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90 Ramani VIJAYAN
Benedetti F, Pollo A, Lopiano L, et al. Conscious expectation and unconscious conditioning in analgesic, motor and
hormonal placebo/nocebo responses. J Neurosci 2003;23:4315–23.
Benedetti F, Amanzio M, Baldi S, et al. e specific effects of prior opioid exposure on placebo analgesia and placebo
respiratory depression. Pain 1998;75:313–9.
Bilodeau BA, Degner LF. Information needs, sources of information and decisional roles in women with breast cancer.
Oncol Nurs Forum 1996;23:691–6.
Blackhall L, Murphy S, Frank G, et al. Ethnicity and attitudes towards patient autonomy. JAMA 1995;274:820–5.
Blackhall LJ, Frank G, Murphy ST, et al. Ethnicity and attitudes towards life sustaining technology. Soc Sci Med
1999;48:1779–89.
Brody B. e Nuremberg Code. Reprinted in Brody B. e Ethics of Biomedical Research. An International Perspective.
New York: Oxford University Press, 1947;213.
Bubela N, Galloway S, McCay E. Factors influencing patients’ informational needs at time of hospital discharge. Patient
Educ Couns 1990;16:21–8.
Casarett D, Karlwish J, Sankar P, et al. Obtaining informed consent for clinical pain research: Patients’ concerns and
information needs. Pain 2001;92:71–9.
Casarett DJ, Karlawish J. Beyond informed consent: e ethical design of pain research. Pain Med 2001;2:138–46.
Casarett DJ, Karlawish J. Are special ethical guidelines needed for palliative care research? J Pain Symptom Manage
2000;20:130–9.
Cassileth BR, Zupkis RV, Sutton-Smith K, et al. Informed consent — why are goals imperfectly realized? N Engl J Med
1980;302:896–900.
Cavanaugh TA. e ethics of death-hastening or death-causing palliative analgesic administration in the terminally ill.
J Pain Symptom Manage 1996;12:248–54.
Charlton JE. Ethical standards in pain management and research. In Charlton JE, ed. Core Curriculum for Professional
Education in Pain. Seattle: IASP Press, 2005;27–31.
Cobb LA, omas GI, Dillard DH, et al. An evaluation of internal mammary artery ligation by a double-blind
technique. N Engl J Med 1959;260:1115–8.
Coughlin SS. Ethically optimized study designs in epidemiology. In Coughlin SS, Beauchamp TL, eds. Ethics and
Epidemiology. New York: Oxford University Press; 1996:145–55.
Department of Health and Human Services. Protection of human subjects. Title 45. Part 46: Revised. Code of Federal
Regulation. 1991; June 18.
Dimond EG, Kittle CG, Crockett JE. Comparison of internal mammary artery ligation and sham operation for angina
pectoris. Am J Cardiol 1960;5:484–6.
Donaldson GW. e factorial structure and stability of the McGill Pain Questionnaire in patients experiencing oral
mucositis following bone marrow transplantation. Pain 1995;62:101–9.
Dubois MY. e birth of an ethics charter for pain medicine. Pain Med 2005;6:201–2.
Emmanuel L. Ethics and pain management. Pain Med 2001;2:92–6.
Fan R. Self-determination versus family-determination — two incommensurable principles of autonomy: A report
from East Asia. Bioethics 1997;11:309–22.
Fin JJ, Maltby BS, Friedmann E, et al. Contracts, covenants and advance care planning: An empirical study of the moral
obligations of patient and proxy. J Pain Symptom Manage 2005;29:55–68.
Gallagher JA, Goodstein J. Fulfilling institutional responsibilities in health care: organizational ethics and the role of
mission discernment. Bus Ethics Q 2002;12:433–50.
Global Forum for Health Research. Geneva: Global Forum for Health Research. e 10/90 Report on Health Research,
2000.
Harris E, Turner M. Health technology transfer. BMJ 2000;321:817–20.
Howe EG. Organizational ethic’s greatest challenge: Factoring in less-reachable patients. J Clin Ethics 1999;10:263–
70.
International Narcotics Control Bureau. Report of the International Narcotics Control Bureau, 2001.
Joranson DE, Rajagopal MR, Gilson AM. Improving access to opioid analgesics for palliative care in India. J Pain
Symptom Manage 2002;24:152–9.
Kocet MM. Ethical challenges in a complex world: Highlights of the 2005 ACA Code of Ethics. J Couns Dev
2006;84:228–34.
Latimer EJ. Ethical care at the end of life. Can Med Assoc J 1998;158:1741–7.
Martinson BC, Anderson MS, De Vries R. Scientists behaving badly. Nature 2005;435:737–8.
McGrath P. It’s OK to say no! A discussion of ethical issues arising from informed consent to chemotherapy. Cancer
Nurs 1995;18:97–103.
Miller FG. Sham surgery — An ethical analysis. Am J Bioeth 2003;3:41–8.
Mosely JB, O’M
alley K, Petersen NJ, et al. A controlled trial of arthroscopic surgery for osteoarthritis of the knee. N
Engl J Med 2002;347:81–8.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
https://t.me/medicina_free
Ethics in Pain Medicine 91
National Commission for the Protection of Human Subjects of Biomedical and Behavioural Research. e Belmont
Report. Ethical principles and guidelines for the protection of human subjects of research. Washington DC: U.S.
Government Printing Office, 1979; April 18.
Orr R. Pain management rather than assisted suicide: e ethical high ground. Pain Med 2001;2:131–7.
Pellegrino ED. Decisions to withdraw life-sustaining treatment: A moral algorithm JAMA 2000;283:1065–9.
Ray SL. Whistleblowing and organizational ethics. Nurs Ethics 2006;13:438–45.
Rich BA. Advance directives: e next generation. J Leg Med 1998;19:63–97.
Rucker KS, Metzler HM. Predicting subsequent employment status of SSA disability applicants with chronic pain. Clin
J Pain 1995;11:22–35.
Rucker KS, Metzler HM, Kegler J. Standardization of chronic pain assessment: A multiperspective approach. Clin J
Pain 1996;12:94–110.
Schneider GW, Snell L. C.A.R.E.: An approach for teaching ethics in medicine. Soc Sci Med 2000;51:1563–7.
Skevington SM. Investigating the relationship between pain and discomfort and quality of life using the WHOQOL.
Pain 1998;76:395–406.
Singer P. Quality end-of-life care: Patients’ perspectives. JAMA 1999;281:163–8.
Sugarman J, McCroy D, Hubal R. Getting meaningful informed consent from older adults: A structured literature
review of empirical research. J Am Geriatr Soc 1998;46:517–24.
Sullivan M. Ethical principles in pain management. Pain Med 2001;2:106–11.
Sullivan M, Terman GW, Peck B, et al. APS position statement on the use of placebos in pain management. J Pain
2005;6:215–7.
Sumathipala A, Siribaddana S, Patel V. Under-representation of developing countries in the research literature: Ethical
issues arising from a survey of five leading medical journals. BMC Med Ethics 2004;5:5–10.
Sulmasy DP, Pellegrino ED. e rule of double effect: Clearing up the double talk. Arch IntMed 1999;159:545–9.
Todd KH, Samaroo N, Hoffman JR. Ethnicity as a risk factor for inadequate emergency department analgesia. JAMA
1993;269:1537–9.
Todd KH, Deaton C, D’Adamo AP, et al. Ethnicity and analgesic practice. Ann Emerg Med 2000;35:11–6.
World Health Organization. Cancer Pain Relief and Palliative Care. Geneva: World Health Organization, 1990.
World Medical Association. World Medical Association Declaration of Helsinki: Recommendations Guiding Physicians in
Biomedical Research Involving Human Subjects, 1964, revised in Tokyo 2004. Available at: HYPERLINK “http://www.
wma.net/e/policy/b3.htm” www.wma.net/e/policy/b3.html. Accessed October 10, 2006.
Weber LJ. Taking on organizational ethics. To do so, ethics committees must first prepare themselves. Health Progress
1997;78:20–3.
Yabroff KR, Mandelblatt JS, Ingham J. e quality of medical care at the end-of-life in the USA: Existing barriers and
examples of process and outcome measures. Palliat Med 2004;18:202–16.
Zimmerman M. Ethical guidelines for investigations of experimental pain in conscious animals (editorial). Pain
1983;16:109–10.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
51.
52.
53.
54.
55.
56.
57.
58.
59.
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Introduction
What is acute pain?
Acute pain can be defined as pain of recent onset and usually
with an identifiable temporal and casual relationship to injury
or disease [234]. Although acute pain has been referred to
as “protective”, in alerting us to the presence of a noxious
insult, unrelieved acute pain has been associated with adverse
physiological outcome [154].
e goal of acute pain management is to provide subjective
comfort and minimise physiological side effects of unrelieved
pain. By blocking nociceptive impulses via different
neurological pathways and mechanisms, the autonomic and
somatic reflex responses to pain can be blunted. As a result,
the patient has less stress on the cardiovascular system, better
respiratory function and can ambulate earlier. High quality
pain relief after surgery not only influences the immediate
postoperative course but also long-term outcome.
Adverse eects of unrelieved acute pain
Unrelieved acute pain and tissue trauma has significant
implications to patient health and may result in a number of
harmful physiological and psychological effects (Table 8.01)
[138, 154].
Acute pain experience
Pain is a subjective experience and may bear little relationship
to the severity of tissue damage. Sensory input from the
nociceptor is only one of the factors that influence the final
pain experience of an individual. Compared with males,
female patients may report a higher level of pain [279]. Pre-
operative anxiety, fear of pain and catastrophising can also lead
Acute Pain Management
8
Phoon Ping CHEN, Christopher Ping Wing CHU,
Edmond Kin Nam CHUNG
INTRODUCTION
What is acute pain?
Adv
erse effects of unrelieved
acute pain
Acute pain experience
ACUTE PAIN SERVICE
PRINCIPLE OF
A
CUTE PAIN
MANAGEMENT
Acute neuropathic pain and
chronic postsurgical pain
P
ATIENT EVALUATION
PHARMACOLOGY OF
ACUTE
PAIN MANAGEMENT
Pre-emptive and preventive
analgesia
Routes of analgesic
administr
ation
Non-steroidal anti-inflammatory
drugs and par
acetamol
Opioids
Local anaesthetic agents
Adjuvant drugs
PATIENT-CONTROLLED
AN
ALGESIA
EPIDURAL AN
ALGESIA
Epidural opioids
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94 Phoon Ping CHEN, Christopher Ping Wing CHU, Edmond Kin Nam CHUNG
to higher pain intensity after surgery [46, 124, 133, 193, 217].
In addition, pre-existing psychiatric illnesses such as depression
and neurosis can lead to an increased postoperative pain score
[28, 46, 144]. Extrapolating our knowledge in chronic pain,
several other factors can influence the experience of acute
pain. Heightened attention to pain sensation could lead to
higher pain scores [171]. Previous experience of pain may
influence the subsequent severity of pain through learning and
Level of epidural insertion
Complications of epidural
analgesia
Epidural patient-controlled
analgesia
Outcomes with epidural
analgesia
ACUTE PAIN MANAGEMENT
AFTER TRA
UMA
P
AIN RELIEF IN BURNS
Acute burns
Procedural pain in the burns
patient
P
AIN RELIEF IN OBSTETRICS
Anatomy of labour pain
Monitoring
Methods of labour pain relief
A
CUTE PAIN MANAGEMENT IN
OLDER PERSONS
ACUTE P
AIN MANAGEMENT IN
CHILDREN
PATIENTS WITH SUBSTANCE USE
DISORDER
REFERENCES
Table 8.01
Ad
verse effects of unrelieved acute pain and tissue
injury
System Adverse effects
Neuroendocrine
and metabolic
Increased catabolic hormones
(catecholamines, glucagon, cortisol,
antidiuretic hormone, growth hormone,
etc.) and decreased anabolic hormones
(insulin) result in insulin resistance,
hyperglycaemia, glucose intolerance,
increased protein catabolism, increased
lipolysis, sodium and water retention,
impaired wound healing, muscle wasting
Cardiovascular Hypertension, tachycardia, increased
systemic vascular resistance, cardiac
arrhythmias, increased myocardial oxygen
consumption, altered coronary blood flow,
myocardial ischaemia and infarction
Respiratory Diaphragmatic splinting, decreased
lung volume including function residual
capacity, atelectasis, worsening in
ventilation-perfusion mismatch, impaired
cough, sputum retention, infection,
hypoxaemia
Musculoskeletal Reduced and delayed mobility may lead to
pulmonary complications, muscle wasting
Nervous system Increased sympathetic discharge, chronic
pain
Gastrointestinal Increased sympathetic discharge leading to
decreased gastric and bowel motility and
ileus
Coagulation Tissue injury causes an imbalance of the
coagulatory-fibrinolytic system leading to
hypercoagulability. Immobilisation due
to pain together with hypercoagulability
result in thrombo-embolic complications
Immune Impaired cellular and humoral immune
function especially in major surgery
Psychological Anxiety, fear, sense of loss of control
and helplessness, sleep disturbance,
demoralisation, abnormal behaviour
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Acute Pain Management 95
memory processes [128]. Other factors like coping
ability and cognitive processes may also affect the
pain perception [75, 221]. In contrast, there is
no evidence to support a pain-prone personality
[75]. Ethnicity does not affect the report of acute
pain and analgesic requirement, although it may
influence the prescribing behaviour of physicians
[148, 195].
Acute Pain Service
It is essential to have an institutional approach
to develop an organised team and programme
to provide and evaluate acute pain management.
Without such an acute pain service programme,
staff efforts to treat pain may become sporadic and
ineffectual. e organisation of an Acute Pain Service
(APS) varies among different institutes, ranging
from a wholly nurse-led team to multidisciplinary
services. Usually the team leader and supervisor
of the acute pain service is an anaesthetist, who
views this responsibility as an extension of his role
as perioperative care physician. e pain nurse is
an important member of the team as an educator,
administrator, co-ordinator, clinical nurse and
researcher, and is usually the immediate access to the
APS team. Good co-ordination, communication,
and co-operation within the team, as well as
outside with surgeons and other postoperative care
team members such as the surgical nursing staff,
physiotherapists and occupational therapists, are
the crucial factors for success.
e APS aims to deliver safe and effective pain
relief to patients. ese objectives can be achieved
by providing education to patients and staff,
pain management protocols and guidelines
appropriate for the institution, and a total quality
management programme to evaluate and monitor
the effectiveness of the pain service [34, 47, 106].
An APS can also provide 24-hour acute pain
management supervision and support to clinical
wards, and facilitate local clinical research on pain.
Although the evidence is inconclusive, there
is a trend to indicate that APS can lead to an
improvement in postoperative pain relief and a
reduction in postoperative nausea and vomiting
[296]. An interesting study examined the role
expansion of APS to critical care outreach services
and found that it decreased the incidence of serious
postoperative adverse events [267].
Principle of Acute Pain
Management
is section discusses the principle of acute pain
management with special emphasis on postoperative
pain as this type of pain is one of the most frequently
encountered acute nociceptive pain conditions
that require our attention and intervention.
Nevertheless, the principle of management is
applicable to all types of nociceptive pain.
Patients should be educated that pain relief is an
important part of their health care. Information
about options for pain control should be available
to them and discussion of the various options,
including the risks involved and the expected
effects and side effects [3], with the health care team
should be possible. ey should be educated about
the need to communicate unrelieved pain so that
they can receive prompt evaluation and treatment.
Aggressive pain prevention and control which takes
place before, during and after surgery and medical
procedures may lead to both short- and long-term
benefits.
e modality of analgesic intervention and
its regimen should be tailored to individual
patients according to the current pain status,
clinical conditions and the expected course of
rehabilitation. A multimodal analgesic regimen
should be considered to block pain signals via
different mechanisms to achieve superior analgesia
with fewer (or equivalent) side effects [3, 127].
Recently, procedure-specific postoperative pain
management has been advocated by the Prospect
group [194]. Different pharmacological agents and
pain relief techniques may be effective in one type
of operation but not another. It was recommended
that acute pain management should target a specific
procedure. As an example, for total knee arthroplasty
[92] and primary total hip replacement [91],
general anaesthesia combined with a peripheral
nerve block or an intrathecal injection of local
anaesthetic and opioid were recommended. ese
techniques should be followed with a step-down
approach using paracetamol and non-steroidal anti-
inflammatory drugs, with strong or weak opioids as
required.
Pain intensity and relief must be assessed and
reassessed at frequent regular intervals to evaluate
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96 Phoon Ping CHEN, Christopher Ping Wing CHU, Edmond Kin Nam CHUNG
the effectiveness of treatment. When the patient
complains of pain in the postoperative period
or other acute situation, the site and cause of the
pain must be ascertained. Not all pain is caused
by the physical injury at the site of surgery or
trauma (Table 8.02). Unexpected levels of pain
which are unrelieved by well-established treatment
or unexplained by surgical trauma must be re-
evaluated for other causes. e patient must also be
appropriately monitored during the pain therapy
and rapidly treated for any intolerable side effect or
adverse complication. With effective postoperative
pain relief, patients should be allowed to mobilise
and eat as early as possible. Optimal postoperative
outcome and economic benefit can only be realised
with an active convalescence programme [36, 137].
Acute neuropathic pain and
chronic postsurgical pain
Acute neuropathic pain may be an under-recognised
component of postoperative and trauma pain.
Inadequately treated nociceptive pain during the
perioperative period and nerve injury sustained
during surgery or trauma may cause central
sensitisation [139]. e resulting mechanisms
leading to acute neuropathic pain may occur within
hours to days after the injury. One study found
the incidence of neuropathic pain reported to the
APS after surgery and trauma to be 1–3% [112].
Appropriate and early treatment has been reported
to prevent the development of chronic pain in these
patients, especially after some operations such as
thoracotomy [251]. e incidence of chronic pain
after surgery has been reported to be rather high:
amputation (30–85%), thoracotomy (5–67%),
mastectomy (11–57%), cholecystectomy (3–56%),
inguinal hernia (0–63%) [162, 219]. Neuropathic
pain requires different pharmacological treatment to
nociceptive and inflammatory pain. It is important
to recognise the possibility of acute neuropathic
pain in patients who have pain unresponsive to
opioid or when pain relief is only possible with
large doses of analgesics.
Patient Evaluation
e evaluation of patients with acute pain starts with
history taking and clinical examination that include
past and pre-existing medical history, comorbidity,
current clinical status and drug treatment. Patient
evaluation must also assess the cause, site, severity
and impact of the pain condition. Psychological
components such as anxiety and depression should
also be taken into consideration as they will affect the
patient’s experience of pain. As both acute pain and
the analgesic intervention can also cause systemic
side effects and complications, it is important to
assess the patient globally besides the pain scores.
Global assessment produces an insight to the quality
of analgesic intervention as well as the patient’s
recovery towards normal health (Table 8.03).
e single most reliable indicator of the existence
and intensity of acute pain is the patient’s self-report
[192].
Common self-reporting pain measurement
scales used in adults include verbal descriptive scales,
visual numeric rating scales and visual analogue
scales (VAS) (see Chapter 3). ese scales measure
the intensity of pain and allow the comparison of
the pain between two points in time. e VAS has
been used to measure pain with relative accuracy
in Chinese patients [12]. On a 0–100 mm VAS
scale, 0–5 mm indicates “no pain”, 5–44 mm
“mild pain”, 45–74 mm “moderate pain” and more
than 70 mm “severe pain” [10]. Patient assessment
methods and tools are discussed in Chapter 3 and
4. Behavioural and physiological measures are also
used as adjunctive methods in assessing the severity
of pain (Table 8.04).
Once the patient is receiving analgesic intervention,
regular monitoring should be applied to evaluate
the effectiveness, side effects and complications
Table 8.02 Causes of postoperative pain
Wound Skin and subcutaneous tissue
Deep tissue Trauma from retraction and
manipulation, coagulation
Positional Compression sores, nerve
compression and traction
IV site Needle trauma, extravasation,
venous irritation
Tubes Drains, nasogastric tube, sore
throat from endotracheal tube
Supports Plaster cast, dressing too tight
Surgical Residual surgical pathology,
complication of surgery
Rehabilitation Joint stiffness and muscle ache
Other pain Acute neuropathic pain
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Acute Pain Management 97
(Table 8.05). Feedback from the monitoring
should then be used to modify the current regimen
by adding new adjuvant drugs or changing to a
different intervention. Observation should be
Table 8.03 Patient’s assessment
Pain • Location, radiation, character
• Adequacy of pain relief
· Static pain score
· Dynamic pain score, e.g. coughing and movement over wound site
· Trend of pain intensity
• Aggravating and relieving factors
• Any unusual or unexplained pain pattern
Analgesic intervention • Pain relief modality and route of administration
• Proper equipment functions, settings and drug delivery
• Drug consumption and drug reserve
• Adjunct analgesic drug/therapy
• Catheter patency and catheter site conditions
• Side effects and complications of the analgesic intervention
Systemic assessment and
relevant medical history /
co-morbidity
• Conscious level and vital signs
• Ability to tolerate oral intake
• Ability to ambulate
• Ability to cough and clear sputum
• Amount of blood in drainage bottle
• Concurrent medications
· Consider potential interaction with analgesic intervention, e.g. MAOI,
anticoagulation and antiplatelet drugs, tranquilisers and sedatives
• Relevant signs and symptoms in at-risk patient, e.g.
· Fever, shortness of breath, oxygen desaturation, chest infection, angina,
congestive heart failure
Other factors influencing
pain perception
• Fear and anxiety
• Depression
• Past experience
Table 8.04 Common features observed in patients
with pain
Behavioural features
Moaning
Facial expression, e.g. grimacing
Refusal to cough
Refusal to move
Restlessness
Avoidance of deep breathing
Abnormal body posture
Physiological features
High blood pressure
Fast pulse rate
Sweatiness
Shallow breathing
made frequently at the start of the regimen and the
interval gradually lengthened as the drug reaches
a more steady level. For example: hourly for the
first 4–6 hours, then every 2 hours for the next
4–6 hours, then 4-hourly until the end of the
intervention. Longer monitoring is required if a
delayed side effect of the drug is anticipated, e.g.
respiratory depression from intrathecal morphine
can occur 12 hours after administration.
Pharmacology of Acute Pain
Management
Pre-emptive and preventive
analgesia
Pre-emptive analgesia is defined as analgesic
treatment given before any surgical incision is
made. As the transmission of pain signals leads
to sensitisation of the peripheral and central pain
pathways, it is postulated that pre-injury analgesic
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98 Phoon Ping CHEN, Christopher Ping Wing CHU, Edmond Kin Nam CHUNG
treatment offers a protective effect to reduce
sensitisation, and therefore can be more effective
than the same treatment given after the injury [307].
e systematic review of the subject by Moiniche
has failed to show definitive benefits of pre-emptive
analgesia [179]. is may be due to different
definitions and designs of clinical trials. By applying
a more precise definition and stringent criteria,
two recent articles have shown the benefits of pre-
emptive analgesia. McCartney et al. demonstrated
in their systematic review that N-methyl D-aspartic
acid (NMDA) receptors antagonists (ketamine and
dextromethorphan) provided extended analgesic
effects when comparing pre-surgical treatment
and non-treatment [167]. A recent meta-analysis
also demonstrated the pre-emptive benefits of
epidural analgesia, peripheral local infiltration and
systemic non-steroidal anti-inflammatory drugs
(NSAIDs) when comparing pre-surgical treatment
and treatment started after the operations [203].
Recently, a multimodal approach to perioperative
analgesia reduced chronic postsurgical pain after
major abdominal [146] and breast cancer surgery
[87].
Preventive analgesia aims to prevent sensitisation
of peripheral and central pain pathways during
the initial tissue injury as well as the later
inflammatory phase. e analgesic intervention
may be given before or after the surgery and is
expected to have an effect on postoperative pain
which exceeds the expected duration of action of
the drug. Consequently, postoperative pain and/or
analgesic consumption are reduced relative to a
different analgesic treatment, a placebo treatment,
or no treatment [136, 142]. In McCartney’s
review described above [167], a selected point
of time equivalent to five half-lives of the study
drug demonstrated the preventive analgesic effects
of NMDA receptors antagonists. Katz has also
provided some evidence of the preventive effects
of analgesic intervention in a systematic review
[136].
Preventive analgesia places emphasis on the
completeness of analgesic intervention which covers
both the initial tissue injury and the inflammatory
stage in the postoperative period. On the other
hand, pre-emptive analgesia focuses mainly on the
timing of treatment before tissue injury and may
Table 8.05 Parameters regularly assessed during analgesic intervention
Parameter Rationale
Cardiovascular
Blood pressure, Pulse
Intravascular volume status especially in postoperative setting may be altered;
side effects such as hypotension from epidural analgesia may occur; may also
indicate sympathetic response due to unrelieved pain
Respiratory rate,
Oxygen saturation
Respiratory depression from opioid overdose or a high level of centroneuraxial
block may occur; postoperative atelectasis may occur in susceptible patients
Conscious level Over-sedation from drug overdose may occur; agitation due to drug side effects,
e.g. ketamine
Pain level
Static and dynamic
Static pain scores can reflect quality of sleep and low level dynamic pain allows
patients to deep-breathe and mobilise
Temperature Pyrexia may indicate infection
Nausea and vomiting Nausea and vomiting due to anaesthetic and analgesic drug effects or surgery
may prevent early feeding
Pruritus Pruritus may occur due to opioid side effects
Urinary retention Urinary retention may occur as the result of opioid or epidural local anaesthetic
side effects
Muscle power
and sensory level
Excessive peripheral or epidural neural block may result in motor weakness and
sensory deficit; migration of a catheter to the subarachnoid space and spinal cord
compression due to haematoma or infection may cause unexpected neurological
deficits
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Acute Pain Management 99
not truly reveal the importance of sensitisation
from inflammatory injury [142].
Routes of analgesic
administration
Analgesic drugs can be given either locally or
systemically. Direct local administration includes
topical application, wound infiltration, perineural
injection and intra-articular injection, and has
the advantage of confining the site of action and
therefore limiting the systemic side effects of the
drug. Drugs administered transdermally may
exert both local and systemic effects. As skin is
a very effective barrier, only a few drugs can be
administered transdermally, e.g. lipid soluble
opioids such as fentanyl and sufentanil, and certain
non-steroidal anti-inflammatory drugs such as
aspirin and ibuprofen. Onset and offset of the drug
are slow due to the slow wash-in and wash-out with
the skin acting as a depot for the drug. e recent
development of iontophoresis may overcome these
problems. e drug is ionised and the charged
molecules are propelled transdermally by the
repulsive electromotive force generated by the
iontophorectic chamber of the same charge. With
iontophoresis, drugs can be applied transdermally
with more reliable results (see Patient-controlled
Analgesia below).
As long as the patient is allowed oral intake, the oral
route is probably the simplest route of systemic drug
administraton. However, the drug bioavailability
can be affected by the first-pass effect of hepatic
metabolism and the incomplete absorption due to
nausea/vomiting and delay in gastric emptying. To
bypass the hepatic first-pass metabolism, drugs can
be administered via other non-invasive routes such
as sublingual, buccal and intranasal. It should be
noted that drugs absorbed through the nasal mucosa
may be subjected to metabolism by enzymes in the
nasal mucosa. Although the drug absorbed from
the lower half of the rectum will pass to the inferior
vena cava, thus bypassing the portal system and
the hepatic first-pass metabolism, the absorption is
variable and may cause local irritation. e patient’s
acceptance of this route is another consideration
when prescribing analgesic via the rectal route.
More invasive routes of administration include
intramuscular (IM), subcutaneous (SC) and
intravenous (IV) injections. Apart from needling,
the main disadvantage of IM and SC injections is
unreliable absorption. Poor peripheral perfusion
can delay the systemic absorption of the analgesic
drugs, and render low drug levels and an inadequate
analgesic effect. Intravenous injection of analgesic
drugs avoids the disadvantage of unreliable
absorption of IM/SC routes and ensures more rapid
onset of action. However, because of the fear of a
higher incidence of side effects and complications,
the practice of intermittent IV bolus of analgesics
(especially opioids) is far less common than IM/SC
injection.
Analgesic drugs can also be administered intrathecally
and epidurally. Intrathecal and epidural drugs exert
their effects at the level of the spinal cord. A higher
dose of epidural drug is needed to achieve the same
effect as compared with intrathecal administration.
When administered epidurally, some of the drug will
be absorbed into the systemic circulation and fatty
tissues. In acute pain relief treatment, continuous
infusion of local anaesthetic agent and opioid via
an epidural catheter provides prolonged analgesia
while intrathecal drugs are usually administered as a
one-off treatment. Continuous intrathecal infusion
via a microcatheter has been associated with cauda
equina syndrome [27].
Non-steroidal anti-inammatory
drugs (NSAIDs) and paracetamol
Pharmacological management of mild to
moderate acute pain should begin with a simple
analgesic such as paracetamol or an NSAID unless
contraindicated. Non-steroidal anti-inflammatory
drugs do not relieve severe pain but are efficacious
as a component of multimodal pain relief therapy.
ey are often used as adjuncts (co-analgesics) to
opioid in severe postoperative pain as their opioid-
sparing effect allows a lower therapeutic dose of
the opioids and reduces the incidence of opioid
side effects. Paracetamol is especially useful and
effective in this respect. More information regarding
NSAIDs can be found in Chapter 22.
ere are numerous NSAIDs in the market but most
of them have similar efficacy and side-effect profiles
(Table 8.06). e selection of NSAID depends
mainly on the preferred route of administration
and relative risk of adverse effects. Paracetamol has
fewer side effects in comparison but should be used
cautiously in patients with liver dysfunction. e
latest generations of NSAIDs are selective cyclo-
oxygenase isoenzyme-2 (COX-2) inhibitors, which
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