Anesthesia and Analgesia
Anesthesia and Analgesia
This domain tests pre-anesthetic assessment, drug selection, monitoring depth, and multimodal pain management. Expect dose calculations and questions about recognizing an anesthetic complication early.
Core rules
- ASA classification runs I (healthy) to V (moribund); the suffix E marks an emergency. Class drives drug choice and monitoring intensity.
- Premedication reduces anxiety and induction dose. Common classes: anticholinergics (glycopyrrolate, atropine), opioids (butorphanol, buprenorphine, hydromorphone), α2-agonists (dexmedetomidine, xylazine), and benzodiazepines (midazolam, diazepam).
- Induction agents include propofol, alfaxalone, and ketamine combined with a benzodiazepine; maintenance is usually isoflurane or sevoflurane.
- Monitoring includes heart and respiratory rate, mucous membrane color, capillary refill time, SpO2, ETCO2, blood pressure (Doppler or oscillometric), temperature, jaw tone, palpebral reflex, and eye position.
- Analgesia should be multimodal: opioid plus NSAID plus a local block where feasible. NSAIDs are avoided in hypovolemia, dehydration, and renal disease.
Worked example
A 12 kg dog is ordered hydromorphone 0.1 mg/kg IV. Dose = 12 kg × 0.1 mg/kg = 1.2 mg. The vial is 2 mg/mL, so volume = 1.2 ÷ 2 = 0.6 mL. Check the route on the order and record the calculation on the treatment sheet.
Traps
- Converting pounds to kilograms incorrectly (divide pounds by 2.2).
- Applying dog heart rates to cats; a cat at 120 bpm is bradycardic.
- Deepening anesthesia for a patient that is actually light and responding to surgical stimulation.
- Forgetting to warm the patient; hypothermia prolongs recovery.