Week Five: LA Systemic Complications Flashcards
What are the three major causes of adverse systemic reactions to local anaesthetics?
- Psychogenic
- Hypersensitivity
- Toxicity
If a psychogenic adverse systemic reaction to LA occurs, what are the presenting symptoms?
- Syncope
- Panic attack
- Nausea
- Vomiting
What are causes of psychogenic adverse systemic reaction to LA?
- Emotional disturbances such as stress or fear: This may lead to vaso-vagal response or effects of myocardial depression and vasodilation (drop BP)
How do you manage an psychogenic adverse systemic reaction to LA?
- Maybe syncope, ensure patient is lying down and elevate the legs
- Always try and rouse the patient via sound and pain
- Calm the patient once roused
What is hypersensitivity regarding an adverse systemic reaction to LA?
- An exaggerated response of the patients immune system
- Adverse reactions to local anaesthetics are not uncommon
- True allergy is very rare
Comment on esters and amides, regarding hypersensitivity adverse systemic reactions to LA
Esters: in this case there would be a sensitivity to their metabolite, para-aminobenzoic acid (PABA)
Amides can be used as alternatives in those patients.
Hypersensitivity: true allergic reactions, what is it usually indicative of?
The sodium metabisulfites (antioxidants) and methylparaben (preservatives)
What are symptoms of a hypersensitivity reaction during an adverse systemic reaction to LA?
Skin: itching, flushing, hives, oedema
GIT: Cramps, nausea, vomiting, incontinence
Respiratory: Tightness, pain in chest, wheeze, shortness of breathing, respiratory distress, cyanosis, constriction of airways from swelling
Cardio vascular system: Pallor, light headedness, palpitations, increased heart rate, decreased BP, Arrhythmias, Loss of conscience, Cardiac arrest
How do you manage allergies? Mild case:
- Cease dental treatment
- Remove allergen
- Give oral antihistamine, using during day time
If the allergen is unknown, refer for investigation
If a mild allergy is associated with hypotension and evidence of anaphylaxis, how do you manage this?
- Cease dental treatment
- remove allergen
Call 000 and for Red Bag give Intra Muscular adrenaline (Epipen) and Monitor patients vital signs and perform Basic Life Support Until assistance arrives
If the allergen is unknown, refer for investigation
What is toxicity?
- Toxic side effects of LA are predominately neurological
- Can be caused by both solution itself, and the vasoconstrictor
When can toxicity occur?
May arise after:
- Inadvertent intramuscular injection
- Rapid systemic absorption
- Excessive dose administration
- Impaired drug clearance
Name twelve factors that impact risk of toxicity.
◦ Pt age and weight ◦ Medications/adverse interactions ◦ Vasoactivity of L.A ◦ Concentration ◦ Dose ◦ Rate of injection ◦ Site of injection ◦ Vascularity of injection site ◦ Presence of vasoconstrictors ◦ Compromised pt ◦ Genetic aberrations ◦ Idiosyncratic
What are the key characteristics of LA that can affect the CNS - CVS?
- Local anaesthetics effects are an excitable tissues
- Rapid equilibrium phase (heart, brain)
- High plasma concentration of drug may exert effects on these tissues
Adverse systemic effects are usually seen in a…
Continuum as plasma concentration increases.
What are symptoms of CNS complications?
- Stimulation/pre-convulsive phase/ convulsive phase
What are warning signs of CNS complications?
Stimulation
- Restlessness, tremor, confusion or agitation
Further increase = depression
- PRE-CONVULSIVE: drowsiness, loss of concentration, slurred speech, dizziness, disorientation, visual disturbances, bilateral togue numbness, dream like state
Further increase = convulsive phase
- Respiratory depression
What are some CVS complications?
- Increased LA causing myocardial depression causing cardiac arrest
- Increased adrenaline causing vasoconstriction or coronary arteries causing angina. MI and possible cardiac arrest
What are the warning signs of CVS complications?
- Increased or decreased heart rate
- Increased or decreased BP
- Palpitations
- Arrhythmias
- Light headedness
- Loss of conscience/fainting
Summarise complications for CNS:
Initial Signs of elevated blood levels =
Low levels= STIMULATION
Restlessness, tremor, confusion or agitation
Further increase= DEPRESSION
PRE- CONVULSIVE: drowsiness, loss of
concentration, slurred speech, dizziness,
disorientation, visual disturbances, bilateral
tongue numbness, dream like state
Further increase
CONVULSIVE phase
Respiratory depression
Summarise CVS complications:
Usually do not see CVS effects until levels are approaching overdose level
Myocardial depression – decreased heart rate. Due to
action of local anaesthetic drug on the neurons/nerve fibres of the heart
Vasodilation– via smooth muscle relaxation in walls of blood vessels These effects combined will result in a
fall in blood pressure, which may result in fainting, coma or in extreme cases death from circulatory collapse
Toxicity of adrenalin causes?
- Anxiety
- Restlessness
- Trembling
- Pounding headache
- Palpitations
- Sweating with pallor
- Weakness
- Dizziness
- Respiratory distress
How do we manage toxicity?
PREVENTION • Thorough Medical History • Aspiration • Slow injections • Dose limitation and adherence to recommended dose for weight
When a toxic reaction occurs, what do you do?
When a toxic reaction occurs • If Mild • Reassure client • If severe • Stop the treatment • Administer oxygen • Provide basic life support • Call for medical assistance • Protect pt from injury • Monitor vital signs
What are considerations regarding toxicity?
• Adherence to the recommended maximum doses • Where do we find this information? • Overdose on younger children, can occur relatively easily • Aspiration is mandatory!
