Isoflurane (Furane) 1979, Sevoflurane (Ultane) 1990s general description ,physical properties and anesthetic properties . Effects on organ system, contraindications, drug interaction.

1. Volatile Anesthetics
Isoflurane , Sevoflurane
Mahmood Hasan Taha
HD/ Anesthesia
Zakho General H.
Aug/ 2022

2. Isoflurane (Forane) 1979

3. General Description:
• Non flammable.
• Non explosive.
• Pungent ethereal odor.
• Chemical isomer with the same
molecular weight as Enflurane.
• MAC = 1.2
• Blood/Gas: 1.43, Oil/ Gas: 91
(Blood/ Gas: 2.3, Oil/ Gas: 224 for Halothane)

4. • Color code: purple.
• Colorless liquid in brown glass bottle, without
preservative.
• Boiling point: 48.5℃ SVP: 31.9 mmHg.
(50.2℃, SVP 32.5 mmHg for Halothane).
• Soda lime: compatible.

5. • Vaporizers: a specifically calibrated plenum
vaporizers.
The physical properties of boiling point and
saturated vapor pressure are very similar to
Halothane, so the vaporizer design is also closely
related.

6. Effects on organ systems

7. Cardiovascular:
• Minimal left ventricular depression.
• SVR ↓↓
• B.P ↓↓
• H.R ↑
• Coronary vasodilation → steal (diversion of
coronary blood away from fixed stenosis).
• COP : no change.

8. Respiratory:
• As Halothane, except in less tachypnea.
( Net result more ↓ in Vm.)
• Even 0.1 MAC can blunt the normal
ventilatory drive.
• Irritation to upper airway, increases bronchial
secretions and salivary secretions.
2 MAC → irritation at 50% of patients.
• Good bronchodilator but < Halothane.

9. Cerebral:
• CBF ↑
• ICP ↑
• CMRO2 ↓↓
The CBF & ICP increased by > 1 MAC less than
Halothane & can be reversed by
hyperventilation.
• At 2 MAC → silent EEG.
• Anesthesia, no analgesia, not epileptogenic.

10. Neuromuscular: more than Halothane & can
relax skeletal muscle.
Renal: same as Halothane: RBF ↓ , GFR ↓,
UOP ↓.

11. Liver:
• HBF ↓ ( Hepatic O2 supply is better maintained
than with Halothane & LFTs usually not affected).
• Safe for Liver & Kidneys functions.

12. Contraindications:
• Non absolute.
• Hypovolemia.
• It can trigger malignant hyperthermia.

13. Drug Interaction:
• Epinephrine safe up to 4.5 mcg/kg.
> 1.5 mcg/kg should be avoided with Halothane.
• Non depolarizing NMBA ↑↑↑ by Isoflurane.
Metabolism:
Primarily via lungs, 0.2% in the liver.

14. Sevoflurane (Ultane) 1990

15. General Description:
• Sweet.
• Excellent choice for smooth & rapid inhalational
induction in pediatrics & adults.
• MAC = 2.0
• Blood/Gas: 0.69, Oil/Gas: 53
Blood/Gas: 1.43, Oil/ Gas: 91 for Isoflurane.
• Color code: yellow.

16. • No preservative, supplied in brown plastic
bottles.
• Boiling point: 58.6 ℃, SVP:21.3 mmHg.
48.5℃ SVP: 31.9 mmHg for Isoflurane.
• Soda lime: compatible but may produce
Compound A.

17. Effects on organ systems

18. Cardiovascular:
• Myocardium contractility mildly ↓.
• B.P ↓.
• SVR ↓.
• HR: no change or little ↑ → COP ↓ or
maintained.
• Coronary vasodilatation < Isoflurane.
• QT interval prolongation even 60 minute
following emergence.
• No myocardial sensitization to catecholamine.

19. Respiratory:
• Vt ↓.
• RR ↑.
• Bronchodilator like Isoflurane.
• No airway irritation.

20. CNS:
• Anesthesia, no analgesia, not epileptogenic.
• Slight ↑ in CBF & ICP but < Isoflurane.
• 1.5 MAC impair auto regulation.
• CMRO2 ↓.

21. Neuromuscular:
• Adequate M.R for intubation of a child !!.
• NMBA (non depolarizing) ↑↑.
Renal: RBF↓, GFR↓ , UOP↓.

22. • A plasma fluoride ion concentration of 50
micromole/L is quoted as the threshold for
renal toxicity , Sevoflurane metabolism can
produce levels above this threshold, yet
clinically significant renal dysfunction has not
been associated with sevoflurane anesthesia.

23. • Alkali such as barium hydroxide lime or soda
lime (but not calcium hydroxide) can degrade
sevoflurane producing another proven ( at
least in rats) nephrotoxic end product
(compound A), accumulation of compound A
increases with increased respiratory gas
temperature, low flow anesthesia, dry barium
hydroxide absorbent (baralyme), high
sevoflorane concentrations, and anesthetics of
long duration.

24. Liver:
• Venous ↓ , Arterial ↑ : maintained Blood
supply or mildly ↓.
• No immune- mediated hepatotoxicity.
• Safe for liver & kidneys.
• Uterus: uterine relaxation in pregnancy similar
to isoflurane.

25. Contraindications:
• Sever hypovolemia.
• History of Malignant hyperthermia.
• I.C. hypertension.

26. Drug interaction:
not sensitize the heart to catecholamine.
Metabolism:
predominantly via the lungs, 5% only
metabolized by the liver.