Abstract
Dear Editor:
An implanted intrathecal drug delivery system provides pain relief with reduced drug side effects in patients with refractory cancer pain. 1 Infections of the implanted systems are rare, mostly occurring during the first weeks following implantation. 2
We report a late pump pocket infection and discuss our strategy and relevant ethical considerations in the management of this complication in a patient with refractory end-of-life pain. A 48-year-old patient with left supraclavicle sarcoma was receiving the equivalent of 1700 mg oral morphine per day associated with significant cognitive impairment, sedation, bradypnea, and nonetheless inadequate pain control. A percutaneous intrathecal catheter was initially placed and an infusion of morphine, clonidine, and ziconotide was started. The patient improved rapidly, with significantly lower pain scores while remaining alert. Subsequently, because of a life expectancy up to 3 months, an intrathecal drug delivery pump (Medtronic SynchroMed II™, Medtronic Inc., Minneapolis, MN) was implanted. During a routine pain consultation appointment 4 months later, swelling and fluctuation at the area overlying the pump pocket was noted, whereas the patient had no signs of systemic infection. The pump pocket was punctured and pus was aspired. Laboratory analysis of the aspirated fluid revealed abundant polymorphonuclear neutrophils and bacterial growth of Staphylococcus epidermidis. At the time of the pocket pump infection diagnosis, the patient was receiving intrathecally 42 mg morphine per day associated with 75 μg clonidine per day (ziconotide had been withdrawal several weeks before because of serious neurological adverse events). As our patient had otherwise refractable end-of-life pain, a decision was made following the consent of both the patient and his family to maintain the implanted intrathecal drug delivery system despite the risks of meningitis, epidural abscess, and severe sepsis. Long-term antibiotic therapy with oral pristinamycin was instituted and percutaneous pump filling was maintained at 3–4 week intervals.
In palliative patients with severe refractory cancer pain, relief with fewer opioid side-effects can be achieved with central neuraxial blocks. It also has been suggested that implanted intrathecal drug delivery systems may be associated with prolonged survival. 1 Although the underlying ethical principles for clinical practice in palliative care are no different from those in any other branch of medicine, the nature and complexity of the situations can make decision making very intricate and challenging. Standard-of-care practice in cases of device-related infections as the one we present would require removal of the device and appropriate intravenous antibiotic therapy. 3 Moreover, the patient would be required to receive an equianalgesic dose of 4200 mg per day of intravenous morphine in replacement of the intrathecal opioid to expect to achieve equal levels of pain relief. The risk of severe infection was counterbalanced by the risk of palliative sedation for intractable pain control. In patients suffering with pain near the end of life, effective symptom control may be more important than eradicating infection.
At the time of writing this letter, the patient was still alive at 5 months following pump implantation without signs of systemic or neurological infection. Disease progression with probable opioid-induced hyperalgesia and tolerance necessitated the increase of the intrathecal pain medication to daily doses of up to 60 mg morphine and 100 μg clonidine, as well as the addition of intrathecal ketamine at a dose of 7.5 mg per day.