Arab Board Anesthesia Final Written key terms

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 and is reduced by obesity, pregnancy, supine posture, and restrictive lung disease.

The lung volume at which small dependent airways begin to close during expiration. When closing capacity exceeds functional residual capacity, airway closure occurs during tidal breathing, producing shunt and hypoxemia, especially in the elderly, obese, and supine patients.

Continued oxygen uptake from the alveoli into blood during apnea, driven by the mass flow of oxygen down its concentration gradient while carbon dioxide accumulates. It prolongs safe apnea time when a patent upper airway and high-flow oxygen are maintained.

Administration of high inspired oxygen before induction of anesthesia to replace alveolar nitrogen with oxygen, maximizing the body's oxygen stores. It extends the safe apnea period and is a key step in airway crisis prevention.

The alveolar concentration of an inhaled anesthetic at one atmosphere that prevents purposeful movement in 50 percent of subjects in response to a standardized noxious stimulus. It allows comparison of potency among volatile agents and is modified by age, temperature, pregnancy, and adjuvant drugs.

The time required for the plasma concentration of an intravenously infused drug to fall by half after the infusion is stopped, measured from the moment of cessation. It lengthens with longer infusion duration for lipophilic drugs and guides recovery prediction after total intravenous anesthesia.

The estimated concentration of a drug at its site of action, modeled from plasma pharmacokinetics and equilibration delay. Target-controlled infusion systems use it to titrate hypnotic and opioid delivery to a desired clinical endpoint.

The phenomenon in which rapid uptake of a high-concentration gas such as nitrous oxide increases the alveolar concentration of a concurrently administered volatile agent, accelerating its equilibration. It results from alveolar volume contraction during brisk gas uptake.

A transient fall in alveolar oxygen partial pressure at the end of nitrous oxide anesthesia, caused by rapid efflux of nitrous oxide from blood into alveoli and dilution of alveolar gases. It is prevented by administering high inspired oxygen during emergence.

A bedside airway assessment that grades visible oropharyngeal structures with the patient seated, mouth open, and tongue protruded. Higher classes indicate reduced visibility of the uvula and pharynx and predict greater difficulty with direct laryngoscopy and mask ventilation.

A four-grade system describing the laryngeal view obtained during direct laryngoscopy, ranging from full visualization of the vocal cords to no glottic structures seen. Higher grades predict difficult intubation and prompt consideration of alternative devices or techniques.

The inability of an unassisted anesthesia provider to maintain oxygen saturation and adequate ventilation by face mask, marked by excessive leakage, need for high gas flows, or absent capnography. It is an independent predictor of difficulty with rescue oxygenation.

An airway adjunct inserted blindly above the glottis to provide ventilation without tracheal intubation. It is used for rescue ventilation, as a conduit for intubation, and for procedures where intubation is unnecessary, but it does not protect against aspiration.

Indirect laryngoscopy using a camera at the blade tip to display glottic structures on a screen, allowing intubation with less cervical spine movement and better views in difficult airways. Success depends on operator familiarity and device-specific technique.

A technique designed to minimize aspiration risk during induction, combining preoxygenation, a rapidly acting induction agent, and a neuromuscular blocker with avoidance of positive-pressure ventilation before intubation. Cricoid pressure may be applied according to local protocol.

A modified gamma-cyclodextrin that encapsulates and inactivates aminosteroid neuromuscular blockers, reversing even deep rocuronium or vecuronium blockade within minutes. It enables rapid recovery and is useful in cannot-intubate cannot-ventilate situations.

The ratio of the fourth to the first evoked muscle twitch in response to four supramaximal stimuli delivered to a peripheral nerve. A ratio of 0.9 or greater indicates adequate recovery from neuromuscular blockade and reduces residual paralysis risk.

Persisting weakness after anesthesia due to incomplete reversal of muscle relaxants, defined by a train-of-four ratio below 0.9. It is associated with airway obstruction, aspiration, and postoperative pulmonary complications and is prevented by quantitative monitoring and adequate reversal.

The continuous display of inspired and expired carbon dioxide over time, providing information on ventilation, airway patency, and perfusion. Its shape confirms tracheal placement, detects disconnection or obstruction, and can suggest bronchospasm or low cardiac output.

The partial pressure of carbon dioxide measured at the end of expiration, approximating alveolar and arterial values in healthy lungs. It guides ventilation, confirms tracheal intubation, and falls abruptly with low pulmonary blood flow or cardiac arrest.

Inadvertent placement of a tracheal tube into the esophagus, resulting in absent or diminishing exhaled carbon dioxide, gastric insufflation, and hypoxemia if unrecognized. It is excluded by sustained capnography plus clinical signs and is managed by removal and reoxygenation.

The difference between mean arterial pressure and intracranial pressure, representing the driving pressure for cerebral blood flow. It is targeted in neuroanesthesia and after head injury, with typical goals around 60 to 70 millimeters of mercury in adults.

The intrinsic ability of an organ's vasculature to maintain relatively constant blood flow across a range of perfusion pressures. In the brain it is impaired by trauma, ischemia, and some anesthetics, making perfusion pressure-dependent flow more likely.

The pressure exerted within the rigid cranial vault by brain tissue, cerebrospinal fluid, and blood. Sustained elevation reduces cerebral perfusion and risks herniation, so anesthesia care avoids factors that raise it and treats it with positioning, hyperventilation, and osmotic agents.

A flow-directed catheter placed through the right heart into the pulmonary artery to measure cardiac output and filling pressures. Its use has declined in favor of less invasive monitoring because outcome benefit is unproven in many populations.

Ultrasound imaging of the heart from a probe in the esophagus, providing real-time assessment of ventricular function, valves, and volume status. It is central to cardiac surgery and increasingly used for hemodynamic rescue in critical care.

The percentage change in stroke volume across the respiratory cycle during controlled positive-pressure ventilation, used as a dynamic index of fluid responsiveness. Values above roughly 13 percent suggest that a fluid bolus will increase cardiac output, provided rhythm and ventilation are stable.

A perioperative strategy in which fluid administration is titrated to dynamic measures of cardiac output or stroke volume rather than fixed volumes. It aims to optimize tissue perfusion while avoiding both hypovolemia and fluid overload.

A multidisciplinary pathway combining preoperative counseling, opioid-sparing analgesia, early feeding and mobilization, and evidence-based perioperative care to shorten hospital stay and reduce complications. Anesthesia practice within it emphasizes regional techniques and avoidance of unnecessary drains and catheters.

The combined use of two or more analgesic agents or techniques with different mechanisms to improve pain relief while reducing individual drug doses and side effects. It is a cornerstone of opioid-sparing perioperative care.

A regional technique in which local anesthetic is deposited between the internal oblique and transversus abdominis muscles to block somatic nerves supplying the anterior abdominal wall. It provides visceral-sparing analgesia for abdominal incisions and is often used with multimodal regimens.

A dose-related syndrome of neurological excitation followed by cardiovascular depression after local anesthetic absorption or inadvertent intravascular injection. Management includes airway support, benzodiazepines for seizures, and lipid emulsion rescue for cardiac arrest.

Extensive neuraxial blockade reaching the cervical cord or brainstem, causing hypotension, bradycardia, apnea, and loss of consciousness. It is a rare complication of spinal or epidural anesthesia requiring immediate airway and circulatory support.

A postural headache that worsens on standing and improves when lying flat, caused by cerebrospinal fluid leakage through a dural puncture. It is treated conservatively, with caffeine or an epidural blood patch for persistent cases.

Bleeding into the epidural space that can compress the spinal cord, presenting with progressive back pain, motor weakness, or bladder dysfunction after neuraxial procedures. Urgent imaging and surgical decompression are needed to prevent permanent deficit.

An inherited hypermetabolic crisis triggered by volatile anesthetics and depolarizing muscle relaxants, marked by rising temperature, rigidity, hypercapnia, and tachycardia. Treatment requires stopping triggers, dantrolene, aggressive cooling, and management of hyperkalemia and arrhythmias.

A severe systemic hypersensitivity reaction causing bronchospasm, hypotension, urticaria, and airway edema, often to antibiotics, neuromuscular blockers, or latex. Epinephrine is the first-line treatment alongside fluids and withdrawal of the trigger.

Chemical lung injury from inhalation of gastric contents, causing bronchospasm, hypoxemia, and a radiographic infiltrate typically within hours. Management is supportive with airway protection, oxygen, and lung-protective ventilation; antibiotics are reserved for suspected infection.

Collapse of lung tissue causing loss of aerated alveoli and intrapulmonary shunt, common after induction of anesthesia and in the supine position. Prevention includes recruitment maneuvers, positive end-expiratory pressure, and early mobilization.

Myocardial injury with ischemic features occurring during or after surgery, most often within the first 48 hours. It frequently presents without chest pain and is detected by troponin surveillance and electrocardiography in at-risk patients.

A validated tool estimating the risk of major cardiac complications after noncardiac surgery using six clinical factors including ischemic heart disease, heart failure, cerebrovascular disease, diabetes, renal impairment, and high-risk surgery. It guides preoperative testing and shared decision-making.

Evaluation of a patient's ability to perform physical activity, commonly expressed in metabolic equivalents, to estimate perioperative cardiac reserve. Poor capacity predicts complications and helps decide whether further cardiac testing adds value.

A structured, stepwise plan for managing unanticipated difficulty with ventilation, intubation, or rescue oxygenation. It prioritizes oxygen delivery, limits repeated attempts, and defines triggers for supraglottic rescue, surgical airway, or waking the patient.

An outcome in patient safety taxonomy describing permanent or long-term injury attributable to healthcare management rather than the underlying disease. It is used in incident analysis to grade severity and target system improvements.

A structured peer review meeting in which adverse events and deaths are examined to identify system failures and educational opportunities. It supports a nonpunitive safety culture and quality improvement rather than individual blame.

The process of disclosing material risks, benefits, and alternatives of a proposed intervention and confirming the patient's voluntary agreement. In anesthesia it includes discussion of technique, awareness risk, and regional versus general options.