LOCAL ANESTHETICS,IV SEDATION AND PAIN MANAGEMENT

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LOCAL ANESTHETICS,IV SEDATION AND PAIN MANAGEMENT

• MORAYA ALQAHTANI,MD

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Local Anesthetichistory

• Cocaine-1800
• Niemann-1859
• 1884-1st use in clinical practice
• 1904-procaine
• 1925-dibucaine
• 1932-tetracaine
• 1942-Licocaine
• Mepivicaine,prilocaine,bupivicaine,etidocaine.
• ropivicaine

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neurophysiology
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Nerve structure
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pharmacokinetics

• Weak bases
• Lipid soluble
• Pka8-9 at physiological pH
• Lipophilic portion-hydrophilic portion
• and intermediate link

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pharmacokinetics

• Degree of ionization.
• Both are involved in the blockage of the nerve
• They act by blocking Na channel
• Duration of esters are shorter

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pharmacokinetics

• Vasoconstrictor activity at low doses
• Vasodilatation at higher doses
• MetabolismEsters by plasma cholinesterase ?PAMA
• Amides metabolized in
  the liver

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pharmacokinetics

• Vasoconstrictor activity at low doses
• Vasodilatation at higher doses
• MetabolismEsters by plasma cholinesterase ?PAMA
• Amides metabolized in
  the liver

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pharmacokinetics

• Clearanceamide mainly hepatic,
• widely distributed compared to esters
• More stable
• Minimal allergic reaction

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Pharmacological factors

• Lipid solubility
• Absorption and distribution
• pharmacological factors
• Physical factorsage,hepatic,renal,inflammation

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• pharmacological factors
• injection site
• dosage
• presence of epinephrine ,carbonation
  
• protein binding
• chemical properties

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Classification of LA
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LA

• Preparation
• - topical ointments,cream,lotion,spray
• -Injection
• EMLAEutotic Mixture of Local Anesthetics
• 2.5 prilocaine
• 2.5 lidocaine

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TOXICITY
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Toxicity

• Allergic reaction
• Local toxicity
• Systemic toxicity

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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

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Local toxicity

• Direct trauma
• Intraneuronal injection
• Rare
• preventable

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Systemic toxicity

• CNS
• CVS
• Methemoglobinemia

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CVS

• Conduction
• Contractility
• Peripheral effect
• CVS more resistant than CNS
• Bupivicaine more cardiac toxicity
• Ropivicaine less cardiac toxicity
• Lidocaine anti arrhythmic drug

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CNS

• Concentration dependant
• Low concentration
• CNSincreases with hypoxia,acidosis ,pregnancy
• Adverse effect
• drowsiness,light headiness
• slurred speech,restlessness,
• vertigo,tinnitus, muscle twitching,
• tremors,convulsion, coma,

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• IV Sedation

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Practical consideration

• Quite environment
• Repeated cuff blood pressure measurement should
  be avoided
• Monitors should be muted apart from alarm.

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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.

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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.

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IV Anesthetics

• Neuroleptanesthesia
• Neuroleptic drugs   
• Phenothiazines e.g.
  Chlorpromazine.
• Butyrophenones e.g. Haloperidol,
  Droperidol.
• Rarely used in anesthesia because of hypotension
• droperidol fentanyl (Innovar )

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IV Anesthetics

• Butyrophenones result in significant
•          Sedation.
•          Tranquility.
•          Immobility
• Antiemesis

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IV Anesthetics

• Their side effects include
•    An extrapyramidal syndrome with
  face and neck
  dyskinesia.
•    Oculogyric crises.
•    Torticollis.
•    Agitation
• Hallucination

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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
  Parkinsons disease.

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Benzodiazepines

• Diazepam (valium) 1959
• Lorazepam (ativan) 1971
• Midazolam (versed) 1976

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pharmacokinetics

• Small molecule
• Lipid soluble
• Metabolized in the liver
• Habitual use of alcohol
• Lorazepam has higher
• affinity to receptors

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Benzodiazepines

• 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

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Benzodiazepines

• Hypnotic
• Sedative
• Anxiolytic
• Amnestic
• Anticonvulsantincreases seizure threshold
• Muscle relaxant

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Benzodiazepines

• Uses Sedation,Induction,maintainance
• Contraindication
•      Hypersensitivity, myasthenia gravis, COPD,
  acute narrow angle glaucoma.
• Safety has not been established in children and
  pregnant females

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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).

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Benzodiazepines

• Dosage
• midazolam
•  IM 0.07 mg/kg (5mg) 30 60 min.prior (50 of
  dose if gt60 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 gt60yo).

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• Diazepam (Valium ) IM/PO premedication 5-10
  mg. 1 to 2 h prior (reduce dose by 50 if gt60yo).
•         IV sedation 5 - 10 mg IV q3h. (Reduce by
  50 if gt60yo).
• Lorazepam (ativan)
• PO/SL premedication 50mcg/kg
  (maximum 4mg) 1-2 hour prior (50 of dose if more
  than 60 yo)

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• OPOIDS

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Classification

• Natural
• Semisynthetics
• synthetics

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Natural opoids

• Morphine
• Codeine
• Papaverine
  
• Semisynthetic
• Heroin -dihydromorphone

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Synthetic opoids

• Levorphenols
• -Methadone
• -pentazocine
• Phenypiperidine
• -meperidine
• -fentanyl

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opoids

• Inhibit the action of opoid neurotransmitters
• Analgesic effect differences
• -access to the receptor
• -binding affinity
• -lipophility,ionization
• -distribution,clearance

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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

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opoids

• Morphine
• Pharmacology Onset of action 2 to 5 min.
• Duration of
  action 4-5 hrs.
• IndicationAnalgesia, induction of anesthesia.
• Contraindication
• Hypersensitivity, MAO inhibitors within 14 days
  (hpertensive crises, tachyarrethmias).
•  Dosage 0.1-0.2 mg/kg IV/IM/SC q3h.

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opoids

• Hydromorphone
• -7-8 times stronger than morphine
• -rapid distribution
• -good in renal failure patient
• -dose2-4 mg po

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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 
• Dosageup to 1.8 mg/kg IM/SC/IV q2h.

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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

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katamine

• Cataleptic, analgesic, and dissociative
  anesthetic agent.
• Onset of action 30 sec. For IV ,12-25 min for IM
  dosing. 
• Dosageinduction 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.

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katamine

• ContraindicationHypersensitivity,
  pregnancy,uncontrolled HTN
• Adverse effectHR,BP,RR, pleasant dreams 5,
  unpleasant dreams 2, hallucinations 1,
  confusion 3 (give BDZ with it to prevent bad
  trips).

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Other IV anestheticspropofol

• Most resent 1977
• High lipid solubility
• Alkylphenols
• Viscous milky white substance
• 1 of propofol
• 1soy bean oil
• 2.25 glycerol
• 1.2 pure egg

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Propofol

• 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 effectsrespiratory depression

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PAIN MANAGEMENT
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• Definition
• Effect of pain
• -Neuroendocrine system
• -CVS
• -Resp
• -GIT
• -GUT
• -immunity

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NSAIDs

• Limited use for acute PO pain
• Mechanism of action
• Prostaglandins -?fever ,pain,vasodilatation

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Classification
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Mechanism of action
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pharmacokinetics

• Rapidly absorped
• Metabolized in the liver,inactive metabolites
• High protein bound
• Action dose dependent

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Side effects

• Gastropathy
• Hemostasis
• nephrotoxocity

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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

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Toradol

• Most sufficient for sever pain
• 0.3 incidence of PU
• Bleeding with long term use
• Increases bleeding time

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Nausea and Vomiting

• History of PO emesis
• Female
• Obesity
• Pain
• Type of surgery
• Anesthetic drugs
• Gastric distension

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Treatment

• Prophylactic antiemetic droperidol 10 to 20
  micgm/kg
• Ondansetron 4 to 8 mg IV
• Metoclopramide (10 to 20 mg IV)
• Transdermal scopolamine