Cambodia Medicine Exit Exam cheat sheet

Acute STEMI: dual antiplatelet (aspirin + P2Y12 inhibitor), anticoagulation, and reperfusion; primary PCI is preferred if achievable within 120 minutes of first medical contact, otherwise fibrinolysis within 12 hours of symptom onset.

Diabetic ketoacidosis: IV 0.9% saline resuscitation, insulin infusion 0.1 U/kg/h started after potassium is known; if K+ <3.3 mmol/L, hold insulin and replace potassium first. Add 10% dextrose when glucose falls below ~14 mmol/L (250 mg/dL).

Heart failure with reduced ejection fraction: quadruple therapy - ARNI/ACE inhibitor, beta-blocker, mineralocorticoid receptor antagonist, SGLT2 inhibitor - plus loop diuretic for congestion.

Cirrhosis ascites: sodium restriction plus spironolactone 100 mg with furosemide 40 mg daily, titrated in a 100:40 ratio; therapeutic paracentesis with albumin 6-8 g per litre removed for large-volume taps.

Nephrotic syndrome: proteinuria >3.5 g/day, albumin <30 g/L, oedema, hyperlipidaemia; in adults, membranous nephropathy and focal segmental glomerulosclerosis are common causes, and renal vein thrombosis is a classic complication.

Hyperkalaemia with ECG changes: IV calcium gluconate first for membrane stabilisation, then insulin-dextrose, salbutamol nebulisation, and sodium bicarbonate if acidotic; dialysis for refractory cases.

Acute upper GI bleed: resuscitate, start a proton pump inhibitor infusion for suspected peptic ulcer bleed, and perform endoscopy within 24 hours; use terlipressin plus antibiotics for suspected variceal bleeding.

Thyroid storm: fever, tachyarrhythmia, agitation, and heart failure; treat with a beta-blocker, thionamide, iodine load given at least 1 hour after the thionamide, and glucocorticoid.

ATLS primary survey sequence: catastrophic haemorrhage control, Airway with cervical spine protection, Breathing, Circulation with haemorrhage control, Disability, Exposure with prevention of hypothermia.

Tension pneumothorax is a clinical diagnosis: immediate needle decompression (2nd intercostal space midclavicular line or 5th intercostal space anterior axillary line) followed by chest tube; never wait for imaging.

Acute appendicitis: migration of pain to right iliac fossa, McBurney point tenderness, and Alvarado score components (migration, anorexia, nausea, tenderness, rebound, fever, leukocytosis, left shift).

Acute mesenteric ischaemia: pain out of proportion to examination; early CT angiography, IV fluids, heparin, and broad-spectrum antibiotics; laparotomy if peritonitis or bowel infarction suspected.

Burns: Parkland formula gives 4 mL/kg per % total body surface area of crystalloid in the first 24 hours, half in the first 8 hours from the time of injury; use the Lund-Browder chart in children.

Small bowel obstruction: IV fluids, nasogastric decompression, and serial examination; operate urgently for strangulation signs - fever, tachycardia, peritoneal signs, rising lactate, or closed-loop pattern on CT.

Open fracture: tetanus prophylaxis, IV antibiotics within 1 hour (cefazolin plus gentamicin for severe contamination), saline irrigation, and temporary stabilisation before definitive fixation.

Shock index (heart rate divided by systolic blood pressure) above 0.9 suggests occult haemorrhage in trauma even when blood pressure appears normal.

Postpartum haemorrhage: uterine atony is the commonest cause; treat with uterine massage, oxytocin, then ergometrine, carboprost, or misoprostol, tranexamic acid 1 g IV within 3 hours, and balloon tamponade or surgery if refractory.

Preeclampsia with severe features: blood pressure ≥160/110 mmHg or symptoms or organ dysfunction; give magnesium sulfate for seizure prophylaxis and deliver after stabilisation at ≥34 weeks.

Magnesium sulfate regimen for eclampsia: 4 g IV loading over 20 minutes plus 10 g IM, then 1 g/h IV infusion or 5 g IM every 4 hours; monitor respiratory rate, reflexes, and urine output; antidote is calcium gluconate.

Ectopic pregnancy: unstable patients need immediate laparotomy; stable patients with unruptured ectopic and low beta-hCG may receive methotrexate if criteria (size <3.5 cm, no fetal cardiac activity, hCG below threshold) are met.

Gestational diabetes screening: 75 g oral glucose tolerance test at 24-28 weeks; thresholds commonly used are fasting ≥5.1, 1-hour ≥10.0, and 2-hour ≥8.5 mmol/L, with any single value diagnostic.

Shoulder dystocia manoeuvres in sequence: McRoberts position, suprapubic pressure, internal rotation (Rubin II or Woods screw), delivery of posterior arm, and episiotomy if needed; never apply fundal pressure.

Cervical cancer screening: HPV testing is the preferred primary screen from age 30; in resource-limited settings, visual inspection with acetic acid or HPV testing with treatment of positives is used.

Ovarian torsion: sudden unilateral pelvic pain with nausea and an enlarged ovary on ultrasound; surgical detorsion with ovarian preservation is the treatment of choice regardless of Doppler findings.

Paediatric weight estimation: approximately 8 kg at 1 year, 2 × (age in years) + 8 kg from 1 to 6 years, and 7 × (age) − 5 over 7 years; use a length-based tape in emergencies.

WHO severe acute malnutrition criteria: weight-for-height z-score below −3, mid-upper arm circumference <115 mm, or bilateral pitting oedema; treat hypoglycaemia and hypothermia first, then F-75, and add F-100/RUTF during rehabilitation.

Neonatal resuscitation: warm, dry, stimulate, position airway; positive pressure ventilation with room air at 40-60 breaths/min if apnoeic or heart rate <100; chest compressions if heart rate <60 after effective ventilation.

Paediatric dehydration: WHO plan A for no dehydration, plan B with oral rehydration solution 75 mL/kg over 4 hours for some dehydration, and plan C with IV Ringer's lactate 100 mL/kg for severe dehydration.

Kawasaki disease: fever ≥5 days plus 4 of 5 features (conjunctivitis, mucosal changes, rash, extremity changes, cervical lymphadenopathy); treat with IV immunoglobulin 2 g/kg and high-dose aspirin; risk of coronary aneurysm.

Croup: barking cough, stridor, hoarseness; treat with a single dose of oral dexamethasone 0.15-0.6 mg/kg and nebulised adrenaline for moderate to severe stridor.

Acute otitis media: bulging tympanic membrane or otorrhoea; first-line amoxicillin 80-90 mg/kg/day; observe for 48-72 hours in selected children aged over 2 years with mild disease.

Febrile seizure: occurs in children aged 6 months to 5 years with fever and no CNS infection; simple febrile seizures last under 15 minutes and do not recur within 24 hours; antipyretics do not prevent recurrence.

Severe falciparum malaria: artesunate IV is first-line, with artemether IM as alternative; treat for a minimum of 24 hours and until oral therapy can be tolerated, then complete a full oral ACT course.

Dengue warning signs: abdominal pain, persistent vomiting, mucosal bleeding, lethargy, liver enlargement >2 cm, and rising haematocrit with falling platelets; give isotonic crystalloid 5-10 mL/kg/h and avoid NSAIDs.

Tuberculosis: new pulmonary TB treated with 2 months of rifampicin, isoniazid, pyrazinamide, ethambutol, then 4 months of rifampicin and isoniazid; use fixed-dose combinations and check for drug interactions with antiretrovirals.

HIV: first-line antiretroviral therapy typically combines two nucleoside reverse transcriptase inhibitors with dolutegravir; start within 7 days of TB treatment initiation and screen for cryptococcal antigen when CD4 is below 100.

Typhoid fever: blood culture is the standard early diagnostic; treat with ceftriaxone or azithromycin depending on local resistance; fluoroquinolone resistance is widespread in Asia.

Tetanus: clinical diagnosis; treat with human tetanus immunoglobulin, metronidazole, wound debridement, and benzodiazepines or magnesium for spasm control in a dark, quiet room.

Leptospirosis: fever, myalgia, jaundice, and conjunctival suffusion after water exposure; treat with doxycycline or ceftriaxone; Jarisch-Herxheimer reaction may occur after the first dose.

Rabies post-exposure prophylaxis: immediate wound washing with soap and water for 15 minutes, then vaccine on days 0, 3, 7, and 14; add rabies immunoglobulin for category III exposures.

Levels of prevention: primary prevents onset (immunisation, sanitation), secondary detects early (screening), tertiary limits disability (rehabilitation), and quaternary prevents overmedicalisation.

Sensitivity = true positives / (true positives + false negatives); specificity = true negatives / (true negatives + false positives); both are properties of the test, not of the population prevalence.

Positive predictive value = true positives / all positives; it rises with prevalence, so a highly specific test is most useful when prevalence is low.

Herd immunity threshold = 1 − 1/R0; for measles with R0 around 12-18, coverage above roughly 95% is needed to interrupt transmission.

Crude birth rate = live births per 1,000 population per year; total fertility rate is the average number of children a woman would have over her lifetime at current age-specific rates.

Maternal mortality ratio = maternal deaths per 100,000 live births; under-5 mortality rate = deaths under age 5 per 1,000 live births; neonatal mortality is deaths in the first 28 days.

Case-control studies are efficient for rare diseases but cannot directly give incidence; cohort studies give incidence and relative risk but are costly and prone to loss to follow-up.

Cambodia's health system: health centres serve as the first contact level, referral hospitals provide secondary care, and health equity funds reduce financial barriers for the poor.

Relative risk = incidence in exposed / incidence in unexposed; attributable risk = incidence in exposed − incidence in unexposed; attributable fraction = attributable risk / incidence in exposed.

Odds ratio approximates relative risk only when the outcome is rare (roughly under 10%); it is the standard measure in case-control studies.

Confounding: a variable associated with both exposure and outcome but not on the causal pathway; control by randomisation, restriction, matching, or statistical adjustment.

Bias types: selection bias in who enters the study, information/recall bias in how exposure is measured, and confounding by a third variable; random error is reduced by increasing sample size.

95% confidence interval for a proportion ≈ p ± 1.96 × √(p(1−p)/n); if the interval for a risk ratio excludes 1, the association is statistically significant at the 5% level.

Sample size for a proportion: n = Z² × p(1−p) / d²; for comparing two means, n per group ≈ 2 × (Zα/2 + Zβ)² × SD² / difference².

Sensitivity analysis examines how conclusions change under different assumptions; intention-to-treat analysis preserves randomisation by analysing participants in their assigned group.

Outbreak investigation steps: verify the diagnosis, define and find cases, describe by person, place, and time, generate hypotheses, test with an analytical study, and implement control measures.

Pharmacokinetics: volume of distribution = dose / plasma concentration; clearance = rate of elimination / plasma concentration; half-life = 0.693 × volume of distribution / clearance.

Zero-order kinetics (saturation, e.g. phenytoin, ethanol) eliminates a constant amount per unit time; first-order kinetics eliminates a constant fraction per unit time.

Loading dose = volume of distribution × target concentration / bioavailability; maintenance dose rate = clearance × target concentration / bioavailability.

Cytochrome P450 interactions: rifampicin, carbamazepine, and phenytoin are inducers; azoles, macrolides, and grapefruit juice are inhibitors; warfarin, statins, and many antiretrovirals are affected.

Aminoglycosides and vancomycin are nephrotoxic and ototoxic; monitor levels and renal function; aminoglycosides act on the 30S ribosomal subunit and are concentration-dependent killers.

Adverse drug reactions: type A are dose-dependent and predictable; type B are idiosyncratic and unpredictable (e.g. anaphylaxis, Stevens-Johnson syndrome).

Antimicrobial stewardship: de-escalate based on culture and sensitivity, use the narrowest effective agent, and complete the shortest effective course; avoid unnecessary antibiotics for viral illness.

Paracetamol overdose: N-acetylcysteine is the antidote; use the Rumack-Matthew nomogram from 4 hours after ingestion; the toxic dose is roughly 150 mg/kg or 10 g in adults.

Adult basic life support: compressions at 100-120/min, depth 5-6 cm, full recoil, ratio 30:2 with 2 breaths, and minimise interruptions to under 10 seconds.

Cardiac arrest rhythms: shockable rhythms (ventricular fibrillation, pulseless ventricular tachycardia) get immediate defibrillation plus adrenaline after the second shock; non-shockable rhythms get adrenaline as soon as possible.

Anaphylaxis: adrenaline 0.5 mg IM (0.01 mg/kg in children, maximum 0.5 mg) into the anterolateral thigh, repeated every 5 minutes; give oxygen, IV fluids, and adjunctive antihistamine and steroid.

Sepsis: recognise with a screening tool, measure lactate, take cultures, give broad-spectrum antibiotics within 1 hour of recognition, and give 30 mL/kg crystalloid for hypotension or lactate ≥4 mmol/L.

Glasgow Coma Scale: eye 1-4, verbal 1-5, motor 1-6; a score of 8 or less indicates need for airway protection; record the components, not just the total.

Poisoning: activated charcoal is useful within 1 hour of ingestion for a conscious patient with a protected airway; do not induce vomiting; treat specific antidotes (naloxone, flumazenil, atropine for organophosphates).

Acute severe asthma: high-flow oxygen to target saturation, repeated inhaled salbutamol, ipratropium, systemic corticosteroid, and magnesium sulfate IV for severe cases; consider intubation for exhaustion.

Diabetic emergencies: check capillary glucose and ketones; treat hypoglycaemia with oral glucose if conscious or IV 50% dextrose if not, and follow with a complex carbohydrate meal.

Four principles of biomedical ethics: autonomy (respect for patient choices), beneficence (act in the patient's interest), non-maleficence (do no harm), and justice (fair allocation).

Informed consent requires capacity, adequate disclosure of risks and alternatives, understanding, and voluntariness; document the discussion and use an interpreter when the patient does not speak the clinician's language.

Confidentiality may be breached only when legally required (notifiable diseases, court order) or when there is a serious and imminent risk to others; disclose the minimum necessary information.

Medical confidentiality in Cambodia: the Law on the Management of Private Medical, Paramedical and Medical Aid Services and the Code of Ethics for Physicians oblige doctors to protect patient information.

Breaking bad news: use a structured approach such as SPIKES - setting, perception, invitation, knowledge, empathy, and strategy/summary.

Research ethics: institutional review board approval, informed consent, and special protections for children and pregnant women; the Declaration of Helsinki and the Belmont Report are key frameworks.

Professional boundaries: avoid treating family members when a reasonable alternative exists; declare conflicts of interest; refuse gifts that could influence clinical decisions.

Negligence requires a duty of care, a breach of the standard of care, causation, and resulting harm; documenting clinical reasoning is the best defence against unfounded claims.

Cardiac cycle: S1 is closure of the mitral and tricuspid valves; S2 is closure of the aortic and pulmonary valves; the left ventricle ejects about 70 mL per beat with an ejection fraction of 55-70%.

Renal physiology: glomerular filtration rate ≈ 125 mL/min; filtration is driven by hydrostatic pressure minus oncotic pressure; the proximal tubule reabsorbs about 65% of filtered sodium and water.

Acid-base: Henderson-Hasselbalch equation pH = 6.1 + log([HCO3−] / (0.03 × PaCO2)); respiratory acidosis has raised PaCO2, metabolic acidosis has reduced HCO3−, and compensation never fully corrects the pH.

Glycolysis yields net 2 ATP and 2 NADH per glucose; the Krebs cycle and oxidative phosphorylation yield about 30-32 ATP in total; anaerobic glycolysis produces lactate.

Coagulation: intrinsic pathway (factors XII, XI, IX, VIII) measured by aPTT; extrinsic pathway (factor VII) measured by PT/INR; common pathway (X, V, II, I) is shared.

Bacterial classification: Gram-positive cocci in clusters suggest Staphylococcus, in chains Streptococcus; Gram-negative rods include Escherichia coli and Klebsiella; acid-fast bacilli suggest Mycobacterium.

Hepatitis B serology: HBsAg indicates infection; anti-HBs indicates immunity; HBeAg indicates high infectivity; anti-HBc IgM indicates acute or recent infection.

Cell injury: reversible injury shows swelling and fatty change; irreversible injury shows membrane rupture, mitochondrial failure, and nuclear changes (pyknosis, karyolysis, karyorrhexis); apoptosis is programmed and does not cause inflammation.