Anesthesia and Pharmacology
Anesthesia and pharmacology tests the RNFA’s ability to anticipate anesthetic effects, dose local anesthetics safely, recognize emergencies, and avoid drug interactions in the perioperative period.
Core rules and concepts
- Sedation is a continuum; capnography and continuous observation are required because a patient can slip from moderate sedation to general anesthesia.
- Local anesthetic maximums in typical adults: lidocaine 4.5 mg/kg plain and 7 mg/kg with epinephrine; bupivacaine 2.5-3 mg/kg; use actual body weight cautiously and reduce for cardiac, hepatic, or frail patients.
- LAST: stop injection, call for help, secure the airway with 100% oxygen, give a benzodiazepine for seizures, and start 20% lipid emulsion at 1.5 mL/kg bolus followed by infusion per protocol. Avoid vasopressin; small epinephrine boluses may be used for cardiovascular collapse.
- Malignant hyperthermia: unexplained rising ETCO2, rigidity, tachycardia, and hyperthermia; stop triggers, call for the MH cart, and give dantrolene 2.5 mg/kg IV, repeating as needed.
- Reversal and antiemetics: sugammadex for rocuronium; neostigmine with an anticholinergic; multimodal PONV prophylaxis.
Worked example
A 70 kg patient receives lidocaine with epinephrine. The maximum is 7 mg/kg × 70 = 490 mg. A 1% solution contains 10 mg/mL, so the limit is 49 mL. If the surgeon asks for 60 mL of infiltration, the RNFA raises the dose limit and suggests splitting the dose, changing agent, or using dilute tumescence rather than exceeding the maximum.
Traps
Calculating mg/kg with the wrong concentration; forgetting that epinephrine changes the lidocaine limit; giving more local anesthetic when early LAST symptoms appear; and treating MH with cooling alone.