IAA Flashcards
What is MAC?
Minimum alveolar concentration- where 50% of the patients do not respond to painful stimulus
What is MAC awake?
It is a third of MAC and the patient starts to wake up but is still in sleep
What is MAC Bar?
It stands for Minimum alveolar concentration that blocks autonomic response- so things like pupil dilation,heart rate and blood pressure
What factors decreases MAC?
- shock
- pregnancy
- acute alcohol intoxication
- Elderly
- low body temperature
What factors increases MAC?
- chronic alcohol intoxication
- ephedrine
- cocaine
- acute amphetamine
What receptor does N20 work at and what does it do?
It works at NMDA and it inhibits it
Where do the 4 IAA work on?
GABA A receptor and it increases it
What is a medical metabolism condition that halothane is assciated with?
Hepatitis because 15-20% of it is metabolised in the liver
What is the effect of halothane on the cardiovascular system?
-Decreases BP
-Decreased CO
-Decreased Heart Rate
which leads to hypercarbia and evidently ventricular extra systoles (VES)
What is the MAC of halothane?
0,75 which means it is the most potent of all the IAA drugs
What can we use halothane for when it comes to bronchospasm?
It can be used as a potent bronchodilator
Which IAA smells noxious?
isoflurane
What is the MAC of isoflurane?
1,15
Which IAA do we prefer for liver and neurosurgery?
Isoflurane
What is the MAC of sevoflurane?
2
Which IAA smells the best?
sevoflurane
Why is sevoflurane faster for the pt to wake up?
Because the blood gas ratio is 0,65 which means it is not very soluble in the blood and so we can reverse it easily
What about sevoflurane makes it nephrotoxic?
Potential to have compound A in rats which is nephrotoxic
Why is desflurane not recommended for inhaled induction?
It causes severe laryngospasm and coughing and possible increase in airway resistance
What is the effect of halothane, isoflurane and sevoflurane on the respiratory system?
It causes bronchodilation
Properties of N20 that are positve?
- It is a drug used concurrently with other IAA
- has a fast wash in and wash out mechanism(so has low solubility)
- analgesic
Disadvantages of N20?
- mac 105%
- hypoxic diffusion
- suppresses vitamin B12
- Expands air filled spaces(cannot use in pneumothorax)
What are some basic influences of the alveolar concentration?
- Fresh Gas Flow
- Inspiratory fraction of the inhalational agent
- alveolar minute ventilation
What would cause a decrease in the alveolar inhalational agent concentration?
- Cardiac output- a increase in co means that blood flows past the alveolar more
- solubility of the IAA
- Mixed venous concentration IAA
