Intrathecal Morphine Infusion Therapy in Management of Chronic Pain: Present and Future Implementation in Korea

PURPOSE

Intrathecal morphine pump (ITMP) infusion therapy is efficient in managing malignant and nonmalignant chronic pain refractory to standard treatment. However, the high cost of an ITMP is the greatest barrier for starting a patient on ITMP infusion therapy. Using the revised Korean reimbursement guidelines, we investigated the cost effectiveness of ITMP infusion therapy and conducted a patient survey.

MATERIALS AND METHODS

A retrospective chart review of 12 patients who underwent ITMP implantation was performed. Morphine dose escalation rates were calculated, and numeric rating scale (NRS) scores were compared before and after ITMP implantation. We surveyed patients who were already using an ITMP as well as those who were candidates for an ITMP. All survey data were collected through in-person interviews over 3 months. Data on the cost of medical treatment were collected and projected over time.

RESULTS

The NRS score decreased during the follow-up period. The median morphine dose increased by 36.9% over the first year, and the median time required to reach a financial break-even point was 24.2 months. Patients were more satisfied with the efficacy of ITMP infusion therapy than with conventional therapy. The expected cost of ITMP implantation was KRW 4000000-5000000 in more than half of ITMP candidates scheduled to undergo implantation.

CONCLUSION

The high cost of initiating ITMP infusion therapy is challenging; however, the present results may encourage more patients to consider ITMP therapy.

Respiratory failure following delayed intrathecal morphine pump refill: a valuable, but costly lesson

BACKGROUND

Spinal analgesia, mediated by opioid receptors, requires only a fraction of the opioid dose that is needed systemically. By infusing a small amount of opioid into the cerebrospinal fluid in close proximity to the receptor sites in the spinal cord, profound analgesia may be achieved while sparing some of the side effects due to systemic opioids. Intraspinal drug delivery (IDD) has been increasingly used in patients with intractable chronic pain, when these patients have developed untoward side effects with systemic opioid usage. The introduction of intrathecal opioids has been considered one of the most important breakthroughs in pain management in the past three decades. A variety of side effects associated with the long-term usage of IDD have been recognized. Among them, respiratory depression is the most feared.

OBJECTIVE

To describe a severe adverse event, i.e., respiratory failure, following delayed intrathecal morphine pump refill.

CASE REPORT

A 65-year-old woman with intractable chronic low back pain, due to degenerative disc disease, and was referred to our clinic for an intraspinal drug delivery evaluation, after failing to respond to multidisciplinary pain treatment. Following a psychological evaluation confirming her candidacy, she underwent an outpatient patient-controlled continuous epidural morphine infusion trial. The infusion trial lasted 12 days and was beneficial in controlling her pain. The patient reported more than 90% pain reduction with improved distance for ambulation. She subsequently consented and was scheduled for permanent intrathecal morphine pump implantation. The intrathecal catheter was inserted at right paramedian L3-L4, with catheter tip advanced to L1, confirmed under fluoroscopy. Intrathecal catheter placement was confirmed by positive CSF flow and by myelogram. A non-programmable Codman 3000 constant-flow rate infusion pump was placed in the right mid quandrant between right rib cage and right iliac crest. The intrathecal infusion consisted of preservative free morphine, delivering 1.0 mg /day. Over the following 6 months, the dosage was gradually titrated up to 4 mg/day with satisfactory pain control without significant side effects. However, the patient was not able to return to the clinic for pump refill until 12 days later than the previously scheduled pump-refill date. Her pump was accessed and was noted to be empty. Her intrathecal pump was refilled with preservative free morphine, delivering 4 mg/day (the same daily dose as her previous refill). However, on the night of pump refill, 10 hours after the pump refill, the patient was found to be unresponsive by her family members. 911 was called. Upon arriving, paramedics found her in respiratory failure, with shallow breathing at a rate of 5/min, pulse oxymetry showing oxygen saturation about 55-58%. She was emergently intubated on site and rushed to local hospital ER. The on call physician for our clinic was immediately contacted, and advised the administration of intravenous Naloxone. Her respiratory effort improved dramatically after receiving a total of 0.6 mg IV Naloxone IV over 25 minutes. Her intrathecal pump was immediately accessed by clinic on call physician and the remainder of the medication in the catheter space was aspirated. The pump infusate was immediately diluted with preservative free normal saline, to deliver preservative free morphine at 1mg/day. She was transferred to the intensive care unit and extubated the next morning. She recovered fully without any sequelae.

CONCLUSION

Loss of opioid tolerance due to delayed pump refill may subject patients to the development of severe respiratory depression. Meticulous approach should be employed when refilling pumps in these patients when their pumps are completely empty. To our knowledge, this is the first reported case of this type.

Conduite à tenir devant une recrudescence de spasticité chez un patient porteur d'une pompe à baclofène

INTRODUCTION

The incidence of complications after baclofen pump implantation is relatively high. Diagnosis of these complications can be difficult. A diagnostic tree would be a useful tool in cases of suspected malfunctioning of the intrathecal bacolfen infusion system and would standardise the diagnostic procedure.

METHOD

From results in the literature and the experience of our department, we designed a diagnostic tree to aid in finding the cause of a recrudescence of spasticity in patients with implanted baclofen pumps.

RESULTS

The potential causes of recrudescence of spasticity are described and a diagnostic pathway is proposed.

DISCUSSION

The aim of a standardised hierarchical method of diagnosis of the cause of increased spasticity in patients with intrathecal baclofen pumps is to gain time in the diagnosis and treatment. Such diagnosis should improve patient care by permitting rapid restoration of an adequate level of baclofen infusion as well as decreasing the length of hospital stay and, as a consequence, the cost relating to malfunctioning pumps.

Cost-effectiveness of continuous subcutaneous insulin infusion (CSII) in children: illusion or delusion?

Cost-effectiveness of continuous subcutaneous insulin infusion (CSII) in children is reviewed in the context of possible improvement of percentage of hemoglobin A1c (HbA1c) and of other clinical benefits over multiple daily injections (MDI). Cost-effectiveness depends on clinical efficacy but reported clinical efficacy parameters may overlook definite benefits perceived by children and parents using CSII. There are few detailed reports on cost comparisons between CSII and MDI in adults, even less in children or adolescents. Review of direct extra costs for CSII over conventional treatment, including MDI, suggest that these may double, 5000-6000 EUR vs. 3000 EUR per patient year. An example is given of how to calculate direct cost differences, showing local differences. Randomized comparisons between CSII and MDI in childhood and adolescence show few marked clinical effects, but non-randomized comparisons favor CSII. Quality of life parameters fall short in any such comparison in children and adolescents alike. The reasons for the apparent discrepancy between non-randomized childhood studies and the randomized prospective ones are given. There is a dire need for better parameters to assess the well-being of diabetic children treated by CSII or MDI. Only then is it warranted to estimate the cost-effectiveness of CSII vs. MDI in childhood and adolescence.

Insulin pump therapy in type 1 diabetes mellitus

OBJECTIVES

To review the current experience with insulin pump therapy in children and adolescents in order to guide pediatricians regarding indications and complications.

SOURCES OF DATA

Systematic review of articles published in the literature referring to the use of insulin pump therapy, indications, complications and response to treatment. All articles published between 1995 and 2005 and appearing in the MEDLINE and LILACS databases were reviewed. The keywords were: insulin pump, type 1 diabetes mellitus and diabetes mellitus. The articles covering the subject of interest and referring to children and adolescents were selected.

SUMMARY OF THE FINDINGS

Insulin pump therapy is not required for all patients with type 1 diabetes, since intensive treatments produce very similar results in terms of glycated hemoglobin and control of complications over the medium and long terms. However, the pump allows for greater comfort for patients, with less rigid meal schedules and better quality of life. The first requirement for patients intending to use the pump is getting used to having a device attached to the body and following strict glucose control; otherwise, pump therapy is not advantageous. Complications are rare due to the technologies currently available. The cost, however, is greater than with conventional treatments.

CONCLUSION

The development of infusion pumps and glucose monitors, including continuous monitoring systems, will lead to "intelligent pumps," so that a true "artificial pancreas" will be available, which can even be implanted in the patient, allowing non-diabetic persons to lead a normal life.

Posição de consenso da Sociedade Brasileira de Diabetes: insulinoterapia intensiva e terapêutica com bombas de insulina

Este artigo relata a posição de consenso da Sociedade Brasileira de Diabetes sobre a insulinoterapia intensiva e a terapêutica com bombas de infusão de insulina, obtida durante simpósio de atualização realizado especificamente para esta finalidade, em 2003. Estas modalidades de tratamento do diabetes são aqui conceituadas, seus fundamentos são colocados, e os aspectos práticos de indicações, exeqüibilidade, limites, técnicas e relação custo-benefício são analisados. As técnicas envolvem os esquemas de auto-monitorização glicêmica sugeridos e as doses, tipos, formas de administração da insulina e fatores de cálculo utilizados em cada modalidade de tratamento intensivo, tanto no DM1 quanto no DM2. O papel da SBD na implementação dos tratamentos intensivos do diabetes e a atuação dos vários profissionais envolvidos são discutidos e comentados. Conclui-se com as respostas de consenso a questões orientadoras do tema, formuladas na apresentação do simpósio.

A prospective randomized trial demonstrating valved implantable ports have fewer complications and lower overall cost than nonvalved implantable ports

BACKGROUND

The purpose of the current study was to evaluate whether a totally implanted valved subcutaneous port system would have fewer complications as compared to a standard nonvalved port.

METHODS

Study subjects requiring port placement were randomized to receive a valved port (PASV; Boston Scientific, Natick, MA) or a nonvalved port (BardPort; Bard Accesss Systems, Salt Lake City, UT). Each port was placed with standard operative technique. Difficulty with blood return, excess time spent accessing the port, and required interventions were reported over the initial 180 days of port usage.

RESULTS

Seventy-three patients were randomized to receive either a valved port (n = 37) or a nonvalved port (n = 36). No major complications were identified from port placement, and there were no differences in rates of infection between the 2 ports. A reported inability to withdraw blood was noted in the valved port group on 21 of 364 (5.8%) port accessions and in the nonvalved port group on 37 of 341 (11%) accessions (P = 0.02). Significantly more total time was spent ensuring adequate blood draw from nonvalved ports as opposed to valved ports (750 minutes vs. 1545 minutes, respectively) (P <0.03).

CONCLUSIONS

This study revealed that the PASV valved port is associated with significantly fewer instances of poor blood return and less nursing access time, indicating that a port with a PASV valve may be superior to a nonvalved device.

[Implantable drug pumps for spinal opioid analgesia: technical solutions and problems]

Among the many technical appliances for pain therapy which are currently available, the use of implantable drug pumps for prolonged pain treatment is of increasing importance. Since this kind of pain therapy can be used without any problems outside the hospital, it improves the quality of life of the patient. Furthermore, it is combined with a reduction of side-effects which frequently occur when analgesics are given orally or parenterally in big single doses. High initial costs are compensated by a good cost-benefit ratio of this kind of pain treatment, which enables the use of analgesics in low doses in out-patients. Based on the use of gas mixtures which can be compressed repeatedly, implantable mechanically-driven pumps are a nearly inexhaustible propulsion unit for drug infusions. The development of new gas mixtures and of innovative control mechanisms allows greater independence from surrounding influences and higher precision regarding infusion rates. Mechanically-driven pumps are characterized by prolonged functioning and low cost of purchase. Therefore, they will continue to be available on the medical market in future. Special progress in cardiac pacemaker therapy as well as further miniaturization of portable infusion pumps with peristaltic propulsion have led to the development of programmed implantable pumps with lithium batteries as energy sources. The advantages of these pumps, particularly those with "externally" programmable infusion rates (continuous, bolus, periodical bolus, etc.) point to the future. With these devices, evacuation and refilling of the pumps due to necessary changes of drug concentrations, as has to be done with mechanically working pumps with fixed infusion rates, are no longer necessary. Therefore, these programmable pumps can also be used for infusion of drug concentrates. At present, however, high costs and the battery-dependent limited duration of functioning of these devices are disadvantageous. As with cardiac pacemakers, battery exchange is necessary. Using implantable drug pumps, relevant changes of body temperature and atmospheric pressure lead to more or less considerable deviations of the infusion rates. These deviations differ from product to product and can be studied in the informative material published by the manufacturer.

Hepatic artery chemotherapy for colorectal liver metastases: technical considerations and review of clinical trials

Hepatic artery infusion (HAI) of chemotherapeutic agents for colorectal hepatic metastases is associated with significantly higher response rates compared to systemic chemotherapy. However, response rates have not consistently translated into improved survival. Several randomized trials have evaluated the implantable pump for treating unresectable colorectal hepatic metastases. Meta-analysis of these studies have demonstrated an improved survival advantage with pump therapy as well as improved quality of life. Recent studies of HAI of chemotherapy as adjuvant therapy following liver metastases resection have also demonstrated a potential survival advantage. Toxicities of HAI can be treatment limiting, but measures have emerged for overcoming these side effects. These randomized clinical trials have established HAI as a reasonable therapeutic option in patients with unresectable disease, and as adjuvant therapy in patients with resectable disease.

Functional benefits and cost/benefit analysis of continuous intrathecal baclofen infusion for the management of severe spasticity

OBJECT

Intrathecally delivered baclofen has been used as a treatment for severe spasticity since 1984. Despite this, there are uncertainties surrounding the benefits of treatment and the costs involved. The authors assessed the evidence of benefits and identified costs and the cost/benefit ratio for continuous intrathecal baclofen infusion in the treatment of severe spasticity.

METHODS

A systematic literature review was conducted to estimate the effect of continuous intrathecal baclofen infusion on function and quality-of-life (QOL) measures in patients with severe spasticity. Outcomes were related to standard QOL scores to estimate potential gains in quality-adjusted life years (QALYs). Information on the costs of continuous intrathecal baclofen infusion was obtained from hospitals in the United Kingdom. This information was combined to estimate the cost/benefit ratio for the use of continuous intrathecal baclofen infusion in patients with different levels of disability from severe spasticity. Studies indicate that bedbound patients are likely to improve their mobility and become able to sit out of bed. Patients with severe spasm-related pain are likely to have major improvement or complete resolution of this pain. Many other benefits are also reported. Such benefits are related to costs per QALY in the range of 6,900 pounds to 12,800 pounds ($10,550-$19,570 US).

CONCLUSIONS

In carefully selected patients who have not responded to less invasive treatments, continuous intrathecal baclofen infusion is likely to lead to worthwhile functional benefits. Continuous intrathecal baclofen infusion has an acceptable cost/benefit ratio compared with other interventions that are funded by the health service.

[Apomorphine therapy versus deep rain stimulation. Clinical and economic aspects in patients with advanced Parkinson disease]

Long-term dopaminergic treatment of Parkinson's disease is complicated by the occurrence of dyskinesia and motor fluctuations and is responsible for increasing the costs of treatment. In these patients, continuous subcutaneous therapy with the dopamine agonist apomorphine or deep-brain stimulation represents a promising strategy. While the costs for the treatment with apomorphine are covered by health insurance, separate reimbursement for deep-brain stimulation does not exist in Germany. The case reports (n = 3) presented here emphasize that deep-brain stimulation is less cost-intensive than subcutaneous treatment with apomorphine in selected patients. Even in the first postoperative year costs for medication and hospital stays were reduced by approximately 60%. Moreover, in all three patients, motor complications improved after deep-brain stimulation in comparison to previous subcutaneous application of apomorphine. Thus, to further ensure deep-brain stimulation in parkinsonian patients it is mandatory to find a mode of reimbursement for the institutions concerned.

[Home anti-cancer therapy with a venous port]

Home anti-cancer chemotherapy and palliation in the terminal stage were performed for patients with advanced cancer of the digestive system, using a venous port implanted beneath the skin via the subclavian vein. Patients under 75 years of age (5 with esophageal, 61 gastric, 59 colorectal, 5 cholangio, 5 pancreatic, 1 hepatic and 1 ileal cancer) were treated. With two portable balloon pumps, continuous intravenous infusion of 5-FU (300 or 400 mg/body/day) combined low-dose injection of cisplatin (5 mg/body/day) was continued for 10 days, and repeated 3 times for 6 weeks. The response rate was 17.9% in 78 patients according to valuation of the tumor mass. In 119 patients also undergoing a tumor marker evaluation, an effect was seen in 26.1%. No severe side effects such as renal dysfunction or bone marrow suppression were seen, and no special infusion was needed. Therefore, such treatment can be continued for a long time. Use of a venous port should make easy the switchover to HPN and the amelioration of the symptoms of the terminal stage, such as pain, and helps patients cope with the worry. Therefore, the present technique is useful in a series of cancer treatments including surgery, chemotherapy and the amelioration of symptoms.

Advanced colorectal cancer: quality of life and toxicity in patients after weekly 24-hour continuous infusions of biomodulated 5-fluorouracil

It is generally agreed that chemotherapy prolongs survival and relieves symptoms more than the best supportive care in advanced colorectal cancer. Since its introduction over 35 years ago, 5-fluorouracil (5-FU) has been the only effective chemotherapeutic option available for the treatment of advanced colorectal cancer. Efforts have focused on the use of various 5-FU-based regimens. A commonly used regimen, frequently extolled as the "gold standard" for clinical trials in advanced colorectal cancer, is the Mayo Clinic regimen; this option has, however, been associated with considerable dose-limiting toxicity. Another approach has involved 5-FU administration by continuous intravenous infusion. In this paper we present our experience on 10 Dukes D colorectal cancer patients treated with 24-hour continuous infusion of biomodulated 5-FU delivered in an ambulatory setting with an intravenous infusional pump. The number of treated patients was admittedly not sufficient to evaluate the clinical response of this 5-FU chemotherapeutic regimen. This is not the goal of our work; however, other rationale for adopting this approach is justified: the regimen has a favourable toxicity profile and can provide considerable benefit in terms of improved quality of life while at the same time the health care costs are alleviated since hospitalization is generally not required.

Hepatic arterial chemotherapy in metastatic colorectal patients

Hepatic metastases are a major cause of morbidity and mortality for patients with colorectal cancer (CRC). The rationale for hepatic arterial chemotherapy has both an anatomical and pharmacological basis. Several randomized clinical studies of fluoropyrimidine showed higher response rates in all trials when the drug was given as an hepatic arterial infusion (HAI) versus systemic administration. However, the studies did not accurately define survival for the following reasons: (1) some allowed a crossover; (2) some were too small; and (3) some used inadequate systemic chemotherapy. Patients who have failed to respond to previous systemic chemotherapy have an approximately 50% response rate with HAI treatment. Hepatic toxicity, especially biliary sclerosis, is the dose-limiting toxicity, occurring in 6% to 25% of patients. Adding dexamethasone to HAI fluoropyrimidine decreases the hepatobiliary toxicity. The therapeutic benefit of HAI in one study was also demonstrated by an increased time with normal quality of life. To truly define the role of regional therapy in patients with CRC confined to the liver, the current Cancer and Leukemia Group B (CALGB) study is randomizing patients to HAI versus systemic therapy without a crossover to demonstrate if HAI improves survival and/or quality of life in addition to response rates.

[Elements for a cost/utility analysis of long term intravenous devices]

Three long-term intravenous infusion strategies were compared, namely an implantable port (IP), a tunneled central catheter (TCC), and repeated peripheral catheterization (RPC). A decision analysis model was used in which the sequence of decisions and their possible consequences was described as a decision tree for each of the three strategies. The likelihood of each event occurring was determined based on a literature review. Each event was assigned a cost and a utility. Direct medical costs for the society include the cost of the material, the cost of implantation and removal of the device in the operating room, and the cost of treating complications directly ascribable to the strategy used. Utility is a combination of efficacy (as evaluated based on the likelihood of use of the strategy for one year) and quality of life (as evaluated by experts). In the basic analysis, RPC was the most cost-saving method but had an adverse effect on quality of life (0.82). The cost of using IC or TCC for one year was higher, with the main contributors to the excess cost being the insertion procedure and the management of complications (primarily deep vein thrombosis and infection). Quality of life was better with IC (0.98) than with TCC (0.93). IC also had a higher cost-utility ratio (11,738 French francs [FF]) versus 17,393 FF). A one-way sensitivity comparison of IC and TCC showed that the only realistic change capable of reversing the order between these two methods was a decrease by one-third in the risk of infection with TCCs. This model, used here for the first time, establishes that IC is superior over TCC.

Totally implantable central venous access ports for long-term chemotherapy. A prospective study analyzing complications and costs of 333 devices with a minimum follow-up of 180 days

BACKGROUND

A few data are available from analyses of the complications and costs of central venous access ports for chemotherapy. This prospective study deals with the complications and global costs of central venous ports connected to a Groshong catheter for deliverance of long-term chemotherapy.

PATIENTS AND METHODS

Patients with a variety of solid neoplastic diseases requiring chemotherapy who were undergoing placement of implantable ports over a 30-month period (1 October 1994 to 31 March 1997) have been prospectively studied. Follow-up continued until the device was removed or the study was closed (30 September 1997); patients with uneventful implant experience and subsequent follow-ups of less than 180 days were not considered for this study. A single port, constructed of titanium and silicone rubber (Dome Port, Bard Inc., Salt Lake City, USA), was used, connected to an 8 F silastic Groshong catheter tubing (Bard Inc., Salt Lake City, USA). Two-hundred ninety-six devices were placed in the operating room under fluoroscopic control even in the patients treated and monitored in a day-hospital setting: 37 of them were in an angiographic suite. A central venous access form was filled in by the operator after the procedure and all ports were followed prospectively for device-related and overall complications. The average purchase cost of the device was obtained from the hospital charges, based on the costs applied during the 30-month period of the study. Insertion and maintenance costs were estimated by obtaining the charges for an average TIAP implant and its subsequent use; the costs of complication management were assessed analytically. The total cost of each device was defined as the purchase cost plus the insertion cost plus the maintenance cost plus the cost of treatment of the complications, if any. The cost of removing the TIAP was also included in the economic analysis when required by the treatment of the complication.

RESULTS

Three hundred thirty-three devices, for a total of 79,178 days in situ, were placed in 328 patients. Five patients received second devices after removal of the first. In all cases the follow-up was appropriate (median 237 days, range 180-732). Early complications included 10 pneumothoraxes (3.4%; six tube-thoracostomies were applied, 1.8%) and six revisions for port and/or catheter malfunction (overall early complications = 16, 4.48%). Late complications comprised five instances of catheter rupture and embolization (1.5%, 0.063 episodes/1000 days of use), five of venous thrombosis (1.5%, 0.063 episodes/1000 days of use), one of pocket infection (0.3%, 0.012 episodes/1000 days of use), and eight of port-related bacteremia (2.4%, 0.101 episodes/1000 days of use). The infections were caused by coagulase-negative Staphylococcus aureus (five cases), Bacillus subtilis (one case), Streptococcus lactaceae (one case) and an unknown agent (one case); port removal was necessary in six of eight cases. The total cost per patient treated for a six-month period, consisting of the costs of purchase and implantation, treatment of early and late complications, and of maintenance of the device, is US$1,970.

CONCLUSIONS

This study represents the largest published series of patients with totally implantable access ports connected to a Groshong catheter. We have shown that US$2,000 are sufficient to cover six months of chemotherapy in one patient using the most expensive commercially available implantable port. According to the present study, totally implantable access ports connected to a Groshong catheter are associated with high purchase and insertion costs, a low complication rate and low maintenance costs. These data support their increasing use in current oncologic medical practice.

Cost-effectiveness of long-term intrathecal morphine therapy for pain associated with failed back surgery syndrome

A decision analytic study was conducted using computer simulation to project the outcomes in a simulated cohort of patients whose treatment for back surgery had failed. The objective of this study was to estimate the direct cost of intrathecal morphine therapy (IMT) delivered via an implantable pump relative to alternative therapy (medical management) over a 60-month course of treatment. IMT administered by way of an implantable pump can provide effective pain relief for selected patients whose less invasive treatment modalities have failed. Previous research suggested that a pump implant is less costly than alternative methods providing comparable analgesia for treatment exceeding 12 to 18 months. However, those analyses did not include the cost of complications or pump replacement. Scenarios representing the course of IMT, devised by a panel of experts, were represented as treatment pathways in a Monte Carlo simulation. Adverse event rates were drawn from published data supplemented by expert judgment. Direct costs were based on a health insurer paid claims perspective (direct costs) discounted at a 5% annual rate. The cost-effectiveness of IMT was calculated based on a report of 65% to 81% "good to excellent" pain relief relative to alternative (medical) management. With both adverse event probabilities and costs set at most likely (base case) values, the expected total cost of IMT over 60 months was $82,893 (an average of $1382 per month). In a sensitivity analysis, the best case (low adverse event rate, low cost) estimate was $53,468 ($891/mo), whereas the worst case (high adverse event rate, high cost) estimate was $125,102 ($2085/mo). Cost-effectiveness estimates ranged from $7212 (best case) to $12,276 (worst case) per year of pain relief. Results from a computer simulation designed to collect the costs not included in previous empiric research indicate that IMT appears to be cost-effective when compared with alternative (medical) management for selected patients when the duration of therapy exceeds 12 to 22 months.

In vitro and in vivo studies of subcutaneous hydromorphone implants designed for the treatment of cancer pain

Unrelieved cancer pain remains a significant problem worldwide. Patients receive inadequate analgesia for a variety of complex and multifactorial reasons. Limited availability of opioids secondary to concerns about potential diversion of these medications for illicit use and poor compliance with oral regimens are significant factors in many countries. This study was designed to develop and test an implantable opioid delivery device capable of releasing a potent opioid subcutaneously at a continuous rate for 4 weeks. A low temperature solvent casting technique was used to formulate ethylene vinyl acetate (EVA) copolymer disks containing 50% hydromorphone by weight. The release characteristics of disks of different height and diameter, coated and uncoated, and with and without a central uncoated channel were studied. The effect of temperature and pH were also evaluated. In vitro assessments were conducted in phosphate buffer using UV spectrophotometry. In vivo studies employed New Zealand White Rabbits and a radioimmunoassay. Plasma levels following hydromorphone delivery by polymer, osmotic pump, and intravenous administration were compared. In vitro, uncoated EVA polymer disks measuring 1.05 cm in diameter and 0.27 cm in height released an initial large burst of hydromorphone. Coating the disks with 100-200 microM of poly(methyl-methacrylate) prevented drug egress from the polymer. A central uncoated channel measuring 1.25 mm in diameter in an otherwise coated polymer virtually eliminated the initial burst of drug release and provided near zero-order hydromorphone release at an average rate of 164 micrograms per hour for 4 weeks. Doubling the height of the polymer approximately doubled the release rate while doubling the diameter of the polymer extended the duration of drug release to over 8 weeks. In rabbits, stable plasma hydromorphone concentrations (23-37 ng/ml) were sustained for 4 weeks following implantation of 2 polymers with an uncoated central channel. No initial burst of hydromorphone release was noted. Increasing the number of polymers produced sustained and predictable increases in plasma hydromorphone concentrations. Plasma levels were similar with subcutaneous hydromorphone delivered by polymer and osmotic pump and much less variable than with intravenous bolus hydromorphone. A uniquely configured implantable drug delivery device has been developed using materials which are approved for human use. It safely and reproducibly releases hydromorphone for weeks in vitro and in vivo without an initial burst of drug release. Varying the thickness, diameter, and number of implants provides flexibility in the release rate and duration of release. This implantable opioid delivery device could provide a sustained subcutaneous infusion of hydromorphone to patient with cancer pain in developed and developing nations without pumps, catheters, or extensive outpatient support services. In addition, it should improve compliance and reduce concern regarding illicit diversion of opioids.

Ambulatory infusion pumps: application to oncology

OBJECTIVE

To provide an overview of the various types of ambulatory pumps available in relation to mechanism of delivery, patient selection criteria, potential complications, and educational support.

CONCLUSIONS

Ambulatory pumps are an important means of drug delivery in a wide range of clinical conditions. Technologies permitting drug self-administration and automated drug delivery outside the hospital have become increasingly more sophisticated and adaptable; more than 600 models are available. With the shift of health care delivery from the hospital setting to the outpatient and home settings, reliable effective ambulatory pumps are necessary to safely deliver medications.

IMPLICATIONS FOR NURSING PRACTICE

The use of ambulatory pumps is becoming more common as they are initiated as a part of front-line patient therapy. The nurse involved in the selection and management of ambulatory pumps is challenged to be familiar with the large variety available. Selecting the best type of pump is based on several factors, such as the type of therapy, disease state, reimbursement, and the ability to operate and troubleshoot complications.

Subcutaneous morphine pump for postoperative hemorrhoidectomy pain management

PURPOSE

Many anorectal procedures are currently being performed on an outpatient basis, hemorrhoidectomy being the exception because of the need for parenteral narcotics postoperatively. We investigated the effectiveness of a subcutaneous morphine pump (SQMP) for outpatient posthemorrhoidectomy pain control.

METHODS

In Phase 1 of our study, 22 patients undergoing radical hemorrhoidectomy were started on an SQMP protocol postoperatively. Twenty-nine patients received conventional postoperative narcotic dosing. In Phase 2, 19 patients enrolled in an SQMP protocol underwent hemorrhoidectomy in an ambulatory setting. Length of hospitalization, catheterization rate, and pain control were evaluated.

RESULTS

In Phase 1, zero patients in the study group and two in the control group required additional hospitalization beyond 23 hours for pain control. The rates of catheterization were similar between the two groups. Pain control was considered satisfactory in 21 of 22 study patients. There was no correlation between pain level and morphine dose. Eighteen of 22 patients experienced minor side effects, necessitating pump removal in two patients. In Phase 2, 18 of 19 patients on the SQMP were discharged from the recovery room. Cost analysis shows the combination of outpatient hemorrhoidectomy and the SQMP to be cost-effective in comparison with an inpatient stay.

CONCLUSIONS

The SQMP enables hemorrhoidectomy to be done on an outpatient basis. It provides effective pain control, enjoys high patient acceptance, and is cost-effective.

The spring-driven implantable pump. A low-cost alternative

In the current era of cost containment in medicine, manufacturing economics have become increasingly important. The authors devised an implantable pump powered by spring force from an elastomeric Belleville washer, which is also the outer flexible wall of the drug reservoir. Use of formed and injection molded parts provides for low-cost manufacturing, in contrast to the precision welded alternative designs. Additional advantages include insensitivity to changes in ambient temperature and pressure. Finite element modeling of the elastomer spring allows prediction of the effects of parameter changes on performance, so that expansions and reductions of scale can be made without compromising the uniform spring rate of the device. A concern that subcutaneous fibrous encapsulation might markedly alter reservoir pressure was not supported by experimental data. In a unit implanted subcutaneously in a dog, reservoir pressures measured over a 4 year period were stable. This new, simple, implantable infusion pump can serve as an economical vehicle for prolonged parenteral drug treatment of ambulatory subjects in circumstances where continuous single-rate infusion is appropriate.

[Outpatient cancer chemotherapy employing implantable systems]

Outpatient cancer chemotherapy (OCC) employing implantable systems was introduced and the objects, conditions and problems of OCC were discussed based on experiences in 324 cases. The aims of OCC are improved QOL and the continuation of chemotherapy. Our requirements are safety, effectiveness, easy management and non-disturbance of activity. Implantable systems are very useful for OCC, especially continuous infusion combined with ambulatory pumps. However, the improvement of ambulatory pumps and the establishment of methods to evaluate OCC are required to further develop OCC.

Cost analysis of two implantable narcotic delivery systems

This survey compares costs of two commonly utilized implantable narcotic delivery systems. The systems are classified into type-I (exteriorized system using the DuPen epidural catheter) and type-II (implanted system using the Synchromed pump). Costs were analyzed by reviewing actual patient hospital financial service records and Homecare vendor quotations. From the perspective of cost analysis alone, we conclude that savings accrue when patients requiring treatment beyond 3 months duration are managed with a type-II implanted system compared with a type-I system with an external pump.

Experience with an implantable venous access system for chemotherapy

Seventy-one patients receiving prolonged outpatient chemotherapy for solid tumours had a totally implanted venous access system inserted (Port-A-Cath--Pharmacia). These remained in situ for a mean of 278 days. In 98.6% of patients the catheter functioned throughout treatment. This high reliability reflects low rates of sepsis (11%) and occlusion (1.4%). Six catheters were removed because of complications; for sepsis (2), catheter occlusion (1), erosion (2), and wound dehiscence (1). An implanted system may be more economical than external exiting systems for patients requiring a catheter for longer than two months despite a high capital cost, because of lower costs during use. The Port-A-Cath is safe, reliable and acceptable to patients.

Circadian continuous chemotherapy of renal cell carcinoma with an implantable, programmable infusion pump

The authors treated 42 metastatic renal cell carcinoma (RCC) patients who had received no previous chemotherapy or radiation therapy with circadian venous continuous infusion of 5-fluoro-2-deoxyuridine (FUDR). The drug was delivered by Medtronic Synchromed implantable pump (Medtronic, Inc., Minneapolis, MN) in 14-day cycles alternating with 14-day intervals of heparinized physiologic saline infusion. In the course of 24 months 444 cycles of therapy have been given for a total of 12449 days of pump function. Of the patients observed for at least 3 months (range, 3 to 23 months; median, 7 months) three showed complete response (7%; 95% confidence interval, 0% to 15%), three partial response (7%; confidence interval, 0% to 15%), 18 stable disease, and 18 showed progression. Eighteen patients, all with advanced disease at the time of implantation, were living 6 months after treatment started. Circadian continuous central venous infusion of FUDR is minimally toxic. The FUDR can be delivered safely and conveniently in this way for long spans. This therapy is as active as any currently available treatment, is administered in an entirely outpatient setting, and is associated with a normal quality of life.