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Intractable Pain — Solutions to the Problem

Monday March 14, 2005
The intrathecal space is accessed by advancing the needle beyond the epidural space, through the dura mater, and into the subarachnoid space where cerebral spinal fluid continuously bathes the spinal cord.
The intrathecal space is accessed by advancing the needle beyond the epidural space, through the dura mater, and into the subarachnoid space where cerebral spinal fluid continuously bathes the spinal cord.
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In 1846, Dr. William Morton first demonstrated the use of ether anesthesia at the Massachusetts General Hospital. Since then, we've come a long way in our care and treatment of patients who are in pain, whether it be chronic or acute.
Intraspinal analgesia and anesthesia has changed the standard of care for patients with intractable pain, says Maureen Cooney, RN, MS, FNP, CCRN. A nurse practitioner for the Department of Pain Medicine at Westchester Medical Center, Valhalla, N.Y., she explains, "We target the specific origins of pain so that patients find comfort without excess sedation, fatigue, and immobilization. It's amazing to watch their progress."
Cooney says that patients with extensive abdominal surgeries are able to ambulate the next day with less difficulty than when receiving traditional postoperative regimens. The terminally ill can go home to families without living in anguish. People with chronic pain can get their lives under control. Treatment with intraspinal analgesics improves both patient outcomes and quality of life. In an interview with Nursing Spectrum, Cooney answered some specific questions about the care and treatment of patients in pain.
Q. What is the difference between intrathecal analgesia and epidural analgesia?
The term "intraspinal" refers to the spaces and potential spaces that surround the spinal cord into which drugs can be administered. Intraspinal medication can be given into the intrathecal or epidural space. Intraspinal medication delivery places drugs in close proximity to receptor sites in the spinal cord, thereby permitting much smaller doses to be administered to achieve desired effects than would be required with systemic administration.
It is important to differentiate between intrathecal and epidural drug delivery because potency, distribution, absorption, and bioavailability of medications will vary depending on the selected route. Intrathecal and epidural spaces are accessed by inserting a needle between the vertebrae. For the epidural route, the needle is advanced through the ligamentum flavum and into the epidural space, a potential space that exists between the vertebral canal and the dura mater and consists of blood vessels, fat, and nerves. The intrathecal space is accessed by advancing the needle beyond the epidural space, through the dura mater, and into the subarachnoid space where cerebral spinal fluid continuously bathes the spinal cord.
Once the desired space is accessed, medication may be injected or a catheter may be threaded to permit subsequent boluses and/or continuous infusion. Depending on the patient's pain management needs, temporary catheters may be used, which are connected to external infusion pumps, or catheters may be tunneled for long-term use with drug delivery via external or implanted infusion pumps.
Q. How do you determine appropriate dosing?
It's important for nurses to recognize that appropriate dosing depends on the route of medication delivery. Having drug delivery close to the central nervous system increases the relative effectiveness of drugs and calls for a fraction of their usual oral or parenteral doses.
An example would be a patient who is given morphine before leaving the operating room to reduce postoperative pain. Intrathecal morphine is thought to be up to 100 times more efficacious and epidural morphine up to 10 times more efficacious than the same dose of morphine given intravenously. Consequently, the dose must be carefully adjusted according to the route of administration.
While the patient is likely to experience pain reduction in the subsequent 12 to 24 hours, he or she must be carefully monitored for respiratory depression and excessive sedation for up to 24 hours in the general population and even longer in some individuals. Nurses should be aware that morphine, because of its hydrophilicity, generally remains within the cerebral spinal fluid (CSF) for up to 24 hours and spreads rostrally (toward the brain) after intraspinal injection, thus allowing for the long duration of action and a second phase of sedation that occurs within the 24 hours after single dose administration.
For this reason, additional opioids and sedating medications should not be given to anyone who has already had spinal morphine without contacting the pain service. We have standing orders to ensure that this guideline is followed. Epidural analgesia with other opioids, such as fentanyl, often combined with a local anesthetic, such as bupivacaine, are frequently employed for optimal postoperative pain control.
Fentanyl is a lipophilic opioid, which means that it will remain in the aqueous CSF for a short time and will be redistributed to other tissues, so there is minimal rostral spread. The greatest concentration of fentanyl is found at the tip of the epidural catheter, therefore, optimal analgesia is provided at the dermatomal level, which corresponds to the location of epidural solution delivery. Opioids and local anesthetics work together to provide better pain relief at lower doses and with fewer adverse effects than would be experienced with parenteral analgesics. Consequently, patients need less, if any, parenteral intravenous opioids.
Q. What are the three modes of epidural administration for acute pain?
Acute pain management with intrathecal analgesia would only be provided during intraoperative use of spinal anesthesia delivered during surgery, because the risks associated with a direct connection between the external environment and the CSF are far too great. There are three methods of administering epidural analgesia for acute pain: bolus dosing, continuous infusion, and a combination of both.
Bolus dosing is the administration of a dose of medication injected through a catheter. Intermittent bolus dosing, like parenteral dosing, delivers relatively large doses of analgesia that do not maintain a steady blood level when given on a PRN basis. Their "peak and trough" effect may cause nausea and sedation, even when analgesia is good and pain has subsided. Therefore, it is usually beneficial to give smaller bolus dosing around the clock or to use a continuous infusion.
For a continuous epidural infusion, the analgesic is delivered continuously by the regulation of an infusion pump which must be clearly identified as a pump "for epidural administration only." Along with a continuous infusion, additional bolus doses for breakthrough pain may also be delivered by the clinician or the patient. Patients can administer these breakthrough doses of epidural analgesics using a patient-controlled pump (PCEA.)
Q. Who might benefit from epidural analgesia?
Epidural analgesia works especially well for patients with thoracotomies, chest wall trauma, and large abdominal surgeries, as well as for patients with pelvic pain, and hip and lower extremity pain. A combination of opioid and local anesthetic may be given through the epidural catheter.
In the appropriately selected patient, the use of an epidural infusion may provide dramatic physiologic as well as analgesic benefits. For example, a patient with multiple rib fractures with epidural analgesia may experience improved lung expansion, increased vital capacity, increased mobility, and fewer complications as a result of greater pain control.
Q. Can intraspinal analgesics be used for chronic pain?
Intraspinal analgesics are used for long-term control of cancer- and non-cancer-related chronic pain. Various pumps allow externalized as well as internalized access to the epidural and intrathecal spaces.
Intrathecal pumps may be implanted in patients with chronic pain. The pump is set to automatically release a predetermined amount of medication from its reservoir, which is filled with a solution that may contain opioids, local anesthetic, and the alpha2 agonist clonidine, or a combination of these agents.
Because of its direct access to the CSF, an intrathecal for long-term use is connected to an infusion pump, which is implanted in a pocket of subcutaneous tissue. Its reservoir can hold between 10cc to 18cc of a solution and, depending on the patient and dosing, may be refilled every three months.
The choice of medications and the infusion rate may be determined after a brief trial with an externalized catheter. The infusion rate is programmed into the pump by a radio-frequency programmer. This system works well in chronic pain where the level of baseline is somewhat constant. If analgesic requirements change, the delivery rate can be reprogrammed to meet the changing requirements.
Q. Can intraspinal analgesia be used in palliative care?
Patient-controlled, self-administered analgesia has helped move the process of palliative care forward by giving patients control of their own analgesia. An epidural catheter may be placed at the proper vertebral level and then tunneled under the skin to reduce the risk of infection. The catheter is brought to the surface, where it is connected to an infusion pump that may be programmed for bolus or continuous, or a combination of both delivery methods. The health care provider, pharmacist, nurse, and patient can collaborate to make rate or epidural solution adjustments.
A patient's medical status or life expectancy may negate the use of an implanted device. Pain medications must be administered according to individual needs, making an implanted device impractical for some patients with highly variable pain.
With adequate pain control for the terminally ill, nurses provide a high standard of care and facilitate reasonable discharge planning. Staff can help families set realistic goals about their loved ones' care, while patients resume some decision-making about their lives. Epidural analgesia can give the patients enough relief so that other opioids are kept at a minimum and the patients remain alert while taking part in their own care. Patients are discharged with epidural catheters in place; infusion pumps can be strapped to fanny packs while patients are up and mobile. Home care agencies provide pharmacy support for manufacturing and distribution of solutions and nursing support for patient education, assessment, and home care management.
Q. What are the potential complications?
Infection of these systems is always a concern. Therefore, the pain team follows a protocol to clean and dress surgical and insertion sites. Sterility must be maintained, given the proximity of these catheters to the central nervous system. All sites must be inspected and the patient's temperature and white blood cell count must be monitored when infection is suspected. Following catheter insertion, the patient's sensation and motor strength are assessed for any deficits.
Epidural hematoma formation is a rare but serious potential complication of epidural catheter placement, since the accumulation of fluid impinging on the spinal cord can result in paralysis. Consequently, anticoagulation therapy is restricted to avoid bleeding.
Q. Do you have any other pointers for nurses who are caring for these patients?
I have to stress the importance of patient assessment. These catheters are used to improve management of pain; therefore, a thorough pain assessment is essential. It's important to -
Perform a comprehensive patient assessment to identify any possible complications or side effects from intraspinal medication delivery.
Monitor sedation levels and adequacy of ventilation for patients receiving opioids.
Exercise caution in concomitant use of other medications, such as anxiolytics or antihistamines, that could increase the risk of oversedation. Vigilantly monitor sedation levels and respiratory status.
Assess sensation and motor function and consider them in the plan of care.
Note the location of catheters and monitor for any migration by examining the insertion sites.
Patient safety is of paramount importance and some simple measures can be taken to minimize safety risks. For example, external catheters, lines, solution bags, and pumps should be clearly labeled and identified to prevent confusion with other infusions. Patients and their families should be knowledgeable about proper techniques in the home.
Intraspinal analgesia has become an effective alternative treatment for chronic and some acute pain. New drug delivery systems are making the use of opioids safer and more efficient, and funding for pain research at the National Institutes of Health holds exciting promise.
These devices are only "tools of the trade," however, for professionals committed to easing the distress of patients with intractable pain. They are successful only as long as there is a comprehensive approach to patient assessment, care planning, continuous monitoring, and follow-up. The diligence of nurses, pain management teams, and other practitioners is crucial to facilitate intraspinal analgesia when conventional techniques fail at providing comfort and improving patient outcomes.
Research results
Studies have reinforced positive outcomes for patients who are treated with epidural analgesia postoperatively. According to Pasero, patients who receive epidural analgesia postoperatively experience less fatigue, better pain relief, increased mobility, improved bowel function, better satisfaction scores, higher mental status, and are deemed ready for discharge earlier than those treated with traditional methods of intravenous pain management.1
Mary Raju Cole, RN, MS, FNP, APRN, BC, is a contributing writer for Nursing Spectrum.
Reference
1. Pasero C. Epidural Analgesia for Postoperative Pain: Excellent analgesia and improved patient outcomes after major surgery. Am J Nurs.. 103(10); October 2003: 62-64.