INHALATIONAL ANAESTHETICSMCQS
Q1. Index of potency of general anesthesia isa. Minimum alveolar concentrationb. Diffusion coefficientc. Dead space coefficientd. Alveolar blood concentration Ans: A)Minimum alveolar
concentration
Minimum alveolar concentration
It is the alveolar concentration of inhaled anesthetic that prevents movement in 50 percent of patients in response to standard stimulus (eg standard stimulus)
Best measure of anesthetic potency
primarily mediated by anaesthetic action in spinal cord
Q2. Potency of inhalational anaesthetic depends ona. Blood gas partition coefficientb. Oil gas partition coefficientc. Gas pressured. Blood pressure
Ans B)Oil gas partition coefficient
Partition coefficient
The relative solubilities of an anesthetic in air, blood & tissues are expressed partial coefficient
Blood gas partition coefficient measures solubility of GA .Most important factor in determining the uptake agent and so the speed of induction and recovery.
Oil-gas partition coefficient (lipid solubility) measures anesthetic potency.
Q3. Which one of the following is the fastest acting agent?a. Halothaneb. Isofluranec. Etherd. Sevoflurane
Ans D)Sevoflurane
Blood gas partition coefficient measures solubility of GA .Most important factor in determining the uptake agent and so the speed of induction and recovery.
Agents in increasing order of B/G coefficients
Xe(0.14) > Desflurane(0.42) > Cyclopropane (0.44) > N2O (0.47) >
Sevoflurane(0.69) > Isoflurane(1.38) > Enflurane(1.8) > Halothane(2.4) > Chloroform(8) > Trilene(9) >Ether(12) > Methoxyflurane(15)
Q4. All of the following factors decrease the minimum alveolar concentration (MAC) of an inhalational anaesthetic agent excepta. Hypothermiab. Hyponatremiac. Hypocalcemiad. Anaemia
Ans C)Hypocalcemia
Factors affecting increase on MAC
Young Chronic abuse of alcohol Hypernatremia Acute Amphetamine toxication Cocaine, Ephedrine
Factors affecting decrease on MAC
Hypothermia, Hyperthermia Elderly Anemia Pregnancy PaO2<40mmHg,PaCO2>95mmHg Drugs: Local anesthetics, Opiods,Ketamine,Barbiturates, Verampil, Lithium,Symptholytics. Chronic use of Amphetamine
Q5. True about xenon anaesthesiaa. Rapid induction and recoveryb. Low potencyc. High blood solubilityd. Non explosivee. Heavier than air
Ans)A,D,E
Xenon
is inert, colorless, odorless, non irritating, non inflammable and environmental friendly
more potent than N2O
It is neuro and cardioprotective
non teratogenic and safe(to liver and kidney)anesthetic
Xenon's B/G partition coefficient is the lowest, resulting in rapid induction and recovery.
Q6. Pungent volatile anaesthetic isa. Halothaneb. Isofluranec. Sevofluraned. Desfluranee. Nitrous oxide
Ans) B and D
Pungent volatile anaesthetic agents are
Desflurane Isoflurane Enflurane Ether
Q7. Which of the following inhaled gas is used to decrease pulmonary artery in adults and infants?a. Nitrous oxideb. Nitrogen dioxidec. Nitric oxided. Nitrogen
Ans C Nitric oxide
Nitric oxide or endothelium derived relaxing factor is synthesised from L-arginine by nitric oxide synthase (NOS) enzyme in endothelium of blood vessels.
Physiologically it causes vasodilation and decreases vascular resistance throughout the body.
Inhaled NO is a selective pulmonary –vasodilator decreases pulmonary artery pressure in infants and adults and improves V/P ratio..So it is used in treatment of pulmonary artery pressure
Q8. Diffusion hypoxia is seen duringa. Induction of anaesthesiab. Recovering anaesthesiac. Pre operativelyd. Post operatively
Ans B) Recovering anesthesia
Diffusion hypoxia is seen during recovery phase after discontinuation of prolonged N2O anaesthesia .
It can be prevented by continuing 100 % O2 inhalation for few minutes after discontinuing N2O
Q9. Use of nitrous oxide is contraindicated in all of the following surgeries excepta. Cochlear implantb. Microlaryngeal surgeryc. Vitreoretinal surgeryd. Exentration surgery
Ans D)Exentration surgery
Excentration is enclueation + wide dissection of periorbital tissue.In it there is no closed space formation so N2O can be used.
In microlaryngeal lesser surgery,N2O is contradicated due to risk of airway fire.
Q10. Soda lime circuit is not used with a. Enfluraneb. Isofluranec. Methoxyfluraned. Trilene
Ans D) Trilene
Sodalime with trilene forms phosgene (neurotoxic) gas.
It should not be used with: Chloroform Trilene Sevoflurane
Q11. Stages of anaesthesia was established bya. Etherb. N2Oc. Halothaned. Chloroform
Ans A) Ether
Guedel’s staging of anesthesia was given for ether
Stage I -Analgesia
Stage II-Delirium or Excitement Partially dilated pupil
Stage III- has 4 planes 1 moving eye to fixed eye 2 corneal or laryngeal reflex lost 3 light reflex lost 4Intercostal paralysis
Abdominal respiration Pupils fully dilated
Stage IV-Medullary Paralysis
Q12. Anaesthesia agent with least analgesic propertya. N2Ob. Halothanec. Etherd. Propane
Ans B)Halothane
Halothane
is a potent,non inflammable ,non toxic,colourless liquid with relatively non pungent vapour
Anesthesia agent with least analgesic agent
It’s a bronchodilator,uterine relaxant and vasodilator
Anesthesia of choice for uterine contraction and inversion
Q13. Which of them are the following contraindications for halothane use?a. Middle ageb. Recent halothane usec. Associated liver pathologyd. Obesity Ans-B and C
Contraindications of halothane
Liver dysfunction
Halothane use with in 3 months
Hypovolemia & severe cardiac disease
Pheochromocytoma and exogenous catecholamines administration
Q14. In increased ICT, agent used for anaesthesiaa. Isofluraneb. N2Oc. Trilened. Ether
Ans A) Isoflurane
Isoflurane
is anesthesia of choice for neurosurgical procedures ,renal failure and myasthenia gravis
Avoided in ischaemic heart disease
Cause coronary steal syndrome
used in daycare anesthesia
Q15. Which of the following is/are false?a. Enflurane interacts with sodalimeb. Sevoflurane causes seizuresc. Ketamine acts through GABA-A
receptorsd. MAC indicates potency of
inhalational agents
Ans B,A
Sevoflurane ,isoflurane and desflurane have anticonvulsant properties.
Enflurane causes epileptiform changes (more commonly during hypocapnia)hence should be avoided in epilepsy.
Enflurane interacts with sodalime but produce clinically insignificant amount of carbonmonoxide
Ketamine is a noncompetitive NMDA (glutamate) receptor antagonist
Propofol has smooth and rapid induction and rapid recovery.
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