All details about N2O and Halothane volatile anesthetic, their physical properties , their anesthetic effect on human body systems, also the indications and the history, the complications and contraindications, the metabolism.
How supplied ? Types of vaporizers, old and modern.
2. Nitrous Oxide (N2O), Laugh Gas
• Clear, colorless, non explosive , non flammable.
• Supplied by pipeline or pressurized cylinders.
• Boiling point -89ċ.
• Gas at room temperature.
• ≈ 5 times more rapid diffusion than N2.
• Inexpensive.!!
3. • Safe ?, weak anesthetic but good analgesic.
• No toxicity to Heart, Liver, Kidneys.
• Prolong exposure to N2O → bone marrow
depression (megaloblastic anemia) &
peripheral neuropathies.
• Teratogenic after long term uses.
• MAC = 105
5. Cardiovascular:
• Minimal tendency to
sympathetic stimulation.
• Myocardial depression:
caution in IHD & sever hypovolemia.
• B.P, COP & HR unchanged or slightly
increased.
6. Respiratory:
• RR ↑
• Vt ↓
• Vm (-)
• Diffusional hypoxia during recovery d.t
elimination of N2O via alveolus is so rapid, this
hypoxia can be prevented by administration of
100% O2 for 5-10 minute after discontinuing
N2O.
7. Cerebral:
• CBF ↑,CBV↑,ICP↑(mild), CMRO2 ↑.
Renal:
• GFR ↓ ,UOP ↓.
Liver:
• HBF ↓ < other volatile Anesthetics.
Gastrointestinal:
• PONV ↑
Neuromuscular:
• ↑ potency of non depolarizing NMBA.
9. • Metabolism: 0.004%.
• 70% nitrous oxide for >2hours have
been shown to have more postoperative
complications: atelectasis, fever, pneumonia,
and wound infections.
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11. General Description:
• Non flammable.
• Non explosive.
• Potent anesthetic.
• Induction is pleasant.
• Recovery delayed.
• Shivering is common.
12. • Malignant hyperthermia & hepatitis ?
• Rarely used nowadays.
• MAC = 0.75
• Blood/ Gas: 2.3, Oil/ Gas: 224
• Boiling point 50.2℃, SVP 32.5 mmHg.
• Color code: red.
• Clear, colorless liquid in brown glass bottle.
13. • 0.1% Thymol as preservative to protect against
decomposition by light.
• The Thymol preservative does not readily
evaporate, and therefore builds up in the
vaporizer, which requires drainage and
cleaning at regular intervals.
14. • Slightly water soluble.
• Soda lime: compatible.
• Halothane may corrode or tarnish most metals:
with the exception of chromium , nickel and
titanium; Halothane attacks aluminum, tin, lead,
magnesium, brass and solder alloys in the presence
of water; this contact causes rubber and some
plastic materials to deteriorate rapidly.
15.
16. • Suitable vaporizer:
Old design: Goldman vaporizers.
• Designed by an English physician Dr. Victor Goldman
(1903b. – 1994d). tow models: 1956 - 1962.
Modern and New design:
a specifically calibrated plenum vaporizers e.g:
(TEC3,4,5&7, Dräger Vapor, Penlon, Blease).
The term plenum= pressurized chamber in which the
FGF is above atmospheric pressure.
40. Liver:
• HBF↓↓.
• Halothane hepatitis:
Extremely rare (1 : 35000).
Multiple exposure at short interval.
Middle age obese females.
Family history.
Personal history.
Avoidance??
42. Contraindications:
• History of unexplained liver dysfunction,
jaundice following prior administration.
• Risk of triggering malignant hyperthermia.
• With caution in neurosurgical procedure d.t ↑
ICP or ↑ CBF.
• Hypovolemic patient or sever left ventricular
failure.
• With exogenous epinephrine or with pheochrom-
ocytoma.