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.
