BSMMU Residency Phase-A cheat sheet

Brachial plexus roots C5-T1; cords named by relation to the second part of the axillary artery (lateral, medial, posterior); the musculocutaneous nerve pierces coracobrachialis.

Erb palsy (C5-C6): waiter's tip posture; Klumpke palsy (C8-T1): claw hand with Horner syndrome if sympathetic fibers involved.

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

Frank-Starling law: increased end-diastolic volume raises stroke volume up to a physiologic optimum; mean arterial pressure ≈ diastolic + one-third pulse pressure.

Renal clearance Cx = (Ux × V) ÷ Px; inulin clearance equals GFR, PAH clearance approximates renal plasma flow; filtration fraction ≈ 20%.

Oxygen-hemoglobin curve shifts right (reduced affinity) with increased 2,3-BPG, CO2, H+, temperature; fetal hemoglobin shifts left.

Enzyme kinetics: Michaelis-Menten Km equals substrate at half Vmax; competitive inhibitors raise Km with unchanged Vmax, non-competitive lower Vmax.

Rate-limiting enzymes: glycolysis phosphofructokinase-1, gluconeogenesis fructose-1,6-bisphosphatase, TCA cycle isocitrate dehydrogenase, heme synthesis ALA synthase.

Acute MI: serial high-sensitivity troponin plus ECG; ST elevation in two contiguous leads defines STEMI; aspirin 300 mg chewed plus P2Y12 inhibitor is immediate antiplatelet therapy.

Diabetic ketoacidosis: anion gap metabolic acidosis with ketonemia; manage with isotonic saline, insulin infusion after potassium ≥3.3 mmol/L, and potassium replacement.

Hyperkalemia with ECG changes: IV calcium gluconate stabilizes myocardium, then insulin-dextrose, salbutamol, and dialysis for refractory cases.

Nephrotic syndrome: proteinuria >3.5 g/day, hypoalbuminemia, edema, hyperlipidemia; minimal change disease is commonest in children, membranous in older adults.

Cirrhosis complications: ascites managed with spironolactone plus furosemide, paracentesis with albumin for large-volume taps, lactulose for hepatic encephalopathy.

Thyroid: primary hypothyroidism shows high TSH with low free T4; Graves disease shows diffuse goiter with TSH-receptor antibodies and suppressed TSH.

Anemia classification by MCV: microcytic (iron deficiency, thalassemia, anemia of chronic disease), normocytic (hemolysis, CKD), macrocytic (B12, folate, alcohol).

Stroke thrombolysis window is up to 4.5 hours from onset with alteplase or tenecteplase after excluding hemorrhage by imaging.

Acute appendicitis: migrates from periumbilical to right iliac fossa; Alvarado score uses migration, anorexia, nausea, tenderness, rebound, fever, leukocytosis.

Shock classification: class I <15% blood loss, class II 15-30%, class III 30-40%, class IV >40%; tachycardia and narrowed pulse pressure appear early.

Burns: Parkland formula 4 mL/kg/%TBSA crystalloid in 24 hours, half in first 8 hours; rule of nines assigns 9% to each arm and 18% to each leg.

Intestinal obstruction: erect abdominal X-ray shows multiple air-fluid levels; closed-loop obstruction and strangulation are surgical emergencies.

Breast carcinoma: sentinel node biopsy for clinically node-negative axilla; triple assessment is clinical examination, imaging, and tissue diagnosis.

Thyroidectomy risks: recurrent laryngeal nerve injury causes hoarseness, external branch of superior laryngeal nerve injury causes voice fatigue, hypocalcemia follows total thyroidectomy.

Fracture healing stages: hematoma, fibrocartilaginous callus, bony callus, remodeling; open fractures need antibiotics and debridement within 6 hours.

Hernia: indirect inguinal passes lateral to inferior epigastric vessels through the deep ring; direct passes medial through Hesselbach triangle.

Estimated date of delivery by Naegele rule: first day of last menstrual period plus 7 days minus 3 months plus 1 year.

Preeclampsia: hypertension after 20 weeks with proteinuria or organ dysfunction; magnesium sulfate is the drug of choice for seizure prophylaxis.

Postpartum hemorrhage: uterine atony is commonest cause; manage with uterine massage, oxytocin, then carboprost, misoprostol, or tranexamic acid.

Fetal heart rate decelerations: early mirrors contractions (head compression), variable reflects cord compression, late reflects uteroplacental insufficiency.

Antepartum hemorrhage: placenta previa presents with painless bleeding, abruptio placentae with painful bleeding and a tender uterus.

Contraception: combined oral pills inhibit ovulation; copper IUCD is toxic to sperm; levonorgestrel emergency pill works mainly by delaying ovulation.

Cervical cancer screening: cytology from age 21 or 25, HPV testing from age 30; HPV 16 and 18 cause most cases.

Ectopic pregnancy: amenorrhea with lower abdominal pain and spotting; transvaginal ultrasound shows empty uterus with beta-hCG above the discriminatory zone.

Neonatal resuscitation: warm, dry, stimulate, position airway; positive pressure ventilation for apnea or heart rate below 100; chest compressions if below 60.

APGAR score assesses appearance, pulse, grimace, activity, respiration at 1 and 5 minutes; it does not guide resuscitation decisions.

Growth: birth weight doubles by 5 months, triples by 1 year; infant weight formula is (age in months + 9)/2 kg.

Breastfeeding: exclusive for 6 months, complementary feeding from 6 months with continued breastfeeding to 2 years; vitamin D and iron supplementation as indicated.

Acute gastroenteritis: oral rehydration solution is first-line; zinc for 10-14 days reduces duration and severity of diarrhea.

Kawasaki disease: fever over 5 days plus conjunctivitis, oral changes, rash, extremity changes, cervical lymphadenopathy; IV immunoglobulin plus aspirin prevents coronary aneurysm.

Nephrotic syndrome in children: prednisolone 60 mg/m2/day for 4-6 weeks then alternate-day tapering; biopsy if steroid-resistant.

Congenital hypothyroidism: newborn screening with TSH; early levothyroxine prevents irreversible intellectual disability.

Incidence measures new cases per population at risk per time; prevalence measures all existing cases and rises with longer disease duration.

Sensitivity = true positives ÷ (true positives + false negatives); specificity = true negatives ÷ (true negatives + false positives); predictive values depend on prevalence.

Relative risk is used in cohort studies, odds ratio in case-control studies; attributable risk is incidence in exposed minus incidence in unexposed.

Herd immunity threshold = 1 − 1/R0; higher R0 requires higher vaccination coverage to interrupt transmission.

Screening criteria: important disease, accepted treatment, recognizable latent stage, suitable test, and cost-effective program.

Epidemiological study hierarchy: case reports, cross-sectional, case-control, cohort, randomized controlled trial, systematic review with meta-analysis.

Levels of prevention: primordial, primary, secondary (early detection), tertiary (rehabilitation); lead time bias falsely prolongs apparent survival after screening.

Water and sanitation: chlorination residual free chlorine 0.2-0.5 mg/L; sanitary latrine interrupts fecal-oral transmission of soil-transmitted helminths.

Rigor mortis begins in 1-2 hours in small muscles, peaks at 12 hours, resolves by 24-36 hours; livor mortis fixes by 6-8 hours.

Death categories: somatic (clinical) death versus cellular (molecular) death; brain death requires coma, absent brainstem reflexes, and apnea.

Injury terms: abrasion is superficial, contusion is blunt trauma with intact skin, incised wound is longer than deep, laceration has tissue bridging.

Organophosphate poisoning: SLUDGE and DUMBELS syndromes from acetylcholinesterase inhibition; atropine plus pralidoxime are antidotes.

Carbon monoxide poisoning: cherry-red lividity, carboxyhemoglobin levels; treat with high-flow oxygen and hyperbaric oxygen in severe cases.

Methanol poisoning: metabolic acidosis with visual loss; fomepizole or ethanol blocks alcohol dehydrogenase; hemodialysis for severe cases.

Datura poisoning: anticholinergic toxidrome with dry skin, mydriasis, delirium; physostigmine is the antidote when indicated.

Medicolegal reporting: unnatural deaths, suspected poisoning, and injuries in custody are reportable; chain of custody preserves sample integrity.

Four principles of biomedical ethics: autonomy, beneficence, non-maleficence, justice; autonomy underpins informed consent.

Informed consent requires capacity, adequate disclosure, comprehension, and voluntariness; emergency exceptions apply when harm is imminent.

Confidentiality may be breached only where law requires (reportable diseases, child abuse, court order) or with patient consent.

Research ethics: Declaration of Helsinki governs human research; institutional review board approval and informed consent are mandatory.

Professionalism includes competence, honesty, patient advocacy, and appropriate boundaries; conflicts of interest must be disclosed.

Recent advances: mRNA vaccines, CAR-T cell therapy, CRISPR gene editing, liquid biopsy for circulating tumor DNA, and AI-assisted imaging diagnosis.

Telemedicine requires verified identity, secure data transmission, documented consent, and clear escalation plans for emergencies.

Antimicrobial stewardship: prescribe only for bacterial infection, use narrowest effective agent, complete course, and monitor resistance patterns.