Anesthesiology Syllabus

Name the classic triggers and definitive treatment of malignant hyperthermia.

Triggers: volatile anesthetics and succinylcholine (RYR1 mutation). Signs: rising end-tidal $\ce{CO2}$, rigidity (masseter), tachycardia, hyperthermia. Treatment: dantrolene plus cooling and supportive care.

Describe the ASA Physical Status Classification (ASA I-VI).

I: normal healthy patient; II: mild systemic disease; III: severe systemic disease (not incapacitating); IV: severe disease that is a constant threat to life; V: moribund, not expected to survive without operation; VI: brain-dead organ donor. 'E' suffix denotes emergency.

What are the components of the Mallampati classification and what does it predict?

Based on visible oropharyngeal structures with mouth open/tongue out: Class I (soft palate, uvula, pillars) to Class IV (hard palate only). Higher classes predict a potentially difficult intubation/laryngoscopy.

Which bedside airway measurements suggest a difficult airway?

Thyromental distance $< 6\ \mathrm{cm}$ (or < 3 fingerbreadths), mouth opening (interincisor gap) $< 3\ \mathrm{cm}$, high Mallampati (III-IV), short/thick neck, limited neck extension, and large incisors/receding mandible. Mnemonic LEMON.

State the ASA (2017) preoperative fasting guidelines for clear liquids, breast milk, and solids.

Clear liquids: 2 hours; breast milk: 4 hours; infant formula/non-human milk and a light meal: 6 hours; fried/fatty foods or a full meal: 8 hours.

According to Metabolic Equivalents (METs), what functional capacity is considered adequate for surgery?

Ability to achieve $\geq 4$ METs (e.g., climb two flights of stairs or walk up a hill) without symptoms indicates adequate cardiopulmonary reserve; inability below 4 METs raises perioperative cardiac risk.

Which chronic medications are typically continued versus held on the morning of surgery?

Continue: beta-blockers, statins, most antihypertensives (except often ACE-I/ARBs), inhalers, antiepileptics. Hold: ACE inhibitors/ARBs (hypotension), oral hypoglycemics/SGLT2 inhibitors, and typically warfarin/anticoagulants (bridged as needed).

What are the four stages of general (ether) anesthesia described by Guedel?

Stage I: analgesia/amnesia; Stage II: excitement/delirium (irregular breathing, risk of laryngospasm/vomiting); Stage III: surgical anesthesia (regular breathing, target plane); Stage IV: medullary depression/overdose (apnea, cardiovascular collapse).

Outline the standard sequence of a rapid sequence induction (RSI).

Preoxygenation, then near-simultaneous IV administration of a rapid-acting induction agent (e.g., propofol/etomidate) and a fast-onset paralytic (succinylcholine or rocuronium), applying cricoid pressure (Sellick), with no bag-mask ventilation, then immediate intubation — to minimize aspiration risk.

Contrast spinal and epidural anesthesia in terms of injection site, onset, and dosing.

Spinal: single injection into subarachnoid (intrathecal) space below L2 (into CSF), rapid dense block, small drug dose. Epidural: catheter into epidural (potential) space, slower onset, larger drug volume, titratable and can be continuous.

What is the most common serious complication of spinal anesthesia, and how is hypotension from it managed?

Hypotension from sympathetic (preganglionic) blockade causing vasodilation and bradycardia. Managed with IV fluids and vasopressors (phenylephrine, ephedrine); a high spinal can cause bradycardia/respiratory compromise.

What is a post-dural puncture headache (PDPH): features and treatment?

A positional (worse upright, better supine) frontal/occipital headache from CSF leak after dural puncture; more common with larger/cutting needles and younger patients. Treatment: conservative (fluids, caffeine, analgesia); definitive is an epidural blood patch.

Define Monitored Anesthesia Care (MAC) and how it differs from general anesthesia.

MAC is anesthesiologist-supervised sedation/analgesia with monitoring during a procedure under local anesthesia, where the patient can range from minimal to deep sedation but is expected to maintain their own airway; unlike GA, it does not intentionally render the patient unresponsive with a controlled airway.

List the ASA continuum of depth of sedation: minimal, moderate, deep, and general anesthesia.

Minimal (anxiolysis): normal response to voice. Moderate ('conscious sedation'): purposeful response to voice/touch, airway maintained. Deep: purposeful response only after repeated/painful stimulation, airway may need support. General anesthesia: unarousable even to painful stimulus, airway/ventilation often require intervention.

What are the ASA Standard I and Standard II basic monitoring requirements?

Standard I: qualified anesthesia personnel present throughout. Standard II: continual evaluation of oxygenation (pulse oximetry, $FiO_2$ analyzer), ventilation (capnography/ETCO2), circulation (continuous ECG, BP and HR at least every 5 minutes), and temperature.

How does pulse oximetry work and what are common causes of falsely low or unreliable readings?

It uses two wavelengths (660 nm red and 940 nm infrared) and the differential absorption of oxy- vs deoxyhemoglobin in pulsatile flow. Unreliable with poor perfusion, motion, nail polish, ambient light; carboxyhemoglobin falsely elevates $SpO_2$, methemoglobin drives it toward 85%.

What is capnography and what does a normal end-tidal CO2 value indicate?

Capnography is continuous measurement of exhaled $\ce{CO2}$; normal $ETCO_2$ is $35\text{-}45\ \mathrm{mmHg}$. It confirms tracheal intubation, ventilation adequacy, and cardiac output; a sudden drop to near zero suggests disconnection, esophageal intubation, or cardiac arrest.

What does a rising end-tidal CO2 trend intraoperatively suggest, and what is the a-ETCO2 gradient?

A rising $ETCO_2$ can indicate hypoventilation, increased $\ce{CO2}$ production (fever, sepsis, malignant hyperthermia), or rebreathing. The arterial-to-$ETCO_2$ gradient is normally $2\text{-}5\ \mathrm{mmHg}$ and widens with dead space (e.g., pulmonary embolism, low cardiac output).

Which advanced hemodynamic monitor gives a continuous, beat-to-beat blood pressure and allows frequent ABG sampling?

An indwelling arterial line (arterial catheter), typically placed in the radial artery after a modified Allen test; it provides real-time BP and easy access for arterial blood gases.

What does central venous pressure (CVP) estimate, and what are normal values?

CVP approximates right atrial pressure/right ventricular preload; normal is $2\text{-}6\ \mathrm{mmHg}$ (up to ~8). It is now considered a poor predictor of fluid responsiveness when used alone.

Describe the Bispectral Index (BIS) monitor and its target range for general anesthesia.

BIS is a processed EEG parameter scaled 0 (isoelectric) to 100 (fully awake); a range of $40\text{-}60$ is targeted for adequate general anesthesia and is used to reduce the risk of intraoperative awareness.

What is train-of-four (TOF) neuromuscular monitoring and how is the TOF ratio interpreted?

Four supramaximal stimuli at 2 Hz are applied over a nerve; the TOF ratio is the amplitude of the 4th twitch divided by the 1st ($T_4/T_1$). Fade indicates non-depolarizing block. A $T_4/T_1 \geq 0.9$ indicates adequate recovery for extubation.

How does the pattern of neuromuscular fade differ between depolarizing (phase I) and non-depolarizing blockade?

Non-depolarizing (and phase II) block shows fade on TOF and post-tetanic potentiation. Depolarizing phase I block (succinylcholine) shows NO fade and NO post-tetanic potentiation — all four twitches decrease equally.

What is post-tetanic count (PTC) used for in neuromuscular monitoring?

When the block is too deep for any TOF response, PTC assesses depth: a tetanic stimulus is followed by single twitches; the number of detectable post-tetanic twitches estimates time until TOF recovery — a low PTC means very deep block.

Why do pediatric patients desaturate faster than adults during apnea?

Children have higher oxygen consumption ($\approx 6\text{-}8\ \mathrm{mL/kg/min}$ vs ~3 in adults) and a proportionally smaller functional residual capacity (FRC), so their oxygen reserve depletes rapidly during apnea/induction.

List key anatomical airway differences in infants relevant to anesthesia.

Large head/occiput and tongue, high (cephalad) larynx at $\approx C3\text{-}C4$, long floppy omega-shaped epiglottis, and the narrowest point historically at the cricoid ring (funnel-shaped airway); obligate nasal breathers when young.

What physiologic changes in the elderly alter anesthetic requirements and drug dosing?

Decreased MAC and drug requirements, reduced hepatic/renal clearance, decreased lean body mass and total body water, blunted baroreceptor reflexes (more hypotension), reduced pulmonary reserve, and greater sensitivity to opioids/benzodiazepines (higher delirium risk).

What is aortocaval compression (supine hypotensive syndrome) in obstetric anesthesia and how is it prevented?

After ~20 weeks, the gravid uterus compresses the inferior vena cava and aorta when supine, reducing venous return and cardiac output causing hypotension. Prevented by left uterine displacement (left lateral tilt of $\geq 15^{\circ}$).

Why is the pregnant patient considered a 'full stomach' and at higher aspiration risk?

Progesterone relaxes the lower esophageal sphincter and the enlarging uterus increases intragastric pressure and delays gastric emptying, raising aspiration risk (Mendelson's syndrome) — favoring RSI and aspiration prophylaxis for general anesthesia.

How does MAC change in pregnancy and what are the analgesia options for labor?

MAC decreases by $\approx 30\text{-}40\%$ in pregnancy. Labor analgesia options: neuraxial (lumbar epidural or combined spinal-epidural — gold standard), IV opioids/remifentanil PCA, and inhaled nitrous oxide (Entonox).

Describe laryngospasm: cause, and stepwise management.

Reflex glottic closure, often during light anesthesia/Stage II or from secretions/stimulation. Management: remove stimulus, apply 100% oxygen with continuous positive airway pressure and jaw thrust (Larson's maneuver at the 'laryngospasm notch'); if unresolved, deepen anesthesia (propofol) and give succinylcholine, then ventilate/intubate.

What is negative-pressure pulmonary edema, and what airway complication classically precedes it?

Post-obstructive pulmonary edema caused by forceful inspiration against a closed glottis (large negative intrathoracic pressure), classically following laryngospasm or biting an ETT; presents with pink frothy sputum and hypoxia soon after the obstruction, treated with oxygen, PEEP/CPAP, and supportive care.