Fluids

Question 1

Discuss calculating maintenance requirements

Answer 1

Maintenance requirements

• replace insensible loss
• replace ongoing abdnormal loss
• attend to specific o2 carrying, coagulation, electrolyte or acid-base and nutritional requirements

Average
Water: 30ml/kg/day
sodium: 2mmol/kg/day
Potassium:1mmol/kg/day

Question 2

Discuss insensible losses

Answer 2

Faeces 100ml/day
lungs 400ml/day
skin 600ml/day

Question 3

Discuss common sites of abnormal fluid loss in ICU

Answer 3

Stoma, drains, fistula
Vomiting and diarrhoea
polyuria
gastric aspirates

Question 4

Discuss use of cyrstalloids

Answer 4

Essentially sterile water with the addition of electrolyes
may be hypo, iso or hypertonic

Advantages

• Cheap
• nil need for cross matching
• no anaphylaxis
• resus ECF
• promotes urine output

Disadvantages

• only 25% remains in circulation rest enters the interstium
• risk of peripheral and pulmonary oedema
• requires large resus volumes up to 3 x

Question 5

Discuss use of coloid

Answer 5

examples include albumin, 6% hetastarch and 10% pentastarch

Advantage:

• 50-100% remain intravascular
• spares pulmonary and interstitial space

Disadvantage

• expensive
• does not retore interstitial volume
• enters interstitial space if leaky
• immune reaction and problem with cross matching
• long tissue half life

Question 6

Discuss FFP

Answer 6

Usually for non-specific coagulation disturbances
FFP has an INR of 1.6 and cannot lower the INR lower then 1.7
Contains vitamin K dependent factors in a ratio of 1unit per ml
FFP contains all coagulation factors in normal concentrations.

Question 7

Discuss prothrombinex

Answer 7

The 3 factor prothrombin complex contrate

provision of factors II, IX and X

Question 8

Discuss the use of platelets

Answer 8

Both thrombocytopenia and platelet function disorders are an indication for platelet transfusion

Aim to keep above 100 if active bleeding

IN sepsis threshold for transfusion is <5 in all patient and <30 in patient with additional risk of bleeding

Question 9

Discuss TRALI

Answer 9

Defined as hypoxia and bilateral pulmonary oedema in the absence of other causes such as cardiac failure

Pathophys:
2 hit” model: lung capillaries are primed by an underlying illness then triggered by exposure to irritant in blood transfusion
— Step 1: underlying illness -> complement activation -> pulmonary sequestration of neutrophils
— Step 2: transfusion -> neutrophil activation -> endothelial cell damage and capillary leak syndrome

Diagnosis

• acute onset ALI(within 6 hours of a transfusion
• hypoxia (PaO2/FiO2 <= 300mmHg regardless of PEEP or SpO2)
• bilateral pulmonary infiltrates
• not cardiogenic in origin (PAWP < 18mmHg)