Amnesia prevent memory formation eg Barbiturates Attenuation of autonomic

Amnesia prevent memory formation eg barbiturates

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Amnesia – prevent memory formation ( e.g., Barbiturates ) Attenuation of autonomic responses ( e.g.,anti-cholinergics ) paralytics
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General Anesthesia Approaches Induction Progressive deepening of anesthesia as concentration at sites of action Surgical anesthesia is reached before body water & fat stores reach equil. Induction w/ inhaled agents, higher conc. than maintenance ; Maintenance Keep patient at proper level of anesthesia during surgical procedure Accomplished w/ inhaled agents; but more likely includes IV agent Conc. of inhaled agent is lowered from induction phase Choice of agent(s) depends upon length of procedure being done Recovery Recovery is based on the same factors as induction ( reversed ) D/C of low-soluble agent results in rapid in arterial concentration With high solubility agents, arterial concentration falls more slowly Recovery can be accelerated by stimulating respiration Clearance of anesthetic agent can speed process
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Complications - General Anesthesia Induction Overdose Some patients require more anesthetic Airway disturbances Maintenance Keeping patient asleep & alive for a long procedure Sudden changes in fluid / blood volume Acute need for more muscle relaxation Recovery Period of irrationality Pain Compromised body system(s) function Restlessness
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General Anesthesia: Inhaled Anesthetics
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1. Affect nerve transmission in the brain Low-doses Substantia gelatinosa in spinal cord Higher doses distribution to other brain regions 2. Mechanism of Action: Allosteric modulator GABA A -receptor Activation of glycine receptor Antagonize NMDA-receptor 3. Gases & vapors are soluble in blood, tissue fluids & tissues 4. Inhaled anesthetics are generally lipophilic 5. Administered & eliminated by respiratory tract 6. Requires continuous administration Inhaled Anesthetics
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Inhaled Anesthetic Agents: Gases and Volatile Liquids Nitrous oxide – N 2 O Diethylether – C 4 H 10 O Halothane – C 2 ClF 3 HBr Enflurane – C 3 ClF 5 H 2 O Isoflurane – C 3 ClF 5 H 2 O Desflurane – C 3 F 6 H 2 O Sevoflurane – C 4 F 7 H 3 O
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Phyisco-chemical Properties of Inhaled Anesthetics Ether ( R -O- R ) hydrocarbons (volatile liquids) Modern ethers contain 4 or less carbons Halogenation (F, Cl, Br, I) Impacts potency, flammability, metabolism, and arrhythmic properties Potency The larger (heavier) the halogen , the more potent the agent Direct correlation between lipophilicity potency
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Phyisco-chemical Properties of Inhaled Anesthetics Flammability Nitrous oxide (N 2 0) is non-flammable but is combustible when it breaks down; i.e., oxidizer Halogenated ethers are much less flammable Chemical stability Halogen substitution of H atoms stability Metabolism Desflurane: ~ 0.05% metabolism Isoflurane: ~ 1% metabolism Sevoflurane: ~ 2- 5% metabolism Enflurane: ~ 8% metabolism Halothane: ~ 40% metabolism
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Absorption / solubility of anesthetic gases Drug is less soluble in blood Drug is more soluble in blood Transport of gas via simple diffusion Series of partial pressure (pp) gradients
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  • Pharmacology, Morphine, Halothane,  Barbiturates,  Paralytics

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