LOCAL ANESTHETICS,IV SEDATION AND PAIN MANAGEMENT

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LOCAL ANESTHETICS,IV
SEDATION AND PAIN
MANAGEMENT
MORAYA ALQAHTANI,MD
Local Anesthetic
history
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Cocaine-1800
Niemann-1859
1884-1st use in clinical practice
1904-procaine
1925-dibucaine
1932-tetracaine
1942-Licocaine
Mepivicaine,prilocaine,bupivicaine,etidocaine.
ropivicaine
neurophysiology
Nerve structure
pharmacokinetics
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Weak bases
Lipid soluble
Pka:8-9 at physiological pH
Lipophilic portion-hydrophilic portion
and intermediate link
pharmacokinetics
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Degree of ionization.
Both are involved in the blockage of the nerve
They act by blocking Na channel
Duration of esters are shorter
pharmacokinetics
• Vasoconstrictor activity at low doses
• Vasodilatation at higher doses
• Metabolism:Esters by plasma cholinesterase
PAMA
Amides metabolized in the liver
pharmacokinetics
• Vasoconstrictor activity at low doses
• Vasodilatation at higher doses
• Metabolism:Esters by plasma cholinesterase
PAMA
Amides metabolized in the liver
pharmacokinetics
• Clearance:amide mainly hepatic,
• widely distributed compared to esters
• More stable
• Minimal allergic reaction
Pharmacological factors
• Lipid solubility
• Absorption and distribution:
• pharmacological factors
• Physical factors:age,hepatic,renal,inflammation
pharmacological factors
*injection site
*dosage
*presence of epinephrine ,carbonation
*protein binding
*chemical properties
Classification of LA
Short acting
Procaine
60-90 min
Chloroprocaine
30-60 min
Intermediate
acting
Mepivicaine
Prilocaine
20-24
20-24
Long acting
Lidocaine
Tetracaine
Bupivicaine
90-200
80-600
Etidocaine
DRUG
Maximum
Plain(mg)
Maximum
Epinephrine(mg)
Chloroprocaine
800
1000
Lidocaine
300
500
Mepivacaine
300
500
Prilocaine
500
600
Bupivacaine
175
225
Etidocaine
300
400
LA
• Preparation:
- topical :ointments,cream,lotion,spray
-Injection
• EMLA:Eutotic Mixture of Local Anesthetics
2.5% prilocaine
2.5% lidocaine
TOXICITY
Toxicity
• Allergic reaction
• Local toxicity
• Systemic toxicity
Allergic reaction
• Rare condused with adverse effects
• More with esters-PABA
• Delayed type
• No cross sensitivity
• prevention: *proper Hx & PE
*skin test- 20%-30% false positive
Local toxicity
• Direct trauma
• Intraneuronal injection
• Rare
• preventable
Systemic toxicity
• CNS
• CVS
• Methemoglobinemia
CVS
• Conduction
• Contractility
• Peripheral effect
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CVS more resistant than CNS
Bupivicaine more cardiac toxicity
Ropivicaine less cardiac toxicity
Lidocaine :anti arrhythmic drug
CNS
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Concentration dependant
Low concentration
CNS:increases with hypoxia,acidosis ,pregnancy
Adverse effect:
drowsiness,light headiness
slurred speech,restlessness,
vertigo,tinnitus, muscle twitching,
tremors,convulsion, coma,
IV Sedation
Practical consideration
• Quite environment
• Repeated cuff blood pressure measurement should
be avoided
• Monitors should be muted apart from alarm.
Requirements of analgesia
• 1.Continuous IV access.
• 2.Continuous monitoring with both ECG and
pulse oximeter.
• 3.Both the practitioner and the assistant should
have recently certified in CPR.
• 4.Resuscitation equipments should be available
(crash cart).
• 5.Possibility to transfer for full critical care
facilities e.g. Other hospital, ICU, OR.
Steps to Sedoanalgesia
• 1.Premedication with BDZ
• 2.Adequate local or regional anesthesia
• 3.IV sedation e.g. Midazolam
• 4.Adjuvant analgesia with narcotics only if
local/regional anesthetic is ineffective.
IV Anesthetics
• Neuroleptanesthesia
• Neuroleptic drugs :
Phenothiazines e.g. Chlorpromazine.
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Butyrophenones e.g. Haloperidol, Droperidol.
• Rarely used in anesthesia because of hypotension
• droperidol –fentanyl (Innovar )
IV Anesthetics
• Butyrophenones result in significant:
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Sedation.
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Tranquility.
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Immobility
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Antiemesis
IV Anesthetics
• Their side effects include:
• An extrapyramidal syndrome with
face and neck dyskinesia.
• Oculogyric crises.
• Torticollis.
• Agitation
• Hallucination
IV Anesthetics
• Droperidol (like other Butyrophenones) affect
GABA receptors and alters the balance of
dopamine and acetylcholine in certain brain sites.
• Neuroleptanesthesia is contraindicated in patients
receiving Mono Amine Oxidase Inhibitors,
abusing drugs or alcohol and those with
Parkinson’s disease.
Benzodiazepines
• Diazepam (valium)
1959
• Lorazepam (ativan)
1971
• Midazolam (versed)
1976
pharmacokinetics
• Small molecule
• Lipid soluble
• Metabolized in the liver
• Habitual use of alcohol
• Lorazepam has higher
affinity to receptors
Benzodiazepines
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Action mediated through GABA
Mainly on CNS ,minimal action on PNS
Cells become hyperpolarized resistant to exitation
Function is blood level dependant
20%
:anxiolytic
30%-50%
:sedation
60%
:loss of consciousness
• Tolerance
Short acting
Midazolam
6-11ml/kg/min
Intermediate
acting
Lorazepam
0.8-1.8ml/kg/min
Long acting
Diazepam
0.2-0.5ml/kg/min
Benzodiazepines
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Hypnotic
Sedative
Anxiolytic
Amnestic
Anticonvulsant:increases seizure threshold
Muscle relaxant
Benzodiazepines
• Uses Sedation,Induction,maintainance
• Contraindication:
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Hypersensitivity, myasthenia gravis, COPD,
acute narrow angle glaucoma.
• Safety has not been established in children and
pregnant females
Benzodiazepines
• Side effects
*high safety margin
*free allergic reaction
*inactive non toxic metabolite
*respiratory problem
*venous irritation,thrombophlebitis
*unpredictable interval of amnesia
Rx: Flumazenil (Anexate) 0.2 mg IV over 15 sec. Then
0.1mg IV q60 sec. To effect (max. 1mg).
Benzodiazepines
• Dosage:
midazolam:
IM 0.07 mg/kg (5mg) 30 – 60 min.prior (50% of
dose if >60 years)
I.V. sedation: titrate with small doses (2mg
initial followed by 1mg q2 min to effect)
(max.dose 0.1mg/kg) (reduce dose by 30% if
premedicated and by 50% if >60yo).
• Diazepam (Valium ) : IM/PO premedication: 5-10
mg. 1 to 2 h prior (reduce dose by 50% if >60yo).
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IV sedation: 5 - 10 mg IV q3h. (Reduce by 50%
if >60yo).
• Lorazepam (ativan):
PO/SL premedication: 50mcg/kg (maximum
4mg) 1-2 hour prior (50% of dose if more than 60
yo)
OPOIDS
Classification
• Natural
• Semisynthetics
• synthetics
Natural opoids
• Morphine
• Codeine
• Papaverine
Semisynthetic
• Heroin
-dihydromorphone
Synthetic opoids
• Levorphenols:
-Methadone
-pentazocine
• Phenypiperidine
-meperidine
-fentanyl
opoids
• Inhibit the action of opoid neurotransmitters
• Analgesic effect differences:
-access to the receptor
-binding affinity
-lipophility,ionization
-distribution,clearance
OPOIDS
• In general most of them
*respiratory depression
*bradycardia except demerol
*anti tussive
*sleep
*nausea,vomiting,constipation
*hypersensitivity
• Overdose :naloxone 0.4 mg IV q 2min
opoids
• Morphine:
• Pharmacology: Onset of action 2 to 5 min.
Duration of action 4-5 hrs.
• Indication:Analgesia, induction of anesthesia.
• Contraindication:
• Hypersensitivity, MAO inhibitors within 14 days
(hpertensive crises, tachyarrethmias).
Dosage: 0.1-0.2 mg/kg IV/IM/SC q3h.
opoids
• Hydromorphone :
-7-8 times stronger than morphine
-rapid distribution
-good in renal failure patient
-dose:2-4 mg po
Demerol
• Pharmacology: Onset of action 2 to 5 min. via IV
duration of action 2-4 hrs.
• absorbed slowly
• 7 to 10 times less potent than morphine
• 60% bound to protien
• Dosage:up to 1.8 mg/kg IM/SC/IV q2h.
Fentanyl
• Demorol family
-100x morphine
• High lipid solubility
• Metabolized in the liver , excreted by bile or
kidney
• Poor hypnotic and sedative activity at low doses
• No histamine release
katamine
• Cataleptic, analgesic, and dissociative anesthetic
agent.
• Onset of action 30 sec. For IV ,12-25 min for IM
dosing.
• Dosage:induction 2.0 mg/kg IV over 60 sec or 10
mg/kg IM (adults and children).
• Maintenance of anesthesia: 50% of induction dose
IV or IM, as anesthesia is lost.
katamine
• Contraindication:Hypersensitivity,
pregnancy,uncontrolled HTN
• Adverse effect:HR,BP,RR, pleasant dreams 5%,
unpleasant dreams 2%, hallucinations 1%,
confusion 3% (give BDZ with it to prevent bad
trips).
Other IV anesthetics
propofol
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Most resent 1977
High lipid solubility
Alkylphenols
Viscous milky white substance
1% of propofol
*1%soy bean oil
*2.25% glycerol
*1.2% pure egg
Propofol
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Metabolized in the liver
Iactive metabolite ,98% protein bound
Hypnotic,analgesic,induction
Titratable level of sedation
Dose: sedation 10-50 micgm/kg/min
induction 0.1-1 mg/kg over 3 min
• Side effects:respiratory depression
PAIN MANAGEMENT
• Definition
• Effect of pain
-Neuroendocrine system
-CVS
-Resp
-GIT
-GUT
-immunity
NSAIDs
• Limited use for acute PO pain
• Mechanism of action
• Prostaglandins -fever ,pain,vasodilatation
Classification
Mechanism of action
pharmacokinetics
• Rapidly absorped
• Metabolized in the liver,inactive metabolites
• High protein bound
• Action dose dependent
Side effects
• Gastropathy
• Hemostasis
• nephrotoxocity
Ketorolactromethaminne
(Toradol)
• Pyrolle acetic acid
• High analgesic potency
• 2mg of toradol = 1mg og morphine = 6-10mg of demerol
• Dose 60mg IM followed by 30 mg IM q 6h
• 50% in renal problem
Toradol
• Most sufficient for sever pain
• 0.3% incidence of PU
• Bleeding with long term use
• Increases bleeding time
Nausea and Vomiting
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History of PO emesis
Female
Obesity
Pain
Type of surgery
Anesthetic drugs
Gastric distension
Treatment
• Prophylactic antiemetic droperidol 10 to 20
micgm/kg
• Ondansetron 4 to 8 mg IV
• Metoclopramide (10 to 20 mg IV)
• Transdermal scopolamine

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