complications of conscious sedation

Question 1

What is the definition of conscious sedation?

Answer 1

Patient is given a drug which depresses the CNS so that verbal contact with the patient can be maintained throughout the period of sedation
The drugs and techniques used should carry a margin of safety wide enough to render loss of conscious unlikely

Question 2

Name 4 complications of cannulation

Answer 2

Any from:
- venospasm
- extravascular injection
- intra-arterial injection
- haematoma
- fainting

Question 3

What is venospasm?

Answer 3

Also called disappearing vein syndrome
Veins collapse at attempted venepuncture

Question 4

How is venospasm managed?

Answer 4

Time - gets worse with repeated attempts
Efficient technique - slow skin puncture makes it worse
Ask patient to wear gloves or put warm water on hands

Question 5

What is extravascular injection and what does it cause?

Answer 5

Active drug injected into the interstitial space causing pain and swelling
Can delay the absorption of the drug

Question 6

How is extravascular injection managed?

Answer 6

Prevention by good cannulation and using a test dose of saline
Treated by removing the cannula, applying pressure and reassuring the patient

Question 7

Name 4 signs that are used to diagnose intra-arterial injection

Answer 7

Any from:
- pain on venepuncture
- red blood in cannula
- pain radiating distally from site of cannulation
- loss of colour or warmth to limb
- weakening pulse

Question 8

How is intra-arterial injection prevented?

Answer 8

Avoid anatomically prone sites eg antecubital fossa
Palpate first

Question 9

How is intra-arterial injection managed?

Answer 9

Monitor for loss of pulse, limb cold and discoloured
Leave cannula in situ for 5 minutes post drug
If no problems, remove the cannula
If symptomatic, leave the cannula and refer to the hospital

Question 10

What is a haematoma and what causes it?

Answer 10

Extravasion of blood into soft tissues (bruising)
Due to damage to the vein walls - can be caused at venepuncture or during removal of cannula

Question 11

How can haematomas be prevented?

Answer 11

Good cannulation technique - avoid multiple holes in vein wall
Pressure post-operatively from the operator
Take care with the elderly

Question 12

How is haematoma treated?

Answer 12

Time
Rest
Reassurance
If severe, initial ice pack then moist heat after
Consider heparin containing gel

Question 13

What causes fainting during venepuncture and how is this treated?

Answer 13

Anxiety related
Worse if patient has not eaten
Lie patient with feet up

Question 14

What are the types of complications during IV sedation?

Answer 14

Hyper-responders
Hypo-responders
Paradoxical reactions
Oversedation
Allergic reactions

Question 15

What is hyper-respondance in IV sedation and how is it prevented?

Answer 15

Deep sedation using a minimal dose
Use 1mg increments when titrating drug

Question 16

What is hypo-respondance and how is it first managed?

Answer 16

Little sedative effect with large doses
First check the cannula is in the vein

Question 17

What types of tolerance may cause hypo-respondance?

Answer 17

Benzodiazepine induced
Cross tolerance
Idiopathic

Question 18

What is the threshold to abandon treatment with midazolam?

Answer 18

10mg
Can be up to 15mg with specialists

Question 19

What are paradoxical reactions?

Answer 19

Patient appears to sedate normally but then reacts extremely to all stimuli

Question 20

How are paradoxical reactions treated?

Answer 20

Relax the patient when stimuli is removed
Check for failure of LA
Do not add any more sedative - reverse the sedative

Question 21

In whom are paradoxical reactions most found?

Answer 21

Immature teenagers

Question 22

What is oversedation?

Answer 22

A loss of responsiveness
Patient has respiratory depression and loses the ability to maintain their airway and undergoes respiratory arrest

Question 23

How should an allergic reaction during IV sedation be managed?

Answer 23

Do not use flumazenil to reverse - patient could be allergic to this also as it is a benzodiazepine
Manage anaphylaxis as if the patient is not sedated

Question 24

What are the complications of inhalation sedation?

Answer 24

Oversedation
Patient panics

Question 25

Why is oversedation sometimes seen in IS?

Answer 25

Caused by a misjudged dose

Question 26

Name 4 signs and symptoms of nitrous oxide overdose

Answer 26

Any from:
- patient discomfort
- lack of cooperation
- mouthbreathing
- giggling
- nausea
- vomiting
- loss of consciousness

Question 27

How is nitrous oxide overdose managed?

Answer 27

Decrease nitrous oxide concentration by 5-10%
Reassure patient
Don’t remove nosepiece - this can cause diffusion hypoxia

Question 28

How are patient panics managed during IS?

Answer 28

Ensure you have the correct sedation technique
Reassure the patient
If the patient cannot cope, abort the sedation