CHAPTER 26. Pain and Comfort Management
Linda Wilson, H. Lynn Kane and Kathleen Falkenstein
OBJECTIVES
At the conclusion of this chapter, the reader will be able to:
1. Define pain, commonly used terms, and types of pain.
2. Describe nociception: basic process of normal pain transmission.
3. Describe harmful effects of unrelieved pain.
4. Identify pain and comfort management in the perianesthesia settings, including special considerations and key concepts in analgesic therapy.
5. Identify pharmacological and non-pharmacological interventions, including those for children and management of opioid complications.
6. Define comfort.
7. Identify the contexts in which comfort occurs.
I. PAIN
A. Definition of pain
1. Pain is whatever the experiencing person says it is, existing whenever he or she says it does.
2. Pain is unpleasant sensory and emotional experience associated with actual or potential tissue damage.
B. Types of pain
1. Nociceptive pain—normal processing of stimuli that damages normal tissue or has the potential to do so if prolonged; usually responsive to nonopioids and/or opioids
a. Somatic pain—usually aching or throbbing in quality and is well localized
(1) Arises from:
(a) Bone
(b) Joint
(c) Muscle
(d) Skin
(e) Connective tissue
b. Visceral pain—arises from visceral tissue, such as the gastrointestinal (GI) tract and pancreas
2. Neuropathic pain—abnormal processing of sensory input by the peripheral nervous system or central nervous system (CNS)
a. Treatment usually includes adjuvant analgesics.
b. Centrally generated pain
(1) Deafferentation pain—injury to either the peripheral nervous system or CNS
(2) Sympathetically maintained pain—associated with dysregulation of the autonomic nervous system
c. Peripherally generated pain
(1) Painful polyneuropathies—pain felt along the distribution of many peripheral nerves
(2) Painful mononeuropathies—usually associated with a known peripheral nerve injury, and pain felt at least partly along the distribution of the damaged nerve
C. Definition of commonly used pain terms
1. Acute pain—usually elicited by the injury of body tissues and activation of nociceptive transducers at the site of local tissue damage; pain that extends until period of healing
2. Chronic pain—usually elicited by an injury but may be perpetuated by factors that are both pathogenetically and physically remote from originating cause: pain that extends beyond the expected period of healing (3-6 months since the initiation of pain)
3. Recurrent pain—episodic or intermittent occurrences of pain with each episode lasting for a relatively short period but recurring across an extended period
4. Transient pain—elicited by activation of nociceptors in the absence of any significant local tissue damage; this type of pain ceases as soon as the stimulus is removed (e.g., venipuncture).
5. Addiction—a behavioral pattern of psychoactive substance abuse; addiction is characterized by overwhelming involvement with the use of a medication, the securing of its supply, and a high tendency to relapse.
6. Adjuvant analgesia—a medication that is analgesic in some painful conditions, but that medication’s primary indication is something other than analgesia
7. Allodynia pain—caused by stimulus that does not normally provoke pain
8. Analgesia—absence of the spontaneous report of pain or pain behaviors in response to stimulation that would normally be painful
9. Anxiolytic—a medication used primarily to treat episodes of anxiety
10. Central pain—initiated or caused by primary lesion or dysfunction in the CNS
11. Dysesthesia—an unpleasant, abnormal sensation, whether spontaneous or evoked
12. Hyperalgesia—an increased response to a stimulus that is normally painful
13. Hypoalgesia—diminished pain in response to a normally painful stimulus
14. Hypochondriasis—an excessive preoccupation that bodily sensations and fears represent serious disease despite reassurance to the contrary
15. Malingering—a conscious and willful feigning or exaggeration of a disease or effect of an injury to obtain a specific external gain
16. Neuralgia—pain in the distribution of a nerve or nerves
17. Neurogenic pain—initiated or caused by a primary lesion, dysfunction, or transitory perturbation in the peripheral nervous system or CNS
18. Neuropathic pain—initiated or caused by a primary lesion or dysfunction in the nervous system
19. NMDA— N-methyl- d-aspartate; an example of an NMDA receptor blocker is ketamine.
20. Noxious stimulus—a stimulus that is capable of activating receptors for tissue damage
21. Pain behavior—verbal or nonverbal actions understood by observers to indicate that a person may be experiencing pain and suffering
22. Pain relief—report of reduced pain after a treatment
23. Pain threshold—the least level of stimulus intensity perceived as painful
24. Pain tolerance level—the greatest level of noxious stimulation that an individual is willing to tolerate
25. Paresthesia—an abnormal sensation, whether spontaneous or evoked
26. Physical dependence—a pharmacologic property of a medication (e.g., opioid) characterized by the occurrence of an abstinence syndrome after abrupt discontinuation of the substance or administration of an antagonist; this does not imply addiction
27. Psychogenic pain—report of pain attributed primarily to psychological factors, usually in the absence of an objective physical pathology that could account for pain
28. Suffering—reaction to the physical or emotional components of pain with a feeling of uncontrollability, helplessness, hopelessness, intolerability, and interminableness
29. Tolerance—a physiological state in which a person requires an increased dosage of a drug to sustain a desired effect
D. Nociception: basic process of normal pain transmission
1. Transduction—conversion of one energy from another
a. Process occurs in the periphery when a noxious stimulus causes tissue damage.
b. Damaged cells release substances that activate or sensitize nociceptors.
c. This activation leads to the generation of an action potential.
d. Sensitizing substances released by damaged cells
(1) Prostaglandins
(2) Bradykinin
(3) Serotonin (5-hydroxytryptamine)
(4) Substance P
(5) Histamine
e. An action potential results from:
(1) Release of the preceding sensitizing substances (nociceptive pain)
(2) A change in the charge along the neuronal membrane
(3) Abnormal processing of stimuli by the nervous system neuropathic pain
(4) A change in the charge along the neural membrane
(a) Change in charge occurs when sodium ion (Na +) moves into the cell and other ion transfers occur.
2. Transmission—the action potential continues from the site of damage to the spinal cord and ascends to higher centers; transmission may be considered in three phases.
a. Injury site to spinal cord
(1) Nociceptors terminate in the spinal cord.
b. Spinal cord to brainstem and thalamus
(1) Release of substance P and other neurotransmitters continues the impulse across the synaptic cleft between the nociceptors and the dorsal horn neurons.
(2) From the dorsal horn of the spinal cord, neurons such as the spinothalamic tract ascend to the thalamus.
(3) Other tracts carry the message to different centers in the brain.
c. Thalamus to cortex
(1) Thalamus acts as a relay station sending the impulse to central structures for processing.
3. Perception of pain—conscious experience of pain
4. Modulation—inhibitor nociceptive impulses
a. Neurons originating in the brain stem descend to the spinal cord.
b. Released substances inhibit the transmission of nociceptive impulses.
(1) Endogenous opioid
(2) Serotonin
(3) Norepinephrine (Figure 26-1)
 |
| FIGURE 26-1 ▪ Pain transmission. BK, Bradykinin; H, histamine; 5HT, 5-hydroxytryptamine (serotonin); NE, norepinephrine; PG, prostaglandins; SP, substance P. (From McCaffery M, Pasero C: Pain: Clinical manual, St Louis, 1999, Mosby.) |
E. Harmful effects of unrelieved pain
1. Endocrine
a. Increase in the following:
(1) Corticotropin (Adrenocorticotropic hormone—ACTH)
(2) Cortisol
(3) Antidiuretic hormone
(4) Catecholamines
(a) Epinephrine
(b) Norepinephrine
(5) Growth hormone
(6) Renin
(7) Angiotensin II
(8) Aldosterone
(9) Glucagons
(10) Interleukin-1
b. Decrease in:
(1) Insulin
(2) Testosterone
2. Metabolic
a. Gluconeogenesis
b. Hepatic glycogenolysis
c. Hyperglycemia
d. Glucose intolerance
e. Insulin resistance
f. Muscle protein catabolism
g. Increased lipolysis
3. Cardiovascular
a. Increase in the following
(1) Heart rate
(2) Cardiac output
(3) Peripheral vascular resistance
(4) Systemic vascular resistance
(5) Hypertension
(6) Coronary vascular resistance
(7) Myocardial oxygen consumption
(8) Hypercoagulation
(9) Deep vein thrombosis
4. Respiratory
a. Decreased flows and volumes
b. Atelectasis
c. Shunting
d. Hypoxemia
e. Decreased cough
f. Sputum retention
g. Infection
5. Genitourinary
a. Decreased urinary output
b. Urinary retention
c. Fluid overload
d. Hypokalemia
e. Hyperkalemia
6. Gastrointestinal (GI)
a. Decreased gastric motility
b. Decreased bowel motility
7. Musculoskeletal
a. Muscle spasm
b. Impaired muscle function
c. Fatigue
d. Immobility
8. Cognitive
a. Reduction in cognitive function
b. Mental confusion
9. Immune response
a. Depression
10. Developmental
a. Increased behavioral and physiological response to pain
b. Altered temperaments
c. Higher somatization
d. Infant distress behavior
e. Possible altered development of the pain system
f. Increased vulnerability to stress disorders
g. Addictive behavior
h. Anxiety states
i. Cultural considerations
11. Debilitating chronic pain syndromes
a. Postmastectomy pain
b. Postthoracotomy pain
c. Phantom pain
d. Postherpetic neuralgia
12. Quality of life
a. Sleeplessness
b. Anxiety
c. Fear
d. Hopelessness
e. Increase thoughts of suicide
F. Special considerations
1. Key principle: all patients deserve the best possible pain relief and comfort measures that can be safely provided.
2. The following emphasizes some important key elements of care in patients with special needs.
a. Elderly patients
(1) Same pain assessment tools may be used in both cognitively intact elderly and younger patients.
(2) Report of pain may be altered.
(a) Physiological
(b) Psychological
(c) Cultural differences
(3) Often have acute and chronic painful diseases
(a) More than 80% have various forms of arthritis.
(b) Most will have acute pain at some time.
(4) Have multiple diseases
(5) Take many medications
(6) Prevalence of pain two-fold higher in those older than 60
(7) Increased sensitivity to therapeutic and toxic effects of analgesics
(a) Influenced by age-induced changes
(i) Drug absorption
(ii) Distribution
(iii) Metabolism
(iv) Elimination
(8) Prone to constipation when given opioid analgesic
(9) All nonsteroidal anti-inflammatory medications (NSAIDs) must be used with caution because of increased risk.
(a) GI problems
(b) Renal insufficiency
(c) Platelet dysfunction
(10) More sensitive to analgesic effects of opioid medications
(a) May experience a higher peak effect
(b) Longer duration of pain relief
(c) Reduce initial dose by 25% to 50%.
(d) Careful dose titration
(e) Close monitoring of patient’s responses
b. Patients with known or suspected chemical dependency or history of such
(1) Usually experience traumatic injuries
(2) Experience a variety of health problems
(3) Possible withdrawal caused by opioid absence may stimulate sympathetic nervous system.
(a) Restlessness
(b) Tachycardia
(c) Sleeplessness
(4) Focus on managing pain or discomfort, not detoxification.
(5) There is no evidence that:
(a) Withholding analgesics will increase the likelihood of recovery from addiction
(b) Providing analgesics will worsen addiction
(6) Higher loading and maintenance doses of opioids may be required to reduce intensity of pain.
(7) Provide nonpharmacological interventions concomitantly with pharmacological interventions.
(8) May refer to an addiction specialist for ongoing care and rehabilitation after the acute pain period
(9) Patients with chronic alcoholism who are actively drinking
(a) Maintain on benzodiazepines or alcohol throughout the intraoperative and postoperative periods to prevent withdrawal reaction or delirium tremens.
(b) Dosage based upon individual evaluation
c. Concurrent medical conditions
(1) Involving either hepatic or renal impairment: result is medication accumulation
(a) Elimination decreased in patient with renal failure
(b) Doses must be lowered or given less frequently.
(2) Observe patient with respiratory insufficiency and chronic obstructive disease.
(3) Observe patient taking anxiolytics or other psychoactive medications for interaction with pain medications.
d. Patients with shock, trauma, or burns
(1) Observe for cardiorespiratory instability in the first hour of injury.
(a) Carefully titrate opioid dosage.
(b) Monitor closely.
(2) Peripheral nerve damage may result in neuropathic pain requiring adjuvant analgesics.
(a) Tricyclic antidepressants
(b) Anticonvulsants
(c) Opioids
(d) Nonopioids
e. Patients having procedures outside the operating room
(1) Analgesia may be withheld for a painful procedure when:
(a) Immediate treatment of cardiorespiratory instability required
(b) A competent patient declines treatment.
(2) Clinicians giving anesthetic or analgesic agents must understand:
(a) Proper technique of administration
(b) Dosage
(c) Contraindications
(d) Side effects
(e) Treatment of overdose
(3) Monitor closely according to institutional policy when analgesic or adjuvant given.
f. Patients with chronic pain in perianesthesia setting
(1) Require special consideration and planning for pain management
(2) May request consultations with an acute pain management service and/or anesthesiologist familiar with chronic pain management
(3) Individualized detailed pain management plan communicated through all phases of perioperative care
g. Pediatric patients
(1) Provide adequate and unhurried preparation of the child and family.
(a) Parental prediction of the child’s response highly correlates with the actual degree of distress.
(2) Optimally manage preexisting pain.
(3) Requires frequent assessment and reassessment
(a) Presence
(b) Amount
(c) Quality
(d) Location of pain
(4) Emotional distress accentuates the experience of pain.
(a) Focus on prevention.
(b) Reduce anticipated pain.
(5) Inclusion of parents or caregiver essential to pain assessment
(6) Tailor assessment strategies to the development level and personality of the child.
(7) Physiological indicators may vary among children who are experiencing pain.
(8) Interpretation of physiological indicators crucial
(a) In the context of the clinical condition
(b) In conjunction with other assessment methods
(9) Effective interaction key to effective pain management
(10) Preferences of the child and family warrant respect and careful consideration.
(11) Primary obligation to ensure safe and competent care
(12) Environmental factors such as cold or crowded rooms and alarms on machines can intensify distress.
h. Obstetric patients
(1) During pregnancy
(a) Analgesic considerations
(i) May increase vascular resistance or decrease placental flow
(ii) May cause transient or permanent harm to the fetus or infant
(b) Encourage the use of nonpharmacological pain-relieving measures and caution against the use of analgesics.
(c) Analgesics
(i) Acetaminophen: safe for use in therapeutic doses
(ii) NSAIDs: generally not recommended
(iii) Opioid analgesics: a long history of safely relieving perinatal pain
[a] Mu-agonists are recommended.
[1] Morphine
[2] Hydromorphone
[3] Fentanyl
[4] Oxycodone
[5] Hydrocodone
[6] Meperidine: not recommended as first-line opioid
(iv) Adjuvant analgesics are used to treat pain of neuropathic origin.
[a] Local anesthetics
[b] Antidepressants
[c] Anticonvulsants
[d] Corticosteroids
[e] Benzodiazepines
(v) Types of pain related to pregnancy
[a] Round ligament pain (sides of the uterus)
[b] Headache
[c] Back pain
[d] Pyrosis (heartburn)
[e] Braxton Hicks contractions
(2) During childbirth
(a) Labor pain considered the most agonizing of pain syndromes
(b) Factors contributing to suffering
(i) Lack of appropriate analgesics
(ii) Lack of support person
(iii) Hunger
(iv) Fatigue
(v) Low self-confidence
(c) Alternate pain management methods
(i) Relaxation
(ii) Distraction
(iii) Imagery
(iv) Effleurage
(v) Water heat
(vi) Acupuncture
(d) Analgesics
(i) Mu-opioid agonists commonly used
(ii) Meperidine not recommended
(iii) Local anesthetic bupivacaine used most often for epidural analgesia and anesthesia
(iv) Benzodiazepines recommended for muscle spasm only, and their use for childbirth not recommended
(e) Regional techniques used
(i) Intrathecal analgesia
(ii) Epidural analgesia and anesthesia
(iii) Combined spinal-epidural analgesia
3. During postpartum
a. Effective pain management very important postpartum
(1) Clotting factors elevated
(2) Increased risk for thrombophlebitis
(3) Pain relief should be aimed at maximizing patient’s mobility.
b. Bonding with baby encouraged
c. Types of pain
(1) Uterine contractions
(2) Episiotomy
(3) Breast
(4) Nipple
(5) Post Cesarean section
4. During breast-feeding
a. Secretion of medications into breast milk: considerations
(1) High lipid solubility
(2) Low molecular weights
(3) Nonionized state
5. Neonates may receive 1% to 2% of the maternal dose of a medication.
a. Medicating right before or right after breast-feeding may minimize medication transfer.
b. Acetaminophen safe
c. NSAIDs generally not recommended
d. Opioid analgesics
(1) Codeine
(2) Fentanyl
(3) Methadone
(4) Morphine
e. Adjuvant analgesic for neuropathic pain
G. Key concepts in analgesic therapy
1. Balanced analgesia
a. Continuous multimodal approach in treating pain
b. Considered as the ideal by experts
c. Use combined analgesic regimen.
(1) Reduces the likelihood of significant side effects from a single agent or method
d. Opioids commonly used in the balanced analgesia approach
(1) Administered preemptively as well as after the noxious event occurs
2. Preemptive analgesia
a. Intervention implemented before noxious stimuli are experienced
b. Designed to reduce the CNS impact of these stimuli
c. NSAIDs reduce activation and centralization of nociceptors.
d. Local anesthetics used to block sensory inflows
e. Opioids act centrally to control pain.
f. Local anesthetics provide effective preemptive analgesia.
(1) Long-acting regional blocks indicated before painful procedures
(2) Indicated whenever pain management expected to be difficult
3. Around-the-clock (ATC) dosing
a. Two basic principles of providing effective pain management
(1) Preventing pain
(2) Maintaining a pain rating that is satisfactory to patient
b. Indicated whenever pain is predicted to be present for at least 12 to 24 hours
c. ATC dosing should be accompanied by provision of additional analgesic doses to relieve:
(1) Breakthrough pain
(2) Ongoing extreme pain
d. Short-acting mu-agonist opioid analgesics used in breakthrough pain
(1) Recommend that rescue doses are the same route and opioid as the ATC.
e. Pain can have a sudden or gradual onset, and it can be brief or prolonged.
4. As needed (PRN) dosing
a. Ordinarily, the patient requests analgesia.
b. Effective PRN dosing requires active participation of patient.
(1) Prompt patient to ask for medication before the pain is severe or out of control.
c. Opioid analgesic is appropriate.
d. ATC can be replaced with PRN dosing when acute pain is resolved.
5. Patient-controlled analgesia (PCA)
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a. An interactive method that permits patients to treat their pain by self-administering doses of analgesics.
b. Initiating PCA in the post anesthesia care unit (PACU) is recommended.
(1) Allows evaluation of patient’s response to the therapy early in postoperative course
(2) Prevents delays in analgesia on the nursing unit
c. Types
(1) Subcutaneous infusions
(a) Rarely used for acute pain management
(i) Slow onset
(ii) When there is limited intravenous (IV) access
(iii) Oral opioids not tolerated
(iv) Intermittent bolusing for children
(b) Hydromorphone and morphine most commonly used
(c) Methadone causes irritation to the site.
(d) Absorption and distribution dependent on needle placement and the patient’s adipose tissue
(e) Opioid concentrations high because infusion volumes must be limited
(i) Most patients can absorb 2 or 3 mL/h.
(ii) Some can absorb 5 mL/h.
(iii) Infusion pump must be able to deliver in tenths of milliliter (0.1 mL/h).
(f) Primary site of infusion
(i) Left or right subclavicular anterior chest wall
(ii) Left, right, or center abdomen
(iii) Upper arms
(iv) Thighs
(v) Buttocks
(2) IV PCA
(a) Used for immediate analgesic effect for acute, severe escalating pain
(i) Includes bolus
(ii) Continuous infusion
(b) A steady state maintained better with continuous infusion
(c) Duration of analgesia by bolus administration is dose dependent; the higher the dose, usually the longer the duration.
d. Special considerations for pediatric IV PCA
(1) Safe and effective use in children older than 5 years
(2) Instruct parents and caregivers that only the designated child’s pain manager should press the PCA.
(3) Adult and pediatric selection guidelines are the same in the use of PCA.
(4) Principles of starting dose estimates and titration for adults apply also to children.
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