Managing Systemic Diseases Flashcards

A patient with chronic kidney disease (CKD Stage 4, eGFR 22 mL/min) presents for sedation-assisted dental extraction. Which opioid analgesic poses the GREATEST risk of prolonged CNS depression in this patient due to active metabolite accumulation?

Answer: Morphine

Morphine is metabolized to morphine-6-glucuronide (M6G), a pharmacologically active metabolite that is renally cleared. In CKD Stage 4 patients, M6G accumulates significantly, causing prolonged and potentially dangerous CNS and respiratory depression. Fentanyl is preferred in renal impairment because it has no active metabolites and undergoes hepatic metabolism. Hydromorphone also has an active metabolite (hydromorphone-3-glucuronide) but it is neuroexcitatory rather than sedating. Buprenorphine is hepatically metabolized and considered safer in renal impairment.

A 58-year-old patient on long-term warfarin therapy (INR 2.8) requires IV sedation for a complex extraction. The oral surgeon asks whether the INR needs to be corrected before sedation. Which statement BEST reflects current evidence-based practice?

Answer: Warfarin need not be discontinued for most routine dental procedures if INR is within therapeutic range and local hemostatic measures are used

Current evidence and guidelines (including ADA and ACCP recommendations) support continuing warfarin at therapeutic INR levels (typically 2.0–3.5) for routine dental procedures, including extractions, when effective local hemostatic measures (e.g., pressure, sutures, oxidized cellulose) are employed. The risk of thromboembolic complications from stopping anticoagulation generally outweighs the bleeding risk. Bridging therapy, FFP, or vitamin K reversal are not routinely indicated for standard dental procedures and expose the patient to unnecessary risk.

During IV sedation, a patient with a known history of myasthenia gravis (MG) receives succinylcholine for emergency intubation following laryngospasm. Which of the following outcomes is MOST expected in this patient compared to a patient without MG?

Answer: Resistance to succinylcholine requiring a larger dose to achieve intubating conditions

Patients with myasthenia gravis have a reduced number of functional postsynaptic nicotinic acetylcholine receptors due to autoimmune destruction. Succinylcholine, a depolarizing neuromuscular blocker, requires binding to these same receptors to cause depolarization. With fewer available receptors, MG patients are RESISTANT to succinylcholine and typically require higher doses (up to 2–2.5 mg/kg vs. the standard 1–1.5 mg/kg). Conversely, MG patients are exquisitely sensitive to non-depolarizing agents (e.g., vecuronium, rocuronium), which can cause prolonged blockade.

A patient with uncontrolled hyperthyroidism (Graves' disease, TSH undetectable) presents urgently for incision and drainage of a dental abscess under sedation. Which of the following anesthetic considerations is MOST critical to avoid precipitating thyroid storm?

Answer: Limiting epinephrine-containing local anesthetics and avoiding sympathomimetic agents

In uncontrolled hyperthyroidism, the sympathetic nervous system is already hyperactivated due to increased catecholamine sensitivity. Administering epinephrine or other sympathomimetics can precipitate thyroid storm—a life-threatening hypermetabolic crisis characterized by hyperpyrexia, tachyarrhythmias, and cardiovascular collapse. Epinephrine in local anesthetics should be minimized or avoided. Ketamine is relatively contraindicated because it stimulates sympathetic outflow, which could trigger storm. Benzodiazepines have no direct effect on thyroid synthesis and can be used for anxiolysis. Propofol does not inhibit thyroxine release in a clinically meaningful way.

A patient with severe obstructive sleep apnea (AHI 45, CPAP non-compliant) is scheduled for office-based IV sedation. In addition to standard monitoring, which physiologic parameter provides the EARLIEST warning of impending upper airway obstruction in this patient population?

Answer: End-tidal CO₂ (EtCO₂) via capnography

Capnography (EtCO₂ monitoring) detects apnea and airway obstruction significantly earlier than pulse oximetry because it continuously measures exhaled CO₂ on a breath-by-breath basis. Loss or dampening of the EtCO₂ waveform immediately signals absent or obstructed breathing, whereas SpO₂ desaturation is a lagging indicator—particularly dangerous in patients pre-loaded with supplemental oxygen, who may have a long oxygen reserve before desaturation becomes apparent. In OSA patients undergoing sedation, capnography is considered a critical safety monitor for detecting early obstruction before hypoxemia develops.

A 62-year-old patient with type 2 diabetes managed with metformin (1000 mg twice daily) and a GLP-1 receptor agonist (semaglutide) is scheduled for IV sedation. The patient last ate 3 hours ago. Which pre-sedation consideration is MOST specific to the pharmacology of GLP-1 agonists in this clinical scenario?

Answer: Gastroparesis-like gastric emptying delay from GLP-1 agonists may increase aspiration risk despite the reported NPO duration

GLP-1 receptor agonists (e.g., semaglutide, liraglutide) significantly delay gastric emptying as part of their mechanism of action. This effect is dose-dependent and persists throughout therapy. Current anesthesia guidance (including 2023 ASA advisories) recognizes that standard NPO intervals (e.g., 2 hours for liquids, 6–8 hours for solids) may be insufficient in patients on GLP-1 agonists because gastric contents may not have cleared, elevating aspiration risk. This is the most clinically specific and urgent concern. Metformin-associated lactic acidosis risk during routine dental sedation is extremely low and not a universal reason to hold it. GLP-1 agonists do not independently cause hypoglycemia and do not interact with benzodiazepine metabolism.