Iraqi Board Anesthesia flashcards

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

Context-sensitive half-time

Time for plasma drug concentration to fall by 50% after stopping an infusion. Short for remifentanil regardless of duration; longer for propofol and fentanyl with prolonged infusion.

Volume of distribution

Apparent volume relating total drug dose to plasma concentration (Vd = dose/concentration). Large Vd means extensive tissue uptake and longer elimination half-life.

Oxygen content formula

CaO2 = (1.34 × haemoglobin × SaO2) + (0.003 × PaO2), expressed in mL O2 per dL blood. The dissolved fraction contributes little at atmospheric pressure.

Laplace law in alveoli

Alveolar pressure P = 2T/r, where T is surface tension and r is radius. Small alveoli have higher collapsing pressure unless surfactant reduces surface tension.

Nerve fibre block order

Local anaesthetics block small unmyelinated fibres first: sympathetic B, then pain C and A-delta, then touch A-beta, and motor A-alpha last. Explains differential blockade.

Revised Cardiac Risk Index

Six predictors of perioperative cardiac events: ischaemic heart disease, heart failure, cerebrovascular disease, insulin-treated diabetes, creatinine >177 µmol/L, and high-risk surgery.

METs threshold

Four metabolic equivalents, equivalent to climbing a flight of stairs or heavy housework, indicates adequate functional capacity for most surgery.

STOP-BANG score

Eight yes/no items: snoring, tiredness, observed apnoea, pressure, BMI >35, age >50, neck circumference >40 cm, male sex. Score ≥5 indicates high OSA risk.

Dual antiplatelet deferral

After drug-eluting coronary stent placement, defer elective surgery for 6 months; after bare-metal stent, 1 month, unless the risk of waiting exceeds bleeding risk.

3-3-2 rule

Airway assessment: 3 fingerbreadths mouth opening, 3 fingerbreadths thyromental distance, 2 fingerbreadths hyoid-to-thyroid cartilage distance. Predicts difficult laryngoscopy.

Cormack-Lehane grade

Laryngoscopic view: grade 1 full vocal cords, grade 2 partial cords, grade 3 epiglottis only, grade 4 neither epiglottis nor soft palate visible.

Cannot intubate cannot oxygenate

Failure to intubate and failure to maintain oxygenation despite supraglottic airway and mask techniques. Requires emergency front-of-neck access, usually scalpel-bougie-tube cricothyroidotomy.

Suxamethonium contraindications

Hyperkalaemia, burns or denervation beyond 24-48 hours, malignant hyperthermia susceptibility, pseudocholinesterase deficiency, and raised intraocular pressure where relevant.

Minimum alveolar concentration

Alveolar concentration at one atmosphere preventing movement in 50% of patients to a standard stimulus. Sevoflurane ≈2%, isoflurane ≈1.15%, desflurane ≈6%.

Epidural test dose

3 mL lidocaine 1.5% with epinephrine 1:200,000. Heart rate rise >20 bpm or systolic pressure rise >15-20 mmHg suggests intravascular placement.

Local anaesthetic maximum doses

Lidocaine 3 mg/kg plain and 7 mg/kg with adrenaline; bupivacaine 2 mg/kg; ropivacaine 3 mg/kg; levobupivacaine 2.5 mg/kg.

Lipid emulsion for LAST

Treat local anaesthetic systemic toxicity with 20% lipid emulsion: 1.5 mL/kg bolus, then 0.25 mL/kg/min infusion, alongside airway support and seizure control.

Train-of-four ratio

Ratio of the fourth to first twitch in train-of-four stimulation. A ratio ≥0.9 at the adductor pollicis indicates adequate neuromuscular recovery and safe extubation.

Bispectral index target

Processed EEG index from 0 (isoelectric) to 100 (awake). Values 40-60 indicate adequate depth of general anaesthesia and reduce awareness risk.

WHO Surgical Safety Checklist

Three phases: sign-in before induction, time-out before incision, and sign-out before the patient leaves theatre. Reduces surgical morbidity and mortality.

Capnography disconnection

Sudden fall of end-tidal CO2 to zero suggests disconnection, oesophageal intubation, or circuit leak. A rising trace suggests hypoventilation or CO2 absorption.

Aortic stenosis anaesthesia

Maintain sinus rhythm, preload, and systemic vascular resistance. Avoid tachycardia and sudden vasodilation, which cause severe hypotension and myocardial ischaemia.

Pheochromocytoma preparation

Preoperative alpha blockade with phenoxybenzamine for 10-14 days, then beta blockade. Intraoperative hypertensive crisis treated with sodium nitroprusside or phentolamine.

Pulmonary hypertension triggers

Avoid hypoxia, hypercapnia, acidosis, hypothermia, and pain, all of which raise pulmonary vascular resistance and can precipitate right ventricular failure.

ARDS Berlin definition

Acute onset within one week, bilateral opacities, not explained by cardiac failure, and PaO2/FiO2 ≤300 mmHg on PEEP ≥5 cmH2O.

Lung-protective ventilation

Tidal volume 6 mL/kg predicted body weight, plateau pressure ≤30 cmH2O, and driving pressure ≤15 cmH2O to reduce ventilator-induced lung injury.

Septic shock definition

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

Opioid equivalence

Oral morphine 30 mg ≈ oral oxycodone 20 mg ≈ IV morphine 10 mg ≈ IV fentanyl 100 µg. Use for converting between opioids and routes.

Neuropathic pain first line

Gabapentin, pregabalin, amitriptyline, or duloxetine. Tramadol is an alternative. Opioids are not first-line for chronic neuropathic pain.

Adult cardiac arrest basics

Compressions 100-120/min at 5-6 cm depth with full recoil, ratio 30:2, early defibrillation, adrenaline 1 mg every 3-5 min, and amiodarone 300 mg after third shock.

Reversible arrest causes

Four Hs: hypoxia, hypovolaemia, hypo/hyperkalaemia, hypothermia. Four Ts: tension pneumothorax, tamponade, toxins, thromboembolism.

Apfel PONV score

Four predictors, one point each: female sex, non-smoker, history of PONV or motion sickness, and postoperative opioids. Higher scores warrant multimodal prophylaxis.

Malignant hyperthermia treatment

Stop volatile agents and suxamethonium, hyperventilate with 100% oxygen, cool, and give dantrolene 2.5 mg/kg IV repeated to a maximum 10 mg/kg.

Four ethical principles

Autonomy, beneficence, non-maleficence, and justice. Used to structure clinical ethical reasoning and resolve conflicts between patient wishes and clinical recommendations.

Capacity assessment

Patient can understand, retain, weigh, and communicate a decision. If capacity is lacking, act in best interests with the least restrictive option.