Perioperative anaelgesia

Question 1

What’s anaesthesia triad?

Answer 1

• muscle relaxation
• anaesthesia
• hypnosis

Question 2

Analgesic ladder

Answer 2

Question 3

What drugs are used to provide intra-operative analgesia?

Answer 3

Stages 2 and 3 are most commonly used to provide intraoperative analgesia

• Stage 2 e.g. diclofenac or ibuprofen
• Stage 3 e.g. morphine or fentanyl

Question 4

Is simple analgesia of any use in the provision of analgesia during surgery?

Answer 4

Simple analgesics, such as paracetamol, and NSAIDs, such as diclofenac and ibuprofen, may provide sufficient analgesia for short, day-case analgesia, sometimes in combination with local anaesthesia

Question 5

What’s the most commonly used intraoperative analgesia for more painful surgery?

Answer 5

Opioid → Fentanyl

It is useful to combine simple analgesics and NSAIDs with fentanyl to reduce the total dose of opioid required, and provide a degree of postoperative analgesia, as well as to limit unwanted effects of opioids

Question 6

What happens to the opioid dose requirement if local or regional anaesthesia is used?

Answer 6

The opioid requirements will be markedly reduced

Question 7

What’s the difference between ‘opiate’ and ‘opioid’?

Answer 7

Opiate → naturally-occurring opioid e.g. morphine

Opioid → synthetic drugs e.g. fentanyl

Question 8

How are syringes containing opioid drug identified?

Answer 8

By blue labels

Question 9

What’s more potent: morphine or fentanyl?

Answer 9

Fentanyl is about 100 times more potent than morphine

Question 10

When an initial dose of Fentanyl is given (in terms of surgery)?

Answer 10

At induction because:

• it takes 5 mins to be effective
• it reduces the response to laryngoscopy

(if endotracheal intubation is planned)

Question 11

How long does Fentanyl analgesic effect last?

Answer 11

15-30 minutes in usual doses (50-100 µg intraoperatively)

* it may be repeated (depending on the duration of surgery, analgesic plan, painful surgical stimulation)

Question 12

Where is fentanyl metabolised?

Answer 12

in the liver

Question 13

Side effects of fentanyl

- intraoperative

• post-operative

Answer 13

Intraoperative:

• bradycardia
• fall in BP
• respiratory depression (due to a reduction in respiratory rate)

Postoperative:

• nausea and vomiting
• urinary retention
• constipation and itching

Question 14

When and how to use morphine + fentanyl in combination?

Answer 14

• Morphine has a slower onset time than fentanyl
• It is more common to use fentanyl initially
• then use morphine intraoperatively if further analgesia is required, particularly if severe pain is anticipated in the early postoperative phase in recovery

Question 15

How long does analgesic effect of morphine last?

Answer 15

For the usual intraoperative dose of morphine (2-5 mg bolus) it last 30-40 min

*repeated-dose usually needed

Question 16

Can we give morphine 10 minutes before surgery ending?

Answer 16

The longer onset time to peak effects means that the timing of intraoperative morphine requires to care

if given within 10 min of surgery ending → respiratory depression may slow recovery

*In a surgery that is anticipated to be very painful postoperatively, an intravenous bolus dose of morphine of 0.1-0.15 mg/kg can be given about 45 min before the end of surgery.

Question 17

Where does the metabolism of morphine occur?

Answer 17

In the liver

Question 18

What’s morphine-6-glucuronide?

Answer 18

• an active metabolite of morphine
• it is more potent than morphine
• it is only important in patients with renal failure who receive repeated doses of morphine

Question 19

Side effects of morphine

Answer 19

• bradycardia
• fall in BP
• Respiratory depression
• Nausea and vomiting postoperatively
• Urinary retention
• Constipation
• Itching

*Morphine can also cause histamine release; in asthmatics bronchospasm may be triggered

Question 20

How can Diclofenac be given intraoperatively?

Answer 20

IV or suppository

(consent must be gained for suppository)

Question 21

Can we combine NSAIDs + Paracetamol + Fentanyl?

Answer 21

It is useful to combine NSAIDs with paracetamol and fentanyl in theatre, since the NSAIDs have a further opioid-sparing effect that not only allows less fentanyl to be used, but also reduces the postoperative opioid requirements by 20-30%

Question 22

How can Paracetamol be given intraoperatively?

Answer 22

IV or suppository

Usually 1g for an adult person

Question 23

How does IV Paracetamol should be given?

Answer 23

the vial contains 1 g of paracetamol as a solution in 100 ml; this should be given intravenously over about 20 min

Question 24

When should suppository Diclofenac or Paracetamol be given?

Answer 24

It should be placed per rectum after induction of anaesthesia and before surgery starts to allow time for absorption

Question 25

Do we prefer to give intraoperative simple analgesia by IV or suppository routes?

Answer 25

The rectal route is less reliable than the intravenous route for drug administration, but is sometimes preferred for very short duration surgery

Question 26

Do we need to repeat paracetamol dose intraoperatively?

Answer 26

The duration of action of paracetamol is much longer than for the intravenous opioids; a repeat dose is rarely used unless surgery takes more than 6 h.

Question 27

Contraindications to Ibuprofen use

Answer 27

• Previous or existing upper GI ulcers
• Avoid in asthmatics who are intolerant of aspirin
• Use with care in patients with renal impairment

Question 28

Side effects of Ibuprofen

Answer 28

The most common side-effects are upper GI tract bleeding and inhibition of platelet aggregation.

Question 29

Contraindications to Diclofenac use

Answer 29

• Previous or existing upper GI ulcers
• Avoid in asthmatics who are intolerant of aspirin
• Use with care in patients with renal impairment
• Porphyria

Question 30

Side effects of Diclofenac

Answer 30

Like ibuprofen, the most common side-effects of diclofenac are upper GI tract bleeding and inhibition of platelet aggregation

Question 31

How often morphine could be administrated to a patient on patient-controlled analgesia (PCA) device?

Answer 31

• 1-2 mg (whichever is preset by the anaesthetist) to be given on demand with a 5 min lockout period

*The lockout period may be set by the anaesthetist and is to prevent overdose, which carries the risk of respiratory depression

* Close and charted observation is required if PCA is prescribed

Question 32

Can strong opioids be used in day cases?

Answer 32

NO

If NSAIDs are not tolerated and it is anticipated that a stronger analgesic than paracetamol is needed, then codeine phosphate may be prescribed for a limited period: usually enough for 72 h. The dose of codeine phosphate is 30-60 mg every 4 h