•       Obtain a reference haematocrit before intravenous fluid therapy begins.

•       Intravenous fluid therapy in DHF during the critical period.

Indications for IV fluid:

•       When the patient cannot have adequate oral fluid intake or is vomiting.

•       When HcT continues to rise 10%–20% despite oral rehydration.

•       Impending shock/shock.

The general principles of fluid therapy in DHF include the following:

The following fluids are recommended both crystalloids and colloids

Crystalloids

1.     0.9% NaCl (isotonic normal saline solution) (0.9%NS) (Preferable)

2.     0.45% half strength normal saline solution (0.45%NS) (For children <6months)

3.     5% dextrose in lactated Ringer's solution (5%DRL)

4.     5% dextrose in acetated Ringer's solution (5%DRA)

5.     Hartman solution (Preferable)

Colloids

1.     Plasmasol

2.     Dextran 40

3.     Human Albumin

4.     Plasma

5.     Hemaceel

6.     Blood & Blood Components

•       Isotonic crystalloid solutions should be used throughout the critical period excepting the very young infants <6 months of age in whom 0.45% sodium chloride may be used. Give only isotonic solutions such as 0.9% saline, Ringer's lactate or Hartmann's or Lactate solution.

•        

•       Hyper-oncotic colloid solutions (osmolarity of >300 mOsm/l) such as dextran 40 or starch solutions may be used in patients with massive plasma leakage, and those not responding to the minimum volume of crystalloid. Iso-oncotic colloid solutions such as blood and blood component may not be as effective.

•        

•       A volume of about maintenance +5% dehydration should be given to maintain “just adequate” intravascular volume and circulation. The duration of intravenous fluid therapy should not exceed 24 to 48 hours for those with shock. However, for those patients who do not have shock, the duration of intravenous fluid therapy may have to be longer but not more than 60 to 72 hours. This is because the latter group of patients has just entered the plasma leakage period while shock patients have experienced a longer duration of plasma leakage before intravenous therapy is begun.

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•       In obese patients, the ideal body weight should be used as a guide to calculate the fluid volume

•        

•       Fluid Requirement:

The fluid requirement, both oral and intravenous, in critical phase (48 hours) is calculated as M+5% (maintenance + 5% deficit). 5% deficit is calculated as 50 ml/kg up to 50kg.

In general, the fluid allowance (oral + IV) is about maintenance (for one day) + 5% deficit (oral and IV fluid together), to be administered over 48 hours.

The rate of IV replacement should be adjusted according to the rate of plasma loss, guided by the clinical condition, vital signs, urine output and haematocrit levels.

The admitted patient (Category B) should be started with recommended fluid at a rate of 1.5ml/kg/hr or 40ml/hr (12 d/min) for adults and should be given for 6 hours. If patient's vital signs are stable, then the escalation of fluid is not needed and the same rate can be maintained for a period of 48 hours.

If patient started with 1.5ml/kg/hr (adult 40ml/hr) for 6 hours doesn’t have stable vital signs and adequate urine output, the fluid should be escalated to 3ml/kg/hr (adult 80ml/hr or 20 drops/min) for another 6 hours. If patient's vital signs are stable, then the escalation of fluid is not needed and the same rate can be maintained for a period of 48 hours. This fluid can be escalated to 5ml/kg/hr (adult 120ml/hr or 30d/min and then upto 7ml/kg/hr or adult 200ml/hr or 50d/min) if every 6 hours doesn’t have stable vital sign or urine output.

Patient should be monitoring every 2 hours with special attention to vital signs, urine output, respiratory signs and haematocrit etc. In 6 hours of escalation, if patient become stable regarding clinical parameters, the fluids can be gradually decline from 7 to 5 to 3 to 1.5 (ml/kg /hr) or from stages where he wasstable. But the fluids should be maintained always for at least 48 hours.

Reassess the clinical status, repeat the haematocrit and review fluid infusion rates accordingly.

Patients with warning signs should be monitored by health-care providers until the period of risk is over. A detailed fluid balance should be maintained.

Parameters that should be monitored include:

•       vital signs and peripheral perfusion (1−4 hourly until the patient is out of the critical phase),

•       urine output (4−6 hourly),

•       haematocrit (before and after fluid replacement, then 6−12 hourly),

•       blood glucose

•       other organ functions (such as renal profile, liver profile, coagulation profile, as indicated).

Platelet transfusion is not recommended for thrombocytopenia (no prophylaxis platelet transfusion). The indication of which may be as follows:

1.     Very severe Thrombocytopania who need urgent surgery

2.     Clinical judgement of the treating physician

If platelet concentrate is not available fresh whole blood may be transfused as per guidelines given under DHF management.

The goals of fluid resuscitation include:

• improving central and peripheral circulation – i.e. decreasing tachycardia, improving BP and pulse volume, warm and pink extremities, a capillary refill time <2 seconds

• improving end-organ perfusion – i.e. achieving a stable conscious level (more alert or less restless)

• urine output ≥ 0.5 ml/kg/hour or decreasing metabolic acidosis.

Treatment of shock

Compensated shock:

•       DSS is hypovolemic shock caused by plasma leakage and characterized by increased systemic vascular resistance, manifested by narrowed pulse pressure (systolic pressure is maintained with increased diastolic pressure, e.g. 100/90 mmHg).

•       When hypotension is present, one should suspect that severe bleeding, and often concealed gastrointestinal bleeding, may have occurred in addition to the plasma leakage.

•       Most cases of DSS will respond to 10 ml/kg in children or 300–500 ml in adults over one hour or by bolus if necessary further.

•       However, before reducing the rate of IV replacement, the clinical condition, vital signs, urine output and haematocrit levels should be checked to ensure clinical improvement.

•       It is essential that the rate of IV fluid be reduced as peripheral perfusion improves; but it must be continued for a minimum duration of 24 hours and discontinued by 36 to 48 hours.

•       Excessive fluids will cause massive effusions due to the increased capillary permeability

Laboratory investigations for Acidosis, Bleeding, Calcium & Blood Sugar (ABCS) should be carried out in both shock and non-shock cases when no improvement is registered in spite of adequate volume replacement.

Decompensated shock (DSS, Profound hypotension)

•       Preferably this group of patient need to manage in ICU setting.

•       Oxygen should be started immediately.

•       The bolus 10-20 ml/kg crystalloids should be given within 15-30 min.

•       If the vital signs and HcT improved, the fluid can be reduced from 10 ml/kg/hr to

•       6ml/kg/hr for 2 hours, then from 6 to 3 ml/kg/hr for 2-4 hrs and then 3 to 1.5 ml/kg/hr for another 2-4 hrs. Fluid should be discontinued after 24-48 hrs.

•       If there is no clinical improvement after bolus crystalloids, check HcT. If the HcT is raising (more than 45%, then the fluid should be changed to colloid at (10- 20ml/kg/hr) and if there is improvement, then changes the fluid to crystalloids and successfully reduce as stated before. The highest dose of colloid will be 30 ml/kg/24 hour.

•       If the initial bolus crystalloids fluid does not have improvement in vitals sign and HcT is reduced, then suspect concealed bleeding and blood transfusion should be started immediately at 10ml/kg whole blood or packed RBC at 5ml/kg.

•       In case of refractory hypotension, look for ABCS and IV inotropes with crystalloids as per requirement is to be continued.

•       In case of acidosis, hyperosmolar or ringers’ lactate should not be used.

•       HcT measurement every hour is more important than platelet count during management.

Patients at risk of severe bleeding are those who:

•       Have profound/prolonged/refractory shock;

•       Have hypotensive shock and multi-organ failure

•       Have pre-existing peptic ulcer disease;

•       Have any form of trauma, including intramuscular injection.

•       Are given non-steroidal anti-inflammatory agents;

•       Are on anticoagulant therapy;

The action plan for the treatment of hemorrhagic complications is as follows:

•       If possible, attempts should be made to stop bleeding if the source of bleeding is identified e.g. severe epistaxis may be controlled by nasal adrenaline packing.

•       Give aliquots of 5−10 ml/kg of fresh -packed red cells or 10−20 ml/kg. Of fresh whole blood (FWB) at an appropriate rate and observe the clinical response.

•       It is important that fresh whole blood or fresh red cells are given.

•       Oxygen inhalation-2-4 L/min

•       Consider repeating the blood transfusion if there is further overt blood loss or no appropriate rise in haematocrit after blood transfusion in an unstable patient.

•       There is no evidence that supports the practice of transfusing platelet concentrates and/or fresh-frozen plasma for severe bleeding in dengue.

•       Transfusions of platelet concentrates and fresh frozen plasma in dengue were not able to sustain the platelet counts and coagulation profile. Instead, in the case of massive bleeding, they often exacerbate the fluid overload.

•       In certain situations, such as obstetrical deliveries or other surgeries, transfusions of platelet concentrate with or without fresh blood should be considered in anticipation of severe bleeding.

•       In gastrointestinal bleeding, H-2 antagonist and proton pump inhibitors have been used, but their efficacy have not been studied.

•       Great care should be taken when inserting a nasogastric tube or bladder catheters which may cause severe hemorrhage. A lubricated orogastric tube may minimize the trauma during insertion. Insertion of central venous catheters should be done with ultra-sound guidance or by an experienced person.

•       It is essential to remember that blood transfusion is only indicated in dengue patients with severe bleeding.

Glucose control

Hyperglycaemia and hypoglycaemia may occur in the same patient at different times during the critical phase.

Hypoglycaemia should be treated as an emergency with 0.1−0.5g/kg of glucose, rather than with a glucose-containing resuscitation fluid.

Electrolyte and acid-base imbalances

•       Hyponatraemia is a common observation in severe dengue

•       The use of isotonic solutions for resuscitation will prevent and correct this condition.

•       Hyperkalaemia is observed in association with severe metabolic acidosis or acute renal injury.

•       Life-threatening hyperkalaemia, in the setting of acute renal failure should be managed with Resonium A and infusions of calcium gluconate and/or insulindextrose.

Metabolic acidosis

•       Compensated metabolic acidosis is an early sign of hypovolaemia and shock.

•       Lactic acidosis due to tissue hypoxia and hypoperfusion is the most common cause of metabolic acidosis in dengue shock.

•       Correction of shock and adequate fluid replacement will correct the metabolic acidosis.