Acute pain management

Acute Pain Management

Presented by

Dr. Hussein Sabri, FRCA, DA, DMProfessor Of Anesthesia & Intensive Care

Ain-Shams University – Cairo

Pain - definition

”an unpleasant sensory and emotional experience with actual or potential tissue damage or described in terms of such damage” (IASP, 1986)

“Pain is defined as an unpleasant sensation , which stimulates pain receptors e.g Bradykinin ,Histamine , Serotonin , K ions and prostaglandins”

“Pain is defined as an unpleasant sensation , which stimulates pain receptors e.g Bradykinin ,Histamine , Serotonin , K ions and prostaglandins”


= Introduction

= Pathophysiology Of Pain

= Modalities in use

= Drugs in common use

= Epidural & intra-thecal techniques

= TENS

= Patient Controlled Analgesia

=Acute Pain management Service


What do we mean by “ Acute Pain Management ” ?

Surgical as :

= Post Operative Pain= Trauma= Burns & Others . . . . . . . . . . . .

Medical as := Acute Myocardial Infarction= Acute Pancreatitis= Acute Herpes Zoster & Others . . . .


Reasons often cited for poor analgesia a = A belief that pain is not harmful to the patient/or that it is a normal consequence of surgery & injury b = Concerns that pain relief will obscure a surgical diagnosis or mask the signs of surgical complications

c = A tendency to underestimate a patient’s pain and not recognize the variability in patients’ perception of pain d = Lack of frequent and regular assessment of pain and any pain relieving measures

e = Fears that the patient will become addicted to Opioids


Reasons often cited for poor analgesia – cont.

f = Concerns of a high risk of respiratory depression with Opioids g = Inadequate preoperative patient education regarding postoperative analgesia

h = Patient reluctance to request analgesia i = Lack of understanding of the enormous interpatient variability in Opioids requirements

j = Lack of recognition that age is a better predictor of Opioids requirement than weight in the adult patient


Reasons often cited for poor analgesia – cont. k = Prolonged dosing intervals and a belief that Opioids must not be given often than every 4 hours l = Insufficient flexibility in dosing schedules (dose / intervals)

m = Lack of understanding of the need to titrate analgesics to meet the needs of each patient n = Lack of accountability for pain management and considering the link ( . ) regional anesthesia & post op. pain relief


Why Should Acute Pain Management be improved ?

Possible harmful effects of under treated severe acute pain Cardiovascular Tachycardia,hypertension,PVR,

myocardial.VO2, angina, DVT Respiratory lung volumes, atelectasis

cough,Sp.ret, infection, O2 Gastrointestinal gastric & bowel motility Genitourinary urinary retention Neuro-endocrine Catabolic hormones /metabolic Anabolic hormones Musculo-skeletal m.spasm,immobility Psychological Anxiety, fear, sleeplessness

Pathophysiological Aspects

Pain Mechanisms Tissue damage caused by injury, disease or inflammation

releases endogenous chemicals, called algogenic, algesic or pain-

producing substances, into the extra cellular fluid that surround the

nociceptors.

These substances include H+, K+, serotonin, histamine,

prostaglandins, bradykinin, substance P (sP ), many others.

They play a causal role in pain associated with inflammation,

trauma, bone tumours, ischemia, and a variety of other

pathophysiologic conditions.

Pathophysiological Aspects – cont.

Pain Mechanisms – cont.

In addition to direct excitatory action on the membrane of

nociceptors, these agents may have an indirect excitatory action by

altering the local microcirculation.

The algesic substance can cause increased capillary

permeability and either vasoconstriction or vasodilatation.


Location Of Algesic Substances

Serotonin, histamine, K+, H+ prostaglandins and other members

of the arachidonic acid cascade are located in tissues; Kinins are in

plasma; and sP is in nerve terminals

Histamine is found in platelets, basophils, and the granules of

mast cells, Serotonin is present in mast cells and platelets.

Release of these amines may be induced by mechanical injury,

noxious heat, radiation, and certain by-products of tissue damage,

most notably neutrophil lysosomal materials, thrombin collagen, and

epinephrine.

Peripheral Nociceptor System

Somatic Structures: A. Skin

= Nociceptors : Distinct types, activated by tissue damage

= Free nerve endings : transmit transduced stimuli to the dorsal

horn of the Spinal cord or the Medulla

1- A- delta (high threshold mechanoceptors)

2- A-delta ( myelinated mechano-thermal nociceptors)

3- C- polymodal nociceptors

B. Muscles, Joints, Fasciae & other deep structures

by C- group IV-N. fibers & !! A-delta group III-N. fibers

Visceral Structures:

By C- and A-delta afferent fibers activated by disease,

inflammation, contraction, ischemia, rapid distention & others…

Peripheral Nociceptor System

Augmentation of nociceptors:

A. Sensitization: Repeated stimulation of most sensory organs

lead to fatigue ( less responsive )

*** But the Polymodal high threshold C-fibers show the

opposite response ----- prolonged , enhanced response

B. lowering of threshold: by pain producing substances

C. Segmental reflex responce

Inhibition of nociceptors: by counter irritation of the skin

e.g. Rubbing , Vibration , electrical stimulation or Acupuncture


Neurochemistry of endogenous opiate system

= Endorphins: 3 classes of Opioids:

1- Enkephalins

2- Dynorphins

3- β-endorphins

= Opiate Receptors: = ( mu ) – for morphine

= (Kappa)

= ( sigma )

= ( epsilon )

= ( delta )

Pain is better managed with combination of

- Medications - Educational programs- Physical therapy - Social interventions- Psychological methods - Complementary therapies

Pain can be treated


Modalities in use

¤ Medications ( Opioids, NSAID, … ) given via :

= Oral = IM = IV = Rectal = TD = Transmucosal

= Intrathecal = Epidural = PCA / Accufusser

¤ Regional Analgesic techniques :

Epidural / Intrathecal / Nerve blocks / Intra-Articular

¤ Transcutaneous Electrical Nerve Stimulation ( TENS )

¤ Acupuncture ¤ Heat Application

¤ Cryoanalgesia ¤ Ultrasonic stim.

Pharmacological Aspects

Opioids & Non-steroidal Anti-inflammatory Analgesics


Opioids

# Morphine like substances

# Opium contains > 25 diff.alkaloids

# Opium contain 2 alkaloid types:

= Phenanthrene series ( morphine , codeine ) the only analgesic

= Benzylisoquinoline series ( as Papaverine … )

# Classification: a) Naturally occurring opium alkaloids as

Morphine , Codeine, Papaverine

b) Semi synthetic as Oxy & Hydromorphone,

& Heroin

c) Synthetic Opioids as Meperidine, Fentanyl,

Alfentanil, Sufentanil, Methadone, Naloxone,..


Effects Of Opioids - cont

# ANALGESIA

= Possible side effects

# EFFECTS ON THE RESPIRATORY SYSTEM

= Respiratory depression

= Post-operative hypoxemia

# NAUISIA & VOMITING

= stimulation of the CTZ

# On CNS :

= Miosis, Sedation, Euphoria, Muscle rigidity

= Confusion


Effects Of Opioids - cont

¤ = Antiemetics: Antidopaminergic ( Droperidol-Prochlorperazine-

Metoclopramide), Antiserotinergic ( Ondansetron ),

Anticholinergic,

Antihistamines

# EFFECTS ON THE CARDIOVASCULAR SYSTEM

Morphine vascular sympathetic tone ---- vasodilatation

# EFFECTS ON GIT & GUT : Altered smooth muscle activity

# PRURITUS – Histamine release / !! Centrally mediated

# ALLERGY


Commonly used Opioid Agonists – cont

receptor agonists

¤ Morphine – new oral slow release formulation

¤ Papaveretum – a mixture of opium alkaloids

¤ Codeine – low affinity for Opioid receptors– good antitussive

¤ Diamorphine ( Heroin ) – no analgesic activity / is a prodrug

¤ Meperidine ( Pethidine ) – some atropine like actions

¤ Fentanyl & its analogues – Highly lipid soluble synthetic

¤ Tramadol – Centrally acting – ceiling dose 600 mg

Pharmacological Aspects – cont.

Nonsteroidal Antiinflamatory Drugs

= Often chemically unrelated

= Do not demonstrate tolerance

= All have analgesic properties

By inhibiting the formation of prostaglandins

= Cross the Blood Brain Barrier

= Salicylates : half life with ing dose

One week is needed to achieve steady state conc. When

the dose is 3 g / day


Drug ( Generic )

Drug ( brand ) T ½ β (h)

Acetaminophen Novalgin 2.8 Aspirin(Salicylates) 0.25 Diclofenac Voltaren 1-2

Ibuprophen Brufen 2-2.5

Indomethacin Indocid 6

Ketoprophen 1.5

Ketorolac Ketolac 5.5

Piroxycam Feldene 48.5

** T ½ β (h): elimination half life

NSAID - Pharmacokinetics


NSAID – Hazards & Toxicity

= Inter patient diff. in drug responsiveness

= The least toxic: coated, buffered aspirin, salicylate

= The most toxic is the taken in lowest doses

= GIT bleeding

= Renal toxicity

= Hematologic toxicity

= Hepatic toxicity

Pre-emptive Analgesia

Analgesics given to patients prior to the onset of pain

aiming to prevent changes in the spinal cord that

occur with repetitive painful stimuli from the site of

injury.

Benefits were shown only in animal studies but not in

clinical human studies – long term benefits may occur

Epidural & Intrathecal Analgesia

Epidural Analgesia One of the most effective techniques available for the

management of acute pain

¤ Advantages :

¤ Safety Precautions ( When used on the ward )


Drugs in common use

¤ Local Anesthetics:

= Xylocaine : 2 – 0.5 %

= Bupivacaine ( Marcaine) : 0.5, 0.25, 0.125, 0.1, 0.625 %

= Ropivacaine Hcl ( Naropin ) : 0.75 , 0.2 %

¤ Opiates:

= Morphine: 2-4 mg

= Fentanyl : 50 -200 m

¤ Others: As Clonidine, NSAID, Neostigmine, Ketamine, …


Intrathecal Analgesia

¤ Local Anesthetics:

= Xylocaine : 2 %

= Bupivacaine ( Marcaine) : 0.5, 0.25, 0.125, 0.1, 0.625 %

¤ Opiates:

= Morphine: 2-4 mg

= Fentanyl : 50 -200 m

¤ Others: As Medazolame, Clonidine, NSAID, Neostigmine,

Ketamine, …

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Celiac Ganglion Block

Lumbar Sympathetic Block

Intercostal Nerve Block

Pain management in Trauma Patients

¤ Thoracic Injuries:

= Intercostal nerve blocks +/- parentral opiates

= Intra-pleural injection + catheter

= Thoracic epidural using local anesthetics ( Bupivacaine

0.25 % ) or narcotics ( morphine 2 mg or fentanyl 50 g )

¤ Pain management of intra abdominal injuries

= Aggressive pain management benefit upper abdominal & high risk patients

= Low or mid thoracic epidural unless contra indicated


¤ Pain management of extremity injuries [ Blunt / Penetrating ]

( Bony disruption, major somatic nerves, vascular injury, soft

tissue injury as in crush injuries )

= Sympathetic blocks : provide pain relieve & improve outcome

= Brachial plexus – Stellate ganglion – Lumbar sympathetic

= Catheter technique – use dilute solutions of LA

= narcotic addition is not indicated ( no opiate receptors )

= Tachyphylaxis to LA can occur - conc.

= Max. Bupivacaine dose = 0.4 mg /kg / hour

= In Reflex sympathetic dystrophy – after crush injuries –

sympathetic blockade remains the treatment of choice

= the same for Causalgia ( due partial somatic nerve injury )


¤ Headinjured patients and pain management:

= In severe head injuries , pain management that interferes

with neurological monitoring should be avoided

= Neurological side effect with sedatives & Opioids !!!

¤ Pain management Paradigm for the trauma patient :

should be designed

¤ Contraindication to epidurals in trauma patients :

= Coagulation abnormalities / Sepsis / severe mental affection

Acute Pain Management Service “APMS”

* Started by Reddy in USA 1984

* Nurse based , Anesthesiologist supervised model

* Role :

- Education ( initial, update ) : to Anesthesiologists, Surgeons,

pharmacists, nurses, patients & families, medical & nursing

students, ………….

- Introduction of more advanced analgesic techniques as PCA

- Improving traditional analgesic treatment regimens

- Standardization of : Equipment, policies, medications

- 24 – hour availability

- Regular audit of activity and continuous quality improvement

- Clinical research.

Thank You

Thank You

Thank You

Acute pain management

Health & Medicine

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