Premedication

Question 1

Give two examples of benzodiazepines used for premedication to allay anxiety

Answer 1

Temazepam

Lorazepam

Question 2

Which benzodiazepines should be avoided in short operations and why?

Answer 2

Long acting benzodiazepines

Question 3

List the short acting benzodiazepines with elimination of half life < 5 hours

Answer 3

"ATOM" mnemonic - atoms are small = short half life
Alprazolam 
Triazolam
Oxazempam
Midazolam

Question 4

List the intermediate acting benzodiazepines with elimination half life 5 - 24 hours

Answer 4

Good for premedication therefore = “tendor loving care” for patient before surgery to allay anxiety: TLC

Temazepam
Lorazepam
Clonazepam

Question 5

List the long acting benzodiazepines with an elimination half life of > 24 hours

Answer 5

FCCD - Patient will be ‘fccd’ during recovery if this is given prior to a short operation

Chlorazepate
Chlordiazepoxide
Diazepam
Flurazepam

Question 6

List the benzodiazpines that are safe to use in liver failure

Answer 6

“OTL” = Out The Liver

Oxazepam
Temazepam
Lorazepam

Question 7

What effects does temazepam have on the CVS and RSP and the excretion

Answer 7

No significant effect on CVS
Only depresses RSP at higher doses

Some metabolism in the lover and mainly excreted in the urine

Question 8

What the usual dose of temazepam?

Answer 8

10 -20 mg (similar to the night time dose for its common clinical use to aid sleep)

Question 9

What is the usual premedication dose of Lorazepam?

Answer 9

1 - 2 mg

Question 10

What are the goals of premedication in reflux disease?

Answer 10

Increased gastric pH
Reduced gastric volume

However, RSI will be used, so premedication is not mandatory

Normal continuation of PPI/H2 receptor antagonist

Question 11

Which medications can be considered to reduce the risk of acid aspiration? Give a brief description of each

Answer 11

Antacids - raise pH but no change to volume and short DOA not valuable at the end of the anaesthetic. Sodium citrate is regularly used nowadays, particularly in the obstetric setting

PPIs/H2RA - raise ph, decrease gastric volume. Omeprazole 20mg. Ranitidine 150mg. (also protect against S/E of NSAIDS)

Metoclopramide - increases gastric emptying

• antiemetic
• reduce transit time for drugs to reach small intestine where they are absorbed - speeding onset of action

Question 12

What is the aim of administering analgaesic premedication

Answer 12

Usually used in the Day surgery setting

Achieve effective concentrations of analgaesic agents prior to the end of the operation, in order to optimize pain control in the recovery phase.

Question 13

When should paracetamol be given as a premedication

Answer 13

In all patient, unless specifically contraindicated. More effective when combined with a weak opioid

Question 14

What is the mechanism for NSAIDS

Answer 14

Metabolism of membrane phospholipids form arachidonic acid which is metabolized by the enzyme cyclo-oxygenase to form cyclic endoperoxidases which are used to produce various substances in various places

1. Platelets - TXA2
2. Vascular endothelium - PGI2 (prostacyclin)
3. Widespread - PGF2, PGF2a, PGD2

Prostaglandins protect the stomach and the kidneys.

NSAIDS inhibit Cyclo-oxygenase

1. Anti-inflammatory
2. Protective effect on kidneys and stomach lost

Question 15

Why is LMWH preferred over unfractionated heparin?

Answer 15

1. Once daily dose
2. Lower risk of thrombocytopaenia
3. No monitoring required

Question 16

How is preoperative LMWH prescribed for premedication

Answer 16

Low risk - no enoxaparin

Moderate risk - 20 mg enoxaparin 1-2 hours before surgery then 20 mg OD

High risk - 40 mg enoxaparin the night before and the 40mg OD

Question 17

What is the potential conflict between the use of LMWH and neuraxial blockade

Answer 17

Spinal/epidural anaesthesia is contraindicated within 10 hours of a dose of LMWH –> prevent the rare complication of epidural hematoma

Question 18

Name the medications that should be stopped prior to surgery

Answer 18

ACE I / ARBs
Warfarin
Clopidogrel
Oral contraceptive

Question 19

When and why should ACE I / ARBs be stopped preoperatively

Answer 19

Omitted on the day of the surgery.
Cause PROFOUND HYPOTENSION during general anaesthesia

All other antihypertensives and antianginal medication should be taken as usual

Question 20

When and why should warfarin be stopped preoperatively?

Answer 20

Stop this 5-7 days prior to surgery to allow normalization of INR.

Either unfractionated heparin or LMWH should be used depending on the patient specific context and on discussion with the surgeon

Question 21

When and why should clopidogrel be stopped preoperatively?

Answer 21

7 days prior to neuraxial blockade

However, this should be considered with the patient specific context in mind: keeping cardiac stents patent and preventing stroke perioperative bleeding

Question 22

When and why should oral contraceptive pills be discontinued preoperatively?

Answer 22

6 weeks prior to surgery (ideally)

Risk/benefits should be discussed with each individual patient

Question 23

How should a type 1 DM patient be managed the night and morning prior to the surgery

Answer 23

Starved as per normal protocols

Omission of morning insulin

Question 24

Name the two approaches used to maintain stable glucose levels in a type 1 insulin dependent diabetic

Answer 24

APPROACH 1
1. Variable rate IV insulin infusion 50U actrapid in 50ml 0.9% NaCl (hourly Hgt with sliding scale for insulin rate)

2. Separate dextrose (500 ml of 5%) with KCl (1g) at 100ml/hr

APPROACH 2 (Alberti regimen)
2. Dextrose (500ml of 10%) + KCl (1g) + Actrapid 10 Units (2 hourly measurement Hgt and potassium

BE FAMILIAR WITH LOCAL PROTOCOL

Question 25

How should a type 2 diabetic patient be manage the day prior and the morning before surgery?

Answer 25

Starved
Omit morning dose of oral hypoglycaemic

(ideally long acting hypoglycaemics should be converted to short acting hypoglycaemics a week before surgery)

RISK to PATIENT IS HYPOGLYCAEMIA especially after overnight fasts

MINOR SURGERY - no further action if Hgt well controlled
If MAJOR SURGERY or if poor control –> insulin sliding scale with regular blood sugar measurements

Question 26

How should blood glucose be managed in a type 2 DM patient for minor surgery

Answer 26

Change long acting hypoglycaemic to short acting agent a week before surgery (risk to patient is hypoglycaemia)

Starve patient and omit hypoglycaemic agent on the day of surgery.

No further action if Hgt stable and within normal range

Question 27

How should blood glucose be managed in type 2 DM patient for major surgery or for minor surgery with poor glycaemic control

Answer 27

Insulin sliding scale with regular glucose and potassium measurements

Question 28

Name two short acting hypoglycaemic agents

Answer 28

Gliclazide

Repaglinide

Question 29

Name four long acting oral hypoglycaemic agents

Answer 29

Glibenclamide
Metformin
Glipizide
Rosiglitazone