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doi: 10.1097/01.ORN.0000320616.37595.6c
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Patient selection guides epidural analgesia

Hader, Christine Flickinger RN, C, CCRN, CPAN, MSN

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Christine Flickinger Hader is a clinical program manager at Ann May Center for Nursing, Meridian Health, Neptune, N.J., and an advanced practice nurse at The Pain Institute at Jersey Shore University Medical Center, Neptune, N.J.

Adapted from: Flickinger Hader C. Epidural analgesia in the critically ill. Nursing Critical Care. 2007;2(5):20–30.

Pain, caused by a variety of harmful stimuli that result from disease states, injury, surgery, or therapeutic in-terventions, is one of the most common experiences shared by all patients.1,2 The management of pain is the responsibility of all healthcare disciplines and should be treated based on a thorough assessment of the patient's level of comfort.

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Proper management

The Thunder Project II, a study of acutely ill patients' perception and response to diagnostic and care-related procedures, found that less than 20% of patients receive opioid therapy prior to the initiation of a painful procedure. This research supports the need for the correct assessment and anticipation of painful stimuli so appropriate and timely treatment can be rendered to minimize the discomfort and distress of the patient.3

In 2001, The Joint Commission published standards for the assessment and management of pain. The intent was to ensure that all patients receive adequate care through the implementation of a comprehensive pain management plan of care. As a result of these standards, healthcare systems are challenged to implement strategic plans that address pain. This approach provides a framework for organizational assessment and treatment of pain. Administrators have determined that to successfully manage patients' pain, a comprehensive program must be developed, implemented, and monitored for effectiveness.4

Although pain is a common occurrence for the critically ill patient, there continues to be a lack of understanding on the part of healthcare professionals regarding the appropriate assessment, treatment, and intervention of pain in the care of this vulnerable population. Recent data reveal that 64% of surgical patients and nearly 50% of medical patients in intensive care units (ICUs) report experiencing moderate to severe pain. Pain, which is multifaceted and complex, is further complicated by a clinician's inadequate assessment, resulting in poorly controlled symptoms.5

Traditional methods for managing pain (via oral and intramuscular administration) haven't always proven efficacious or practical for use in PACU and the critical care environment. Many patients can't tolerate oral medications, and intramuscular injections have been deemed a poor route of medication administration by the American Pain Society, due to potential adverse effects and unpredictable medication absorption rates.6 With advances in pain management approaches and techniques, clinicians need to be aware of comprehensive and contemporary approaches to pain management for the critically ill patient.

Epidural analgesia is a pharmacologic approach to pain management that should be considered following an appropriate assessment of a patient's pain. When combined with other pharmacologic agents and nonpharmacologic interventions, patients can achieve better pain control, decreased suffering and anxiety, and improved physiologic outcomes. The implementation of comprehensive plans for pain management in this patient population may result in enhanced patient outcomes and reduced lengths of stay. Although the implementation of epidural analgesia requires an experienced anesthesia provider, nurses should be cognizant of the types of patients that may be potential candidates for this method of analgesia. (See Candidates for epidural analgesia.)7–9

To appreciate the benefits that epidural analgesia can offer with regard to pain control, clinicians must possess knowledge and an understanding of pain physiology and the untoward effects that unrelieved pain exerts on the patient.

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Defining pain

A leading expert in the field of pain management offered a comprehensive and holistic definition of pain: “Whatever the experiencing person says it is, existing whenever she/he says it does.”7 Conscious-ness of the pain experience is the totality of the pain process, including the psychological and emotional aspects of the experience.2,10

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Physiology of pain

Figure. Mechanism of...
Figure. Mechanism of...
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Noxious (thermal, chemical, or mechanical) stimuli initiate a series of chemical responses that result in the transmission of the stimulus by way of nerve fibers, and activate the pain pathway. Neuroregulators (neurotransmitters and neuromodulators) are involved in the inhibition or facilitation and the modulation of the painful stimulus. The translation of the stimulus and conscious perception of pain occur at different levels in the brain.

The selection of pain medications depends on the site of the pain, the pharmacologic make up of the medication, and its effect on the pain pathway. Select analgesic agents such as nonsteroidal anti-inflammatory agents (NSAIDs) exert their action on the inflammatory process by inhibiting cyclooxygenase, resulting in decreased synthesis of prostaglandins.

Local anesthetic agents and antiepileptics block or inhibit the production of nociceptive impulses. These medications are often used as adjuvants to opioid analgesics.

Opioid analgesics bind to opioid receptors found in the dorsal horn, primary afferent fibers of the ascending pathway, the brain (cerebral cortex, hypothalamus, and periaqueductal gray matter of the brainstem), and in the efferent fibers of the descending pathway, and yield an effect similar to endogenous opioids. They alter the pain response and produce analgesia through the inhibition of nociceptive impulses. Opioids also stimulate the chemoreceptor trigger zone located in the brain, which can result in nausea and vomiting.6 (See Mechanism of acute pain.)

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Uncontrolled pain

Neuroendocrine, metabolic, inflammatory, and stress responses to critical illness, trauma, and surgery contribute to patient morbidity and mortality. In the already fragile, physiologically compromised patient, uncontrolled pain perpetuates and intensifies these responses which in turn adversely effect major organ systems resulting in poor patient outcomes.4,11,12

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Assessment and evaluation of pain

The most reliable indicator of pain is a patient's self-report. Patients who are critically ill often have difficulty communicating, due to illness or circumstances (such as sedation or neuromuscular blockade), which consequently places them at risk for insufficient pain treatment. No objective biological parameter or objective quantification for pain exists, therefore, clinicians must use unidimensional pain intensity scales (such as Visual Analogue Scales, Numeric Rating Scale, or FACES scale) that allow patients to self-rate their pain intensity.

Pain intensity scales assist in the assessment of pain. These scales need to be carefully selected based upon the patients' age, ability to communicate, emotional and physical status, preference, and cognition. The use of pain intensity scales help to identify the patients' pain intensity and provide direction for the treatment plan. (See Pain intensity scales.)

When patients can't participate in communicating their pain, nurses must rely on behavioral-physiological measures of pain. The American College of Critical Care Medicine's (ACCM) clinical practice guidelines recommend that “patients who cannot communicate be assessed through subjective observation of pain-related behaviors (movement, facial expression, and posturing) and physiological indicators (heart rate, BP, and respiratory rate) and the change in these parameters following analgesic therapy.”12 In a retrospective study of pain assessment and management in critically ill intubated patients, the researchers supported the use of physiological-behavioral observations as indicators for pain.13

After a complete pain assessment is performed, clinicians need to participate in the development of comprehensive plans for managing pain, considering the overall health status of the individual patient and the risks and benefits of the proposed medication regime and route of administration. The challenge with regard to the critically ill patient is to implement a plan for pain management that provides analgesia and limits sedation and un-wanted adverse reactions (balanced analgesia).

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Epidural analgesia

When epidural analgesia is being considered, appropriate patient selection is important. Patients are selected based on an assessment inclusive of the overall patient status, risks, benefits, indications, and contraindications of epidural analgesia.

Anticoagulation, once considered a relative contraindication to the use of epidural analgesia, has been a focus for the American Society of Regional Anesthesia and Pain Medicine (ASRA). The organization has published consensus statements concerning regional anesthesia and anticoagulation. These statements present the safety, efficacy, and risks of neuraxial anesthesia and analgesia based on the timing of needle insertion and catheter removal in relation to the time anticoagulants are administered.14 (See Contraindications for epidural analgesia.)9,15

For the patient selected for epidural analgesia administration, an appropriately placed and functioning epidural catheter can produce pain relief that is superior to other routes of analgesic administration.15 Placement of the epidural catheter requires technical skill on the part of the anesthesia provider, but nurses need to demonstrate a knowledge base regarding the anatomy of the epidural space, the surrounding structures, epidural catheter care, and patient care before and after catheter insertion. (See Anatomy of the epidural space.)

Figure. Pain intensi...
Figure. Pain intensi...
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The epidural space is a potential space occupied by fatty tissue, blood vessels, and lymphatics. The posterolateral portion or the epidural space lies between the dura mater of the spinal cord and ligamentum flavum and laminae.

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Figure. Anatomy of t...
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Epidural analgesia can be administered by three methods: single-injection and intermittent boluses, continuous infusion via an indwelling catheter, or patient-controlled epidural analgesia (PCEA). Single-injection or intermittent epidural bolus requires the use of longer-acting opioids (preservative-free morphine) to achieve a realistic duration of analgesia. The use of morphine for single-injection administration carries an increase in the “risk of delayed onset respiratory depression.”15 Single-injection method or intermittent bolus of opioids results in a delay in the response to patients' complaints of continued pain because the anesthesia provider must be notified and respond to the request for pain management.

Continuous epidural infusion offers the distinct advantage of providing steady-state analgesia when compared with single-injection administration or intermittent boluses, especially when short-acting opioids are used for infusion.

Because it combines the benefits of continuous infusion with intermittent demand boluses, PCEA is gaining favor in many institutions. It affords patients control over their own pain management by allowing self-administration of boluses by way of a preset dose. Patients administer the dose on demand when their severity of pain increases.

To initiate epidural analgesia, the anesthesia provider accesses the epidural space employing aseptic technique. The epidural catheter is inserted with the patient in the sitting or the side-lying position. If the patient is awake during catheter insertion, he or she will require assistance with positioning and reassurance throughout the procedure. The catheter is placed using knowledge of dermatomes as they relate to a level appropriate to the anatomical site of pain. The catheter is secured with a bioocclusive dressing to minimize catheter movement and to allow for inspection of the epidural catheter site for drainage, redness, or inflammation. After the catheter is secured, it should be clearly identified as an epidural catheter.

Continuous epidural infusion can usually provide analgesia for five to seven consecutive dermatome areas. For patients with multiple sites of pain, other methods of analgesia may need to be implemented. An epidural catheter positioned within the derma-tome region of the pain, as well as catheter integrity promote the success of analgesia.

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Pharmacological choices

Analgesia is achieved through the administration of local anesthetics, opioids, or a combination of a diluted concentration of both. Local anesthetics act at the spinal nerve root level (sympathetic ganglion chain) and affect the nerves' action potential by preventing an influx of sodium ions into the cell, resulting in inhibition of nerve impulse transmission. Local anesthetics also influence the inflammatory response by antagonizing the release of prostaglandins. The inhibition of pain and inflammation make local anesthetics valuable in reducing the overall stress response activated in times of critical illness.16,17

Lidocaine (Xylocaine), bupivacaine (Marcaine), and ropivacaine (Naropin) are effective in achieving analgesia. Lidocaine is a short-acting amide that's best indicated for single-injection or bolus dosing because of its rapid onset of action. Bupivacaine is most commonly chosen for continuous infusion because of its longer duration of action and “because of its clinical safety data and wide availability.”8,16

Local anesthetics act to block sympathetic impulses (clinically observed as decreased heart rate, BP, and respiratory rates). The secondary effect is a blockade of the sensory impulses before they enter the dorsal horn of the spinal cord. This effect results in a change in sensation, pain (anticipated effect), touch, and temperature (unintentional effect). The tertiary effect is motor block as doses increase. The consequences range from weakness to paralysis of motor ability in the dermatome-affected region.

The most common adverse effects associated with the use of local anesthetics are tachyphylaxis and hypotension. Tachyphylaxis is an intrinsic effect generally associated with short-acting amides and intermittent bolus dosing. The phenomenon is characterized by an acute tolerance to the anesthetic agent, wherein an increase in successive doses is required to maintain the diminishing duration and quality of analgesia.18 Hypotension is due to sympathetic nerve blockade.

Opioids mimic endogenous opioid compounds and bind to opioid receptor sites (found in the brain and dorsal horn of the spinal cord) as agonists to produce an analgesic effect. In the brain, opioids modify pain perception and reaction to noxious stimuli.7,16,17 They have no effect on sensory, motor, or sympathetic nerve function.

The most frequently administered epidural opioids are the mu-agonists: morphine and fentanyl—all epidural drugs must be preservative-free. One important factor when selecting one of these opioids for epidural administration is an understanding of their lipid solubility. Lipid solubility is a clinical predictor of analgesic action and onset of adverse reactions.

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Lipid solubility

Figure. DermatomesTo...
Figure. DermatomesTo...
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Table. Ramsay scale ...
Table. Ramsay scale ...
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Hydrophilic (water-soluble and lipid-insoluble) opioids such as preservative-free morphine (Duramorph) have a delayed onset (30 to 60 minutes) and long duration of action (12 to 24 hours). Morphine slowly permeates the dura to bind at the opioid receptor sites in the dorsal horn of the spinal cord. Hydrophilic opioids tend to provide a wider segment of analgesia because of the rostral spread (movement of the medication upward in the cerebrospinal fluid (CSF). These drugs tend to spread cephalad because they remain in the CSF for a longer duration of time. This places the patient at risk for late respiratory depression (8 to 24 hours after opioid administration). This response is due to the “cephalic spread of the opioid to the brainstem.”16 Late respiratory depression is more commonly associated with bolus doses.16,19,20

Fentanyl (Sublimaze) is a lipophilic (lipid-soluble) opioid. Lipophilic opioids have a rapid onset (5 to 15 minutes) and short duration of action (2 to 3 hours) because they readily diffuse through the dura and are absorbed into the epidural vasculature. Fentanyl creates a narrower segment of analgesia, when compared with hydrophilic drugs because there's less rostral spread.16,19,20 This means that the outcome is more regionalized to the area (dermatome) where the catheter is placed.

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Medication selection

While most clinicians are concerned about respiratory depression as an adverse reaction related to opioid use, it's helpful to know that the “incidence of clinically significant respiratory depression is reported to be less than 1%.”16

A combination of a dilute local anesthetic agent with an opioid is often used for continuous infusion in an attempt to achieve pain control with minimal adverse reactions. Combination epidural infusions impart coanalgesic advantages, such as a more rapid analgesia, effective sensory (pain) blockade, and prolonged analgesic effect, when compared with single-agent infusions. The two drugs work synergistically and have distinct differences in site of action. In critically ill patients, the clinical outcomes are positive and include improved pulmonary function, decreased cardiovascular effects, and reduced incidence of paralytic ileus.2,8,16,17,19,21

Medication selection for epidural administration must always reflect the individual patient's needs with respect to pain control, hemodynamic stability, and side effect profile of the drug.9 For example, morphine stimulates histamine release that results in adverse reactions such as hypotension. For patients with restrictive airway disease and bronchospasm, the effects can be deleterious, whereas a patient with acute heart failure could benefit from the vasodilating effect secondary to the release of histamine and experience a reduction in preload, thus improving hemodynamic stability.19 These effects can occur when using the epidural route based on medication selection and combination. Doses need to be carefully titrated to achieve positive outcomes.

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Patient monitoring

The focus of nursing care is the identification and management of potential side effects and complications related to epidural analgesia administration. Prudent nursing assessment and close patient monitoring are essential to safe epidural analgesia administration. Patient care policies often vary among institutions, so nurses need to familiarize themselves with their institutional policies regarding patient monitoring and evaluation for potential side effects and complications related to epidural analgesia administration.

Monitoring parameters include respiratory rate, oxygen saturation, BP, pulse, level of sedation, motor function and temperature. Dermatomes are useful in assessing and documenting sensory levels that are affected when a local anesthetic is used. (See Derma-tomes.) Scales such as the Bromage Scale can be used to assess and document motor function.

Monitoring parameters should be assessed according to the facility's PACU protocol and when the patient is transferred to the CCU, parameters should be assessed every hour for 4 hours, then every 4 hours if the patient is stable. The anesthesia provider should be notified if the patient exhibits any of the following symptoms:

Table. Potential adv...
Table. Potential adv...
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* systolic BP less than 90 mmHg

* sedation level is increased (patient difficult to arouse) (See Ramsay scale for assessing level of sedation.)

* respiratory rate less than 9 breaths/minute

* motor assessment reveals an inability of the patient to bend their knees on motor evaluation

* sensory level is above T4/T6 (unless thoracic epidural)

* inadequate analgesia

* persistent nausea

* vomiting

* itching.

Naloxone (Narcan) and ephedrine should be on hand to manage oversedation and hypotension if needed and directed by the anesthesia provider. (See Potential adverse effects and complications related to epidural analgesia.)7,16,18,20

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Multidisciplinary care

Nurses need to be educated and competent with regard to epidural analgesia. Current practice guidelines and policies need to be available to support staff in their efforts to provide quality care to their patients.

The acutely ill patient's analgesic needs should be integrated into his or her multidisciplinary plan of care. Pain management regimes need to be specific and individualized with appropriate parameters for care formulated. Systematic and standardized approaches to pain and its management need to be supported by all team members.

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Candidates for epidural analgesia

The following are common surgical procedures and medical conditions for which epidural analgesia may be considered:

Thoracic surgery

Major upper and lower abdominal surgery (such as abdominal aortic surgery)

Vascular surgery of the lower extremities

Total knee replacement surgery

Amputation of the lower limbs

Major breast reconstructive surgery

Cancer pain

Pancreatitis

Rib fractures

To prevent or reduce pain of a chronic pain syndrome (such as phantom limb pain or complex regional pain syndrome)

Patients with compromised preoperative cardio-vascular or pulmonary function

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Contraindications for epidural analgesia

Absolute

* Patient refusal

* Infection at proposed catheter insertion site

* Systemic infection

* Acute, symptomatic hypovolemia

* Allergy to local anesthetic agents or opioids

Relative

* Coagulopathy

* Increased intracranial pressure

* Neurological disorder

* Spine deformity

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REFERENCES

1. Acute pain management guideline panel. Acute Pain Management: Operative or Medical Procedures and Trauma. Clinical Practice Guideline. Rockville, Md: Agency for Healthcare Policy and Research. U.S. Department of Health and Human Services; AHCPR publication no. 92-0032,1992.

2. Faut-Callahan M, Hand WR. Pain management. In: Nagelhout J, Zaglaniczny K, eds. Nurse Anesthesia. 2nd ed. St. Louis, Mo: Elsevier Saunders; 2005:1157–1174.

3. Puntillo K, White C, Morris AB, et al. Patients' perceptions and responses to procedural pain: results from Thunder project II. Am J Crit Care. 2001;10(4);238–251.

4. Joint Commission. Pain Assessment and Management: An Organizational Approach. Oakbrook Terrace, Ill: JCAHO, 2000:2.

5. Hall L, Oyen L, Murray MJ. Analgesic agents: Pharmacology and application in critical care. In: Vender J, Szokol J, Murphy G, eds. Critical Care Clinics. Philadelphia, Pa: W.B. Saunders Company; 2001:899–921.

6. American Pain Society. Principles of Analgesic Use in the Treatment of Acute Pain and Cancer Pain. 5th ed. Glenview, Ill: American Pain Society; 2003:3–42.

7. McCaffrey M, Pasero C. Pain Clinical Manual. 2nd ed. Philadelphia, Pa: Mosby; 1999.

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14. Horlocker TT, Wedel DJ, Benzon H, et al. Regional anesthesia in the anticoagulated patient: defining the risks (Second Consensus Conference on Neuraxial Anesthesia and Anticoagulation, April 2002). Available at: http://www.asra.com/consensus-statements/2.html. Accessed August 20, 2007.

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18. Burkhard R, Olson RL, Vacchiano CH. Regional anesthesia. In: Nagelhout J, Zaglaniczny K, eds. Nurse Anesthesia. 2nd ed. St. Louis, Mo: Elsevier Saunders; 2005:1157–1174.

19. Casey Z, Wu CL. Epidural opioids for postoperative pain. In: Benzon H, Raja S, Molloy R, et al, eds. Essentials of Pain Medicine and Regional Anesthesia. Philadelphia, Pa: Elsevier; 2005:246–252.

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21. Ashburn M, Caplan R, Carr D, et al. Practice guidelines for acute pain management in the perioperative setting: An updated report by the American Society of Anesthesiologists Task Force on Acute Pain Management. Anesthesiology. 2004;100(6):1573–1581.

© 2008 Lippincott Williams & Wilkins, Inc.

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