Management Of Dengue

Dengue Virus

• The dengue viruses are the members of the genus flavivirus. These small (50nm)viruses contain single stranded RNA.

• There are four virus serotypes, which are designated as DEN-1, DEN-2, DEN-3 and DEN-4.

• Although all four serotypes are antigenicaly similar, they have envelop proteins that have epitopes unique to the serotype

Vector• Dengue is transmitted by the bite of female Aedes mosquito

• The eggs can survive one year without water. At low temperature, however, it may take several weeks to emerge. Ae. aegypti has an average adult survival of fifteen days.

• They breed in artificial containers of water.

• During the rainy season, when survival is longer, the risk of virus transmission is greater. It is a day time feeder and can fly up to a limited distance of 400 meters.

• To get one full blood meal the mosquito has to feed on several persons, infecting all of them.

Clinical Features

Patients with dengue infection can be classified as follows :• Asymptomatic• Undifferentiated Fever• Dengue without warning Signs• Dengue with warning signs• Severe Dengure

Dengue FeverFebrile phase

• Sudden onset high grade fever, 2-7 days.• Associated flushing, skin erythema, generalized body ache, myalgia, arthralgia,

anorexia, nausea, and vomiting, retrobulbar pain may be present.• Minor haemorrhagic manifestations such as petichae and muscosal bleed might be

present.• Liver maybe enlarged 2-5 days (indicates risk for severe disease)

Critical phase• Between 3-7 days of onset of fever• Bleeding, shock• Some children develop organ failure : severe hepatitis, encephalitis or myocarditis

Recovery phase• Some experience generalized pruritus, rash(iles of white in a sea of red), bradycardia

and respiratory depression

Laboratory Investigation• Blood reports

o Increaing packed cell volumeo Low platelet counto Decreasing leukocyte (DD malaria typhoid/paratyphoid) count with increasing

lymphocyteso Decrease in total proteins and albumino SGOT & SGPT levels raisedo Severe cases – hyponatremia, acidosis, raised urea and creatinine levels might be seen.

• X ray : varying degrees of pleural effusion• Ultrasonography : ascites and enlarged gall bladder.

Confirmatory tests• Direct Methods :

– Isolation by culture– Genome detection by PCR

(First 5 days, expensive)– NSI antigen detection

(Preferably for first 8 days, highly sensitive in first 4 days – 100%)

– Antibody determination ( IgM in day 5 in 80% and in 99% by day 10 and disappear in 2-3 months; IgG rise later and remain through out life)

Management

Criteria for hospitalisationIndication for hospitalisation

Dengue with warning signs.• Severe intense abdominal pain, clinical fluid accumulation• Persistent vomiting, mucosal bleed• Restlessness, lethargy, raise in HCT with rapid fall in

platelet count

Indication for ICU admissionSevere Dengue

• Shock• Respiratory Distress• Abdominal Bleeding• Organ Failure eg. Neurological complication, liver or renal

dysfunction

1. Undifferentiated fever

Signs & Symptoms : Non-specific symptoms and signs.Treatment :

a. Paracetamolb. Regular monitoring of BP and look for warning signs

2. Dengue infection without warning signs

Signs & Symptoms : Fever, body aches, rashes or minor bleeds Treatment :

a. Paracetamolb. Regular monitoring of BP, look for warning signs

along with platelet counts and haematocrit.

c. Encourage child to drink plenty of fluidsNote : Avoid salicylates and other NSAIDs

2. Dengue infection with warning signs

Warning signs :(i) Abdominal pain or tenderness(ii) Persistent Vomiting(iii)Clinical fluid accumulation(iv)Mucosal bleed(v) Lethargy, restlessness(vi)Liver enlargement >2cm(vii)Laboratory features – rapid decrease of platelet

count (≤ 1,00,000) and increase in packed cell volume (≤ 20%).

Dengue fever with risk factors

Hospitalise Ringer lactate (RL) 7ml/kg/hr

Assessment at one hr; vitals and haematocrit

No improvement

RL 10ml/kg/hr

Assessment at 2 hr

RL 15ml/kg/hr

Assessment at 3 hrNo improvement Colloids 10ml/kg/hr No

improvement Look for anaemia, acidosis and myocardial dysfunction and treat accordingly

Improvement RL 5 ml/kg/hr

Improvement RL 3 ml/kg/hr

Continue IV fluids until stable for 24hr.Discharge when stable for 24-48 hours

2. Severe Dengue infectionChildren presenting with the following :

(i) Severe plasma leakage leading to a. Shock (Hypotension, tachycardia,

narrow pulse pressure ≤ 20 mmHg and signs of poor perfusion – cold extremities) b. Fluid accumulation with respiratory distress

(ii) Severe bleeding(iii)Severe organ involvement

a. Liver : AST or ALT ≥ 1000 IU/Lb. CNS : Impaired

consciousness c. Heart and other organ involvement

Severe dengue fever

Assessment of shock

HypotensionDSS III

RL 10 – 20 ml/kg/hr

Unrecordable blood pressureDSS IV

RL 20 ml/kg/hr bolus; upto 3 boluses

Assessment

Gradually decrease ringer lactate infusion

No improvement

Improved

Haematocrit decreased

Haematocrit increased

Colloids 10ml/kg

Blood transfusion

Assessment

Improved No improvement

Look for anaemia, acidosis and myocardial dysfunction and treat accordingly

End point of fluid administration

• Minimal urine output of 0.8 – 1 ml/kg/hr is a valuable end point

• Acceptable mean pressure• Normalisation of pulse pressure• Fall in haematocrit to approximately 20% of admission values

Approach for severe dengue and refractory

shock

Stabilise ABC, 6% hetastarch/gelatin 10-20 ml/kg as 2-3 boluses over 15-30 mins. Correct hypoglycaemia, hypocalcaemia acidosis. Monitor haemodynamic. Vitals, clinical indices of perfusion, hourly urine output, 2-4 hourly HCT, transfuse fresh whole blood/PRBC if hypotension still persists.

Evaluate for unrecognised morbidities.

Consider PRBC, inotrope/pressor depending on SBP, Consider ECHO

Consider CVP with great care if expertise is available

CVP low/ HCT high

Consider inotrope/vasopressor depending on SBP• Dopamine/ adrenaline (SBP low)• Dobutamine (SBP normal/high)

Discontinue inotropes if tachycardia or shock worsens.ECHO for LV/RV systolic and diastolic function assess filling

Check IAP. Controlled ascetic fluid drainage with great caution if IAP elevated and shock refractory

Titrate crystalloids/ colloids till CVP target

Respiratory distressConsider ventilation/ nasal CPAP, infuse fluids till CVP/HCT target. Consider inotropes/vasopressor depending on SBP, serial ECHO and clinical response

Haemodynamic improved

Haemodynamics unstable

Wean ventilation and inotrope/pressor. Taper fluids gradually.

Check IAP. Controlled ascetic fluid drainage with great caution if IAP elevated and shock refractory

Management of bleeding

A. Petechial spots or mild mucosal bleeds but haemodynamically stable : Supportive care, hydration and monitoring

B. Severe bleed and haemodynamic instability, excessive mucosal bleed:Blood transfusion and monitoring

Note : • There is little evidence for transfusion of fresh frozen plasma or platelet

concentrate for severe bleeding.• When bleeding cannot be managed with fresh blood, consider possibility of

DIC. In such cases fresh frozen plasma or platelet rich plasma may be considered.

MonitoringHeart rate, respiratory rate, blood pressure and pulse pressure needs to be monitoredIn unstable patients every 30mins till the patient is stable.Haematocrit measured every Q 2-4th hourly in unstable patients for the first 12hrs then Q 6-8th hourlyThere after every 2-4 hours as long as the child is in the hospital.In severely critical cases central venous pressure and urinary output should be measured.

Other supportive therapies • Correction of electrolytes and acidosis : hypoglycaemia,

metabolic acidosis, hyponatraemia and hypocalcaemia.• Sedatives : Chloral hydrate maybe preferred• Antibiotics : not indicated unless co-infections suspected• Oxygen therapy : All children in shock should be given

oxygen in the highest concentration in the least invasive as possible

Criteria for discharge• Return of appetite• Clinical improvement• Good urine output• Stable haematocrit• 2 days after recovery from shock• No respiratory distress from pleural effusion and ascites.