Inhalational Induction Agents

Terms in this set (30)

Stages of Anaesthesia
1. Analgesia
2. Disinhibition
3. Surgical anaesthesia
4. Medullary depression
General Ion Channels Acted on by Inhalational Agents
K-activated
Na-blocked

GABA and NMDA receptors
Relationship Between Blood Flow and Induction Rate
Inverse
Define MAC
The alveolar concentration of the agent at 1 atm needed to abolish movements in 50% of patients in response to a noxious stimuli
Factors That Decrease MAC Value
Increasing Age
N2O
Sedatives
Acute alcohol intoxication
Hypotension
Hypothermia
Myxoedema
Factors That Increase MAC Value
Decreasing Age
Chronic alcohol ingestion
Sedative addiction
Thyrotoxicosis
Sympatho-adrenal stimulation
MAC of Isoflurane
1.2
MAC of Sevoflurane
1.7
MAC of Halothane
0.75
B/G of Halothane
2.3
B/G of Isoflurane
1.4
B/G of Sevoflurane
0.69
Factors Affecting Induction Speed
Alveolar conc
Flow in breathing circuit
Minute ventilation
B/G coefficient
CO
Systemic Effects of Ether
Increased HR (catecholamines)
Normal BP
Bronchodilation
Resp depression
Increased GI secretions
Increased blood sugar
Muscle relaxation
Systemic Effects of Halothane
Reduced BP
Dysrhythmogenic
Catecholamine sensitisation
Increased ICP, CBF
Bronchodilation
Decreased tidal volume
Increased Resp rate
Post op shivering
Relaxes uterus (more bleed)
Presentation of Halothane Hepatitis
Deranged LFT
Jaundice (3-10 days after exposure)
Risk Factors for Halothane Hepatitis
Multiple exposures
Female
Obesity
Middle age

Do not re-expose within 3 months
Advantages of Halothane
Pleasant and non-irritating
Minimal secretions
Bronchodilator
Non-emetic
non-flammable
Disadvantages of Halothane
Very potent/ Easy overdose
Arryhthmia
Hepatotoxic
Post-op shivering
Advantages of Enflurane
Pleasant smell
Less mycardial depression
Used in obstetrics
Disadvantages of Enflurane
Resp depression
Epileptiform activity
Systemic Effects of Isoflurane
Resp depression
Myocardial depression
Hypotension
Coronary steal syndrome
No increase in ICP
Muscle relaxation
Advantages of Isoflurane
Rapid recovery
Minimal hepatotoxicity
No Arrhythmia
Muscle relaxation
Disadvantages of Isoflurane
Pungent
Coronary steal syndrome
What is Desflurane Stored in
Special TEC 6 vapouriser
Effects of Desflurane
Like Isoflurane but no coronary steal and faster recovery
Systemic Effects of Sevoflurane
Resp depression
Bronchodilation
Hypotension
No increase in ICP
Effects of N2O
Diffusion hypoxia
Invasion of body cavities
Contraindications of N2O
Intestinal obstruction
Pneumothorax
Disadvantages of Xenon
Expensive
Needs special equipment
Bronchospasm
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