DAANCE Emergency Drugs and ACLS 2 — Questions and Answers
Question 1: The first drug administered during pulseless ventricular fibrillation (VF) cardiac arrest, following defibrillation, is:
- Lidocaine 1.5 mg/kg IV
- Amiodarone 300 mg IV
- Epinephrine 1 mg IV every 3 to 5 minutes (Correct answer)
- Atropine 1 mg IV
Correct answer: Epinephrine 1 mg IV every 3 to 5 minutes
After the first defibrillation attempt, ACLS guidelines call for epinephrine 1 mg IV/IO every 3 to 5 minutes during ongoing CPR.
Current AHA ACLS guidelines for VF/pulseless VT: defibrillate, then CPR 2 min, then epinephrine 1 mg IV every 3 to 5 min, then consider amiodarone 300 mg IV for shock-refractory VF. Epinephrine alpha-adrenergic effect increases coronary and cerebral perfusion pressure.
Question 2: Diphenhydramine (Benadryl) is used in anaphylaxis management primarily to:
- Reverse bronchospasm rapidly
- Block H1 receptors and reduce urticaria and pruritus (Correct answer)
- Increase blood pressure through vasoconstriction
- Prevent delayed biphasic reactions
Correct answer: Block H1 receptors and reduce urticaria and pruritus
Diphenhydramine is an H1 antihistamine that reduces urticaria, pruritus, and nasal symptoms. It is a secondary medication in anaphylaxis; epinephrine is primary.
In anaphylaxis, epinephrine (1:1000, 0.3 mg IM into the anterolateral thigh) remains the first-line drug. Diphenhydramine addresses H1-mediated symptoms (hives, itching) but does NOT prevent or reverse laryngeal edema or bronchospasm. Corticosteroids are given to prevent biphasic reactions.
Question 3: When administering epinephrine for anaphylaxis in the dental office, the preferred route is:
- Subcutaneous injection into the abdomen
- Intramuscular injection into the anterolateral thigh (Correct answer)
- Intravenous bolus into a peripheral vein
- Sublingual tablet
Correct answer: Intramuscular injection into the anterolateral thigh
IM injection into the vastus lateralis (anterolateral thigh) provides the most reliable, rapid absorption of epinephrine during anaphylaxis.
Subcutaneous epinephrine has slower and less predictable absorption. Anterolateral thigh IM injection delivers epinephrine into a highly vascular muscle with rapid uptake. This route achieves peak plasma concentration faster than deltoid IM or SC injection, which is critical in life-threatening anaphylaxis.
Question 4: Glucagon is used to treat refractory hypotension in anaphylaxis for patients who are:
- Diabetic and cannot tolerate epinephrine
- On beta-blockers, which blunt the response to epinephrine (Correct answer)
- Pregnant, as it is safer than epinephrine in that population
- Hypertensive and at risk of epinephrine-induced stroke
Correct answer: On beta-blockers, which blunt the response to epinephrine
Patients on beta-blockers may not respond adequately to epinephrine since beta-adrenergic effects are blocked. Glucagon increases cAMP independently of beta receptors.
Beta-blocker therapy reduces the effectiveness of epinephrine in anaphylaxis by blocking beta-1 (inotropic, chronotropic) and beta-2 (bronchodilatory) effects. Glucagon activates adenylyl cyclase through a glucagon receptor independent of beta receptors, providing cardiovascular and bronchial support.
Question 5: The recommended compression-to-ventilation ratio during two-rescuer adult CPR is:
- 15:2
- 30:2 (Correct answer)
- 5:1
- 15:1
Correct answer: 30:2
AHA guidelines recommend 30 compressions to 2 ventilations for adults in two-rescuer CPR when an advanced airway is not in place.
The 30:2 ratio optimizes the balance between coronary perfusion (maintained by uninterrupted compressions) and oxygenation (provided by ventilations). When an advanced airway (LMA or ETT) is placed, continuous compressions at 100 to 120/min are given with one breath every 6 seconds.
Question 6: Nitroglycerin (sublingual) is indicated for an emergency involving:
- Hypoglycemia causing altered mental status
- Suspected acute myocardial ischemia with chest pain in a normotensive patient (Correct answer)
- Asthmatic bronchospasm unresponsive to albuterol
- Anaphylactic shock with severe hypotension
Correct answer: Suspected acute myocardial ischemia with chest pain in a normotensive patient
Sublingual nitroglycerin is given for anginal chest pain to reduce preload and myocardial oxygen demand; it is contraindicated if the patient is hypotensive.
Nitroglycerin dilates venous capacitance vessels (reducing preload) and at higher doses dilates coronary arteries, decreasing myocardial oxygen consumption. It is contraindicated in hypotension (SBP less than 90 mmHg) and in patients taking phosphodiesterase-5 inhibitors due to risk of severe hypotension.
DAANCE Emergency Drugs and ACLS 2
The first drug administered during pulseless ventricular fibrillation (VF) cardiac arrest, following defibrillation, is: