1 - Complications of conscious sedation Flashcards
What are the complications of cannulation?
- venospasm
- extravascular injection
- intraarterial injection
- haematoma
- fainting
What is venospasm?
- also known as disappearing vein syndrome
- veins collapse at attempts venepuncture
- may be accompanied with burning
- associate with poorly visible veins
How do you manage venospasm?
- spend time dilating vein (tourniquet)
- efficient technique, slow puncture makes worse
- place hands in warm water or wear gloves prior
What is extravascular injection?
- active drug placed into interstitial space (needle is in tissue)
- pain and swelling
- can cause delayed absorption or over sedation if more drug administered
How do you manage extravascular injection?
- prevention with good cannulation and test dose of saline
- if tissued, remove cannula, apply pressure and reassure
How do you test a cannula is in the vein?
- test dose of saline
- should not bubble or cause pain
- patient may feel cold up their arm
How do you diagnose intraarterial injection?
- pain on puncture
- red blood in cannula
- cannula leaks bright red blood around needle
- pain radiating distally from site of cannulation
- loss of colour or warmth to limb with weakening pulse
How do you manage an intraarterial injection?
- leave cannula in situ for 5 mins and monitor
- if there are no problems remove
- if symptomatic refer to hospital and leave in situ
How do you prevent intraarterial injection?
- avoid anatomically prone sites (ie medial to bicep tendon)
- palpate before insertion (artery pulses)
What is a haemtoma associated with cannulation?
- extravasation of blood into soft tissues due to damage to vein walls
- can occur at venepuncture or at removal of cannula if no pressure applied
- common in elderly
How do you manage a haematoma?
- time, rest and reassurance
- if severe, ice then heat after 24 hours
- consider heparin containing gel
How can you prevent fainting at cannulation?
- ensure patient has eaten
- topical skin anaesthesia
- risk assess
How do you manage fainting at cannulation?
Lie patent flat with feet raised
What are the complications of drug administration in IV sedation?
- hyper-responders
- hypo-responders
- paradoxical reactions
- oversedation
- allergic reaction
What is a hyper-responder?
- deep sedation achieved with minimal dose (1-2mg midazolam)
- common in elderly
What is the normal dose of midazolam for sedation?
5-6mg
What is a hypo-responder?
- little sedative effect with large doses
- may be due to tolerance of previous drug use
What is the threshold to abandon sedation?
10mg of midazolam
What can cause tolerance to midazolam?
- benzos use
- cross tolerance of other drugs
- idiopathic
- methadone users
What are paradoxical reaction?
- patient appears to sedate normally
- react extremely to all stimuli (becomes hyper)
- relaxes if stimuli removed
- requires reversal agent
What are the signs of oversedation?
- loss of responsiveness
- respiratory depression
- loss of ability to maintain airway
- respiratory arrest
How do you monitor respiratory depression?
Oxygen saturation
How do you manage oversedation?
- stop procedure
- try to rouse patient
- use ABCs
- if no response, use reversal agent flumazenil
What is the dosage of flumazenil?
- 200ug initial dose
- 100ug increments at minute intervals
How do you manage respiratory depression?
- stimulate patient (encourage to take deep breaths)
- supplemental oxygen via nasal cannulae at 2l/min
How do you manage an allergic reaction?
- rare to be allergic to sedative but do NOT use flumazenil as it is a benzodiazepine
- reaction is more likely to be to latex or Elastoplast
- manage as normal with IM adrenaline
What are the complications of inhalation sedation?
- oversedation
- patient panics
What is the maximum dose nitrous oxygen can be titrated with oxygen for sedation?
70%
What is the average titration of nitrous oxygen that causes oversedation?
104%
What are signs of nitrous oxide overdose?
- patient discomfort
- lack of cooperation
- mouth breathing
- giggling
- nausea and vomiting
- LOC
How do you manage IS overdose?
- decrease nitrous oxide concentration by 5-10%
- reassure patient
- do not remove nose piece
Why must you not remove the nose piece suddenly during IS?
Diffusion hypoxia
How do you manage the patient panicking during IS?
- reassurance
- abort if patient cannot cope
- encourage the patient to breathe through their nose as the concentration of oxygen will then increase and room should stop spinning
