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Claro M. Isidro md
Loss of consciousness Analgesia Adequate muscle relaxation
Analgesia•Loss of sensation to pain
General Anesthetics• Reversible loss of consciousness• Loss of CNS activity
Local Anesthetics• No loss of consciousness• Reversible loss of pain sensation
INHALATIONAL ANESTHETICS
INTRAVENOUS ANESTHETICS
Stage I: Analgesia Stage II: Excitement/ Delirium Stage III:Surgical Anesthesia
› Plane I: reg. breathing loss of eye movement
› Plane II initiation of IC muscle paralysis
› Plane III: completion ICM paralysis› Plane IV: diaphragmatic paralysis
Stage IV:Medullary Paralysis
Pharmacokinetics: tension (partial pressure) in the brain
depth tension in this tissues rate of
induction and recovery
Flow of anesthetic during induction:Anesthesia Lungs Arterial Brain &
machine blood tissues
GENERAL ANESTHETICS:
Pharmacokinetics: absorption (uptake) distribution metabolism elimination lungs
Principal objective:To achieve a constant and optimal brain partial pressure of the inhaled anesthetic
GENERAL ANESTHETICS:
• 2 PHASES:2 PHASES:
– Pulmonary PhasePulmonary Phase
– Circulatory PhaseCirculatory Phase
GENERAL ANESTHETICS: UPTAKEGENERAL ANESTHETICS: UPTAKE
Pulmonary Phase Concentration of the anesthetic
agent in the inspired gas
Pulmonary ventilation
Transfer of anesthetic gases from alveoli to blood• solubility of the agent• rate of pulmonary blood flow• partial pressure in the alveoli
and mixed venous blood
GENERAL ANESTHETICS: UPTAKEGENERAL ANESTHETICS: UPTAKE
GENERAL ANESTHETICS: SOLUBILITYPartition Partition
CoefficientCoefficientBlood:GasBlood:Gas Brain:BloodBrain:Blood
SolubleSolubleMethoxyfluraneMethoxyflurane 1212 22IntermediateIntermediateHalothaneHalothane 2.42.4 1.91.9EnfluraneEnflurane 1.91.9 1.51.5IsofluraneIsoflurane 1.41.4 1.61.6Poorly solublePoorly solubleNitrous OxideNitrous Oxide 0.460.46 1.11.1DesfluraneDesflurane 0.420.42 1.31.3SevofluraneSevoflurane 0.590.59 1.71.7
Pulmonary Phase Concentration of the anesthetic
agent in the inspired gas
Pulmonary ventilation
Transfer of anesthetic gases from alveoli to blood• solubility of the agent• rate of pulmonary blood flow• partial pressure in the alveoli
and mixed venous blood
GENERAL ANESTHETICS: UPTAKEGENERAL ANESTHETICS: UPTAKE
GENERAL ANESTHETICS: UPTAKEGENERAL ANESTHETICS: UPTAKE• Circulatory or Distribution Phase
SolubilitySolubility tissue:blood solubility coefficienttissue:blood solubility coefficient
Tissue Blood FlowTissue Blood Flow Vessel-Rich group – 75% of COVessel-Rich group – 75% of CO Muscle Group – 3%Muscle Group – 3% Fatty Group – 2%Fatty Group – 2% Vessel-Poor group - <1%Vessel-Poor group - <1%
Partial Pressure of Gas in Arterial Partial Pressure of Gas in Arterial Blood and TissuesBlood and Tissues
RECOVERY and EMERGENCEFactors affecting rate of Elimination
SOLUBILITY IN BLOOD & TISSUE BLOOD FLOW
Flow of anesthetic during elimination:Tissue/ Blood Lungs AnesthesiaBrain Machine
GENERAL ANESTHETICS:GENERAL ANESTHETICS:
Rapid & pleasant induction & recovery Rapid changes in depth of anesthesia Adequate relaxation of smooth muscle Wide margin of safety Absence of toxic effect
GASEOUS ANESTHETIC: NITROUS OXIDE CYCLOPROPANE
VOLATILE ANESTHETIC:A. HalogenatedA. Halogenated B. Non B. Non
HalogenatedHalogenated1. 1. HalothaneHalothane 1. Ether1. Ether2. Enflurane2. Enflurane 2.2. Chloroform Chloroform3.3. Isoflurane Isoflurane 4. Methoxyflurane4. Methoxyflurane5. Sevoflurane5. Sevoflurane6.6. Desflurane Desflurane
2 bromo-111 triflouroethane is a non ether derivative ( an ethane) vapor is pleasant to smell and non-irritating can cause a dose dependent reduction of arterial
blood pressure due to: 1. Direct depression of the myocardium 2. The normal baroreceptor mediated tachycardia
in response to hypotension is obtunded sensitizes the myocardium to catecholamines
leading to cardiac arrhythmia’s causes a dose related reduction in the ventilatory
response to carbon dioxide produce adequate muscle relaxation has no toxic effect on the kidneys
Repeatedadministration over a short period of time has been implicated to produce halothane hepatitis
another dreaded complication is malignant hyperthermia, which is characterized by the following:
1. Rapid rise in body temperature 2. massive increase in oxygen consumption 3. increase production of carbon dioxide Cardiotoxic, Hepatotoxic but not Nephrotoxic
2 chloro-112 trifluroethyl difluromethyl ether an halogenated ether derivative produce mild stimulation of salivation and bronchial cause dose dependent myocardial depression
similar to that of halothane sensitizes the myocardium to the effect of
catcholamines , no unusual effect on the GIT muscle relaxation is greater than that of halothane contraindicated in patient with seizure disorder
because it cause CNS irritability in high doses the free fluoride radical a metabolite of enflurane
has been implicated to its renal toxicity so it is contraindicated in patient with renal disorder
Cadiotoxic, Nephrotoxic but not Hepatotoxic
1 chloro-222 trifluroethyl difluromethyl ether an halogenated ether derivative the chemical and physical properties are similar to
those of its isomer enflurane does not sensitize the myocardium to the effect of
cathecholamines cerebral blood flow is increased while the cerebral
metabolism is reduced produce adequate muscle relaxation less nephrotoxic than enflurane less hepatotoxic than halothane agent of choice for cardiac surgery non Cardiotoxic, non Hepatotoxic, non Nephrotoxic Least vicerotoxic
2,2dichloro- 1,1 difluroethyl methyl ether it is clear, colorless liquid with sweet fruity odor non flammable and non explosive in air most potent of the inhalational anesthetic induction of anesthesia is slow due to its high
solubility coefficient respiratory and cardiovascular depression is
generally similar to that of halothane sensitize the myocardium to the effects of
catecholamines nephrotoxicity and hepatotoxicity are the major
disadvantage most toxic of the inhalational anesthetic Cardiotoxic, Hepatotoxic, and Nephrotoxic
a fluorinated methyl ethyl ether that differ from isoflurane only by substitution of a fluoride atom from chlorine
can produce a dose related decrease in blood pressure and cardiac output
non Cardiotoxic, non Hepatotoxic, non Nephrotoxic
Sevoflurane also a fluorinated methyl ethyl ether not irritating to the airways cardivascular effect is similar to isoflurane
Ether first anesthetic discovered seldom use today because of its flammability
and explosive property
Chloroform no longer use today because of liver toxicity non explosive and non flammable has rapid induction and recovery
Nitrous Oxide sweet smelling, non irritating, colorless gas the only inorganic gas in common use possessing
anesthetic properties potent analgesic but a weak anesthetic in the
sense that it does not produce adequate muscular relaxation
ventilatory drive is not affected little or no cardiovascular effectCyclopropane explosive and flammable property
GASEOUS ANESTHETIC: NITROUS OXIDE CYCLOPROPANE
VOLATILE ANESTHETIC:A. HalogenatedA. Halogenated B. Non B. Non
HalogenatedHalogenated1. 1. HalothaneHalothane 1. Ether1. Ether2. Enflurane2. Enflurane 2.2. Chloroform Chloroform3.3. Isoflurane Isoflurane 4. Methoxyflurane4. Methoxyflurane5. Sevoflurane5. Sevoflurane6.6. Desflurane Desflurane
BARBITURATES the most commonly use barbiturates is the ultra short acting
thiopental following a single IV anesthetic dose of thiopental
unconsciousness occur after 10-20 seconds and returns in 20-30 minutes
poor analgesic and may even increase the sensitivity to pain (hyperalgesia) when administered in inadequate amounts.
Not irritating to the respiratory tract Cerebral blood flow and cerebral metabolic rate are reduced Produce a dose related depression of respiration and circulation Agent of choice for induction of anesthesia in patient with
increased intracranial pressure and hypertension Contraindicated in patient with acute intermittent porphyria
and hypotension
INTRAVENOUS ANESTHETICSINTRAVENOUS ANESTHETICS
first introduced for the treatment of anxiety rapidly absorbed from the GIT after oral
administration hypnosis and unconsciousness may be produced
with large doses cause amnesia in 50% of patients
characteristically Anterograde type may cause moderate depression of circulation
and respiration they are not analgesic and it is necessary to
combine several drugs to achieve surgical levels of anesthesia
Ketamine HCl used for induction of dissociative anesthesia a sensation of dissociation is noticed within 15
seconds and unconsciousness becomes apparent within another 30 seconds and lasts for some 40 minutes
intense analgesia and amnesia are established rapidly
muscular relaxation is poor cardiovascular and respiratory system are stable drug of choice for induction of anesthesia in
children and hypotensive patients contraindicated in patients with hypertension
because it increase sympathetic activity can cause increase intraocular pressure contraindicated in patient with glaucoma
2,6 Diisoprophylpenol produces anesthesia at a rate similar to
that of barbiturates cause marked decrease in systemic blood
pressure during induction post operative vomiting is less common
and may have anti-emetic property hypersensitivity is less common
should not be irritating to tissues should not cause permanent damage
to nerves have low systemic toxicity must be effective should have rapid onset but long
duration of action
MOA: block nerve conduction
Structure:› aromatic group (Hydrophobic lipophilic)› amide group (hydrophilic)
tertiary amine or secondary amine› intermediate chain
Ester or Amide
LOCAL ANESTHETICSLOCAL ANESTHETICS
CH2-CH3
NH2 O-O-CH2-CH2-N
O CH2-CH3
Aromatic grp Alkyl Amide grpLipophilic chain Hydrophilic
METABOLISM:
Ester plasma and liver esterases metabolite: PABA
Amide liver
EXCRETION: kidneys
LOCAL ANESTHETICSLOCAL ANESTHETICS
ROUTES OF ADMINISTRATION:
1. Topical2. Local Infiltration3. Nerve Block4. Spinal or Intrathecal injection5. Epidural 6. Caudal
LOCAL ANESTHETICSLOCAL ANESTHETICS
LOCAL ANESTHETICSLOCAL ANESTHETICS
ESTERS:ESTERS:
1.1. CocaineCocaine2.2. ProcaineProcaine3.3. ChloroprocaineChloroprocaine4.4. TetracaineTetracaine
AMIDES:AMIDES:
1.1. LidocaineLidocaine2.2. BupivacaineBupivacaine3.3. MepivacaineMepivacaine4.4. DibucaineDibucaine5.5. PrilocainePrilocaine6.6. EtidocaineEtidocaine
May also be classified into
a. Short acting – cocaine, procaineb. Intermediate acting – lidocaine,
mepivacaine, dibucaine, prilocainec. Long acting – tetracaine, bupivacaine,
etidocaine
1. Hepatotoxic agent a. Isoflurane2. Nephrotoxic agent b. Barbiturate3. Cardiotoxic agent c. Enflurane4. Thiopental d. Halothane5. Flammable agent e. Ether
a. Amide LA b. Esther LA6. Lidocaine7. Tetracaine8. Cocaine9. Bupivacaine10. Etidocaine