MECEE-PG Nepal cheat sheet

Brachial plexus roots C5–T1; Erb palsy (C5–C6) gives waiter's tip, Klumpke (C8–T1) gives claw hand with Horner syndrome.

Coronary arteries arise from aortic sinuses; right coronary supplies SA node in ~60% and AV node in ~80% of people.

Cardiac output = heart rate × stroke volume; Fick principle: CO = oxygen consumption ÷ arteriovenous O2 difference.

Frank–Starling law: stroke volume rises with end-diastolic volume up to an optimal sarcomere length; excess preload eventually reduces output.

Oxygen–haemoglobin curve shifts right (reduced affinity) with ↑CO2, ↑H+, ↑temperature, ↑2,3-BPG; fetal Hb and HbCO shift left.

Rate-limiting enzymes: glycolysis phosphofructokinase-1, gluconeogenesis fructose-1,6-bisphosphatase, TCA citrate synthase, urea cycle carbamoyl phosphate synthetase I.

Ketone bodies (acetoacetate, beta-hydroxybutyrate, acetone) are made in liver mitochondria but cannot be used by liver (lacks thiophorase).

Wernicke area (superior temporal gyrus, usually left) mediates language comprehension; Broca area (inferior frontal gyrus) mediates motor speech.

Necrosis vs apoptosis: necrosis is passive with inflammation and membrane rupture; apoptosis is energy-dependent, non-inflammatory, with caspase activation.

Acute inflammation mediators: histamine (vasodilation), bradykinin (pain), leukotriene B4 (chemotaxis), C5a (chemotaxis), IL-1/TNF (fever, adhesion).

Granulomas are type IV hypersensitivity lesions; caseating granulomas suggest tuberculosis, non-caseating suggest sarcoidosis or Crohn disease.

Virchow triad for thrombosis: endothelial injury, abnormal blood flow (stasis/turbulence), hypercoagulability.

Tumour suppressor genes (RB, TP53, APC, BRCA1/2) require biallelic loss; oncogenes (RAS, MYC, HER2) need only one activating allele.

TNM staging: T primary tumour size/invasion, N regional nodes, M distant metastasis; grade describes differentiation, stage describes spread.

Nephrotic syndrome: proteinuria >3.5 g/day, hypoalbuminaemia, oedema, hyperlipidaemia; nephritic syndrome features haematuria and hypertension.

Left heart failure causes pulmonary oedema and orthopnoea; right heart failure causes raised JVP, hepatomegaly, ascites and peripheral oedema.

First-order kinetics: constant fraction eliminated per unit time; zero-order: constant amount per unit time (phenytoin, ethanol, aspirin at high dose).

Volume of distribution = dose ÷ plasma concentration; high Vd means extensive tissue uptake and poor dialysis removal.

Half-life = 0.693 × Vd ÷ clearance; steady state is reached after roughly 4–5 half-lives.

Competitive antagonists shift the dose–response curve right without lowering maximal response; non-competitive antagonists reduce maximal response.

Atropine (muscarinic antagonist) treats organophosphate toxicity alongside pralidoxime; atropine causes mydriasis, dry mouth, tachycardia, urinary retention.

Aminoglycosides and loop diuretics are ototoxic and nephrotoxic; vancomycin and aminoglycosides require therapeutic drug monitoring.

Warfarin inhibits vitamin K epoxide reductase (factors II, VII, IX, X, proteins C and S); heparin potentiates antithrombin III.

Paracetamol overdose: N-acetylcysteine replenishes glutathione; hepatotoxicity risk increases with enzyme inducers and chronic alcohol use.

Gram-positive cocci in clusters, coagulase positive: Staphylococcus aureus; in chains, bacitracin sensitive: Streptococcus pyogenes.

Lancefield grouping of beta-haemolytic streptococci uses cell-wall carbohydrate; group A is S. pyogenes, group B is S. agalactiae.

Mycobacterium tuberculosis is acid-fast due to mycolic acids; detected by Ziehl–Neelsen staining and cultured on Löwenstein–Jensen medium.

Vibrio cholerae is a comma-shaped oxidase-positive Gram-negative rod; rice-water stools; treated with oral rehydration plus doxycycline.

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

Sterile immunity is produced by killed vaccines (e.g., tetanus toxoid); live attenuated vaccines (BCG, MMR, OPV) give longer, broader immunity.

Gram stain steps: crystal violet, iodine (mordant), alcohol decolouriser, safranin counterstain; Gram-negative cells lose the primary stain.

Malaria: Plasmodium falciparum causes severe disease with banana-shaped gametocytes and irregular fever; diagnosed by thick and thin blood films.

Acute myocardial infarction triad: ischaemic chest pain, serial ECG changes (ST elevation, Q waves), and rise/fall of troponin.

Diabetic ketoacidosis: hyperglycaemia, ketonaemia, metabolic acidosis with high anion gap, and total body potassium depletion despite normal serum K.

High anion gap metabolic acidosis causes: ketoacidosis, lactic acidosis, renal failure, methanol, ethylene glycol, salicylate (MUDPILES mnemonic).

Hyponatraemia management depends on chronicity; correct no faster than 8–10 mmol/L per 24 hours to avoid osmotic demyelination.

Hyperthyroidism shows low TSH with high free T4/T3; primary hypothyroidism shows high TSH with low free T4.

Nephritic syndrome with haematuria, red cell casts, and hypertension after pharyngitis suggests post-streptococcal glomerulonephritis.

Rheumatoid arthritis: symmetric small-joint synovitis, morning stiffness >1 hour, anti-CCP and rheumatoid factor positivity, erosions on X-ray.

Stroke: thrombolysis with alteplase is considered within 4.5 hours of ischaemic onset after excluding haemorrhage on imaging.

Murphy sign (inspiratory arrest on right subcostal palpation) suggests acute cholecystitis; Courvoisier law links palpable gallbladder to malignant obstruction.

Rovsing sign, rebound tenderness and migration of pain to the right iliac fossa suggest acute appendicitis; Alvarado score aids assessment.

ATLS primary survey sequence: catastrophic haemorrhage control, airway with cervical spine protection, breathing, circulation, disability, exposure.

Burn fluid resuscitation: Parkland formula 4 mL × body weight (kg) × %TBSA of Ringer lactate in 24 hours, half in the first 8 hours.

Shock index = heart rate ÷ systolic blood pressure; a value above 0.9 suggests significant occult haemorrhage.

Anion gap and serum amylase/lipase help evaluate pancreatitis; lipase is more specific; severe disease is scored by Ranson or APACHE II.

Inguinal hernia lies above and medial to the pubic tubercle; femoral hernia lies below and lateral and has a higher strangulation risk.

Postoperative fever timing: within 48 hours consider atelectasis, days 3–5 urinary or wound infection, after day 5 abscess or deep vein thrombosis.

Estimated date of delivery by Naegele rule: first day of last menstrual period + 7 days − 3 months, assuming a 28-day cycle.

Pregnancy-induced hypertension after 20 weeks with proteinuria defines pre-eclampsia; severe features include BP ≥160/110, headache, visual changes, and HELLP.

Magnesium sulphate prevents and treats eclamptic seizures; monitor deep tendon reflexes, respiratory rate, and urine output for toxicity.

Antepartum haemorrhage: placenta praevia causes painless bleeding; placental abruption causes painful bleeding with a tender, tense uterus.

Postpartum haemorrhage is blood loss >500 mL after vaginal or >1000 mL after caesarean delivery; uterine atony is the commonest cause.

Normal labour has three stages; the first stage ends at full cervical dilatation (10 cm), the second at delivery of the baby, the third at placental expulsion.

Ectopic pregnancy: amenorrhoea, lower abdominal pain, and vaginal bleeding; transvaginal ultrasound showing no intrauterine sac with raised beta-hCG supports diagnosis.

Cervical screening: Pap smear detects dysplasia; HPV vaccination prevents infection with high-risk types 16 and 18.

Neonatal weight: physiological loss of up to 10% in the first week, regained by 10–14 days; birth weight doubles by 5 months and triples by 1 year.

Apgar score assesses heart rate, respiratory effort, muscle tone, reflex irritability, and colour at 1 and 5 minutes; each 0–2.

Neonatal jaundice appearing within 24 hours is always pathological; physiological jaundice appears after 24 hours and peaks around day 3–5.

Breastfeeding is exclusive for the first 6 months; complementary feeding starts at 6 months with continued breastfeeding to 2 years.

Kussmaul breathing, dehydration, and abdominal pain in a child suggest diabetic ketoacidosis; fluid resuscitation precedes insulin infusion.

Acute epiglottitis presents with drooling, tripod posture, and high fever; avoid throat examination and secure the airway.

Croup (laryngotracheobronchitis) gives a barking cough and inspiratory stridor; treat with dexamethasone and nebulised adrenaline for severe cases.

Measles: Koplik spots precede a maculopapular rash spreading from the face downwards; vitamin A reduces morbidity and mortality.

Incidence = new cases ÷ population at risk per unit time; prevalence = all existing cases ÷ total population at a point or period.

Attack rate = new cases ÷ population exposed during an outbreak; case fatality rate = deaths ÷ diagnosed cases × 100.

Sensitivity = true positives ÷ (true positives + false negatives); specificity = true negatives ÷ (true negatives + false positives).

Positive predictive value depends on disease prevalence as well as sensitivity and specificity; it rises as prevalence rises.

Relative risk = incidence in exposed ÷ incidence in unexposed; attributable risk = incidence in exposed − incidence in unexposed.

Herd immunity threshold approximates 1 − 1/R0; higher R0 requires a higher proportion immune to interrupt transmission.

Levels of prevention: primordial (risk factor reduction), primary (pre-disease), secondary (early detection), tertiary (disability limitation).

Infant mortality rate = infant deaths under 1 year ÷ live births in the same year × 1000; maternal mortality uses maternal deaths per 100,000 live births.

Glomerular filtration rate depends on net filtration pressure and filtration coefficient; autoregulation keeps renal blood flow stable between MAP 80 and 180 mmHg.

Insulin lowers blood glucose by promoting GLUT4 translocation; glucagon raises it via glycogenolysis and gluconeogenesis.

Respiratory minute ventilation = tidal volume × respiratory rate; alveolar ventilation = (tidal volume − dead space) × respiratory rate.

Bohr effect describes reduced oxygen affinity with rising CO2 and H+; Haldane effect describes increased CO2 carriage by deoxygenated blood.

Cranial nerves with parasympathetic fibres: III (pupil constriction), VII (lacrimal, submandibular), IX (parotid), X (thoracic and abdominal viscera).

Cardiac pacemaker potential in SA node depends on funny current (If) and calcium influx; vagal stimulation slows rate via acetylcholine on M2 receptors.

Enzyme kinetics: Michaelis–Menten Km equals substrate concentration at half maximal velocity; low Km indicates high affinity.

Vitamin deficiencies: thiamine (beriberi, Wernicke), riboflavin (angular stomatitis), niacin (pellagra), vitamin C (scurvy), vitamin D (rickets).