CNS1 General anaesthesia, local anaesthetic and resucitation

Question 1

Which are the three importand anaestetic drugs?

Answer 1

ether
nirous oxide (Stickstoffoxid)
chloroform

Question 2

What are the preoperative assessment of the patient before applying anaesthetics?

Answer 2

• measurement of blood pressure and heart rate
• check the veins for ease of canulation
• examination of the lungs, including chest X-rays if indicated
• ECG if indicated
• examination of any cartoid bruit
• identification of heart murmurs
• test for heamoglobinopathy as appropiate
• check for impaired mobility of the temporomandibular joints and for rheumatoid arthritis associated mobility problems of the neck
• blood tests, including liver function tests

Question 3

What is premedication (Praemedikation) and why is it necessary?

Answer 3

Premedication is the administration of drugs to patients an hour or two before anaestesia and surgery. The objectives of premedication are:

• relieve anxiety
• reduce the production of saliva
• reduce the volume, and increase the pH, of the gastric content.

Question 4

Name 6 anxiolytic drugs (DE: Anxiolytikum, angstmildernd)

Answer 4

• Temazepam (orally)
• Midazolam (orally)
• Diazepam
• Lorazepam
• Alimemazine (orally)
• opioids such as morphone (just given to patients in pain before surgery)

Question 5

Name 3 drugs which reduce salivary secretion

Answer 5

• atropine (das Atropin, intramuscular injection, also orally given but the dose must be twice as much)
• glycopyrronium (Glycopyrroniumbromid, intravenously)
• hysocine (no longer used because it may cause confusiion and restlessness)

Question 6

Name 3 drugs which reduce the volume and increse the pH of gastric contents

Answer 6

• metoclopramide (DE: Metoclopramid) (orally or intravenously) hastens gastric emptying
• sodium citrate (Natriumcitrat) (orally) raises the pH of gastric content by neutralizing acid in the stomach
• ranitidine (DE: Ranitidin) (orally or intravenously) raises the pH of gastric secretions

Question 7

Explain the properties of nitrous oxid (DE: Distickstoffmonoxid)

Answer 7

weak aneastesia
you have to inhale it
faintly smelling and stored as a liquid
needs to be combined with other analgesic because it is very weak

Anastetic containing nitrous oxid
Entonox

• 50:50 mixture of nitrous oxide and O₂
• used for pain relief in labor, by ambulance crews

Question 8

Which is the most commonly used inhalational anaestetics?

Answer 8

Isoflurane (DE: Isofluran) which belongs to the halogenated hydrocarbons. It has little effext on cardiac output and is associated with a repid recovery from anaestesia.

Question 9

What are the positive sided of opioid analgesics?

Answer 9

• little effect on blood pressure and cardiac output
• short acting
• most commonly used are fentanyl (30 min), alfentanil (10 min), remifentanil (a few minutes)

Question 10

Why do most anaesthetics react as muscle relaxants?

Answer 10

to facilitate intubation of the trachea with an endotrachela tube at the beginning of anaesthesia
to relax muscles sufficiently to make surgery possible (especially in abdominal surgery)
to permit artificial ventilation

Question 11

What is curare (DE: Curare)?

Answer 11

It is a tropical plant in South America and its alkaloid is used as a muscle relaxants.

Question 12

How does a muscle relaxant work on a neuromuscular junction?

Answer 12

Muscle relaxants act at the neuromuscular junction by blocking the transmission of nerve impulses from the nerve to the muscle.

Question 13

Name the 2 groups of muscle relaxants which are competitive /non-depolarizing blockers

Answer 13

Aminosteroid group: pancuronium, rocuronium, vecuronium

Benzylisoquinolinium group: atracurium, cisatracurium, gallamine, mivacurium

Question 14

What is suxamethonium?

Answer 14

It is a depolarizing muscle relaxant. It occupies the receptor sites for acetylcholine and initially stimulates the muscle into contracting, visible twitching or fasciculation that occurs almost immediately after it is injected.

Special points:

• quick onset of action, ca. 60 seconds, it is used in patients who may have full stomachs in whom rapid tracheal intubation is indicated
• short duration of action, ca. 5-10min
• rapidly broken down
• side effect is muscle pain

Question 15

How can the effect of muscle relaxants be reversed?

Answer 15

By using anticholinesterase. Anicholinesterase act at the neuromuscular junction, where they temporarily inhibit the enzyme cholinesterase, which normally breaks down
acetylcholine, and allow the concentration of acetylcholine to rise and so help the return of normal neuromuscular transimission mucle strength. But anticholinesterase is associated with the following side effect:

• increseof salivation and tracheobronchial secretions
• bradycardia
• increase if peristaltic activity in the gut→diarrhoea

Those side effects can be prevented by administering neostigmine, edrophonium.

Question 16

Why are anticholinergic drugs used?

Answer 16

They are used during anaesthesia and have the follwing effect:

• to increase pulse rate
• to reduce tracheobronchial and salivary secretion
• to prevent the increase of peristaltic activity

How they work: block the affects of acetylcholine, particularly at postganglionic parasympathetic nerve endings.

Drugs: Atropine, Glycopyrronium