AOBA Anesthesiology cheat sheet

MAC is the alveolar concentration at which 50% of patients do not move in response to a standardized surgical stimulus; MAC-awake is roughly 0.3-0.4 MAC.

Potency of inhaled anesthetics correlates with lipid solubility (Meyer-Overton); lower MAC = higher potency.

Hepatic clearance of drugs: Phase I reactions (oxidation, reduction, hydrolysis via cytochrome P450) then Phase II conjugation (glucuronidation, sulfation) increasing water solubility for renal excretion.

Henderson-Hasselbalch: pH = pKa + log([A-]/[HA]); the fraction of nonionized drug crosses membranes; for local anesthetics, pKa determines onset (lower pKa = faster onset).

Cerebral blood flow is coupled to cerebral metabolic rate; PaCO2 is a potent vasodilator: 1 mmHg change in PaCO2 alters CBF by 1-2 mL/100g/min within the physiologic range.

Coronary perfusion pressure = aortic diastolic pressure - left ventricular end-diastolic pressure; tachycardia reduces diastolic filling time and coronary perfusion.

Renal autoregulation maintains GFR between mean arterial pressures of 70-150 mmHg; below 70, GFR falls linearly.

Neuromuscular junction: acetylcholine binds nicotinic receptors on the motor endplate, causing depolarization; nondepolarizing blockers competitively antagonize, while succinylcholine depolarizes and is metabolized by plasma pseudocholinesterase.

Oxygen content: CaO2 = (1.34 × Hb × SaO2) + (0.003 × PaO2); the dissolved fraction is negligible at atmospheric pressure.

ASA Physical Status: 1 = healthy; 2 = mild systemic disease; 3 = severe systemic disease; 4 = severe disease that is a constant threat to life; 5 = moribund; 6 = brain-dead organ donor; add E for emergency.

Revised Cardiac Risk Index (RCRI) predictors: ischemic heart disease, heart failure, cerebrovascular disease, insulin-dependent diabetes, renal insufficiency (creatinine >2 mg/dL), and high-risk surgery (intraperitoneal, intrathoracic, or suprainguinal vascular).

Mallampati classification (sitting, phonation, tongue protrusion): I = soft palate, uvula, fauces visible; II = soft palate, fauces, uvula partially visible; III = soft palate and base of uvula; IV = hard palate only.

A 12-lead ECG is not routinely indicated for ASA 1-2 patients undergoing low-risk surgery; it is reasonable for patients with known cardiac disease or risk factors undergoing intermediate/high-risk surgery.

Pulmonary function testing: FEV1 < 50% predicted or FEV1/FVC < 0.7 identifies obstructive disease and predicts increased perioperative pulmonary complications.

Fasting guidelines (elective): clear liquids 2 h, breast milk 4 h, infant formula/nonhuman milk 6 h, light meal 6 h, fatty meal/fried food/meat 8 h before anesthesia.

Anticoagulation: neuraxial anesthesia should be avoided until warfarin is stopped ~5 days and INR is normal; DOACs require discontinuation 2-5 days depending on agent and renal function.

Informed consent must include discussion of risks, benefits, alternatives, and the possibility of conversion to general anesthesia; documentation should occur before sedation.

Pipeline gas colors (US): oxygen green, nitrous oxide blue, medical air yellow, nitrogen black, carbon dioxide gray; cylinder colors may differ from pipeline colors.

Pin Index Safety System (PISS) prevents misconnection of small cylinders; Diameter Index Safety System (DISS) prevents misconnection of pipeline hoses.

Oxygen flush valve delivers 100% O2 at 35-75 L/min and bypasses the vaporizer; it can cause barotrauma if used with a closed circuit.

Soda lime absorbs CO2: 2 NaOH + CO2 → Na2CO3 + H2O; exhausted absorbent causes rebreathing and hypercapnia; indicator changes from white to violet (ethyl violet).

Pulse oximetry: functional hemoglobin saturation; inaccurate with carboxyhemoglobin (falsely high), methemoglobin (falsely low, ~85%), poor perfusion, motion, and nail polish.

Capnography waveform: phase I (inspiratory baseline), phase II (expiratory upstroke), phase III (alveolar plateau), phase IV (inspiratory downstroke); end-tidal CO2 approximates PaCO2 in healthy lungs.

Alarm limits: low peak inspiratory pressure suggests circuit disconnection; high peak pressure suggests obstruction, bronchospasm, or decreased compliance.

Electrical safety: microshock risk with intracardiac catheters; line isolation monitor detects leakage current; grounding is essential for equipment.

Difficult airway cart should include video laryngoscope, supraglottic airways, gum elastic bougie, cricothyrotomy kit, and flexible bronchoscope.

Rapid sequence induction: preoxygenation, cricoid pressure (controversial), induction with rapid-onset agent (e.g., etomidate, propofol, ketamine), and succinylcholine or rocuronium; avoid positive-pressure ventilation until airway secured.

Difficult mask ventilation predictors: age >55, BMI >30, edentulous, beard, Mallampati III/IV, limited jaw protrusion, snoring.

Difficult laryngoscopy predictors: Mallampati III/IV, thyromental distance <6 cm, mouth opening <3 cm, limited neck extension, short thick neck, large tongue.

Failed intubation algorithm: call for help, maintain oxygenation, consider supraglottic airway, video laryngoscopy, fiberoptic intubation, or surgical airway; limit attempts to avoid airway trauma.

Laryngeal mask airway (LMA) sits over the laryngeal inlet; contraindicated in full stomach, morbid obesity, and low pulmonary compliance; leak pressure usually 20-30 cm H2O.

Total intravenous anesthesia (TIVA) with propofol/remifentanil provides rapid recovery and reduced postoperative nausea; requires reliable IV access and monitoring for awareness.

Minimum alveolar concentration (MAC) is reduced by hypothermia, pregnancy, opioids, sedatives, and age (approximately 6% decrease per decade after age 40).

Laryngospasm management: 100% oxygen, jaw thrust, gentle positive pressure, deepen anesthesia; if persistent, succinylcholine 0.5-1 mg/kg IV or 4 mg/kg IM.

Postoperative nausea and vomiting (PONV) risk factors: female sex, nonsmoker, history of PONV/motion sickness, use of opioids; Apfel score 0-4 guides prophylaxis.

Local anesthetic systemic toxicity (LAST): stop injection, call for help, airway management, benzodiazepines for seizures, and lipid emulsion 1.5 mL/kg bolus followed by infusion 0.25 mL/kg/min.

Maximum recommended doses (without epinephrine): lidocaine 4.5 mg/kg (7 mg/kg with epi), bupivacaine 2.5 mg/kg, ropivacaine 3 mg/kg, mepivacaine 5 mg/kg.

Spinal anesthesia: local anesthetic injected into subarachnoid space; onset 5-10 min; complications include hypotension, bradycardia, postdural puncture headache, and cauda equina syndrome (rare).

Epidural anesthesia: catheter placed in epidural space; test dose with lidocaine 1.5% + epinephrine 1:200,000 (3 mL) to detect intravascular or intrathecal placement.

Interscalene brachial plexus block reliably anesthetizes the shoulder and upper arm but spares the ulnar nerve and causes phrenic nerve palsy in nearly 100% of patients.

Adductor canal block provides primarily sensory block of the medial thigh and knee with less quadriceps weakness than femoral nerve block.

Transversus abdominis plane (TAP) block provides somatic analgesia for anterior abdominal wall; does not cover visceral pain.

Postdural puncture headache: positional, worse upright; conservative treatment (caffeine, hydration); epidural blood patch is definitive if persistent.

Mean arterial pressure (MAP) = (SBP + 2×DBP)/3; goal MAP generally ≥65 mmHg to maintain organ perfusion.

Stroke volume variation (SVV) >13% and pulse pressure variation (PPV) >13% predict fluid responsiveness in mechanically ventilated patients with sinus rhythm.

Oxygen delivery (DO2) = cardiac output × CaO2 × 10; normal ~1000 mL/min; oxygen consumption (VO2) ~250 mL/min.

Hypoxemia management: increase FiO2, recruit lungs with PEEP, check circuit, suction, verify endotracheal tube position, and consider bronchoscopy.

Hypercapnia causes cerebral vasodilation and increased intracranial pressure; permissive hypercapnia should be avoided in head injury.

Cardiac output monitoring: thermodilution (pulmonary artery catheter), arterial waveform analysis (FloTrac, PiCCO), esophageal Doppler, and transthoracic/transesophageal echocardiography.

Intraoperative hypotension is associated with myocardial injury, acute kidney injury, and mortality; treat based on etiology (hypovolemia, vasodilation, pump failure).

Lung-protective ventilation: tidal volume 6-8 mL/kg predicted body weight, PEEP 5-10 cm H2O, plateau pressure <30 cm H2O, driving pressure <15 cm H2O.

One-lung ventilation: use double-lumen tube or bronchial blocker; confirm position with fiberoptic bronchoscopy; treat hypoxemia with PEEP to dependent lung, CPAP to nondependent lung, and recruitment.

Cardiac surgery: maintain MAP >65 mmHg, avoid tachycardia, and monitor for ischemia; cardiopulmonary bypass causes systemic inflammatory response and coagulopathy.

Neuroanesthesia: maintain cerebral perfusion pressure (CPP = MAP - ICP) >60 mmHg; hyperventilation to PaCO2 30-35 mmHg temporarily reduces ICP.

Obstetric anesthesia: left uterine displacement after 20 weeks gestation; aspiration prophylaxis with nonparticulate antacid and H2 blocker; avoid aortocaval compression.

Pediatric anesthesia: weight-based dosing; uncuffed endotracheal tubes may be used in children <8 years; laryngeal mask airway size based on weight; bradycardia common with hypoxia.

Ambulatory anesthesia: prioritize rapid-onset, short-duration agents (propofol, remifentanil, desflurane, sevoflurane); ensure adequate analgesia and antiemetic prophylaxis for discharge.

Thoracic surgery: protective lung ventilation to the dependent lung; avoid high tidal volumes; monitor for bronchospasm and air leaks.

Neuraxial anesthesia in obstetrics: spinal-induced hypotension treated with fluids, phenylephrine, or ephedrine; ephedrine may cause fetal acidosis.

Postoperative respiratory failure: define by PaO2/FiO2 <300 or need for mechanical ventilation; common causes include atelectasis, aspiration, pneumonia, pulmonary edema, and opioid-induced hypoventilation.

Sepsis-3 definition: life-threatening organ dysfunction caused by dysregulated host response to infection; organ dysfunction defined by SOFA score increase ≥2.

Septic shock: sepsis with vasopressor requirement to maintain MAP ≥65 mmHg and lactate >2 mmol/L despite adequate fluid resuscitation.

Acute respiratory distress syndrome (ARDS) Berlin criteria: onset within 1 week, bilateral opacities, PaO2/FiO2 ≤300 with PEEP ≥5 cm H2O, not fully explained by cardiac failure.

Management of LAST in ICU: supportive care, lipid emulsion, and monitoring for rebound toxicity; avoid vasopressors if possible until lipid given.

Postoperative delirium risk factors: advanced age, cognitive impairment, sensory deprivation, pain, sleep deprivation, and polypharmacy; use nonpharmacologic prevention.

Enhanced recovery after surgery (ERAS): multimodal analgesia, early mobilization, early enteral nutrition, and avoidance of prolonged fasting and drains.

Acute kidney injury (AKI) KDIGO criteria: increase in serum creatinine ≥0.3 mg/dL within 48 h or urine output <0.5 mL/kg/h for 6 h.

Neuropathic pain is characterized by burning, shooting, or electric shock-like sensations, allodynia, and hyperalgesia; first-line medications include gabapentinoids, tricyclic antidepressants, and SNRIs.

Opioid-induced hyperalgesia: paradoxical increase in pain sensitivity with escalating opioid doses; managed by opioid rotation or tapering.

Complex regional pain syndrome (CRPS): type I without nerve injury, type II with nerve injury; features include disproportionate pain, edema, skin changes, and motor dysfunction.

Trigeminal neuralgia: paroxysmal lancinating facial pain; first-line treatment carbamazepine; surgical options include microvascular decompression.

Chronic low back pain: multimodal approach including physical therapy, cognitive behavioral therapy, and interventional procedures (epidural steroid injection, radiofrequency ablation).

Opioid conversion: morphine 10 mg PO ≈ oxycodone 5 mg PO ≈ hydromorphone 2 mg PO ≈ fentanyl 25 mcg transdermal/h; use equianalgesic tables cautiously.

Pain assessment tools: numeric rating scale (NRS), visual analog scale (VAS), and faces pain scale for children or cognitively impaired adults.

Myofascial pain syndrome: trigger points with referred pain; treated with trigger point injections, dry needling, and physical therapy.

Informed consent: patient must have decision-making capacity, be informed of risks, benefits, alternatives, and be free of coercion; surrogate decision-makers act when capacity is lost.

Do-not-resuscitate (DNR) orders: discuss and document perioperative DNR status; may be suspended during anesthesia and surgery after discussion with patient/surrogate.

HIPAA privacy rule protects individually identifiable health information; permitted disclosures include treatment, payment, and health care operations, and as required by law.

Malpractice: four elements must be proven-duty, breach of duty, causation, and damages; documentation is critical for defense.

Conflict of interest: disclose financial relationships with industry; avoid gifts that could influence clinical decisions.

Billing and coding: anesthesia time starts when the anesthesia provider begins preparing the patient and ends when the patient is transferred to postanesthesia care.

Patient safety: report adverse events and near misses through institutional reporting systems; root cause analysis identifies system failures.

Professionalism: maintain competence through continuing medical education, adhere to ASA practice guidelines, and treat colleagues and patients with respect.