RAA flashcards

31 cards. Read the term and the definition here. The deck at the top of this page is optional.

MAC definition

Minimum alveolar concentration at 1 atm that prevents movement in 50% of patients to a standard surgical stimulus; used to compare potency of volatile anesthetics.

Blood oxygen content formula

CaO2 = (1.34 × hemoglobin × SaO2) + (0.003 × PaO2). The dissolved fraction is small, so anemia substantially lowers oxygen delivery despite normal saturation.

Oxyhemoglobin curve right shift

Acidosis, hypercapnia, hyperthermia, and increased 2,3-DPG shift the curve right, reducing hemoglobin affinity for oxygen and enhancing tissue unloading.

Propofol mechanism

Propofol potentiates GABA-A receptor chloride currents, producing rapid hypnosis; it also causes vasodilation and myocardial depression, leading to dose-dependent hypotension.

ASA physical status classes

I healthy; II mild systemic disease; III severe systemic disease; IV constant threat to life; V moribund; VI brain-dead organ donor. Add E for emergency surgery.

Difficult airway predictors

Mallampati III-IV, thyromental distance under 6 cm, interincisor opening under 3 cm, limited neck extension, and short thick neck each raise difficulty risk.

Revised Cardiac Risk Index

Six predictors each score one point: ischemic heart disease, heart failure, cerebrovascular disease, insulin-treated diabetes, creatinine above 2 mg/dL, and high-risk surgery.

Preoperative fasting intervals

Clear liquids 2 hours, breast milk 4 hours, and light solids 6 hours before elective anesthesia in healthy patients; longer intervals apply to fatty or fried meals.

Oxygen failure safety device

When oxygen supply pressure falls, the device shuts off nitrous oxide and other hypoxic gases and sounds an alarm, preventing delivery of a hypoxic mixture.

Oxygen flush valve

A bypass valve that delivers 35-75 L/min of 100% oxygen directly to the breathing circuit, bypassing the flowmeters and vaporizers.

Capnography phase III

The alveolar plateau reflects alveolar gas composition; its slope rises with obstructive lung disease, and its peak is the end-tidal CO2 value.

Pulse oximetry limitations

Readings are unreliable with poor perfusion, motion artifact, and dyshemoglobinemias; carboxyhemoglobin reads falsely high and methemoglobinemia trends toward 85%.

Difficult mask ventilation predictors

MOANS: mask seal difficulty, obesity, age over 55, no teeth, and snoring or stiff lungs; two or more predictors warrant preparation for supraglottic rescue.

Confirmation of intubation

Continuous waveform capnography is the standard confirmation; bilateral breath sounds and chest rise are adjuncts, and an esophageal detector device is not definitive.

Rapid sequence induction

Rapid induction with a fast-onset agent plus succinylcholine 1-1.5 mg/kg and cricoid pressure, avoiding interposed ventilation in patients at aspiration risk.

Cannot intubate cannot oxygenate

An emergency requiring supraglottic airway rescue and, if oxygenation fails, immediate surgical cricothyrotomy; repeated laryngoscopy attempts worsen hypoxia and trauma.

Etomidate characteristics

Etomidate 0.2-0.3 mg/kg provides hemodynamic stability but transiently inhibits 11-beta-hydroxylase, suppressing cortisol synthesis for 24-48 hours.

Ketamine properties

Ketamine 1-2 mg/kg IV antagonizes NMDA receptors, producing dissociative anesthesia with analgesia and sympathetic stimulation; caution with uncontrolled hypertension and raised intracranial pressure.

Succinylcholine contraindications

Avoid in hyperkalemia, burns or denervation older than 24-48 hours, malignant hyperthermia susceptibility, and known pseudocholinesterase deficiency.

Sugammadex reversal dosing

Sugammadex 2 mg/kg reverses moderate rocuronium block, 4 mg/kg reverses deep block, and 16 mg/kg is used for immediate reversal after a large intubating dose.

Lidocaine maximum dose

Lidocaine maximum is 4.5 mg/kg plain and 7 mg/kg with epinephrine; bupivacaine maximum is 2.5-3 mg/kg and it is more cardiotoxic than lidocaine.

Mean arterial pressure formula

MAP = (systolic + 2 × diastolic) / 3. A MAP of 65 mmHg is the usual lower autoregulation threshold for vital organ perfusion.

Phenylephrine use

A pure alpha-1 agonist given as 40-100 mcg IV boluses to treat anesthesia-related vasodilation; it raises blood pressure and may cause reflex bradycardia.

Fluid responsiveness threshold

Pulse pressure variation above 13% or stroke volume variation above 13% in a mechanically ventilated patient predicts that cardiac output will rise with a fluid bolus.

Malignant hyperthermia treatment

Stop triggering agents, give dantrolene 2.5 mg/kg IV repeated as needed, hyperventilate with 100% oxygen, and actively cool while treating hyperkalemia and acidosis.

Anaphylaxis epinephrine dose

Give epinephrine 10-100 mcg IV boluses or 0.5 mg intramuscularly, with fluids, 100% oxygen, and antihistamines; vasopressin may be added for refractory shock.

Lipid emulsion for LAST

For local anesthetic systemic toxicity, give 20% lipid emulsion 1.5 mL/kg bolus followed by 0.25 mL/kg/min infusion; avoid vasopressin and calcium channel blockers.

Aldrete score components

Activity, respiration, circulation, consciousness, and oxygen saturation are each scored 0-2; a total of 9-10 is typically required for postanesthesia care unit discharge.

Naloxone titration

Give naloxone 40-100 mcg IV titrated to restore adequate ventilation rather than full arousal; monitor for renarcotization because naloxone has a shorter half-life than most opioids.

Postoperative shivering treatment

Forced-air warming and meperidine 12.5-25 mg IV reduce shivering, which otherwise increases oxygen consumption and may precipitate myocardial ischemia.

Multimodal analgesia

Combining acetaminophen, NSAIDs, regional blocks, and opioids at reduced doses improves pain control while limiting opioid-related respiratory depression, nausea, and sedation.