Level 2 of 6Must-remember

Dengue: the plasma leak and its fluid management

Assess, manage and stay safe — enough on its own

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The card — assess, manage, caution

Assessment— look, ask, measure

Establish which day of illness the patient is on — dengue is above all a disease of timing, the patient is not most dangerous when the fever is highest but when it comes down, and the day of fever predicts danger better than the examination.
Know the three phases: febrile phase approximately days 1–3 (abrupt high fever, malaise, prostration, facial flushing; plasma leakage has not begun and mortality is very low); critical phase approximately days 3–7, beginning at or just after defervescence and lasting 24–48 hours, where all the deaths occur; recovery phase from about day 7, when the leak stops and reabsorption begins.
Ask about exposure and previous dengue: travel to an endemic area within 14 days of symptom onset supports the diagnosis, dengue is effectively excluded if more than 21 days have elapsed since leaving the area, and severe dengue arises predominantly with the second of the four possible infections — always ask whether the patient has had dengue before.
Look for the febrile-phase features: severe frontal headache with retrobulbar pain that worsens on eye movement (ask the patient to look up and laterally and watch their face), conjunctival suffusion, severe backache with diffuse myalgia and arthralgia, lymphadenopathy, petechiae on the soft palate visible in seconds with a torch, and a transient morbilliform rash appearing first on the limbs and spreading to the trunk.
Cough is uncommon in dengue — a productive cough with focal chest signs points to another diagnosis, or a second one.
Take a baseline haematocrit and platelet count before any intravenous fluid and record the value with the time; a haematocrit taken after a litre of crystalloid has destroyed the information most needed.
The haematocrit is the master investigation: a rise of ≥ 20% above baseline indicates significant plasma leakage, as does a haematocrit that climbs on serial sampling while the platelet count falls — read the two together, on the same sample, every time.
Thrombocytopenia below 100 × 10⁹/L with a rising haematocrit is the classic paired warning and precedes clinical leakage; leucopenia, thrombocytopenia and atypical lymphocytes are the three recurring blood findings, and leucopenia discriminates usefully from bacterial sepsis in which the white count is usually raised.
Calculate and record the pulse pressure with every blood pressure reading — peripheral vasoconstriction maintains the systolic while the diastolic rises, so the pulse pressure narrows before the systolic pressure falls, and a pulse pressure of 20 mmHg or less with a still-normal systolic is the earliest haemodynamic marker of the leak.
Elicit the seven WHO warning signs — any one mandates admission with intravenous fluid: abdominal pain or tenderness; persistent vomiting (three or more episodes in an hour, or inability to retain oral fluid); clinical fluid accumulation (basal dullness, reduced air entry, distended abdomen with shifting dullness, puffy eyelids); mucosal bleeding (gums, nose, vagina, rectum, haematemesis, melaena — inspect the mouth); lethargy or restlessness; hepatomegaly more than 2 cm below the costal margin measured and recorded in centimetres; and a rising haematocrit with a rapidly falling platelet count.
Recognise compensated shock before the pressure falls: normal systolic for age, pulse pressure 20 mmHg or less and narrowing, thready tachycardia, cool clammy peripheries with capillary refill over 2 seconds, restlessness or lethargy, and urine output falling below 0.5 mL/kg/h.
Recognise decompensated shock (dengue shock syndrome): low or unrecordable systolic pressure, very narrow or unmeasurable pulse pressure, feeble or absent pulse, cold mottled cyanosed peripheries, obtundation and anuria.
Severe dengue is any one of: severe plasma leakage causing shock or fluid accumulation with respiratory distress; severe bleeding as judged clinically; or severe organ impairment — AST or ALT ≥ 1000 IU/L, impaired consciousness, or involvement of the heart or other organs.Not available at your setup — Liver function tests.
In children rely on signs other than the systolic pressure: capillary refill beyond 2 seconds, cold peripheries with a warm trunk, tachycardia for age, a pulse pressure of 20 mmHg or less, restlessness, irritability or unusual sleepiness, refusal to feed, no wet nappy for 6 hours, and a sunken fontanelle in an infant — and take seriously a mother who says her child is "not right".
Send a malaria film (thick and thin) and a rapid diagnostic test in every suspected case — malaria shares the geography, the fever and the thrombocytopenia, is immediately treatable, and can coexist with dengue.
Ask specifically about NSAIDs, aspirin and over-the-counter fever powders taken before presentation — in endemic settings one of these has usually already been taken, and several days of exposure warrants a lower threshold for admission, early group-and-save, and a proton pump inhibitor.

Management— do this, in order

There is no antiviral treatment for dengue — management is entirely supportive: analgesia, meticulous fluid titration and the recognition of complications, replacing hour by hour only the plasma that has leaked, for only as long as it is leaking.
Paracetamol only for fever and pain: adult 500 mg–1 g orally or intravenously 6-hourly, maximum 4 g in 24 hours, reduced to a maximum of 2 g in 24 hours with marked transaminitis or tender hepatomegaly; child 10–15 mg/kg per dose orally or intravenously 6-hourly, maximum 4 doses in 24 hours (maximum 60 mg/kg/day).Doctor / Nurse
Where paracetamol cannot be given, use physical cooling — tepid sponging, fanning, removing bedding, cool oral fluids — because there is no acceptable pharmacological substitute.
Group A (no warning signs, tolerating oral fluid, passing urine at least 6-hourly, stable haematocrit, no comorbidity, responsible adult at home): manage as an outpatient with daily review, using oral rehydration solution as the fluid of first choice with rice water, barley water, coconut water, soup, milk and fruit juice as acceptable additions — prescribe a specific daily target volume, not "drink plenty".
Group A surveillance: daily full blood count and haematocrit from day 3 until 48 hours after defervescence, plus a written list of warning signs with confirmation that a relative can repeat them back.
Group B (any warning sign, or comorbidity, pregnancy, infancy or old age): admit, weigh the patient, and begin isotonic crystalloid — 0.9% sodium chloride or compound sodium lactate (Hartmann's / Ringer's lactate) — as a stepped, tapering regimen: 5–7 mL/kg/h for 1–2 hours, then 3–5 mL/kg/h for 2–4 hours, then 2–3 mL/kg/h continued and guided by response.Doctor / Nurse
Reassess before every step change: vital signs including the pulse pressure, capillary refill, hourly urine output targeting 0.5–1 mL/kg/h (sufficient, not more), and the haematocrit 4–6-hourly; if the haematocrit rises or observations deteriorate, step back up to 5–10 mL/kg/h for 1–2 hours and reassess.
Compensated shock: isotonic crystalloid 5–10 mL/kg over 1 hour, reassessed clinically and with a repeat haematocrit at the end of the hour; if improving, step down through 5–7 mL/kg/h for 1–2 hours, then 3–5 mL/kg/h for 2–4 hours, then 2–3 mL/kg/h, tapering to stop over 24–48 hours.Doctor / Nurse
Hypotensive shock (dengue shock syndrome): isotonic crystalloid 20 mL/kg as a rapid bolus over 15 minutes, given by hand — squeezing the bag, or by syringe and three-way tap in a small child, since a gravity line will not deliver this through a 22G cannula; if the pressure recovers continue at 10 mL/kg/h for 1 hour then step down.Doctor / Nurse
If the patient is not improving, repeat the haematocrit and let it choose the next move: still high or rising means the leak is continuing — give a second crystalloid bolus 10–20 mL/kg over 1 hour and, if still unresponsive, colloid 10–20 mL/kg over 30–60 minutes; fallen means concealed haemorrhage until proved otherwise — cross-match and transfuse.Doctor / NurseNot available at your setup — Blood & blood products.
Transfuse for significant bleeding, or for shock with a falling haematocrit unresponsive to fluid: packed red cells 5–10 mL/kg, or fresh whole blood 10–20 mL/kg, over 1–2 hours (faster if exsanguinating), then reassess with a repeat haematocrit.Doctor / NurseNot available at your setup — Blood & blood products.
Antiemesis for persistent vomiting: ondansetron 4–8 mg intravenously in an adult, 0.1 mg/kg intravenously to a maximum of 4 mg in a child; domperidone 10 mg orally three times daily is an adult alternative — give orally or intravenously, never intramuscularly.Doctor / Nurse
Gastric protection for epigastric pain, NSAID exposure or any gastrointestinal bleeding: omeprazole or pantoprazole 40 mg intravenously daily; child 1 mg/kg once daily, maximum 40 mg.Doctor / Nurse
Recognise fluid overload and reduce or stop the fluid — do not reach first for a diuretic: rising respiratory rate, distress, basal crackles, reduced air entry from effusions, puffy eyelids, a tense abdomen, raised jugular venous pressure, and a running fluid total that climbed while the patient appeared to improve; sit the patient up and give oxygen to a saturation target of 94–98%.
Furosemide 0.5–1 mg/kg intravenously (adult 20–40 mg) only once the patient is out of the leak phase, haemodynamically stable and overloaded — given to a patient still leaking and still shocked it will kill them, so withhold it if the phase is uncertain.Doctor / Nurse
Recognise the recovery phase and stop the fluid — that is itself a treatment: returning well-being and appetite, haemodynamic stability, a good or rising urine output, a stabilising or falling haematocrit from haemodilution, a rising platelet count, relative bradycardia, and the confluent itchy erythematous rash with islands of normal skin.
Advise daytime mosquito precautions from the outset — the patient is viraemic and infective to feeding mosquitoes for roughly the first three days of illness, so impregnated nets for daytime rest, topical repellent, screens, sprays and elimination of standing water.
If the diagnosis is insecure in a shocked patient, take blood cultures and give empirical antibiotics, stopping them once dengue is confirmed and cultures are negative — antibiotics do not treat dengue but dengue and bacterial sepsis cannot always be distinguished at first evaluation.Doctor / NurseNot available at your setup — Blood culture.

Caution— what harms

NSAIDs and aspirin are contraindicated at every platelet count — ibuprofen, diclofenac, mefenamic acid, ketorolac, naproxen, aspirin and over-the-counter "fever powders" all increase mucosal and gastrointestinal bleeding, and aspirin in a febrile child additionally risks Reye's syndrome.
Nothing is given intramuscularly — no drug at all, because it produces deep haematoma; give orally or intravenously.
Corticosteroids are of no benefit and should not be given, and there is no antiviral — ribavirin has a role in Lassa fever and the South American haemorrhagic fevers (100 mg/kg intravenously, then 25 mg/kg daily for 3 days and 12.5 mg/kg daily for 4 days) but no role in dengue.
Do not use 5% dextrose or other hypotonic fluid for resuscitation at any age, and calculate volumes on ideal body weight in the obese patient.
Do not give repeated reflex crystalloid boluses to a patient who is not responding — unlike haemorrhagic trauma, in dengue crystalloid that continues to leak straight back out is filling the pleura, not the vessels.
Do not transfuse platelets for a number: prophylactic platelet transfusion for thrombocytopenia alone neither prevents bleeding nor improves outcome, and randomised evidence shows no benefit and a signal of harm — reserve platelets for clinically significant bleeding or an unavoidable invasive procedure, and fresh frozen plasma for documented coagulopathy with active bleeding.Not available at your setup — Blood & blood products.
Do not let a negative test reassure you: a negative NS1 early does not exclude dengue, IgM cross-reacts with other flaviviruses, and a negative tourniquet test excludes nothing — the diagnosis is treated as a syndrome and management never waits for confirmation.
Do not repeat the tourniquet test in a patient who is already bleeding or already has spontaneous petechiae.
Do not be reassured when the fever settles: the patient looks better at the moment they become most dangerous — the temperature normalises, the flush fades, the headache eases and the family ask about discharge while the pulse pressure is quietly narrowing.
Do not read a falling haematocrit as good news in a shocked patient: haemodilution is expected and benign in a patient whose pulse pressure is widening, whose peripheries are warm and who is passing urine, but in a patient who remains shocked it is haemorrhage and calls for cross-match and transfusion, not more crystalloid.
Do not give a vasopressor instead of volume: a vasopressor cannot replace lost plasma volume and improves the monitor while the kidneys fail — noradrenaline or dopamine are for the patient who remains hypotensive after adequate volume replacement with a haematocrit no longer rising and no evidence of bleeding, usually because of myocarditis or coexisting bacterial sepsis.Doctor / Nurse
Do not continue fluid beyond the leak: total duration is usually 24–48 hours and fluid given beyond it will be reabsorbed and will flood the lungs — the commonest iatrogenic death in dengue is fluid given for one day too long.
Avoid hazardous procedures: lumbar puncture in a thrombocytopenic patient is rarely justified and is deferred until the count and coagulation allow it; minimise arterial punctures and compress them for a full five minutes; avoid nasogastric intubation where possible in mucosal bleeding; and drainage of effusions in a thrombocytopenic patient is hazardous and rarely necessary.
Advise against dark red, brown or black drinks and foods, so that vomited blood can be distinguished from vomited cola, and warn the patient that convalescence is slow with severe fatigue, malaise and low mood common for several weeks.

Refer / escalate

Admit any patient with a single WHO warning sign, comorbidity, pregnancy, infancy or old age, and escalate urgently for severe dengue — shock, fluid accumulation with respiratory distress, severe bleeding, AST or ALT ≥ 1000 IU/L, impaired consciousness or cardiac involvement — or for a patient who fails to respond to the first crystalloid bolus, since untreated or late-treated dengue shock syndrome carries a mortality of up to 44% while correctly titrated volume replacement brings case fatality to well under 1%.

The card — assess, manage, caution

Dengue: the plasma leak and its fluid management — Level 1: CorePrevious Dengue: the plasma leak and its fluid management — Level 3: Core practiceNext

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