Key Takeaways
- General anesthesia involves four stages: induction, excitement (Stage II), surgical anesthesia (Stage III), and overdose (Stage IV)
- The "triad of anesthesia" consists of unconsciousness (hypnosis), analgesia (pain relief), and muscle relaxation
- Volatile (inhaled) anesthetic agents include sevoflurane, desflurane, isoflurane, and nitrous oxide
- Muscle relaxants are depolarizing (succinylcholine — only one) or non-depolarizing (rocuronium, vecuronium, cisatracurium)
- Local anesthetics are classified as esters (procaine, tetracaine) or amides (lidocaine, bupivacaine, ropivacaine)
- Epinephrine is often added to local anesthetics to cause vasoconstriction, prolonging anesthetic effect and reducing bleeding
- Maximum lidocaine dose is 4.5 mg/kg without epinephrine, 7 mg/kg with epinephrine
- All medications on the sterile field must be labeled — including syringes, basins, and medicine cups
Last updated: February 2026
Surgical Pharmacology
Pharmacology accounts for 7 scored questions (4.7% of the exam). Focus on anesthesia types, local anesthetics, and medications commonly encountered on the sterile field.
Types of Anesthesia
General Anesthesia
Produces unconsciousness, analgesia, and muscle relaxation (the triad of anesthesia):
| Stage | Name | Characteristics |
|---|---|---|
| Stage I | Induction | From drug administration to loss of consciousness; patient becomes drowsy |
| Stage II | Excitement | From loss of consciousness to regular breathing; patient may thrash, vomit — DANGEROUS stage, move through quickly |
| Stage III | Surgical Anesthesia | Desired state; regular breathing, relaxed muscles, no response to surgical stimulation |
| Stage IV | Overdose | Respiratory and cardiovascular depression; potentially fatal; requires immediate intervention |
Regional Anesthesia
| Type | Description | Common Use |
|---|---|---|
| Spinal | Injection into subarachnoid space (CSF) | C-section, lower extremity surgery |
| Epidural | Injection into epidural space (outside dura) | Labor pain, postoperative analgesia |
| Nerve block | Injection near a specific nerve or plexus | Brachial plexus block (arm), femoral block (leg) |
| IV regional (Bier block) | IV anesthetic in an exsanguinated, tourniqueted extremity | Hand/forearm procedures |
Local Anesthesia
- Applied topically or injected locally at the surgical site
- Patient remains awake and alert
- Used for minor procedures: biopsies, laceration repair, cyst excision
Monitored Anesthesia Care (MAC)
- Local anesthesia + IV sedation administered by anesthesiologist
- Patient is sedated but not intubated
- Common for endoscopy, cataract surgery, arthroscopy
Local Anesthetics
Classification
| Class | Mnemonic | Examples | Onset | Duration |
|---|---|---|---|---|
| Esters | "One I" — all have one "i" in their name | Procaine, Tetracaine, Chloroprocaine, Cocaine | Fast | Short |
| Amides | "Two I's" — all have two "i's" in their name | Lidocaine, Bupivacaine, Ropivacaine, Mepivacaine | Moderate | Longer |
Memory tip: All amide local anesthetics have two "i's" in their name (lidocaine, bupivacaine). All esters have only one "i" (procaine, tetracaine is the exception with two but is still an ester — focus on the "two i's = amide" rule for the exam).
Epinephrine in Local Anesthetics
- Causes vasoconstriction at the injection site
- Prolongs the anesthetic effect (keeps the drug localized longer)
- Reduces bleeding at the surgical site
- Increases the maximum safe dose (e.g., lidocaine: 4.5 mg/kg without epi → 7 mg/kg with epi)
- CONTRAINDICATED in areas with end arteries: fingers, toes, ears, nose, penis (risk of ischemic necrosis)
Common OR Medications
Medications on the Sterile Field
| Medication | Use | Notes |
|---|---|---|
| Epinephrine | Hemostasis, vasoconstriction | Common concentrations: 1:100,000 or 1:1,000 |
| Heparin | Anticoagulant (prevents clotting) | Used in vascular surgery; reversal agent: protamine sulfate |
| Thrombin | Hemostasis (promotes clotting) | Applied topically to Gelfoam; never inject IV |
| Normal saline | Irrigation, dilution | Must be labeled on the sterile field |
| Bacitracin irrigation | Antibiotic irrigation | Mixed with saline for wound irrigation |
| Polymethyl methacrylate (PMMA) | Bone cement | Used in joint replacement; exothermic reaction during curing |
| Methylene blue | Tissue dye/marker | Identifies anatomical structures (e.g., fistula tracts) |
| Indigo carmine | Ureteral identification | Given IV; dye excreted by kidneys turns urine blue |
Medication Safety on the Sterile Field
- ALL medications must be labeled when transferred to the sterile field
- Labels include drug name and concentration
- The circulating nurse reads the label aloud when delivering; the surgical technologist confirms
- Never accept an unlabeled medication on the sterile field
- Never re-cork a multi-dose vial — discard per facility policy
- Heparin and thrombin must NEVER be mixed — they have opposite effects
Test Your Knowledge
What are the three components of the "triad of anesthesia"?
A
B
C
D
Test Your Knowledge
Lidocaine is classified as which type of local anesthetic?
A
B
C
D
Test Your Knowledge
Epinephrine should NOT be used with local anesthetics in which of the following areas?
A
B
C
D
Test Your Knowledge
Which medication reverses the anticoagulant effect of heparin?
A
B
C
D
Test Your Knowledge
Stage II of general anesthesia (the excitement stage) is characterized by:
A
B
C
D
Test Your KnowledgeMulti-Select
Which of the following are rules for medication safety on the sterile field? (Select all that apply)
Select all that apply
All medications must be labeled with drug name and concentration
The circulating nurse reads the label aloud when delivering to the field
Unlabeled medications may be used if the surgical tech knows what they are
Heparin and thrombin must never be mixed
Multi-dose vials may be re-corked and stored for the next case