DAANCE Anesthesia Techniques 5 — Questions and Answers
Question 1: A 68-year-old patient on warfarin requires local anesthetic infiltration for a dental extraction. The primary concern regarding epinephrine use is:
- Potentiation of anticoagulant effect
- Risk of hematoma formation at the injection site (Correct answer)
- Epinephrine-warfarin drug interaction causing cardiac arrhythmia
- Reduced local anesthetic efficacy due to altered tissue pH
Correct answer: Risk of hematoma formation at the injection site
Anticoagulated patients have increased risk of hematoma formation, particularly with regional nerve blocks; infiltration is preferred and pressure should be applied post-injection.
Question 2: The buccal nerve block is MOST commonly used as a supplemental injection to which primary mandibular block?
- Mental block
- Inferior alveolar nerve block (Correct answer)
- Lingual nerve block
- Incisive nerve block
Correct answer: Inferior alveolar nerve block
The buccal (long buccal) nerve is not anesthetized by the IAN block, so it is routinely added when buccal soft tissue anesthesia is needed for mandibular molar procedures.
Question 3: During monitored anesthesia care (MAC), the anesthesia assistant notes the patient's respiratory rate has fallen to 6 breaths per minute. The MOST appropriate immediate action is:
- Administer naloxone 0.4 mg IV push
- Perform jaw thrust and apply positive pressure ventilation if needed (Correct answer)
- Increase oxygen flow rate via nasal cannula
- Document and continue monitoring
Correct answer: Perform jaw thrust and apply positive pressure ventilation if needed
Airway positioning and assisted ventilation take priority before pharmacologic reversal; naloxone is used if opioid-induced respiratory depression is confirmed and ventilation is inadequate.
Question 4: Which pH-related factor makes local anesthetics LESS effective in infected or inflamed tissue?
- Infected tissue has higher vascularity, diluting the anesthetic faster
- Low pH of infected tissue increases ionization of the anesthetic, reducing membrane penetration (Correct answer)
- Inflammation increases the number of pain receptors, overwhelming local anesthetic
- Bacteria directly bind and inactivate local anesthetic molecules
Correct answer: Low pH of infected tissue increases ionization of the anesthetic, reducing membrane penetration
Infected tissue has a lower pH, causing more local anesthetic molecules to exist in the ionized (cationic) form, which cannot cross the nerve membrane to block sodium channels.
Question 5: The recommended maximum epinephrine dose for a healthy adult dental patient in a single appointment is:
- 0.04 mg
- 0.2 mg (Correct answer)
- 0.1 mg
- 0.5 mg
Correct answer: 0.2 mg
The standard recommendation allows up to 0.2 mg of epinephrine per appointment for healthy adults, approximately equivalent to 11 cartridges of 1:100,000 epinephrine.
Question 6: When performing a posterior superior alveolar (PSA) nerve block, over-insertion of the needle increases the risk of which complication?
- Facial nerve paralysis
- Hematoma of the pterygoid plexus (Correct answer)
- Trismus due to masseteric injection
- Inadvertent anesthesia of the mental nerve
Correct answer: Hematoma of the pterygoid plexus
The pterygoid venous plexus lies in the infratemporal fossa; over-insertion of the PSA needle into this area can puncture vessels and cause a significant hematoma.
Question 7: A patient's SpO2 drops from 98% to 91% during IV sedation with midazolam and fentanyl. After repositioning the airway and increasing oxygen flow, SpO2 remains at 91%. The next step is to administer:
- Flumazenil 0.2 mg IV
- Naloxone 0.1–0.2 mg IV titrated (Correct answer)
- A second dose of midazolam to deepen sedation
- Atropine 0.5 mg IV for bradycardia
Correct answer: Naloxone 0.1–0.2 mg IV titrated
Persistent hypoxia after airway maneuvers in a patient receiving opioids warrants titrated naloxone to reverse opioid-induced respiratory depression without precipitating acute pain.
DAANCE Anesthesia Techniques 5
A 68-year-old patient on warfarin requires local anesthetic infiltration for a dental extraction.
The primary concern regarding epinephrine use is: