gas notes 1 Flashcards
dantrolene
the only drug that treats malignant hyperthermia
mallampati score
ASA classification for patient fitness for surgery
six classes:
What does the American Society of Anesthesiologists Classification (ASA) describe?
A patient’s fitness for surgery
The ASA classification helps in assessing surgical risk.
What is the definition of ASA Class I?
A normal healthy patient
Healthy, non-smoking, fit patient.
What characterizes ASA Class II?
A patient with mild systemic disease
BMI 30-40, smoking, perhaps a well-controlled ‘lifestyle’ disease with no functional impact.
What defines ASA Class III?
A patient with severe systemic disease
BMI > 40, severe functional limitation from poorly-controlled disease.
What is the definition of ASA Class IV?
A patient with severe disease that is a constant threat to life
Currently failing organs (heart, lungs, kidneys) but doesn’t need this surgery to survive.
What does ASA Class V refer to?
A moribund patient who would not survive without surgery
This class indicates critical condition requiring immediate intervention.
What is the definition of ASA Class VI?
A brain-dead patient who is an organ donor
This classification is used for patients who have lost all brain function.
Fill in the blank: ASA Class I is for a _______.
normal healthy patient
This class represents the lowest surgical risk.
True or False: ASA Class IV patients require surgery to survive.
False
ASA Class IV patients do not need the surgery to survive.
common risks of anaesthesia
sore throat
drowsiness
headache
nausea and vomiting
rare risks of anaesthesia
dental injury
emergence delirium
aspiration pneumonia
awareness
life threatening risks of anaesthesia
anaphylaxis
death
how long do patients have to fast
eight hours for solids and two hours for clear fluids
triad of anaesthesia
amnesia, analgesia and muscle relaxation
pre oxygenation
After induction, patients will have a period of apnoea. To extend the safe apnoeic time, we pre-oxygenate patients with 100% O2 to replace the nitrogen-rich air in their lungs.
Once apnoeic, that extra oxygen continues to diffuse across the alveolar membrane and maintains oxygenation for about four times longer than normal air.
A patient is sufficiently pre-oxygenated when
the expired concentration of oxygen is greater than 80% (i.e. FetO2 ≥ 0.8).
What is the purpose of paralysis in intubation?
To facilitate intubation and to avoid awareness during surgery
Awareness refers to the experience of being awake but unable to move or breathe.
When should paralysis occur in relation to anesthesia?
After patients have fallen asleep
This timing is crucial to prevent awareness.
What is the onset time for Rocuronium?
90 s
What is the duration of action for Vecuronium?
30 min
What is the onset time for Suxamethonium?
30 s
What is the duration of action for Cisatracurium?
40 min
True or False: Vecuronium has a longer onset time than Rocuronium.
True
What is the onset time for Vecuronium?
3 min
List the four muscle relaxants routinely used in Australia.
- Suxamethonium
- Rocuronium
- Vecuronium
- Cisatracurium
How is bronchospasm managed during anaesthesia?
Inhaled bronchodilators
Inhaled bronchodilators are used similarly to how they are used in awake patients.
Name three inhaled bronchodilators used to manage bronchospasm.
- Salbutamol
- Terbutaline
- Ipratropium
These medications help to relax and open the airways.
What should be done if inhaled therapy for bronchospasm is not effective?
Switch to IV therapy
IV therapy is indicated when inhaled medications do not relieve bronchospasm.
Name two intravenous therapies that can be used for bronchospasm management.
- Aminophylline
- MgSO4
- Ketamine
These medications can be administered intravenously if inhaled therapies fail.
True or False: Wheeze should be treated without considering its trigger.
False
It is important to identify the trigger of wheeze before treatment.
What are common triggers of bronchospasm during anaesthesia?
- Volatile agents
- Anaphylaxis
- Asthma
- Respiratory infections
These factors can provoke bronchospasm, especially in sensitive individuals.
Fill in the blank: Kids with _______ infections are known to bronchospasm with minimal provocation.
respiratory
This highlights the sensitivity of children to bronchospasm when they have respiratory infections.
what causes hypotension and bradycardia?
Hypotension with bradycardia is usually related to an oversized discharge of acetylcholine from the parasympathetic nervous system.
Which types of surgery are especially likely to trigger acetylcholine discharge?
Surgery of the abdomen and cervix are especially likely to trigger such a discharge.
What is the solution for hypotension with bradycardia?
The solution is to give atropine or glycopyrrolate.
What do atropine and glycopyrrolate do?
They antagonise the muscarinic acetylcholine receptor.
Fill in the blank: Hypotension with bradycardia is usually related to an oversized discharge of _______ from the parasympathetic nervous system.
acetylcholine
True or False: Surgery of the abdomen and cervix can trigger bradycardia.
True
name three volatile agents
sevoflurane
desflurane
nitrous oxide
What does MAC stand for?
Minimum alveolar concentration
MAC is pronounced “mack” and refers to the concentration of anaesthetic agent needed to produce immobility in 50% of subjects.
What is the definition of MAC?
The end-tidal concentration of anaesthetic agent (in %) that produces immobility in 50% of healthy middle-aged men when a one centimetre incision is made in their forearm.
What does a higher MAC indicate about an anaesthetic agent’s potency?
Less potent anaesthetic
More is needed for the same effect.
What does a lower MAC indicate about an anaesthetic agent’s potency?
More potent anaesthetic
Less is needed for the same effect.
What is the MAC of Sevoflurane?
1.8%
What is the MAC of Desflurane?
5%
What is the MAC of Nitrous oxide?
105%
Indicates that a very high concentration is required for immobility.
What does MAC technically represent?
Blunting of the spinal cord reflexes
It does not indicate a lack of awareness.
At what percentage of an agent’s MAC is awareness virtually unheard-of?
More than 70%
If you run half a MAC of nitrous oxide and half a MAC of sevoflurane, what will be the result?
Achieve the same depth of anaesthesia as the full MAC of either agent.
What is total intravenous anaesthesia commonly abbreviated as?
TIVA
What type of infusion is primarily used in TIVA?
Propofol target-controlled infusion (TCI)
List three pros of using propofol in TIVA.
- Anti-emetic effects
- Smoother emergence
- No direct greenhouse gas emissions
List two cons of TIVA.
- Patient wakes up (paralysed) if the cannula breaks
- No way to measure blood concentration
What is a significant environmental benefit of TIVA?
Less occupational exposure to fluranes
