Anesthesia Techniques Flashcards

During a Gow-Gates mandibular block, the needle is directed toward which anatomical landmark as the primary target?

Answer: The neck of the mandibular condyle just below the insertion of the lateral pterygoid muscle

The Gow-Gates technique targets the neck of the condyle, depositing anesthetic near the condylar neck just inferior to the lateral pterygoid muscle insertion. This provides a higher block than a conventional IANB, anesthetizing virtually all mandibular nerve branches (V3) including the lingual, buccal, mylohyoid, and inferior alveolar nerves in a single injection. The mandibular foramen is the target in a standard IANB, not the Gow-Gates technique.

A patient receiving intravenous sedation with midazolam and fentanyl suddenly develops muscle rigidity, hyperthermia, diaphoresis, and clonus. Which condition is the MOST likely cause, and what is the immediate priority?

Answer: Serotonin syndrome; discontinue all serotonergic agents and provide supportive care

Serotonin syndrome can be precipitated by fentanyl (a weak serotonin reuptake inhibitor) combined with other serotonergic drugs a patient may be taking (e.g., SSRIs, SNRIs, triptans). The triad of neuromuscular abnormalities (clonus, hyperreflexia, rigidity), autonomic instability, and altered mental status distinguishes it from malignant hyperthermia, which is triggered by volatile anesthetics and succinylcholine—neither of which is used here. Immediate discontinuation of serotonergic agents, supportive care, and possible cyproheptadine are the mainstays of treatment.

When performing a posterior superior alveolar (PSA) nerve block, the needle is advanced at which angle relative to the maxillary occlusal plane, and to what depth?

Answer: 45° upward and 45° medially; 16 mm depth

For the PSA block, the needle is inserted at the height of the mucobuccal fold distal to the maxillary second molar and directed superiorly at 45° to the occlusal plane and medially (toward the midline) at 45°. The standard insertion depth is approximately 16 mm to reach the posterior superior alveolar foramina on the infratemporal surface of the maxilla. Advancing beyond 16 mm significantly increases the risk of penetrating the pterygoid venous plexus and causing a hematoma.

A 62-year-old patient with a documented latex allergy is scheduled for IV sedation. Which of the following items used in standard anesthesia setup poses the GREATEST risk of triggering a type I hypersensitivity reaction?

Answer: Standard rubber injection port on IV tubing

Standard rubber injection ports on IV tubing are frequently made from natural rubber latex and can directly contact IV fluids that then enter the patient's bloodstream—making them a high-risk route for systemic allergen exposure. Rubber stoppers on vials can also leach latex, but withdrawing medication with a needle without touching the stopper minimizes exposure. Silicone and PVC materials are latex-free. All latex-containing components (gloves, tubing ports, dental dams) must be replaced with latex-free alternatives for sensitive patients.

During moderate IV sedation, the Bispectral Index (BIS) monitor reads 62. Which clinical interpretation is MOST accurate?

Answer: The patient is in a clinically appropriate moderate sedation range, but approaching the boundary of deep sedation

BIS scores range from 0 (isoelectric EEG/flat line) to 100 (fully awake). The target for moderate (conscious) sedation is generally 70–85. A reading of 62 falls below this range into the deep sedation zone (40–65), meaning the patient is approaching or at deep sedation where protective airway reflexes may be compromised. General anesthesia is typically BIS < 40. A BIS of 62 is a clinical warning signal requiring reassessment of sedation depth and possibly reducing the infusion rate.

Which of the following local anesthetic combinations creates the HIGHEST risk of methemoglobinemia if the maximum recommended doses are both approached concurrently?

Answer: Prilocaine 4% combined with topical benzocaine 20% gel

Both prilocaine and benzocaine are metabolized to ortho-toluidine and aniline derivatives, respectively, which are potent oxidizers of hemoglobin iron from Fe²⁺ to Fe³⁺ (methemoglobin). Using topical benzocaine gel (which can deliver a large dose rapidly through mucous membranes) together with injectable prilocaine creates additive methemoglobin-forming potential. Patients with G6PD deficiency, anemia, or cardiopulmonary compromise are at greatest risk. Lidocaine, articaine, mepivacaine, bupivacaine, and ropivacaine are not associated with clinically significant methemoglobinemia at therapeutic doses.