

MAIN RESULTS

Twenty-five trials involving 1292 patients satisfied the inclusion criteria. Three agents, each in single trials, were found to be effective for improving (allopurinol RR 3.33, 95% CI 1.06 to 10.49; immunoglobulin RR 1.81, 95% CI 1.24 to 2.65; human placentral extract RR 4.50, 95% CI 2.29 to 8.86) or eradicating mucositis (allopurinol RR 19.00, 95% CI 1.17 to 307.63). Two of these trials were rated as at moderate risk of bias and one as at high risk of bias. The following agents were not found to be effective: benzydamine HCl, sucralfate, tetrachlorodecaoxide, chlorhexidine and 'magic' (lidocaine solution, diphenhydramine hydrochloride and aluminum hydroxide suspension). Six trials compared the time to heal and mucositis was found to heal more quickly with two interventions: Granulocyte Macrophage-Colony Stimulating Factor when compared to povidone iodine, with mean difference -3.5 days (95% CI -4.1 to -2.9) and allopurinol compared to placebo, with mean difference -4.5 days (95% CI -5.8 to -3.2). Three trials compared patient controlled analgesia (PCA) to the continuous infusion method for controlling pain. There was no evidence of a difference, however, less opiate was used per hour for PCA, and the duration of pain was shorter. One trial demonstrated that pharmacokinetically based analgesia (PKPCA) reduced pain compared with PCA, however more opiate was used with PKPCA.

REVIEWERS' CONCLUSIONS

There is weak and unreliable evidence that allopurinol mouthwash, vitamin E, immunoglobulin or human placental extract improve or eradicate mucositis. There is no evidence that patient controlled analgesia (PCA) is better than continuous infusion method for controlling pain, however, less opiate was used per hour, and duration of pain was shorter, for PCA. Further, well designed, placebo-controlled trials assessing the effectiveness of allopurinol mouthwash, immunoglobulin, human placental extract, other interventions investigated in this review and new interventions for treating mucositis are needed.

Topical ketamine in the treatment of mucositis pain

Ketamine oral rinse provided effective palliation of intractable mucositis pain in a 32-year-old woman with squamous carcinoma of the tongue undergoing radiation therapy. Pain at rest and with eating decreased with ketamine, allowing for a tapering of her opiate dose. No side effects of ketamine were reported. Treatment benefits most likely arose from the inhibition by ketamine of peripheral N-methyl D-aspartate receptors, though other mechanisms of action may have been contributory. Further evaluation of topical ketamine in the treatment of mucositis-related pain, and, potentially, other causes of inflammatory oral pain, are warranted.

Target-controlled infusion systems: role in anaesthesia and analgesia

Drug delivery by target-controlled infusion (TCI) allows automatic adjustments of the infusion rate of a drug to maintain a desired target concentration. Since drug effect is more closely related to blood concentration than to infusion rate, drug delivery via TCI is capable of creating stable blood concentrations of intravenous anaesthetics and analgesics. In this article the concept and history of TCI are described. The rational administration of TCI requires an appropriate pharmacokinetic data set and knowledge of the concentration-effect relationship; therefore, general pharmacokinetic and pharmacodynamic aspects of intravenous anaesthetics and analgesics are also addressed. Intraoperative investigations have demonstrated that TCI drug delivery allows rapid titration to a desired effect. The use of TCI for postoperative analgesia is still experimental, but TCI can, in part, overcome the disadvantages associated with continuous infusions and patient-controlled analgesia regimens in the postoperative period. Although TCI is capable of creating stable blood concentrations, when the target concentration is changed the resulting effect correlates better with a theoretical effect site concentration. The efficacy of TCI systems that can perform effect-site steering are still to be explored.

Eyelid pruritus with intravenous morphine

The cause of eyelid pruritus (itching) may be difficult to determine, particularly in preverbal children. Tearing, photophobia, or eye rubbing may be the first manifestation of leukemic infiltration or graft-versus-host disease, necessitating early appropriate therapy. We report a child in whom persistent eye rubbing developed after bone marrow transplantation for leukemia. Morphine administration was found to be the cause of this symptom.

Oral cavity complications of bone marrow transplantation

Bone marrow transplantation, once regarded as experimental, has evolved into a standard treatment for a variety of malignancies. Considerable advances have been made in histocompatibility typing, pretransplantation chemotherapy, and posttransplantation immunosuppressive therapy as well as prophylaxis and treatment of infections. Oral complications develop in almost all patients, and their early recognition may result in the institution of prompt treatment and prolonged survival. Mucositis, often severe and extremely painful, develops in more than three quarters of bone marrow transplant recipients, and its prevention, unfortunately, remains unsatisfactory. Herpes simplex virus and Candida albicans account for most oral infections, although their incidence has been dramatically reduced by the institution of prophylactic agents. Graft versus host disease continues to be a significant complication of marrow transplantation, and the detection of commonly occurring oral changes may support its diagnosis.

[Pharmacotherapy of cancer pain : 2. Use of opioids.]

The adequate use of opioids in the treatment of chronic cancer pain requires sound knowledge of selection criteria for the various opioids, the routes of administration, dosages, dosing schemes and possible side effects. Drug selection depends on the intensity of pain rather than on the specific pathophysiology. Mild to moderate pain can often be treated effectively by so-called "weak" opioids. These include codeine, dihydrocodeine and dextropropoxyphene. Non-opioid analgesics, like acetylsalicylic acid or paracetamol can be added according to the "analgesic ladder" proposed by the World Health Organization (WHO). If adequate pain relief is not achieved "strong" opioids are required. The route of administration that is the safest and the least invasive for the patient should be chosen. Non-invasive (oral, rectal, sublingual, transdermal and intranasal) and invasive routes (intravenous, subcutaneous, spinal and epidural) are available (Table 8). Noninvasive routes are preferred, and most patients can be maintained on oral opioids. Alternatively, in some patients pain can be managed by the sublingual (buprenorphine) route. A transdermal preparation exists for fentanyl, but has not yet been approved for the German market. If the oral route cannot be used or if large doses are required, it will be necessary to change to an invasive route. Intravenous bolus injections provide the fastest onset of analgesic action. They are mostly used in very severe pain. Repeated injections can be avoided by using intravenous or subcutaneous infusions. Various types of pumps delivering analgesics at constant basal infusion rates with the option of rescue doses in case of breakthrough pain are available (patient-controlled analgesia=PCA). Opioids frequently used for s. c. infusion are morphine and hydromorphone. Adjuvant drugs (antiemetics, anxiolytics) can be added. Epidural or intrathecal administration of opioids should only be used in intractable pain or if severe side effects, such as sedation and confusion, will arise with systemic opioids. Morphine, hydromorphone, fentanyl and sufentanil have been used, as have other additional compounds (e.g. local anaesthetics, clonidine). Intracerebroventricular application of morphine has been used only occasionally. In all cases, opioids should be given on to a fixed time schedule thereby, preventing pain from recurring. Additional rescue doses (approximately 50% of baseline single dose) are given for break-through pain. The most frequent side effect of opioids is constipation, and the administration of laxatives is often recommended (Table 5). Nausea, vomiting, sedation and confusion mostly occur in the beginning of opioid therapy. In contrast to constipation, tolerance to these effects develops within days or weeks. True dependence or psychological addiction rarely occurs in patients with chronic cancer pain. In most cases, progression of the underlying disease associated with increasing tissue damage and increasing pain is found. Fear of dependence and addiction often contributes to undertreatment of patients suffering from chronic cancer pain.

Overview of current development in patient-controlled analgesia

Over the past two decades, numerous trials have assessed the safety and efficacy of patient-controlled analgesia (PCA). Advantages over conventional parenteral narcotics reported from these trials include equivalent to superior pain relief, superior patient satisfaction, decreased sedation and anxiety, faster return to normal functional status, and reduction in nursing time and hospitalization. The majority of these trials have been conducted in the postoperative patient population. In the mid to late 1980s, interest arose in applying PCA technology to the management of cancer pain. Factors that served as an impetus for the use of PCA in cancer pain included favorable reports from the postoperative setting and the often-cited statistics regarding the magnitude of the cancer pain problem. Advances in PCA technology coupled with advances in vascular access technology that allow the placement of long-term ports and catheters to facilitate intravenous, epidural, or intrathecal administration of opioid analgesics have made the applicability of PCA in ambulatory cancer patients an attractive option. The greatest breakthrough in PCA technology came with the introduction of devices making it possible to choose between intermittent (demand bolus) and continuous administration (continuous infusion) or both intermittent and continuous modes. A comparison of these types of PCA devices is described. The limitations of the literature involving PCA therapy in cancer patients make it difficult to identify optimal patient selection criteria, PCA administration schedules, drug selection and dosing, and optimal route of administration. The current status and pertinent issues related to these topics are addressed.

Death from a morphine infusion during a sickle cell crisis

A 15-year-old boy died during a vaso-occlusive sickle cell crisis after having received a prolonged infusion of morphine. Even in therapeutic doses, narcotics may cause significant respiratory acidosis and hypoxemia, enhancing polymerization of hemoglobin SS and thereby promoting sickling and vaso-occlusion. When narcotics are used during a sickle cell crisis, the best method is pharmacokinetically based patient-controlled analgesia.

Opioid sensitivity of chronic pain: a patient-controlled analgesia method

Twenty-two patients with chronic pain of malignant or nonmalignant origin were given intravenous morphine by patient-controlled analgesia. A prestudy judgment was made from the characteristics of the pain as to whether it was nociceptive or neuropathic. Analgesic efficacy was assessed by a nurse-observer; adverse events were noted and plasma morphine and metabolitie concentrations measured. Three categories of opioid response were distinguished. Good responders obtained > 70 mm relief on the visual analogue scale, with minimal or manageable adverse events. Moderate responders obtained < 70 but > 30 mm relief with more problematic adverse events, and poor responders had < 30 mm relief with troublesome adverse events. This method for the study of opioid sensitivity allowed a wide dosage range to be studied. The simultaneous analgesic and adverse event measurements showed that the spectrum of observed response was wide, and response category could be judged for the majority by 4 h. In those with poor or moderate response, adverse event severity limited further dose increment. The relationship between pain characteristics and response showed that some pains judged to be neuropathic had a good response to opioid (5/13), and some pains judged to be nociceptive did not (5/14). The study suggests that the pattern of response is not as black and white as the prediction of good response from nociceptive pain and poor from neuropathic pain would suggest, although nociceptive pain was more likely than neuropathic pain to show a good response. For the moderate responders opioid titration may, in the absence of other effective treatments, be useful, but the analgesic endpoint may not be totally satisfactory. The method provides an operational definition of opioid sensitivity.

Patient-controlled analgesic infusions: alfentanil versus morphine

Previously, we found that cancer patients using a pharmacokinetically based patient-controlled intravenous infusion system (PKPCA) to regulate their own morphine infusion rates achieved more relief from oral mucositis pain than similar patients using morphine by bolus-dose PCA. In this study, we employed the PKPCA system to compare efficacy and side-effect intensities of 2 mu-selective opioid analgesics, alfentanil and morphine, in bone marrow transplant (BMT) patients self-administering the drugs to relieve pain from oral mucositis. Patients using morphine by PKPCA obtained more pain relief than patients regulating their own alfentanil infusions during the first 4 days of continuous opioid infusion therapy. Side-effect intensities did not differ between the 2 study groups. In contrast to patients using morphine for 4-14 days, those receiving alfentanil by PKPCA required unexpectedly high plasma concentrations of the drug to obtain equivalent pain relief. Our results indicate that either the relative potencies of these 2 mu-selective opioids differ from previous estimates or analgesic tolerance developed to alfentanil but not to morphine. We conclude that alfentanil has similar efficacy in control of prolonged pain in BMT patients, but the utility of alfentanil in long-term pain management may be limited by relatively rapid tolerance onset.