Anesthesia and Sedation
Core concepts
Know the continuum of sedation: minimal, moderate, deep, and general anesthesia, and that a patient can slip deeper than intended. Sedation depth must match the procedure, patient comorbidities, and monitoring available. Understand MAC (monitored anesthesia care) as anesthesia care with sedation and monitoring, not a drug dose.
Pharmacology anchors: onset, offset, context-sensitive half-time, and organ-dependent elimination. Propofol and remifentanil are rapid on/off; morphine and lorazepam have longer, variable profiles. Recognize drug interactions, especially opioids plus benzodiazepines (respiratory depression), and the role of reversal agents (naloxone, flumazenil) with their risks (resedation, seizures).
Regional and neuraxial techniques: local anesthetic systemic toxicity (LAST) recognition and lipid emulsion rescue, spinal vs epidural differences, and contraindications (coagulopathy, infection, patient refusal).
Traps
- Assuming moderate sedation is always safe because the drug is "just a sedative."
- Forgetting that flumazenil can precipitate seizures in benzodiazepine-tolerant patients.
- Missing that LAST may present with neurologic symptoms before cardiovascular collapse.
- Confusing MAC as a concentration (minimum alveolar concentration) with monitored anesthesia care.
Rule of thumb
Any sedation can become general anesthesia; monitor capnography, oxygenation, and ventilation, and have airway rescue immediately available. For LAST, stop injection, secure the airway, and give lipid emulsion early in severe cases.
Worked example
During a peripheral nerve block, a patient reports tinnitus and metallic taste, then becomes agitated. This is early LAST. Stop injection, call for help, support oxygenation and ventilation, and prepare lipid emulsion; do not wait for seizures or arrest.