Arab Board Surgery Part 1 flashcards

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

Recurrent laryngeal nerve

The right recurrent laryngeal nerve loops around the right subclavian artery, while the left loops around the aortic arch at the ligamentum arteriosum; both ascend in the tracheoesophageal groove.

Inguinal canal walls

Anterior wall is external oblique aponeurosis; posterior wall is transversalis fascia reinforced by conjoint tendon; roof is internal oblique and transversus abdominis; floor is the inguinal ligament.

Calot's triangle

Bounded by the cystic duct, the common hepatic duct and the inferior surface of the liver; it contains the cystic artery and the lymph node of Lund, and is dissected during cholecystectomy.

Midgut rotation

Between weeks 6 and 10 the midgut herniates into the yolk stalk, rotates 270 degrees counterclockwise around the superior mesenteric artery and returns to the abdomen, fixing the caecum in the right iliac fossa.

Cardiac output

Cardiac output equals heart rate multiplied by stroke volume; normal values are 4 to 8 litres per minute, and cardiac index divides this by body surface area, normally 2.5 to 4.0 L/min/m².

Anion gap

Anion gap equals sodium minus the sum of chloride and bicarbonate, normally 8 to 12 mEq/L; it rises in ketoacidosis, lactic acidosis, renal failure and poisoning by methanol, ethylene glycol or salicylate.

Oxygen delivery

Oxygen delivery equals cardiac output multiplied by arterial oxygen content, where content is 1.34 × haemoglobin × saturation plus 0.003 × PaO2; normal delivery is roughly 1000 mL per minute.

Virchow's triad

Three conditions predispose to thrombosis: endothelial injury, abnormal or stagnant blood flow, and hypercoagulability; together they explain venous thromboembolism after surgery and immobility.

p53 tumour suppressor

A tumour suppressor that halts the cell cycle for DNA repair or triggers apoptosis after irreparable damage; loss of function allows uncontrolled proliferation and occurs in most human cancers.

Keloid versus hypertrophic scar

Hypertrophic scars stay within the original wound margins and often regress over months; keloids extend beyond the margins, rarely regress and recur frequently after simple excision.

Sepsis-3 criteria

Sepsis is life-threatening organ dysfunction from a dysregulated host response to infection, defined as an acute increase in SOFA score of at least two points in a patient with suspected infection.

Antibiotic prophylaxis timing

Prophylaxis should be given within 60 minutes before skin incision, or within 120 minutes for vancomycin and fluoroquinolones, and redosed intraoperatively according to half-life and blood loss.

Spaulding classification

Equipment is critical if it enters sterile tissue and needs sterilisation, semicritical if it contacts mucosa and needs high-level disinfection, and noncritical if it touches intact skin only.

Necrotising fasciitis

A rapidly spreading necrotising infection of fascia; type I is polymicrobial with aerobes and anaerobes, type II is group A streptococcus often with Staphylococcus aureus; urgent debridement is essential.

Succinylcholine

A depolarising neuromuscular blocker with rapid onset and short duration; it raises serum potassium, intraocular and intragastric pressure and triggers malignant hyperthermia, so it is avoided in burns and spinal injury.

Malignant hyperthermia treatment

Stop triggering agents, give dantrolene 2.5 mg/kg intravenously repeated up to 10 mg/kg, ventilate with 100% oxygen, cool actively, treat hyperkalaemia and arrhythmias, and maintain urine output.

Lidocaine maximum dose

Three milligrams per kilogram without adrenaline and seven milligrams per kilogram with adrenaline; a 1% solution contains 10 mg/mL, and toxicity causes perioral tingling, seizures and then cardiac arrest.

Propofol

An intravenous induction agent with rapid onset and offset that causes dose-dependent hypotension, vasodilatation and apnoea; it is avoided in haemodynamic instability and suspected mitochondrial disease.

Refeeding syndrome

A dangerous intracellular shift of phosphate, potassium and magnesium after nutrition is restarted in a malnourished patient; thiamine is given first and electrolytes are replaced before and during feeding.

Nitrogen balance

Nitrogen balance equals nitrogen intake minus the 24-hour urinary urea nitrogen plus 4 grams; it is positive during growth and recovery and negative in sepsis, trauma and starvation.

Respiratory quotient

The ratio of carbon dioxide produced to oxygen consumed: 1.0 for carbohydrate, 0.8 for protein and 0.7 for fat; a value above 1.0 suggests lipogenesis from overfeeding.

Metabolic response to injury

In Cuthbertson's ebb phase hypovolaemia lowers metabolic rate; the flow phase raises catecholamines, cortisol, glucagon and antidiuretic hormone, producing fever, catabolism, insulin resistance and sodium and water retention.

Wound tensile strength

A sutured wound regains about 5% of normal tensile strength at two weeks, 20 to 30% at one month and 70 to 80% by one year, depending mainly on collagen cross-linking.

Holliday-Segar rule

Daily maintenance fluid is 100 mL/kg for the first 10 kg, 50 mL/kg for the next 10 kg and 20 mL/kg for each kilogram thereafter; hourly this is 4, 2 and 1 mL/kg.

Braided versus monofilament suture

Monofilaments such as nylon and polypropylene resist bacterial colonisation but have memory; braided sutures such as silk and polyglactin handle better but can harbour organisms and potentiate infection.

Haemorrhagic shock classes

Class I loses under 15% blood volume with normal vital signs; class II, 15 to 30%, causes tachycardia and narrow pulse pressure; class III, 30 to 40%, adds hypotension and confusion; class IV exceeds 40%.

Tension pneumothorax

A clinical diagnosis of trapped air causing mediastinal shift and obstructed venous return; treat immediately with needle decompression in the fifth intercostal space anterior axillary line or second space midclavicular, then a chest drain.

Parkland formula

For burns, give 4 mL/kg body weight per percent total body surface area of lactated Ringer's in the first 24 hours, with half in the first 8 hours from the time of injury.

Glasgow Coma Scale

Scores eye opening out of 4, verbal response out of 5 and motor response out of 6, giving a total of 3 to 15; a score of 8 or less indicates need for a definitive airway.

Informed consent elements

Valid consent requires patient capacity, adequate disclosure of risks, benefits and alternatives, comprehension, and voluntariness; consent must be obtained for the specific procedure proposed.

Sensitivity and specificity

Sensitivity is true positives divided by all diseased patients; specificity is true negatives divided by all healthy patients; predictive values, unlike these, change with disease prevalence in the population.

Swiss cheese model

Accidents occur when holes in multiple layers of defence line up, allowing a hazard to reach the patient; safety therefore relies on redundant barriers rather than on individual perfection.