THIOPENTONE

THIOPENTONE

Q. 1 Thiopentone does not cause:
 A Fall in intracranial tension
 B Decreases oxygen consumption of brain 
 C Decreases metabolic rate of brain
 D Decreases stage 2 of sleep
Q. 1 Thiopentone does not cause:
 A Fall in intracranial tension
 B Decreases oxygen consumption of brain 
 C Decreases metabolic rate of brain
 D Decreases stage 2 of sleep
Ans. D

Explanation:

Thiopentone  decreases oxygen consumption, metabolic rate and ICT. That is why it is agent of choice for cerebral protection. On sleep it increases stage 2 and decreases stage 3, 4 and REM.


Q. 2

All of the following are effects of thiopental, except:

 A

Reduces the cerebral metabolic rate

 B

Produces dose dependent decrease in blood pressure

 C

Causes decrease in minute ventilation and tidal volume

 D

Thiopentone is not lipid soluble so that its redistribution is very slow

Ans. D

Explanation:

Thiopentone is highly lipid soluble,

therefore redistribution is rapid and this accounts for its short duration of action.


Q. 3

Thiopentone is contraindicated in

 A

Acute intermittant porphyria

 B

Electro convulsive therapy

 C

Sarcoidosis

 D

Diabetic patients

Ans. A

Explanation:

Ans. is ‘a’ i.e., Acute intermittant porphyria

o Thiopentone is contraindicated in acute intermittant porphyria.


Q. 4

Sodium Thiopentone is ultra short acting d/t

 A

Rapid absorption

 B

Rapid metabolism

 C

Rapid redistribution

 D

Rapid excretion

Ans. C

Explanation:

C i.e. Rapid redistribution


Q. 5

% of thiopentone used in induction

 A

0.5%

 B

1.5%

 C

2.5%

 D

4.5%

Ans. C

Explanation:

C i.e. 2.5%


Q. 6

Use of Thiopentone­

 A

Seizure

 B

Truth spell

 C

Reduction of ICP

 D

All

Ans. D

Explanation:

D i.e. All


Q. 7

Dose of Thiopentone used for induction is

 A

1 mg/kg

 B

2 mg/ kg

 C

5 mg/ kg

 D

10 mg/kg

Ans. C

Explanation:

C i.e. 5 mg/kg


Q. 8

All are true about Thiopentone except: 

 A

NaHCO3 is a preservative

 B

Contraindicated in Porphyria

 C

Agent of choice in shock

 D

Has cerebroprotective action

Ans. C

Explanation:

C i.e. Agent of choice in shock

Thiopentone, a pale yellow powder, is ultrashort acting smooth inducing agent because of rapid redistributionQ. It is used in 2.5% conc. at 2.5 – 4.5 mg/kg mixed with 6% anhydrous Na2CO3 as perservativeQ

Thiopentone is contraindicated in porphyria, status asthmaticus, severe shock, pericardial temponade and uncompensated myocardial diseaseQ


Q. 9 Thiopentone is C/I in:

 A

Acute intermittent porphyria

 B

Bronchial Asthma

 C

Both

 D

None

Ans. A

Explanation:

A i.e. Acute intermittent porphyria

– In porphyria (AIP), barbiturates (eg thiopentone, methohexital & thiamylal), etomidate, pentazocine and ropivacaine are avoided/ contraindicatedQ whereas diclofenac, ketorolac, phenacetin, tilidine, chlordiazepoxide, nitrazepam, hydralazine, nifedipine, and phenoxybenzamine are used with extreme caution only.

Barbiturate (Thiopentone) induces aminolevulenic acid synthetase & formation of porphyrin which may precipitate actue intermittent or variegate prophyriaQ. ; so it is contraindicated in porphyria.Q

Due to cholinergic nerve stimulation, histamine release or direct bronchial smooth muscle stimulation, barbiturates may cause bronchospasm; which would be preventable by pretreatment with atropine, so it is not C/I in asthma.


Q. 10 Intravenous thiopentone pentox, produces

 A

Rash

 B

Pain

 C

Spasm

 D

All

Ans. D

Explanation:

A i.e. Rash; B i.e. Pain;  C i.e. Spasm


Q. 11

Intra artireal injection of thiopentone causes:

 A

Vasospasm

 B

Vasodialation

 C

Necrosis of vessel wall

 D

Hypotension

Ans. A

Explanation:

A i.e. Vasospasm


Q. 12

If thiopentone is injected accidently into an artery the first symptom is

 A

Analgesia

 B

Paralysis

 C

Skin ulceration

 D

Pain

Ans. D

Explanation:

D i.e. Pain


Q. 13

Primary mechanism responsible for cerebral protection effect of thiopentone is

 A

GABA action, calcium channel block and free radicle removal

 B

Increased cerebral blood flow

 C

Decreased (lowered) cerebral metabolism

 D

Reduces cerebral 02 demand by limiting CBF

Ans. C

Explanation:

C i.e. Decreased (lowered) cerebral metabolism

  • Barbiturates (thiopental), primarily decreases cerebral metabolism resulting in a dose related depression of cerebral metabolic oxygen consumption (CMRO2).
  • Reduced CMRO2 causes progressive slowing of EEG, a reduction in rate of ATP consumption, cerebral vasoconstriction (reducing cerebral blood flow and intracranial tension) and protection from incomplete cerebral ischemia.

Thiopentone Sodium

  • Thiopentone is a yellow coloured powder used as 2.5 % solution at 5 mg/kg dose for smooth induction.
  • It is ultrashort acting due to rapid redistribution.
  • It is contraindicated in porphyria.

Q. 14 The drug which is not suitable for patients with acute porphyria for intravenous induction is:

 A

Thiopentone sodium

 B

Propofol

 C

Midazolam

 D

Etomidate

Ans. A

Explanation:

A i.e. Thiopentone sodium

Barbiturates (eg thiopentone), etomidate, pentazocine are considered unsafe and should be avoided in porphyriaQ (contraindicated).


Q. 15

A patient selected for surgery was induced with Thiopentone iv through one of anti cubital vein complains of severe pain of whole hand. The next line of management

 A

Give IV propofol through same needle

 B

IV ketamine through same needle

 C

IV lignocaine through same needle

 D

Leave it done

Ans. C

Explanation:

C i.e. IV lignocaine through same needle


Q. 16

Action of i. v. thiopentone is terminated by ‑

 A

Rapidly renal excretion

 B

Oxidation

 C

Redistribution

 D

Conjugation

Ans. C

Explanation:

Ans. is ‘c’ i.e., Redistribution

Three proceeses are involved in the termination of action of barbiturates: the relative importance of each varies with the compound.

Redistribution: it is important in the case of highly lipid soluble thiopentone. After iv injection the action of thiopentone is terminated in 6-10 mins by redistribution while the ultimate disposal occurs by metabolism (tl/ 2 of elimination is 9 hours).

Metabolism: drugs with intermediate lipid solubility (short acting barbiturates) are primarily metabolized in liver by oxidation, dealkylation and conjugation. Their plasma t1/2 ranges from 12 – 40 hours.

Excretion: barbiturates with low lipid solubility (long acting agents) are significantly excreted unchanged in urine. The t1/2 of phenobarbitone is 80-120 hours. Alkalinization of urine increases ionization and excretion.


Q. 17 All of the following about thiopentone are true except‑

 A

It decreases ICT

 B

It has anticonvulsant action

 C

IV injection is painless

 D

It can cause reflex tachycardia

Ans. C

Explanation:

Ans. is ‘c’ i.e., IV injection is painless


Q. 18

Thiopentone is not used in‑

 A

Induction of anesthesia

 B

Medically induced coma

 C

As truth serum

 D

As antidepressant

Ans. D

Explanation:

Ans. is ‘d’ i.e., As antidepressant


Q. 19

Thiopentone is contraindicated in ‑

 A

 Acute intermittant porphyria

 B

 Electro convulsive therapy

 C

 Sarcoidosis

 D

Diabetic patients

Ans. A

Explanation:

Ans. is ‘a’ i.e., Acute intermittant porphyria 

Thiopentone

  • It is an ultrashort acting barbiturate.
  • It has short duration of action due to rapid redistribution.
  • It causes fall in BP due to vasodilatation – Cardiovascular collapse may occur if hypovolemia, shock or sepsis are present.
  • It can cause respiratory depression.
  • It has anticonvulsant action – agent of choice for neurosurgical procedures.
  • It is the agent of choice for cerebral protection. because it decreases ICT, and cerebral metabolic rate.
  • Miller 6th/e – 330, 332 .o It is poor analgesic -f painful procedure should not be done.It produces hyperalgesia.
  • It has poor muscle relaxant property.
  • Extravasation of the solution or inadverent intrarterial injection produces intense pain – thrombosis and vasoconstriction can cause necrosis and gangrene.
  • Treatment of this condition includes.
  • Leaving needle insitu
  • Brachial block
  • Heparin injection to → prevent thrombosis
  • Dilution of thiopentol t by injection of saline into the artery.
  • Papaverine injection → to relieve spasm.
  • Urokinase, streptokinase, vasodilators, steroid and lignocaine can also be used.

 Contraindications

    Acute intermittant porphyria

    Cardiovascular instability or shock.

    Respiratory obstruction  

    No availibility of airway equipments.

    Status asthmaticus



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