Halothane

N2O is a potent analgesic but not a potent anesthetic. Halothane is a good anaesthetic but poor analgesic.

Halothane is an inhalational anaesthetic which sensitizes the myocardium to catecholamines and

it produce severe ventricular arrhythmias.

Halothane is a potent inhalational anaesthetic but is not a good analgesic or muscle relaxant.

It potentiates the effect of competitive neuromuscular blockers.

Halothane has little analgesic properties

but ↑ vagal tone resulting in bradycardia, vasodilatation and hypotension.

The frequency of postoperative hepatitis is approximately 1 in 4000 for multiple exposures.

Halothane reduces splanchnic and hepatic blood flow as a consequence of reduced perfusion pressure.

This reduced blood flow has not been shown to produce detrimental effects on hepatic or GI function.

Halothane has little analgesic properties but ↑ vagal tone resulting in bradycardia,vasodilatation and hypotension.

The frequency of postoperative hepatitis is approximately 1 in 4000 for multiple exposures.

 Halothane sensitizes the heart to the arrhythmogenic effects of epinephrine

, so that doses of epinephrine above 1.5 g/kg should be avoided.

Mepivacaine, Gallamine, Methoxy flurane, Ethyl chlonde etc also cause malignant hyperthermia.

Halothane causes an idiosyncratic type of liver injury. It is genetically predisposed.

• Jaundice is usually noted 7-10 days after the exposure.
• Because of the cross-reaction between halothane and methoxyflurane, it should not be used in a patient with a halothane reaction.

Ans. is ‘a’ i.e., Halothane; ‘b’ i.e., Chronic venous congestion

Centrilobular necrosis (CN) is a nonspecific histological finding caused by hepatotoxins such as :

• Acetaminophen
• Paracetamol
• Thioacetamide
• Halothane
• Tetrachloride
• Congestive hepatic injury in veno‐occlusive disease 
• Cardiac hepatopathy due to acute right-sided cardiac failure 
• Hypoxic injury due to ischemia

Ans. is ‘c’ i.e., Halothane

o Halothane tends to sensitize the heart to arrhythmogenic action of adrenaline – contraindicated in pheochromocytoma.

Ans. ‘d’ i.e., Halothane

o Halogenated inhalational anaesthetic agents like halothane are powerful tocolytic agents. Halothane is anaesthetic of choice for internal version and manual removal of placenta.

B.)It senitizes heart to catecholamines .

Extent of metaholism of inhalational anesthetics

• • Methoxyflurane > 70% (maximum metabolism)
• • Halothane > 40%
• • Enflurane 8%
• • Sevoflurane 2-5%
• • Isoflurane < 2%
• • Desflurane < 0.05% (least metabolism)
• • N2O does not undergo any metabolism.

Halothane sensitises the heart to catecholamines, so it is liable to cause cardiac arrhythmias.

Halothane ontains 0.01% thymol for stability.

HALOTHANE (2, bromo, 2 chloro, 1, 1, 1 trifluoroethane)

• • Least expensive & least pungent.
• • Potent anesthetic, no analgesia.It is a potent anesthetic with a MAC of 0.74%
• • Dissolve rubber and corrodes metals.
• • Drager Narko test is done for halothane.
• • Contains 0.01% thymol for stability.
• • Decomposed by light but is stable in amber coloured bottles.
• • 15-20% is metabolized.
• • May persist in the liver upto 12 days & not given in same patient within 3 months (potent hepato toxic).
• • Relaxes skeletal and uterine muscle & blood vessels.
• • Not hepatotoxic in children and combined with its pleasant odor, suitable in children for inhalation induction.
• • Causes 5’H’
  • o Malignant Hyperthermia,
  • o Hepatitis (centrilobular necrosis) extremely rare (1 per 35,000 cases)
  • o Hypotension
  • o Hypercapnia
  • o Heart rate decreases (myocardial depression)
• • Decreases I0P, but ICT is increased
• • Shivering & tremors common (H-shakes) in early post-operative period
• • Myocardial depression of halothane is exacerbated by β-blockers and calcium channel- blocking agents.
• • The combination of halothane and aminophylline serious ventricular arrhythmias.
• Contraindications for halothane:
  • • Pregnancy because it increases the risk of post -partum hemorrhage
  • • Liver dysfunction & Previous use within 3 months: due to halothane hepatitis
  • • Hypovolemia & severe cardiac disease (aortic stenosis); due to negative ionotropic effect
  • • Pheochromocytoma & exogenous catecholamines administration as it sensitize heart to catecholamines.
• Best uterine relaxant is Halothane followed by ether.
• Best muscle relaxant is ether followed by halothane.

A i.e. Causes bronchodialation

C i.e. Recent halothane use 

D i.e. Halothane

B i.e. Halothane

A i.e. Hepatitis 

Halothane causes two types ofhepatotoxicity:
Type I Hepatotoxicity:

• its rnild form with transient elevation of serum transaminases.
• Incidence afier halothane administration is 20-30%,

Type 2 Hepatotoxicity (Halothane hepatitb):

• It is severe form and is characterized by centrilobular necrosis.
• It is very rare winth incidence of apptoximately I: 35, (NO,
• Mortality rate is 30-70%.

B i.e. Halothane

A i.e. Halothane

C i.e. Halothane

D i.e. Halothane

Halothane (2- bromo – 2- chloro – 1, 1, 1 trifluoroethane) is a potent, non inflammable, non toxic (relatively), colourless liquid with relatively non pungent (pleasant) vapour. It is decomposed by light and stabilised by 0.01% thymolQ, but is stable when stored in amber coloured bottles. Although it is decomposed by soda lime, it may be used safely with this mixture. The vapour is absorbed by rubberQ (rubber/gas partition cofficient is 120). It corrodes metals in vaporizers and breathing systemsQ. In the presence of moisture, it corrodes aluminium, tin, lead, magnesium and alloysQ. It should be stored in a closed container away from light and heat. It is soluble in rubber, and plasticsQ commonly found in ansethetic circuits. This has obvious implications for patients with halothane sensitivity, or who are at risk for malignant hyperthermia, in whom anesthetic free circuit should be used.

Halothane, Ketamine & AtropineQ are bronchodialators. These agents decrease airway resistance and increase anatomical dead space.

Aspiration, regurgitation & intubation leads to reflex bronchospasm.

B i.e. Halothane

Among all these options only halothane is hepatotoxic so it should be avoided Lets revise some important facts.

• All coagulation factors with exception of factor VIII (8) & von wille brand factor are produced by liverQ
• Vit K is necessary for synthesis of prothrombin (factor II) and factor VII, IX and XQ.
• PT is normally 11-14 seconds, mesures the activity of fibrinogen, prothrombin and factors, V, VII, and XQ
• All opioids cause spasm of sphincter of oddi & increase biliary pressure
• Halothane hepatitis is more common in middle age, obese, female sex, and a repeated exposure (esp with in 28 days)

B i.e. Halothane

All volatile anesthetic agents reduce portal hepatic blood flow. This decrease is greatest with halothane and least with isofluraneQ.

A i.e. Succinyl choline & halothane predispose B. i.e. Dantrolene useful in all cases

C i.e. Halothane

Ans. is ‘a’ i.e., Halothane 

Ans. A: Unsuitable for pediatric population

Halothane/Fluothane is an inhalational general anaesthetic.

It is the only inhalational anaesthetic agent containing a bromine atom.

It is colourless and pleasant-smelling, but unstable in light. It is packaged in dark-coloured bottles and contains 0.01% thymol as a stabilising agent.

It is a potent anaesthetic.

It is not a good analgesic or muscle relaxant; however it potentiates competitive neuromuscular blockers.

Repeated exposure to halothane in adults results in severe liver injury (Halothane hepatitis) due to the metabolism of halothane to trifluoroacetic acid via oxidative reactions in the liver.

All volatile anaesthetics such as halothane can trigger malignant hyperthermia in genetically susceptible individuals.

Its properties include cardiac depression at high levels, cardiac sensitisation to catecholamines such as norepinephrine, and potent bronchial relaxation.

Its lack of airway irritation made it a common inhalation induction agent in pediatric anaesthesia.

Due to its cardiac depressive effect, it is contraindicated in patients with cardiac failure.

Halothane is also contraindicated in patients susceptible to cardiac arrythmias, or in situations related to high catecholamine levels such as pheochromocytoma.

Ans. is ‘c’ i.e., Constricts bronchi

Halothane

• It is a volatile liquid with a sweet odour, nonirritating, and noninflammable.
• It is a potent anesthetic with poor analgesic and muscle relaxant properties.
• Halothane causes direct depression of myocardial contractility by reducing intracellular Ca. 
• It causes a fall in BP and CO.
• Heart rate decreases due to vagal stimulation.
• It tends to sensitize the heart to the arrhythmogenic action of adrenaline → contraindicated in pheochromocytoma.
• It causes greater depression of respiration and ventilation-perfusion mismatch.
• It dilates the bronchi → inhalation agent of choice in asthmatics (intravenous anesthetic of choice in asthmatics is ketamine).
• It is a hepatotoxic drug and can also cause malignant hyperthermia (Succinylcholine accentuate it).
• Recovery is smooth and reasonably quick.
• It causes postanaesthetic shivering and chills.
• It inhibits intestinal and uterine contractions → agent of choice for assisting external or internal version during late pregnancy.
• Because of its uterine relaxant action, it is contraindicated during labour.
• It is particularly suitable for induction and maintenance in children and as maintenance anesthetic in adults.