Clinical Scenario:
A 7-year-old boy is admitted on the fifth day of illness with persistent vomiting and increasing lethargy. His fever subsided the previous day, but he has become restless and cold over the last 6 hours.
On examination, his pulse is 132/min and weak, blood pressure is 88/72 mmHg, and capillary refill is 4 seconds. His extremities are cold and clammy. The liver is palpable 3 cm below the right costal margin.
Investigations show:
- Hemoglobin: 12.5 g/dL
- Hematocrit: 45%
- Platelets: 38 × 10⁹/L
- WBC: 3,100/mm³
Ultrasound shows gallbladder wall edema and a small right-sided pleural effusion.
What is the most likely mechanism responsible for his current clinical deterioration?
A. Myocardial dysfunction
B. Plasma leakage
C. Severe gastrointestinal bleeding
D. Secondary bacterial sepsis
E. Hemolysis
Correct answer & Explanation:
Explanation
Correct answer: B. Plasma leakage
This child is entering the critical phase of dengue, which commonly occurs around the time of defervescence, usually during days 3–7 of illness. The sudden deterioration after the fever subsides is an important clue.
The child has compensated dengue shock, suggested by:
- Narrow pulse pressure (16 mmHg) — 88 − 72 mmHg
- Weak, rapid pulse
- Cold, clammy extremities
- Prolonged capillary refill
- Restlessness
The underlying mechanism is increased capillary permeability causing plasma leakage from the intravascular space. This leads to reduced circulating volume and eventually shock.
The laboratory and ultrasound findings support plasma leakage. His hematocrit of 45% is disproportionately high for a hemoglobin of 12.5 g/dL, suggesting hemoconcentration. The pleural effusion and gallbladder wall edema are additional manifestations of plasma leakage. Thrombocytopenia is common in the critical phase of dengue.
Why not severe gastrointestinal bleeding? Significant bleeding can cause shock, but would be expected to produce a falling hematocrit rather than hemoconcentration. There is also no clinical evidence of major bleeding.
Why not myocardial dysfunction? Dengue myocarditis or myocardial dysfunction can occur, but the combination of hemoconcentration and extravascular fluid accumulation strongly indicates plasma leakage as the primary mechanism in this case.
Why not secondary bacterial sepsis? Sepsis can cause shock, but the timing around defervescence and the characteristic plasma-leakage findings strongly favor severe dengue.
Why not hemolysis? There are no findings suggesting hemolysis, and hemolysis does not explain the pleural effusion, gallbladder wall edema and hemoconcentration.
Key exam point: In a child with dengue, deterioration around defervescence + narrow pulse pressure + hemoconcentration + evidence of fluid accumulation should immediately suggest plasma leakage with impending or established dengue shock.
Reference:
World Health Organization. Dengue and severe dengue. WHO Dengue and severe dengue
World Health Organization. Dengue: Guidelines for Diagnosis, Treatment, Prevention and Control. WHO Dengue Guidelines
