A 25-year-old man returns from a dengue-endemic area with high fever for 4 days, retro-orbital pain, myalgia, and a petechial rash. Platelet count is 52,000/µL. NS1 antigen is positive. On day 5, fever defervesces but he develops abdominal pain, increasing haematocrit (from 38% to 49%), and a small pleural effusion. What phase of dengue is this and what is the most critical management parameter?
- A Febrile phase; start platelet transfusion immediately
- B Critical phase; monitor haematocrit closely and administer judicious IV fluid to prevent fluid overload ✓
- C Recovery phase; discharge with oral fluids
- D Secondary dengue infection; administer fresh frozen plasma
Correct answer: B. Critical phase; monitor haematocrit closely and administer judicious IV fluid to prevent fluid overload
Explanation
Dengue has three phases: febrile (days 1–3), critical (days 4–6 — the period of defervescence and plasma leakage), and recovery. Fever defervescence with rising haematocrit (by ≥20% — here from 38% to 49% is a 29% rise), thrombocytopaenia, and serosal effusions mark the onset of the critical phase. Management requires careful haematocrit-guided IV fluid therapy (isotonic crystalloids); overzealous fluids cause pulmonary oedema during recovery when plasma re-enters circulation. Platelet transfusion is not routinely given above 20,000/µL without active major bleeding.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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