An overview of pain management

2.  Concept of nociception
 Central sensitisation
 Multimodal analgesia for perioperative pain management
 ASRA 2016 GUIDELINES on Pain management
 Consequences of Inadequate Postoperative pain Relief

3.  IASP - An unpleasant sensory and emotional experience associated with
actual or potential tissue damage, or described in terms of such damage.
 Latin – Poena – Pain
 More than 80% of patients who undergo surgical procedures
experience acute postoperative pain
 And approximately 75% of those with postoperative pain report the
severity as moderate, severe, or extreme

4. PAIN
SOMATIC
SUPERFICIAL
( Skin n subcut tissues )
Eg: Cuts, Burns
DEEP
( Muscle, Bone, Periosteum, Fascia )
Eg :Fractures, Arthritis, Muscle belly
rupture
VISCERAL
Eg : Angina pectoris, Renal colic,
Intestinal colic

5. Are sensory receptors and cutaneous receptors and pain
receptors the same ???

6.  Sensory receptors - Sensory input from various external
stimuli is thought to be received by specific peripheral receptors
that act as transducers and transmit by nerve action potentials
along specific nerve pathways to CNS.
 First order afferents – differentially sensitive

8.  Mechanoreceptors
Tactile non painful stimuli
Pacinian , Meissner corpuscle, Merkel’s disc
2 point discrimination, proprioception
 Thermoreceptors
 Nociceptors
Free Nerve ending that responds to a noxious stimulus

9.  Nociceptor- A high-threshold sensory receptor of the peripheral somatosensory nervous
system that is capable of transducing and encoding noxious stimuli.
 Nociception begins in the nerve terminals of sensory neurons
 Mechanical, Chemical or thermal
 Polymodal
 Silent Nociceptors
 Types of Nociceptors :
Aδ
Unmyelinated C fibers

12. 1. TRP ( Transient receptor potential ) channels
A. Temperature : TRPV1 >42°C
TRPA1 <17°C
B.Chemical : TRPV1 – Capsaicin , Piperine
TRPA2- Cinnamaldehyde
C. Inflammatory signals: Bradykinin, NGF ( TRPV1)
D. Itch signals : Histamine (TRPV1)
E. Mechanosensors : TRPV4
F. Acid sensing : TRPV1 Ph 5.5

14. 2.ACID SENSING ION CHANNELS
eNac family – ph 6.5 to 6.9
Asic3 – Angina
3. PURINOCEPTORS
Neuropathic pain
4. TWO PORE DOMAIN POTASSIUM CHANNEL
5. Voltage Gated Sodium Channel

16. ° TRANSDUCTION
Chemical events to Electrical events in neurons
º TRANSMISSION
Electrical events are transmitted
Molecules in the synaptic cleft transmit information from one cell
surface to another .
ºMODULATION
Up regulation or Down Regulation
ºPERCEPTION

19.  The Substantia Gelotinosa Rolandi– tip of dorsal horn – Called Gate
 NEUROTRANSMITTER – A delta – Glutamate
C fibers – Substance P
 Key role in pain perception
 A Delta – Fast – Terminate at lamina I – Neospinothalamic
 C – Slow – Lamina II &III of dorsal horn – SG -Paleospinothalamic

24.  Multimodal analgesia is achieved by combining different analgesics that act by
different mechanisms and at different sites in the nervous system, resulting in additive
or synergistic analgesia with lowered adverse effects of sole administration of
individual analgesics
 These regimens must be tailored to individual patients, keeping in mind the procedure
being performed, side effects of individual medications and patients’ pre-existing
medical conditions.

26.  PG E2 – Causes reduced pain threshold or incites an inflammatory response
at the site of injury
 NSAIDS inhibit the synthesis of prostaglandins both in the periphery and
spinal cord thus diminishing the hyperalgesic states.
 Only iv NSAID - Ketorolac
Also available as intra nasal
Latest – iv Ibuprofen
Topical 1% Diclofenac

30.  Inhibit the central neuronal sensitisation
 Pregabalin and Gabapentin
 Alpha-2-delta subunit of N-type voltage-gated calcium channels in
DRG and brain
 Reduction in the release of neurotransmitters such as glutamate and
substance P

32.  Ketamine – iv or intra nasal
 Memantine – Oral . Completely absorbed from GIT, Approx
80% remains as parent drug. Usual dose – 10 mg bd with 5-
10 mg / day increments
 Magnesium –inhibition of calcium influx , Antagonism of
NMDA receptors

33.  The alpha-2 adrenergic receptor has high density in the substantia
gelatinosa of the dorsal horn in humans and that is believed to be
the primary site of action by which alpha-2 adrenergic agonists
can reduce pain.
 Dexmeditimidine and Clonidine

34.  Mu opioid receptor agonism
 Noradrenaline reuptake inhibitor
 100 mg tapentadol = 15 mg oxycodone
 Decreased incidence of nausea and vomiting for equipotent
doses of opioids

35.  Sensory and motor block
 Local anaesthetics plus adjuvants

36. 8. PERIPHERAL Nerve block
9. Transdermal fentanyl
10. Extended release epidural Morphine
11. Liposomal Bupivacaine
12. Patient controlled analgesia

38.  Tailored education to patient or responsible caregiver
 Parents of children should receive instruction in methods of
assessing pain and appropriate administration of analgesics
 History of medical and psychiatric comorbidities, substance
abuse ,chronic pain
 Adjust the pain management plan based on adequacy of pain
relief and presence of adverse events
 Validated pain assessment tool to track responses

40.  Multimodal analgesia - Combination of pharmacological
and non pharmacological techniques
 Oral opioids preferred over i.v. opioids for post operative
analgesia
 Avoid intramuscular route of drug administration
 I.V. PCA to be used for post op systemic analgesia
 No basal continuous iv infusion of opioids

41.  Appropriate monitoring of sedation, respiratory sedation in
patients receiving iv opioids
 Acetaminophen and /or NSAIDS as a part of multimodal
analgesia
 200-400mg of celecoxib oral preop
 Gabapentin or Pregaba as a component of multimodal
analgesia
 Use of topical local anaesthetics before giving peripheral
nerve blocks

42.  No intrapleural analgesia for pain control after thoracic surgery
 Surgical site specific peripheral regional anesthesia technique
 Continuous local anesthetic based peripheral regional anesthetic
techniques
 Neuraxial analgesia for major thoracic and abdominal procedures
 Avoid neuraxial administration of magnesium, benzodiazepines,
neostigmine, tramadol and ketamine

43.  Organisational structures and policies and procedures to be
developed and maintained
 Clinicians should have access with consultation to a pain
specialist in case of inadequately controlled post op pain

44. ORGAN SYSTEMS PHYSIOLOGICAL RESPONSE
1. CVS Increase in HR, PVR, SBP, Myocardial
contractility, Increase oxygen demand
2. RS Respiratory muscle splinting
Decreased vital capacity
Impaired ventilation
Atelectasis
Increased V/Q mismatch,
Hypoventilation, Hypoxia, Hypercarbia
Increased pulmonary infection

45. 3. GASTROINTESTINAL Increased anal sphincter tone
Decreased intestinal motility
Ileus
Nausea and vomiting
4.RENAL Increased urine sphincter tone
Urine retention
5. COAGULATION Increased platelet aggregation
Venostasis
Increased DVT
Thromboembolism

46. 6.MUSCULAR Muscle weakness
Limitation of movements
Muscle atrophy
Fatigue
7.PSYCHOLOGICAL Anxiety
Fear
Depression
8.OVERALL RECOVERY Delayed
Prolonged hospital stay
Delayed return to normal life

47.  CRITERIA FOR DIAGNOSIS
1. Pain developed after surgical procedure
2. Pain of atleast 2 months duration
3. Other causes of pain excluded

48.  Peripheral and central sensitisation of nervous system causes
intractable pain that can become chronic
 Repeated noxious stimuli can induce change in chemical profile ,
function or even structure of neurons – increased sensitivity to pain
 Periph sensitisation – hyperexcitability of dorsal horn neurons
 Central sensitisation – Hyperexcitability of spinal nociceptive
neurons , expansion of sensory receptive fields , alterations in
processing of innocuous stimuli

49. 1.NON PHARMACOLOGICAL
a. Transcutaneous electric nerve stimulation
b. Cognitive modalities
2.SYSTEMIC PHARMACOLOGICAL
a. Acetaminophen
b. NSAIDS
c. Oral Opioids
d. Patient controlled i.v. analgesia with opioids
e. Gabapentin and Pregabalin

50. 2.SYSTEMIC PHARMACOLOGICAL
e. Ketamine i.v
f. Lignocaine i.v.
g.Local anesthetic infiltration
h.Intra articular local anesthetic
i. Topical local anaesthetics

51.  J.Peripheral regional anesthetic techniques
 K. Neuraxial analgesia

53. THANK YOU