DCAS Pharmacology for Paramedics 4 — Questions and Answers
Question 1: The antidote for organophosphate poisoning in the pre-hospital setting is:
- Atropine (large doses) plus pralidoxime (2-PAM) — to reverse muscarinic effects and reactivate cholinesterase (Correct answer)
- Naloxone
- Physostigmine
- Flumazenil
Correct answer: Atropine (large doses) plus pralidoxime (2-PAM) — to reverse muscarinic effects and reactivate cholinesterase
Organophosphates inhibit acetylcholinesterase, causing cholinergic toxidrome; atropine blocks muscarinic effects (secretions, bronchospasm, bradycardia), while pralidoxime reactivates the enzyme before ageing occurs.
Question 2: The therapeutic effect of heparin administered in pre-hospital ACS management is:
- Inhibition of Factor Xa and thrombin, preventing thrombus propagation (Correct answer)
- Dissolving existing coronary thrombus
- Vasodilation of coronary arteries
- Platelet aggregation inhibition (same as aspirin)
Correct answer: Inhibition of Factor Xa and thrombin, preventing thrombus propagation
Heparin (unfractionated or LMWH) potentiates antithrombin III to inhibit thrombin and Factor Xa, preventing further clot growth in the culprit coronary artery while fibrinolysis or PCI provides definitive reperfusion.
Question 3: Calcium gluconate IV is indicated in the pre-hospital setting for:
- Hyperkalaemia causing cardiac arrhythmia, or calcium channel blocker overdose — membrane stabilisation (Correct answer)
- All cases of cardiac arrest
- Hypocalcaemia only
- As an antacid in gastric emergencies
Correct answer: Hyperkalaemia causing cardiac arrhythmia, or calcium channel blocker overdose — membrane stabilisation
IV calcium stabilises cardiac myocyte membranes in hyperkalaemia (reducing arrhythmia risk without lowering potassium) and reverses negative cardiac effects of calcium channel blocker overdose through receptor competition.
Question 4: Midazolam's advantage over diazepam for pre-hospital seizure management includes:
- IM, intranasal, and buccal routes of administration — more options than IV-dependent diazepam (Correct answer)
- Greater efficacy at equal doses
- Longer duration of action
- No risk of respiratory depression
Correct answer: IM, intranasal, and buccal routes of administration — more options than IV-dependent diazepam
Midazolam can be given IM, intranasally, or buccally without IV access, providing rapid effective benzodiazepine therapy even when venous access is unavailable — a major practical advantage in seizure management.
Question 5: In the management of suspected cyanide poisoning (e.g., in fire victims with altered consciousness), the antidote is:
- Hydroxocobalamin (Cyanokit) IV — binds cyanide to form cyanocobalamin (vitamin B12) (Correct answer)
- 100% oxygen as the only treatment
- Sodium thiosulphate alone
- Atropine and pralidoxime
Correct answer: Hydroxocobalamin (Cyanokit) IV — binds cyanide to form cyanocobalamin (vitamin B12)
Hydroxocobalamin binds cyanide ions directly, forming non-toxic cyanocobalamin (vitamin B12) which is renally excreted; it is safe, effective, and compatible with concurrent 100% oxygen administration.
Question 6: Norepinephrine (noradrenaline) differs from epinephrine in that it:
- Has predominantly alpha-1 (vasoconstrictor) effects with less beta-1/2 activity — minimal tachycardia and bronchodilation (Correct answer)
- Primarily causes bronchodilation
- Has no cardiac effects
- Is only used in asthma management
Correct answer: Has predominantly alpha-1 (vasoconstrictor) effects with less beta-1/2 activity — minimal tachycardia and bronchodilation
Norepinephrine is predominantly an alpha-1 agonist causing intense peripheral vasoconstriction with minimal beta-2 activity; unlike epinephrine, it does not cause significant bronchodilation or as much tachycardia.
DCAS Pharmacology for Paramedics 4
The antidote for organophosphate poisoning in the pre-hospital setting is: