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Acute pain - Assessment - (3.2.1 - 3.2.13)

Updated: Mar 7, 2022

Assessment of acute pain:

Consider a Functional Activity Score such as Scott and McDonald 2008


3.2.1 - Discuss the role of an acute pain service.

Benefits of APS

  1. Reduced pain

  2. Less side effect

  3. Reduced postoperative mortality and morbidity

  4. Reduced incidence of persistent postoperative pain

  5. Cost-effective

APS role:

  1. Education health professionals and organisations (collaborative)

  2. Advanced analgesic techniques

  3. Improve analgesic regimes

  4. Standardise use of the equipment and ‘standard’ orders

  5. 24-hour available pain personnel

  6. Quality improvement

  7. Research role (collaborative)

Policies and procedures should include:

  1. Education and training of health care providers

  2. Monitoring of patient outcomes

  3. Documentation of monitoring activities

  4. Monitoring of outcomes at the institutional level

  5. 24-hour availability via anaesthetics

  6. A dedicated APS


3.2.2 - Discuss general requirements that might enable safe and effective delivery of

all acute pain management techniques in hospitals including: education of

staff and patient monitoring requirements; responses to inadequate or

excessive medication; use of “standard orders”; and equipment used.

APS Standard orders should include

  • Drugs to use

  • Education of nursing, medical staff and patients

  • Monitoring requirements including analgesic and OIVI

  • Response to inappropriate analgesia

  • Response and treatment of side effects

  • Nursing procedures and protocols

  • Equipment used


3.2.3 - Discuss the issues related to the ongoing management of acute pain

following discharge from the hospital.

  • Determine the appropriateness of further opioid prescription at discharge

  • Opioids should be prescribed according to the duration of treatment required rather than the maximum available

  • Avoid prescribing more than 5-7 days

  • All patients should see their primary care provider within 5-7 days

  • Avoid prescribing slow-release medications unless on these long term and there are rare extenuating circumstances

  • Record all plans and information in the electronic medical record

  • Discuss issues with driving with altered opioid dose

  • Important communication to the primary care provider in a timely manner

  • Discuss with the patient education about how to use medication

  • How to store medication

  • How to dispose of unwanted medication


3.2.4 - Evaluate the role of acute pain management in rehabilitation, including

enhanced recovery or “fast-track” surgery.

Key steps in an ERAS program

- Presurgery

1. Education

2. Counselling

3. Carbohydrate drinks

4. Epidurals for pain

- During surgery

1. Fluid management

2. Judicious opioids

3. Reduce surgical trauma/incision

4. Minimise transfusion

- Post-surgery

1. Early mobilisation

2. Early removal of drains and tubes

3. Early transition to oral pain meds

4. Early allowance of food

Benefits of ERAS

1. Increased patient satisfaction

2. Less postoperative complications

3. Decreased length of hospital stay

4. Improved use of hospital resources

5. Reduced readmissions

Principles of pain management in ERAS

1. Use multimodal analgesia

2. Use regional analgesia

3. Avoid opioids as possible

4. Transition to orals early


3.2.5 - Discuss the risk factors and mechanisms involved in the transition of acute to

chronic pain, and critically evaluate the evidence for measures that may

mitigate this transition.

Acute to Chronic pain:

  • Central and peripheral sensitisation processes

  • The degree of inflammation and tissue damage may potentiate these effects

Preventing Acute to Chronic pain

  • Avoid surgery where possible

  • Regional anaesthesia and epidurals

  • Possibly IV lignocaine or IV ketamine (3 small trials only with possible positive effect)

  • Pharmacology for prevention remains unclear (Cochrane level evidence)

  • The multimodal approach may reduce the incidence and severity of chronic post-surgical pain

  • Type of surgery performed (minimally invasive)

  • Multidisciplinary approach

  • Maybe patient education though evidence to date has been disappointing


3.2.6 - Describe the pharmacokinetics and pharmacodynamics of opioids and local

anaesthetics administered into the epidural space or cerebrospinal fluid.

Epidural Pharmacokinetics

  • The rate of diffusion into CSF is slower (Volume, concentration, lipophilicity, protein binding, CSF flow rate

  • Epidural spaces are irregular, segmental, and encircles the dural sack

  • Two-compartment model - Rapid into epidural fat - then back out

  • Normal metabolism and elimination as peroral intake.

Intrathecal Pharmacokinetics

  • High CSF concentration and short diffusion distance

  • Baracity affects flow of medication

  • Slow absorption with increased half-life - the more lipophilic the faster cleared

  • Normal metabolism and elimination otherwise


3.2.7 - Describe the physiological consequences of a central neuraxial (epidural or

intrathecal) block with local anaesthetics and/or opioids.

Local anaesthetics

  • Local anaesthetic injected into the epidural space diffuses through the dura and subarachnoid membranes in a band like distribution to the nerve roots

  • This results in blockade of motor, sensory and autonomic fibres of the associated level


  • Analgesic effect of opioids binding to opioid receptors in the dorsal horn of the spinal cord after crossing the dura and arachnoid membranes

  • Some absorbed into epidural blood vessels

  • Rostral spread carrying opioid towards the brainstem

  • The less lipid-soluble, the more rostral drift

Physiological consequences at particular levels



  • Blockade of intercostals and abdominal wall muscles

  • Loss of vital capacity

  • Loss of accessory muscle use


  • Diaphragmatic blockade C3-5


  • Respiratory centre depression


  • Sacral - minimal parasympathetic pelvic organ block only

  • Lower thoracic/lumbar - Arteriolar and venous vasodilation in lower abdomen and limbs

  • Upper thoracic - Loss of cardio accelerator fibres above T5 - reduced HR and contractility

  • CNerves - Vagal blockade will reduce PNS tone and attenuate some loss of SNS

  • Brainstem - Inhibition of vasomotor centre and profound drop in CVS parameters


3.2.8 - Describe the adjuvant agents that may be used to enhance the quality or

extend the duration of central neuraxial or other regional analgesia blocks,

and discuss their mechanisms of action, risks and benefits.


  • Descending inhibitory system effects

  • Thought to be safe with LA

  • Reduces LA dose

  • Improved duration and extends motor blockade

  • SE: Sedation, hypotension, bradycardia


  • Vasoconstriction slows the clearance of epidural drugs

  • The benefit with both LA and opioid


Dexmedetomidine (alpha 2 agonist) - Binding


3.2.9 - Discuss the contribution of maladaptive psychological coping skills and

psychiatric illness and socio-environmental factors to the experience of acute

pain (pain ratings, opioid use) and the risks of persistent pain and prolonged

opioid use after discharge from hospital.

  • Anxiety level is strongly associated with the intensity of the surgical pain experience

  • The higher the anxiety score, the higher the postoperative pain intensity

  • Preoperative depression has predicted postoperative higher pain scores following prostate surgery


3.2.10 - Discuss assessment of acute pain (including acute neuropathic pain) in the

adult patient, including the nonverbal patient and those from indigenous or

other culturally and linguistically diverse communities, and the relevance of

functional assessment.

See guide on Indigenous populations (LINK)

  • Numeric scores can be used (VRS, VAS, Faces scales)

  • Functional activity scores are thought to be better however less evidence/studies

  • FAS = A no limitation, B mild limitation, C severe limitation


Abbey pain scale


3.2.11 - Discuss assessment of acute pain in the older patient (especially those with

dementia) including difficulties, relevance of functional assessment and use

of other pain evaluation methods that do not rely on verbal ability

  • Algoplus can be used

  • PainAD can also be used


3.2.12 - Discuss assessment of acute pain in children including difficulties, relevance

of functional assessment and use of paediatric pain scales.


3.2.13 - Recognise causes of delirium in the acute pain setting and the effect this may

have on assessment and treatment of the patient with acute pain.

No tools have been studied in this population - all regular management steps for delirium apply

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