Multimodal Analgesia

Farah Jafri

INTRODUCTION

DEFINATION

A multimodal approach to Acute Pain Management entails

combining several pain relieving techniques with

different mechanisms of action.

The net result is usually better than if a single technique is

relied upon.

Pain pathway

Tissue injury activate nociceptors pain impulse A-delta & C fibers dorsal horn spinothalamic tract thalamuscerebral cortex cerebellum

Multimodal analgesia

AIMS- ⇩ doses of each analgesic

Improved antinociception due to

synergistic/additive effects

may⇩ reduce severity of side effect of

each drugs

Endorsed by

1)Faculty of Pain Medicine, Royal College of Anaesthetists, United Kingdom

2)Royal College of Anaesthetists, United Kingdom

3) Australian Pain Society

4) Faculty of Pain Medicine, College of Anaesthetist of Ireland

5) Recommended to American Academy of Pain Medicine

MULTIMODAL APPROACH TO PAIN MANAGEMENT

DRUGS-

1) PARACETAMOL

2) NSAIDS

3) OPIOIDS- PCA, 'around the clock', prn

4) ANTIDEPRESSANTS

5)ANTI-EPILEPTICS

NERVE BLOCKS- LOCAL ANESTHETICS- I.V, CNB, PNB

- OPIOIDS

NONPHARMACOLOGICAL TECHNIQUES

PARACETAMOL

Mechanism of Action (MOA) -

Direct and indirect inhibition of central cyclo-oxygenases

Activation of the endocannabinoid system and spinal serotonergic pathways

Prevent prostaglandin production at the cellular transcriptional level, independent of cyclo-oxygenase activity

KEY MESSAGES- PARACETAMOL

Paracetamol - effective adjunct to opioid analgesia,

opioid requirements being reduced by 20% to 30%

In the same doses,

Oral paracetamol less effective; slower onset than IV Paracetamol injection,

Paracetamol interacts with warfarin to

NSAID

Refer to both nsNSAIDs and coxibs (COX-2 selective inhibitors).

Analgesic, Anti-inflammatory and Antipyretic

MOA-

NsNSAIDs are ‘non- selective’ cyclo-oxygenase inhibitors that inhibit both COX-1 and COX-2.

COXIBS inhibit only the inducible COX -2

KEY MESSAGES- NSAIDS

Opioids + nsNSAIDs = better analgesia,

reduced opioid consumption

↓ PONV and sedation

Perioperative non-selective NSAIDs ↑risk of severe bleeding

KEY MESSAGE- COXIBS

- Effective analgesics

- adverse effects on renal function

- do not impair platelet function

- GI complications are less.

- do not produce bronchospasm.

KEY MESSAGE - NSAIDS

CARDIOVASCULAR CONCERNS....

FDA concluded that

‘Short-term use of NSAIDs to relieve acute pain, particularly at low doses, does not appear to confer an increased risk of serious adverse CV events (with the exception of valdecoxib in hospitalized patients immediately postoperative from coronary artery bypass surgery)’ (FDA, 2005).

Opioids

Control moderate to severe pain and do

not interfere with clotting.

MOA:

1)Attach to opioid receptors and “modulate” impulse transmission in cord

2) CNS effects alter pain perception

KEY MESSAGES -OPIOIDS

Opioids in high doses can induce hyperalgesia (N) (Level I).

Tramadol is an effective treatment for neuropathic pain (Level I [Cochrane Review]).

Opioid-sparing medications like--Gabapentin, non-steroidal NSAIDs and ketamine reduce opioid-related side effects (N) (Level I).

KEY MESSAGES

Tramadol has a lower risk of respiratory depression and impairs GI function less than other opioids at equianalgesic doses.

The use of pethidine and dextropropoxyphene should be discouraged in favour of other opioids.

Pethidine is not superior to morphine in treatment of pain of renal or biliary colic

ADJUVANTS TO PAIN CONTROL

Ketamine

Adrenaline

Neostigmine

Midazolam

Magnesium

Alpha 2 agonists

ADJUVANTS

KETAMINE-

Non-competitive antagonist of the NMDA receptor,in the peripheral and central nervous systems

Principal effect of ketamine at these doses is as an ‘antihyperalgesic’, ‘antiallodynic’ and ‘antitolerance’ agent and not as a primary analgesic per se.

KEY MESSAGE - ADJUVANTS

Intrathecal clonidine improves duration of analgesia and anaesthesia

Epidural ketamine (without preservative) + opioid-based epidural analgesia regimens improves pain relief

Intrathecal midazolam + local anaesthetic prolongs the time to first analgesia and reduces postoperative nausea and vomiting

Epidural adrenaline (epinephrine) in combination with a local anaesthetic improves the quality of analgesia (2 mcg/ml + bupivacaine 0.1% + inj fentanyl 2 mcg/ml)

Antidepressants

Amitriptyline, imipramine, doxepin, trazodone

Benefits: Help control paresthesias and burning sensations from damaged nerves. They also improve sleep.

MOA: Prevent reuptake of serotonin into neuronal fibers making more serotonin available to inhibit nociception in the dorsal horn

Antidepressant Side Effects

Adverse Effects

Dry mouth, drowsiness, and constipation.

Some cause postural dizziness and vertigo.

Most positive studies report on older cyclic compounds (IMI, AMI, DOX) or MAOIs

Tricyclic doses lower than “antidepressant” doses frequently produce analgesic augmentation

Onset of analgesic benefit occurs early (days-weeks)

KEY MESSAGE ANTI DEPRESSANTS

Tricyclic antidepressants and SSRI are effective in the management of acute neuropathic pain

Tricyclic antidepressants are more effective than SSRI

.

ANTIEPILEPTICS

Gabapentin and Pregabalin

Benefits: Antiepileptics help control paresthesias or burning sensations from nerve injury.

Risks: Common-Drowsiness, dizziness, somnolence, weight gain and edema. Infrequent-hepatotoxicity, anemia, thrombocytopenia

MOA: Direct stimulation of GABAergic receptors or Ca++ channel blockade

KEY MESSAGE ANTI EPILEPTICS

Perioperative gabapentinoids (gabapentin/ pregabalin) reduce postoperative pain and opioid requirements and reduce the incidence of vomiting, pruritus and urinary retention, but increase the risk of sedation (N) (Level I).

Effective in management of acute neuropathic pain

MEMBRANE STABILIZERS

MOA- Local anaesthetics exert their effect as analgesics by the blockade of sodium channels and hence impeding neuronal excitation and/or conduction.

XYLOCAINE- Lignocaine (intravenous or subcutaneous) may be a useful agent to treat acute neuropathic pain

LOCAL ANESTHETICS KEY MESSAGE

The quality of epidural analgesia with local anaesthetics is improved with the addition of opioids

Analgesia and motor block from

ropivacaine= levobupivacaine = bupivacaine

for regional analgesia (epidural and peripheral nerve blockade)

LOCAL ANESTHETICS KEY MESSAGE

Compared with opioid analgesia, continuous PNB (regardless of catheter location) provides better postoperative analgesia and leads to reductions in opioid use as well as nausea, vomiting, pruritus and sedation (N) (Level I)

Perioperative epidural analgesia reduces the incidence of severe phantom limb pain

LOCAL ANESTHETICS KEY MESSAGE

Continuous femoral nerve analgesia = epidural analgesia but with fewer side effects following total knee joint replacement surgery

Continuous local anaesthetic wound infusions

↓in pain scores (at rest and with activity),

↓opioid consumption, postoperative nausea and vomiting,

↓Length of hospital stay

patient satisfaction and there is no difference in the incidence of wound infections (S) (Level I).

Neuroaxial opioids

The absence of consistent dose-responsiveness to the efficacy of intrathecal opioids or the adverse event rate, suggests that the lowest effective dose should be used in all circumstance

Non pharmacological

Non pharmacologic

- psychologic approach

- physical therapy

- education

- neurostimulation

- neuroablative techniques

KEY MESSAGE NON PHARMACOLOGICAL

APPROACH

Distraction is effective in procedure-related pain in children (Level I).

Training in coping methods or behavioural instruction prior to surgery reduces pain, negative affect and analgesic use (Level I).

Acupuncture reduces postoperative pain as well as opioid-related adverse effects

Acute pain step Ladder

SEVERE PAIN ?

Epidural analgesia or morphine PCA or im protocol

plus diclofenac 100-150mg / OTHER NSAID )

plus paracetamol 1g QDS regularly

MODERATE PAIN ?

tramadol 400mg in 24hrs

plus diclofenac 75-150mg in 24 hrs / OTHER NSAID

plus paracetamol 1g x 6hrly regularly

MILD PAIN ?

HOW TO USE MULTIMODAL ANALGESIA ?

EXAMPLES-

IN AMBULATORY SURGERY CASES

TOTAL HIP REPLACEMENT

TOTAL KNEE REPLACEMENT

ACUTE NEUROPATHIC PAIN

AMBULATORY SURGERY

MAIN AIM- EARLY PAIN FREE, NAUSEA FREE DISCHARGE

KEY MODES OF PAIN RELIEF-

1.Infiltration of the wound with local anaesthetic

2.Peripheral nerve blocks with long-acting local anaesthetic agents, single shot/ infusions

3.Regular paracetamol, NSAIDS,

4.AVOID OPIOIDS

ACUTE NEUROPATHIC PAIN

Tramadol +/- OPIOIDS

IV/ PO/ SC Ketamine

IV lignocaine (bolus dose between 1-5 mg/kg I.v over 15 to 60 minutes depending on the dose.)

Amitriptyline improved neuropathic pain in patients with depression

Anticonvulsants reduced central pain and improved sleep and reduced anxiety

CONCLUSION

Multimodal analgesia offers many benefits to patients

Opioids remain an integral part of most analgesic plans.

Techniques that reduce opioid requirements typically improve pain control both at rest and with motion, reduce opioid related side effects, provide better patient satisfaction