Case 10 - General Anaesthesia Flashcards
1
Q
- What are the purposes of anaesthesia?
A
- Analgesia
- Amnesia
- Immobility
- Unconsciousness
- Skeletal muscle relaxation
2
Q
1. Define the following:
- Analgesia
- Amnesia
- Immobility
A
- Loss of response to pain
- Loss of memory
- Loss of consciousness
3
Q
- What are the 3 stages of anaesthesia?
- Which has a quicker onset, IV or inhalation?
A
- Induction, Maintenance, and Reversal
- IV injection
4
Q
- Why is the maintenance phase required?
- What form of anaesthesia is used for this?
A
- The induction phase is short lived and so drugs are required to prolong the anaesthesia
- Inhalation agents
5
Q
- When does recovery of consciousness happen?
- What is used to induce paralysis?
A
- When the concentration of anaesthetic in the brain drops below a certain level
- Neuromuscular blocker to provide temporary muscle relaxation
6
Q
- What procedure are muscle relaxants necessary for?
- What NT do muscle relaxants inhibit?
A
- Endotracheal intubation
- ACh
7
Q
- What class of drugs are these?
(Muscle relaxants, Inhalation agent, IV agent)
- Atacurium
- Suxamethonium
- Curare
- Propofol
- Etiomidate
- Ketamine
- Sodium thiopentone
- Isoflurane
A
- Muscle relaxants (Atacurium, Suxamethonium, Curare)
- Inhalation agent (Propofol, Isoflurane)
- IV agent (Propofol, Ketamine, Etiomidate)
8
Q
- Why is artificial respiration required?
- Why is an endotracheal tube required?
A
- Because muscle relaxants cause paralysis of muscles of respiration, meaning artificial respiration is required
- Because the muscles of the larynx are paralysed so the airway needs to be kept open
9
Q
- What drugs are used to reverse muscle relaxant drugs?
- What is the final stage of anaesthesia?
A
- Acetylcholinesterase drugs
- Reversal
10
Q
- What would respiratory depression lead to?
- What would happen if the patient respired on room air?
A
- Increase in CO2 levels - Hypercapnia
- They would become hypoxic
11
Q
- What is the effect of high lipid solubility?
- Why does this happen?
A
- Accumulate in body fat and can produce a prolonged hangover
- Due to low blood flow to adipose tissue, so can take hours for the drug to enter and leave the fat
12
Q
- What is the difference between sleep and unconsciousness?
- What causes the change from sleep to wakefulness?
A
- You can wake up from sleep voluntarily
- Reticular activating system
13
Q
- What causes the change from wakefulness to sleep?
- What determines the circadian rhythm?
A
- Inhibition of arousal, through blockage of the thalamus and upper brainstem
- Detection of decreases in light levels as night approaches
14
Q
- What do the ganglion cells responsible contain?
- Which tract is responsible for circadian control?
A
- Melanopsin which depolarises to light
- Retino-hypothalamic tract
15
Q
- What cycle is the majority of time spent in during sleep?
- What induces non-REM sleep?
A
- Non-REM sleep
- Non-REM ON GABA neurons in the hypothalamus & Serotonin in the raphe nuclei
16
Q
- What is shown on an EEG during non-REM sleep?
- What happens to muscles during non-REM sleep
A
- Brainstem noradrenergic neurons show decreased activity
- Skeletal muscles relax but maintain tone
17
Q
- What is a concussion?
- What is a coma?
A
- Reversible state of unconsciousness that lasts for a brief amount of time. Without pathological alteration
- Profound state of unconsciousness associated with depressed cerebral activity
18
Q
- What is a generalised seizure?
- What is a partial seizure?
A
- Overactivity in the brain which is across the entire cerebral cortex of both hemispheres
- Overactivity which involves only a limited area of the cortex
19
Q
- What is epilepsy?
A
- When a person has repeated seizures
20
Q
- What do anticonvulsants do?
A
- Potentiate GABA channels therefore hyperpolarising neurons
21
Q
- What is the preferred treatment for elevated ICP?
A
- Intubation, hyperventilation leading to vasoconstriction caused by the lack of O2 and a reduction in cerebral blood volume
22
Q
- What is a craniotomy?
- What is a craniostomy?
A
- Surgical removal of part of the cranium to relieve intracranial pressure
- Where a Burr hole is drilled at several locations to relieve pressure
23
Q
- What is the GCS?
- What are the components?
- What do the following scores show?
- Less than 8
- 9-12
- Greater than 13
A
- Used to assess consciousness
- Test E (4) V (5) M (6)
- Severe- GCS≤8
Moderate - GCS 9 - 12
Minor - GCS ≥ 13.
24
Q
- What are coup v Contracoup lesions?
A
- Contusions and deeper hemorrhages result from mechanical forces that displace and compress the hemispheres forcefully and by deceleration of the brain against the inner skull, either under a point of impact (coup lesion) or, as the brain swings back, in the antipolar area (contrecoup lesion)
25
Q
- What is the normal pH?
A
- 7.35 - 7.45
26
Q
- What is the normal pCO2 level? (In KPa and mmHg)
A
- 4.7 - 6 KPa or 35-45mmHg
27
Q
- What is the normal pO2 level?
A
- 9.3-13.3 kPa / 80-100 mmHg
28
Q
- What is HCO3-?
- What is the normal HCO3- level?
A
- Bicarbonate
- 22-28 mmol/L
29
Q
- What is the normal O2 saturation?
A
- 92-98% saturation
