A 7-year-old boy with dengue fever develops lethargy, cold clammy extremities and a blood pressure of 90/70 mm Hg. Which haemodynamic finding confirms that he has progressed to dengue shock syndrome?

• A Respiratory rate of 26 per minute
• B Systolic pressure above 100 mm Hg
• C Heart rate of 110 per minute
• D Pulse pressure of 18 mm Hg ✓

Explanation

Dengue shock syndrome is defined by circulatory failure manifested as a narrow pulse pressure of 20 mm Hg or less, or hypotension for the given age. Here the pulse pressure is 20 minus nothing: 90 minus 70 equals 20 mm Hg at the cutoff, and a reading below 20 such as 18 mm Hg confirms shock. Tachycardia and tachypnoea are nonspecific, and systolic pressure alone may remain normal until late, which is why pulse pressure is the discriminating sign.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

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Written and medically reviewed by the StethoPrep medical team.