Fluid Therapy Flashcards
What is the fluid intake required for a normal person
- roughly 2-2.5L in a normal person (70kg) over 24 hour
What is the normal losses for fluid in a normal person
- normal daily losses are through urine (1500ml), stool (200ml) and sensible losses (800ml)
How do people tend to get fluid intake
- 1000ml through food
- 1500ml through drink
What does an underfilled fluid balance look like
- tachycardia
- postural drop in BP (or low BP but late sign)
- slow capillary refill
- reduced urine output
- cool peripheries
- dry mucous membranes
- reduced skin turgor
- sunken eyes
What does overfilled fluid balance look like
- raised JVP
- pitting oedema (sacrum, ankles/legs)
- tachypnoea
- bibasal crepitations
- pulmonary oedema on CXR
how much fluid is in each of the fluid compartments in the body
- for a 70kg man, total body fluid = 42L (60% of body weight)
- 2/3 is intracellular 28L
- 1/3 is extracellular 14L
- different types of IV fluids will equilibrate with the different fluid compartments depending n the osmotic content of the given fluid
What are the two types of IV fluid
- Crystalloids
- Colloids
Name the types of crystalloids
- 5% glucose (dextrose)
- 0.9% sodium chloride (normal saline)
- hypertonic glucose (10% or 50%)
- glucose with sodium chloride (1/5 of normal saline)
- Hartmann’s solution
Describe 5% glucose
- Isotonic, but contains only a small amount of glucose (50g/L) and so provides little energy (~10% of daily energy per litre)
- The liver rapidly metabolises all the glucose leaving only water, which rapidly equilibrates throughout all fluid compartments
What is 5% glucose used in
- not used in fluid resuscitation
- suitable for maintaining hydration
What does excess 5% glucose lead to
- water overload and hyponatraemia
Describe 0.9% sodium chloride
- Has about the same Na+ content as plasma (150mmol/L) and is isotonic with plasma
- Will equilibrate rapidly throughout the extracellular compartment only, and takes longer to reach the intracellular compartment than 5% glucose
What is 0.9% sodium chloride used for
- fluid resuscitation - this is because it remains in the extracellular space and thus 1/3 of the given volume in the intravascular space
- maintain hydration
What is hypertonic glucose (10%-50%) used for
- may be used in the treatment of hypoglycaemia
What is the negatives of hypertonic glucose (10-50%) and what can you do about it
- irritant to veins so care in its use is needed
- infusion sites should be inspected regularly and flushed with 0.9% saline after use
when is glucose with sodium chloride used
- Isotonic, containing 0.18% saline (30mmol/L of Na+) and 4% glucose (222mol/L)
- Roughly the quantity of Na+ required for normal fluid maintenance, when given 10-hourly in adults, but is now most commonly used in paediatric setting
What is Hartmann’s solution
- alternative to 0.9% saline
What are colloids
- have a high osmotic content similar to that of plasma and therefore remain in the intravascular space for longer than other fluids
- therefore appropriate for fluid resuscitation but not for general hydration
- expensive and may cause anaphylactic reactions
What fluid do you use in acute blood loss
resuscitate with 0.9% saline via large-bore cannulae until blood is available
What fluid do you use in children
- use glucose with sodium chloride for fluid maintenance
- 100ml/kg, then 10kg, then 50ml/kg for the next 10kg then 20ml/kg thereafter (all per 24 hour)
What fluid do you use in GI losses
(diarrhoea, vomiting, NG tubes)
- replace lost potassium as well as lost fluid volume
What should you use for liver failure
patients often have a raised total body sodium, so use salt-poor albumin or blood for resuscitation, and avoid 0.9% saline for maintenance
What should you use in poor urine output
- aim for >1mg/kg/h, minium is >0.5ml/kg/h
- give fluid challenge , e.g. 500ml 0.9% saline over 1 hour
- recheck urine output
- if not catheterised, exclude retention
- if catheterised ensure catheter is not blocked
What should you do for fluid balance in post operative
– check the operation notes for intraoperative losses, and ensure you chart and replace added losses from drains etc
