Fluid Management

1. Assess fluid status and requirements based on following parameters:

1.1. Hydration & total body water

History and thirst.
Drug and fluid charts.
Weight, oedema & clinical status.
Evidence of continuing losses.
Vascular volume status.

1.2. Cardiovascular clinical status

Arterial trace.
Cardiac output & Echo.
Ultrasonography and venous doppler.
Fluid challenge or leg-raise test.
Na, Cl, K, Lactate, Hb, Venous Sats, Urinary Na.

2. Maintenance (hydration) fluid

2.1. Standard fluid for maintenance: Balanced Salt Solution (e.g., Plasmalyte, Physiomax)

2.2. Set target total fluid intake

<50kg 1500 ml/day.
50-80 kg 2000 ml/day.
>80 kg 2500 ml/day.

2.3. Subtract other intake: Drug fluids, Nutritional fluids, Oral fluid intake.

2.4. Reassess based on end-points like fluid balance, hydration status, minimal symptoms of thirst.

3. Resuscitation fluid

3.1. Standard resuscitation fluid for Critical Care is Balanced salt solution.

3.2. Give Balanced salt solution as bolus (e.g., 250-500 ml) or short infusion to replace:

● Existing hypovolemia.

● Gut: diarrhea or fistula losses.

● Renal: excess losses.

● Skin: excess insensible loss from sweat.

● Inflammation: capillary leak.

3.3. Special Circumstances:

● Give blood when Hb below threshold.

● Give blood & blood products when major bleed (massive transfusion guideline).

3.4. Consider Normal Saline fluid in:

● Traumatic Brain injury, Neurosurgery.

● Diabetes and DKA.

4. Reassess based on end-points

● Volume status.

● Preload and cardiac output.

● Urine output.

5. Management of Oliguria

Assess whether oliguria is pathological or physiological.
Consider ● Previous fluid balance. ● Input of nutrition, drugs and free water. ● Current vascular volume and cellular hydration. ● Urine osmolality and sodium.
Ensure catheter is not blocked – consider flushing or ultrasound scan.
Consider fluid challenge e.g., Balanced Salt Solution 250ml in Pre-Renal Failure (hypovolemia).
Consider fluid restriction and hemofiltration in Acute Renal Failure.
Consider following options in obstructive renal failure: ● Ultrasound to confirm diagnosis. ● Catheter change. ● Percutaneous drainage.

6. Other considerations

6.1. Before giving a fluid bolus consider:

● What is the indication?

● What is today’s fluid balance target?

● What is the goal of this fluid bolus?

● What physiological end-points am I targeting?

6.2. Patients should resume normal oral fluids and nutrition as soon as reasonably practicable after an illness. Drips should only be used if this is not possible.

6.3. Colloids should be avoided.

6.4. Normal saline is avoided as maintenance fluid as it may cause hyperchloremia and hyperchloremic acidosis.

6.5. Dextrose should never be used as resuscitation and maintenance fluid.

6.6. Fluid overload / positive cumulative balance is associated with increased morbidity and poor outcome in critical care and it should be avoided.

6.7. The following phases of fluid management should be kept in mind while managing critically ill patients

Resuscitation	• Aim of the treatment is resuscitation and correction of shock with the achievement of an adequate perfusion pressure • A rapid fluid bolus should be given (usually 3–4 mL/kg given over 10 to 15 min and repeated when necessary), normally in association with vasopressor administration.
Optimization	• Fluids should be administered according to individual needs, reassessed on a regular basis, e.g., using fluid challenge techniques (100–200 mL over 10 min).
Stabilization	• The aim of fluid management is to ensure water and electrolytes to replace ongoing losses and provide organ support. • The target should be a zero or slightly negative fluid balance.
Evacuation	• Removing excessive fluid and will be frequently achieved by spontaneous diuresis as the patient recovers, although ultrafiltration or diuretics might be necessary.

Further Readings:

1. Malbrain, M. L., Langer, T., Annane, D., Gattinoni, L., Elbers, P., Hahn, R. G., ... & Van Regenmortel, N. (2020). Intravenous fluid therapy in the perioperative and critical care setting: executive summary of the International Fluid Academy (IFA). Annals of intensive care, 10, 1-19.

2. Malbrain, M. L., Van Regenmortel, N., Saugel, B., De Tavernier, B., Van Gaal, P. J., Joannes-Boyau, O., ... & Monnet, X. (2018). Principles of fluid management and stewardship in septic shock: it is time to consider the four D’s and the four phases of fluid therapy. Annals of intensive care, 8(1), 1-16.

National Institute for Clinical Excellence. (2013). Intravenous fluid therapy in adults in hospital. NICE clinical guideline, 174.