Lecture Title: Acute Pain Management. Lecturer name: Osama Ibraheim MD,SOB. Lecture date:. Lecture Objectives. Fundamental Considerations. Millions of patients worldwide undergo surgery.
Lecturer name:Osama Ibraheim
Although developing more effective techniques for postoperative analgesia, many patients experience pain.
An unpleasant sensory and emotional experience associated with actual
or potential tissue damage.
IASP, Subcommittee on Taxonomy, 1979
TORSION STRETCH CUT PINCH PRICK COMPRESS CRUSH
Acute: A Symptom of Injury or Disease
Chronic Benign: Pain itself is the disease
Chronic Cancer: Actual Tissue destruction
Cardiovascular: Tachycardia, hypertension, increased SVR, increased cardiac work, increased myocardial O2 demand.
Pulmonary: Hypoxia, hypercarbia, atelectasis, decreased cough, decreased vital capacity and function residual capacity, V/Q mismatch.
Gastrointestinal: Nausea, vomiting, ileus, intolerance for oral intake.
Renal: Oliguria, urinary retention.
Extremities: Skeletal muscle spasm, limited mobility, thromboembolism.
Endocrine: Excessive adrenergic activity, vagal inhibition, catabolic metabolism, increased O2 consumption.
CNS: Sedation, fatigue, anxiety, and fear cause central sympathetic stimulation.
Immunologic: Inhibited cellular immunity, increased risk of infection, ?? impaired wound healing ??
PROSTAGLANDINS SUBSTANCE P29
This electrochemical event that occurs between the site of tissue damage or injury sets off a series of neural transmissions that eventually results in the perception of pain……Collectively this known as nociception
“ FIRST PAIN”
B FIBER....PHYSIOLOGIAL REACTION
A a myelinated motor
A alpha myelinated touch-pressure
A beta myelinated touch-pressure
A delta myelinated pain-temperature
A gamma myelinated proprioception
Balance between A delta and C fibers to dorsal horn determines the intensity of the stimulus that is passed to higher brain center
NOXIOUS STIMULI TRANSLATED INTO ELECTRICAL FIRING AT THE SENSORY NERVE ENDINGS
INTRINIC PAIN MODIFICATION
1.DIFFERENT IN INDIVIDUALS
Prostaglandins, bradykinins, histamine, K, substance P, serotonin (5HT2)
Glutamate, aspartate, amino acids, substance P, norepinephrine (alpha 1)
Peripheral afferent fibers to dorsal horn
Second Neuron Pain
Dorsal horn to thalamic
Third Neuron Pain
Thalamus to cortex
A. Myelinated A- Fibers:
B. Myelinated B-Fibers:
C. Non-Myelinated C- Fibers: Pain, Temperature.
Dorsal horn of spinal cord
C and Ad
Muscle and skin receptorsNociceptive pathways: peripheral sensory nerves
Increased skeletal muscle tone , Increased oxygen consumption , Lactic acid production
Increased Sympathetic tone , Hypothalamic stimulation.
Membrane ion channels of Nociceptive neurons
Directly coupling to membrane receptors
Indirectly (more commonly) mediating intracellular secondary messages
Bradykinins B1, B2
Ask the patient
Look for signs (HR, BP, facial grimacing, tears, sweating, etc)
Find the source
Quantify pain (mild, moderate, severe)
Quantify the patients perception of pain
Correct the cause where possible
Give appropriate analgesics regularly as required
Remember most sedative agents do not provide analgesia
Non-opioid analgesics+opioid analgesics
Regular injections of opioids
Continuous IV or SC infusion of opioids
Patient controlled analgesia (PCA)
Extradural opioids & or local anesthetics
Combined exrtadural + spinal analgesia
Long acting oral opioids
Long acting regional blocks
COX-1 Minor – Moderate pain
COX-2rofecoxib, parecoxib-inj Severe pain
Inhibit synthesis of PG-E
Direct analgesic effect on higher centers
Modify nociceptive responses-bradykinins
Lowers body temp
Adverse gastrointestinal effects
Lower doses only
Analgesic effects of opioids : via receptors in the CNS.
Roots of administeration :I.M. ,I.V. ,Transdermal ,Oral ,Topical ,I.V. regional ,Perineural ,etc.
I.M. root is the most treatment choice after surgery.
The” As Needed” part of the order is often interpreted to mean “As little as possible” .
No relation exists between Gender and opioid requirement.
Sublingual/buccal Epidural (opioid)
Oral transmucosal Intrathecal (opiod)
Intranasal Intra articular (opioid)
Transdermal Topical - EMLA cream
Inhalational Peripheral N block
Subcutaneous Nerve plexus block
Intramuscular Intravenous regional
The goals of new methods are:
1.Precise,controlled delivery of the prescribed dose
2. A rapid onset of action
3. Avoidance of first-pass hepatic metabolism
4. Maintenance of a steady-state concentration of drug
5. An improved side-effect profile and
6. Improved patient compliance
PCA was originally developed to minimize the effects of pharmacokinetic and
Pharmacodynamic variability among patients.
A negative feedback loop exists: experiencing pain>>>Medication demanded>>>Reducing pain >>>No further demand .
SEGMENTAL LOSS OF SENSATION
BY BLOCKING NERVE CONDUCTION
4. INTRAVENOUS ( BIER )
5. AXILLARY (INFILTRATION)
AMIDES MAX / DOSE
ESTERS MAX /DOSE
CHLOROPROCAINE 20 MG/KG
COCAINE 3 MG/KG
NOVOCAINE 12 MG/KG
TETRACAINE 3 MG/KG
Local anesthetics are the drugs, which reversibly block the generation, propagation and oscillations of electrical impulses in the excitable tissues.
Sequence of clinical anesthesia
Sympathetic block (vasodilate & skin T0)
Loss of pain and temperature sensation
Loss of proprioception
Loss of touch and pressure sensation
Loss of motor function
Sciatic and Femoral n. blocks :similar results.
Intercostal n. blocks : 6-12 hrs. analgesia.
Administration of long acting L.A.s from a catheter into pleural cavity :unilat. Analgesia with little or no sensory block.
L.A. infusion into Axillary sheath, Femoral sheath, and the vicinity of the Sciatic n.:analgesia and particularly useful to facilitate perfusion after extensive revascularization.
GU, Low Abdominal
GU, A/R, Legs
Pruritus is a common side effect and is seen more in obstetrics patients.
Urinary retention is higher in volunteers than in patients and in men than in women.
Nausea and vomiting: due to rostral spread of opioid in CSF to the vomiting center and the CTZ .
Sedation produced by intraspinal opioids may be the result of spread of the drug in CSF to receptors in the thalamus, limbic system or cortex and hypercarbia can augment it.
Long term administration: causes bone marrow suppression and leukopenia (reversible when detected early).
Relaxation tapes prior to surgery results in less analgesic use and a smoother recovery.
Because of fear of IM injections alternatives are: sublingual, rectal and transdermal routs.
Treatment of perioperative pain in elderly remains inadequate because:
Anesthesiologists are a logical choice to provide periop. Pain relief, because they are:
1-familiar with the pharmacology of analgesics and L.A.s.
2-aware of short- and long-term effects of drugs given intraoperatively.
3-knowledgeable about pain pathways and their interruption.
4-are skilled in techniques available to provide superior pain control.
Painful IV site
Repeated disturbance from medical personnel
Complications of analgesic drugs
Other pathological complications