Pharm - General Anaesthesia Flashcards
(48 cards)
What are the physiological state induced by General anaesthesia ?
- Analgesia
- Amnesia
- Loss of consciousness
- Inhibition of sensory & autonomic reflexes
- Skeletal muscle relaxation
What type of drugs are given prior to general anaesthesia?
- To relieve anxiety – benzodiazepines.
- To prevent allergic reactions – anti-histamines.
- To prevent nausea & vomiting – anti-emetics
- To provide analgesia – opioids.
- To prevent bradycardia & secretion – atropine
What are the two categories of Anaethesic agents ?
- Inhalation - for maintenance
*Intravenous - For Induction & short procedures
What is Induction of General anaesthesia?
This is the time from administration of GA to achievement of surgical anaesthesia.
What is Recovery of General anaesthesia?
This is the reverse of induction.
What are the types of Inhaled general anaesthetics?
- Halogenated Hydrocarbon
- Non-halogenated gas
What are examples of Halogenated hydrocarbons?
Desflurane
Isoflurane
Sevoflurane
Halothane
” DISH “
What is an example of Non-Halogenated gas?
Nitrous Oxide
How are inhaled general anaesthetics measured?
Their partial pressure or “tension” in the inhaled air or in the blood or other tissue is a measure of their concentration
Fill in the blanks. “ 50% nitrous oxide in inhaled air would have a partial pressure of
__________.”
380 mm Hg
What are the factors influencing the rate at which the therapeutic concentration of inhaled anaesthetics achieved in brain?
- Solubility
- Pulmonary ventilation
- Partial pressure of inhaled gas.
- Alveolar blood flow
- Arteriovenous concentration gradient
What are the most important characteristics of Inhalation GA which govern anaethesia?
- Solubility in the blood (blood : gas partition co-efficient).
- Solubility in the fat
(oil : gas partition co-efficient)
Fill in the blanks.” In regards to the Inhalation agent, _________________ is the single most important factor in determining speed of induction & recovery.”
Solubility in the blood
True or False? “ The more soluble an agent is in the blood the more must be dissolved to raise its partial pressure.”
TRUE!!
True or False? Agents that are less soluble in blood (ex. nitrous oxide) provide a rapid induction because the blood reservoir is small & anaesthetic is available to pass into the brain sooner.
TRUE!!
True or False? The higher the lipid solubility the potent the anaesthetic ex Halothane.
TRUE !!
What is the minimum alveolar concentration (MAC)?
This is defined as the concentration of inhaled anaesthetic, (as a % of inspired air), at which 50% of patients do not respond to a surgical stimulus
True or False? The more lipid soluble the anaesthetic , the lower the MAC and the greater the potency.
TRUE!!
In the event of Malignant hyperthermia caused by the use of Inhaled Anaesthetics except Nitric oxide , what is the drug choice of treatment ?
Dantrolene
What is an Adverse effect of Nitrous oxide?
Risk of bone marrow depression w prolonged administration(›6hr) causes inactivation of methionine synthase, needed for DNA & protein synthesis→ bone marrow depression.
What is the MAC for Nitrous oxide?
100%
Which halogenated hydrocarbon inhaled anaesthetics is a powerful coronary vasodilator?
Isoflurane
What is the MAC of Isoflurane ?
1.4%
Which halogenated hydrocarbon inhaled anaesthetics is used for GA especially in children, b/cause it is not irritating to airways?
Sevoflurane
