Iraqi Board Anesthesia key terms

The volume of gas remaining in the lungs after a normal passive expiration. It balances elastic lung recoil against chest wall outward pull, keeps alveoli open, and acts as the oxygen reservoir during apnea after preoxygenation.

The lung volume at which small airways begin to close during expiration. When it exceeds functional residual capacity, as in supine, obese, or elderly patients, shunting and hypoxemia develop because dependent airways close during tidal breathing.

Collapse of alveoli causing loss of aerated lung and intrapulmonary shunting. It develops rapidly after induction from reduced functional residual capacity, absorbed oxygen, and compression, and is a leading cause of early postoperative hypoxemia.

A brief sustained increase in airway pressure used to reopen collapsed alveoli. It is followed by adequate positive end-expiratory pressure to keep them open; risks include transient hypotension and barotrauma in patients with bullous disease.

Airway pressure maintained above atmospheric at end-expiration. It increases functional residual capacity, reduces atelectasis and shunt, and improves oxygenation, but raises intrathoracic pressure and can impair venous return and cardiac output.

The total oxygen transported to tissues per minute, calculated as cardiac output multiplied by arterial oxygen content. It depends on hemoglobin concentration, saturation, and flow, and falls short of demand in shock or severe anemia.

The volume of oxygen taken up by tissues per minute. It rises with fever, shivering, sepsis, and pain; when delivery cannot meet consumption, anaerobic metabolism and lactic acidosis develop.

The oxygen saturation of blood in the pulmonary artery, reflecting the balance between whole-body oxygen delivery and consumption. A low value suggests inadequate delivery or increased demand; normal is roughly 65 to 75 percent.

The alveolar concentration of an inhaled anesthetic that prevents movement in 50 percent of patients in response to a standard surgical stimulus. It allows comparison of potency and is reduced by age, hypothermia, pregnancy, opioids, and sedatives.

The time for plasma concentration of a drug to fall by half after stopping an infusion, determined by how long the infusion ran. It is short for remifentanil and propofol and long for drugs with slow redistribution or fat accumulation.

The estimated concentration of a drug at its site of action, linked to plasma concentration by a lag described by the ke0 constant. Target-controlled infusion uses this model so that predicted effect matches clinical response.

A pump system that delivers an intravenous drug under model-based control to achieve and maintain a chosen plasma or effect-site concentration. It accounts for distribution and elimination, but accuracy depends on the pharmacokinetic model chosen.

The accelerated rise in alveolar concentration of a carrier gas when a large volume of a highly soluble gas such as nitrous oxide is taken up simultaneously. It results from concentration and volume effects in the alveolus.

Transient fall in alveolar oxygen tension after nitrous oxide is discontinued, because the gas diffuses rapidly from blood into alveoli and dilutes oxygen. It is prevented by giving high inspired oxygen at emergence.

Prolonged paralysis after succinylcholine caused by deficient or atypical plasma pseudocholinesterase. It is suspected when paralysis outlasts the expected minutes, and management is continued sedation, ventilation, and cholinesterase testing of the patient and family.

A non-depolarizing pattern of neuromuscular blockade that develops after repeated or large doses of succinylcholine. It is characterized by fade on train-of-four and tetanic stimulation, and recovery is prolonged.

The ratio of the fourth to the first evoked twitch in response to four supramaximal stimuli. A ratio above 0.9 at the adductor pollicis indicates adequate recovery of neuromuscular function and reduces residual paralysis risk.

Persisting weakness after reversal due to incomplete recovery of neuromuscular function. It raises the risk of aspiration, airway obstruction, and postoperative pulmonary complications, and is detected by quantitative monitoring rather than clinical signs alone.

A modified cyclodextrin that encapsulates rocuronium and vecuronium, rapidly reversing even deep blockade. It allows fast recovery after a large rocuronium dose but can cause anaphylaxis and interferes with hormonal contraceptive efficacy.

A severe IgE or non-IgE mediated hypersensitivity reaction presenting with hypotension, bronchospasm, and rash. Common triggers include neuromuscular blockers, antibiotics, chlorhexidine, and latex; treatment is adrenaline, fluids, and stopping the trigger.

A mast cell enzyme measured after a suspected anaphylactic reaction. Levels peak around one hour after onset and help confirm the diagnosis when compared with a baseline sample taken later; normal levels do not exclude the diagnosis.

The inability of an unassisted operator to maintain oxygen saturation using a face mask with or without airway adjuncts. Predictors include obesity, edentulous state, beard, and age over 55, and it often coexists with difficult intubation.

A life-threatening failure to secure an airway by either intubation or any oxygenating rescue technique. It mandates immediate invasive rescue, typically front-of-neck access, and is managed by a rehearsed emergency plan.

An airway that sits above the larynx and seals the pharynx to deliver ventilation without tracheal intubation. It is useful for rescue ventilation and short procedures but does not protect against aspiration.

The administration of high inspired oxygen before induction to replace nitrogen in the functional residual capacity. It prolongs the safe apnea time and is essential before rapid sequence induction in patients at risk of desaturation.

A technique that minimizes the interval between loss of protective reflexes and tracheal intubation to reduce aspiration risk. It typically uses preoxygenation, a fast-acting induction agent, and a neuromuscular blocker with cricoid pressure sometimes applied.

Chemical injury to the lung from inhalation of gastric contents, causing bronchospasm, hypoxemia, and infiltrates, especially with low pH and large volume. Management is supportive with suction, oxygen, and ventilation as needed.

Injection of local anesthetic into the subarachnoid space to block nerve roots. It produces rapid, dense blockade but causes sympathetic block with hypotension, and is avoided in hypovolemia and raised intracranial pressure.

Injection of local anesthetic into the epidural space, blocking nerve roots outside the dura. It allows catheter-based titration for labor or postoperative analgesia; risks include intravascular or intrathecal misplacement and patchy block.

A postural headache worse on standing and relieved by lying flat, caused by cerebrospinal fluid leak after dural puncture. It is treated initially with hydration, caffeine, and analgesia, and definitively with an epidural blood patch.

A dose-related syndrome of neurological excitation followed by seizures and cardiovascular collapse from local anesthetic overdose or accidental intravascular injection. Treatment includes airway support and intravenous lipid emulsion.

A local anesthetic solution with added epinephrine that slows systemic absorption, prolongs block, and reduces bleeding. It is avoided in digital and other end-arterial territories and used cautiously in patients with severe cardiac disease.

Continuous measurement and display of exhaled carbon dioxide concentration over time. It confirms tracheal tube placement, detects disconnection, obstruction, and low cardiac output, and is a mandatory monitor during general anesthesia.

The peak carbon dioxide concentration at the end of expiration, approximating alveolar and arterial carbon dioxide. Sudden loss suggests esophageal intubation or disconnection, while a rise suggests hypoventilation or absorbed carbon dioxide.

A noninvasive estimate of arterial oxygen saturation using differential light absorption of pulsatile blood. It is affected by poor perfusion, motion, dyshemoglobinemias, and ambient light, and does not measure ventilation.

A core temperature below 36 degrees Celsius during surgery, caused by anesthesia-induced vasodilation and heat loss. It increases bleeding, surgical site infection, cardiac events, and shivering, and is prevented by active warming.

A pharmacogenetic hypermetabolic crisis triggered by volatile anesthetics and succinylcholine, marked by rising temperature, rigidity, hypercarbia, and acidosis. Treatment is dantrolene, stopping triggers, hyperventilation, cooling, and treating hyperkalemia.

A structured perioperative pathway combining evidence-based elements such as carbohydrate loading, opioid-sparing analgesia, early feeding, and early mobilization. It reduces length of stay and complications compared with traditional care.

The use of two or more analgesic agents or techniques acting by different mechanisms to improve pain relief and reduce opioid requirements and side effects. Common components include paracetamol, NSAIDs, local anesthetics, and opioids.

A system allowing the patient to self-administer small intravenous opioid doses on demand within programmed limits. It improves satisfaction and titration but requires monitoring for respiratory depression and programming errors.