Study hub

Interactive tools

Practise interpretation systematically: step-by-step ECG reading, solved cases, lab values in context, antibiotic spectra and clinical calculators.

Read systematically

ECG interpretation in 9 steps

Rate

How fast?

Regular rhythm: divide 300 by the number of large squares between two R waves.

Irregular rhythm: count QRS complexes on a 10-second strip and multiply by six.

Normal

60–100 / min

Pitfall

Applying the 300-rule to an irregular rhythm.

Case gallery

50 solved ECG cases

Case 01Beginner

83 y, male · 117/min · Irregularly irregular

Palpitations and mild breathlessness.

Case 02Intermediate

23 y, female · 148/min · Regular

Sudden palpitations, no chest pain.

Case 03Intermediate

58 y, female · 69/min · Sinus

Crushing chest pain with nausea.

Case 04Advanced

45 y, male · 161/min · Regular, wide complex

Palpitations with pre-syncope.

Case 05Advanced

50 y, female · 32/min · Regular escape rhythm

Syncope and fatigue.

Case 06Intermediate

62 y, male · 78/min · Sinus, widening QRS

Dialysis patient who missed a session.

Case 07Beginner

30 y, female · 165/min · Regular, narrow complex

Young adult, sudden racing heart.

Case 08Intermediate

65 y, female · 69/min · Sinus

Routine pre-operative ECG.

Case 09Beginner

51 y, female · 45/min · Regular sinus

Asymptomatic endurance athlete.

Laboratory

Laboratory values explorer

Haemoglobin (female)

12–15.5 g/dL

520

↑ Polycythaemia vera, chronic hypoxia, dehydration, testosterone therapy.

↓ Iron deficiency, blood loss, haemolysis, chronic kidney disease, B12 deficiency.

Always pair with MCV: microcytic points to iron, macrocytic to B12, folate or alcohol.

MCV

80–100 fL

60120

↑ B12 or folate deficiency, alcohol, hypothyroidism, myelodysplasia.

↓ Iron deficiency, thalassaemia, anaemia of chronic disease, lead exposure.

A normal MCV does not exclude mixed deficiency — check ferritin and B12 separately.

White cell count

4–11 ×10⁹/L

030

↑ Bacterial infection, corticosteroids, stress response, leukaemia.

↓ Viral infection, chemotherapy, sepsis with exhaustion, bone marrow failure.

Neutropenia below 0.5 ×10⁹/L with fever is a medical emergency requiring antibiotics within one hour.

Platelets

150–400 ×10⁹/L

0600

↑ Reactive thrombocytosis after infection, iron deficiency, essential thrombocythaemia.

↓ ITP, sepsis, DIC, heparin-induced thrombocytopenia, liver disease, EDTA clumping.

Below 50 ×10⁹/L avoid invasive procedures; below 20 ×10⁹/L spontaneous bleeding risk rises sharply.

Pharmacology

Antibiotic class matrix

Green = reliable activity, amber = partial, grey = no relevant activity.

Class	Gram +	Gram −	Atypical	Anaerobes	Pseudomonas
Penicillins Penicillin G, Amoxicillin
Mechanism Bind penicillin-binding proteins and block cell wall cross-linking; bactericidal. Penicillin G · Amoxicillin · Amoxicillin/clavulanate · Piperacillin/tazobactam Typical uses · Streptococcal pharyngitis and cellulitis · Community-acquired pneumonia (amoxicillin) · Intra-abdominal and aspiration infection (with clavulanate) Cautions True IgE-mediated allergy is rare; rash with amoxicillin during EBV infection is not an allergy.
Cephalosporins Cefazolin, Cefuroxime
Carbapenems Meropenem, Imipenem/cilastatin
Macrolides Azithromycin, Clarithromycin
Fluoroquinolones Ciprofloxacin, Levofloxacin
Aminoglycosides Gentamicin, Amikacin
Glycopeptides Vancomycin, Teicoplanin
Tetracyclines Doxycycline, Minocycline
Nitroimidazoles Metronidazole, Tinidazole
Folate antagonists Co-trimoxazole (TMP/SMX)
Oxazolidinones Linezolid

Nursing & clinical

Calculators & references

IV drip & infusion rate

Volume (mL)

Time (minutes)

Drop factor (gtt/mL)

42 gtt/min

≈ 125 mL/h on the pump

Glasgow Coma Scale

Eye opening

Verbal response

Motor response

GCS 15 / 15

E4 V5 M6

Mild

Injection angles

Intradermal26–27 G, 10 mm · Volar forearm10–15°
Subcutaneous25–27 G, 12 mm · Abdomen, thigh45–90°
Intramuscular21–23 G, 25–38 mm · Ventrogluteal, deltoid90°
Intravenous18–22 G cannula · Forearm veins15–30°