AOBA Anesthesiology key terms

The alveolar concentration of an inhaled anesthetic at 1 atmosphere that prevents movement in 50% of patients in response to a standardized surgical stimulus. It is used to compare potency and to titrate volatile agents.

The time required for the plasma concentration of a drug given by continuous infusion to decline by 50% after the infusion is stopped. It lengthens as infusion duration increases for lipophilic drugs such as propofol.

The estimated drug concentration at the site of pharmacologic action, derived from pharmacokinetic models and accounting for the delay between plasma concentration and clinical effect. It guides target-controlled infusion dosing.

The accelerated rise in alveolar concentration of a primary inhaled anesthetic caused by the rapid uptake of a concurrently administered high-solubility gas such as nitrous oxide, which concentrates remaining gases in the alveolus.

The volume of gas remaining in the lungs at the end of a normal passive expiration, equal to expiratory reserve volume plus residual volume. It is the main oxygen reservoir during apnea.

The lung volume at which small airways begin to close during expiration. When it exceeds functional residual capacity, airway closure occurs during tidal breathing, promoting atelectasis and hypoxemia.

Administration of high-inspired oxygen before induction of anesthesia to replace nitrogen in the functional residual capacity, prolonging the safe apnea period before desaturation occurs.

An induction technique designed to minimize aspiration risk, using a rapidly acting induction agent and neuromuscular blocker with minimal cricoid pressure and no interposed ventilation before tracheal intubation.

Application of backward pressure on the cricoid cartilage to compress the upper esophagus and reduce passive regurgitation of gastric contents during induction. Its efficacy and safety are debated.

A structured, stepwise decision pathway for managing unanticipated difficulty with ventilation, supraglottic device placement, or intubation, prioritizing oxygenation and limiting repeated traumatic attempts.

A grading system describing the view of the larynx obtained during direct laryngoscopy, from grade 1 (full glottic view) to grade 4 (no laryngeal structures visible), used to document intubation difficulty.

A device inserted blindly into the pharynx to maintain a patent airway above the glottis, such as a laryngeal mask. It does not protect against aspiration and is an alternative to intubation.

Continuous measurement and display of the carbon dioxide concentration in respired gas, producing a waveform used to confirm tracheal intubation, assess ventilation, and detect circuit disconnection or embolism.

The partial pressure of carbon dioxide measured at the end of expiration, approximating alveolar and arterial values in healthy lungs. It guides ventilator adjustment and reflects cardiac output during resuscitation.

Noninvasive estimation of arterial oxygen saturation using differential light absorption of oxygenated and deoxygenated hemoglobin across a pulsatile vascular bed. It is affected by poor perfusion and abnormal hemoglobins.

A condition in which hemoglobin iron is oxidized to the ferric state, impairing oxygen delivery and causing cyanosis with a saturation gap. Treated with methylene blue in symptomatic cases.

Collapse or incomplete expansion of lung tissue, commonly occurring during general anesthesia from airway closure, absorption of oxygen, and reduced functional residual capacity, contributing to postoperative hypoxemia.

Application of positive pressure during expiration to keep alveoli open, increase functional residual capacity, and improve oxygenation. It can reduce venous return and cardiac output.

The product of cardiac output and arterial oxygen content, representing the total oxygen transported to tissues per minute. It depends on hemoglobin concentration, saturation, and perfusion.

The oxygen saturation of blood in the pulmonary artery, reflecting the balance between systemic oxygen delivery and consumption. Low values suggest inadequate delivery or increased metabolic demand.

A dose-related syndrome from excessive local anesthetic absorption, causing perioral numbness, seizures, arrhythmias, and cardiac arrest. Management includes airway support and lipid emulsion rescue therapy.

Administration of a lipid emulsion as a rescue treatment for severe local anesthetic systemic toxicity, believed to sequester lipophilic drug and restore cardiac function alongside standard resuscitation.

A local anesthetic solution combined with epinephrine to cause vasoconstriction, slowing systemic absorption, prolonging block duration, and reducing peak plasma concentration and toxicity risk.

A postural headache caused by cerebrospinal fluid leakage through a dural puncture, worsened by upright position and relieved by lying flat. Conservative treatment is usual; an epidural blood patch may be needed.

Injection of the patient's own blood into the epidural space to seal a cerebrospinal fluid leak and relieve post-dural puncture headache. It is the definitive treatment for persistent cases.

A pharmacogenetic hypermetabolic crisis triggered by volatile anesthetics or succinylcholine, characterized by rigidity, hyperthermia, and acidosis. Treated by stopping triggers and giving dantrolene.

A muscle relaxant that inhibits calcium release from the sarcoplasmic reticulum and is the specific antidote for malignant hyperthermia, given intravenously in repeated doses until the crisis abates.

Reflex closure of the vocal cords triggered by stimulation of the laryngeal nerves, often during light anesthesia or airway irritation. Managed with positive pressure, deepening anesthesia, or small-dose succinylcholine.

Chemical lung injury from inhalation of gastric contents, causing bronchospasm, hypoxemia, and pulmonary edema. Management is supportive with airway protection, oxygen, and suctioning.

Myocardial injury occurring around surgery, often from supply-demand imbalance rather than plaque rupture, diagnosed by troponin elevation with or without ischemic symptoms or electrocardiographic changes.

Nausea and vomiting occurring after anesthesia and surgery, driven by patient, surgical, and anesthetic factors. Prevention uses multimodal antiemetics targeting different receptor pathways.

A multimodal, evidence-based perioperative care pathway emphasizing opioid-sparing analgesia, early feeding and mobilization, goal-directed fluids, and regional techniques to shorten recovery and hospital stay.

Use of two or more analgesic agents or techniques with different mechanisms to improve pain relief and reduce opioid requirements and their adverse effects.

A reduced analgesic response to opioids after repeated exposure, requiring higher doses for the same effect. It complicates perioperative pain management and may prompt opioid-sparing strategies.

A paradoxical increase in pain sensitivity associated with opioid exposure, distinct from tolerance and withdrawal, that may worsen with dose escalation and improve with opioid reduction.

A chronic pain condition, usually after trauma, marked by disproportionate regional pain with sensory, vasomotor, and trophic changes. Management combines physical therapy, medications, and interventional procedures.

The process of disclosing material risks, benefits, and alternatives of a proposed intervention and obtaining voluntary patient agreement. It is an ethical and legal prerequisite for anesthesia care.

A physician order directing that cardiopulmonary resuscitation not be performed. In the perioperative period it should be reviewed and clarified with the patient or surrogate before anesthesia.

Review of settled malpractice claims to identify patterns of injury and error, informing patient safety improvements in anesthesia practice such as monitoring standards and airway management guidelines.