Fluid Balance. Outline of Talk. Fluid compartments What can go wrong Calculating fluid requirements Principles of fluid replacement Scenarios. Where is the Fluid?. Where is the Fluid?. 60% of body weight is fluid 2/3 is intracellular and 1/3 extracellular
Plasma oncotic pressure
Peripheral +/- pulmonary oedema
Hypotonic fluid causes
water to move into
Hypertonic fluid causes
water to move out
of intracellular space
Water move in and out of intracellular space
with changes in extracellular osmolarity
To maintain tissue perfusion by:
1) Maintaining intravascular fluid volume of about 5 litres
2) Correcting any deficits
3) Allowing for ongoing losses
In practice we hardly ever request urine biochem
S3 with functional MR
Water 1.5 - 2.5 litres
Sodium 50 - 100mmol
Potassium 40 - 80mmol
Ongoing Losses +
Crystalloid Colloid Blood
Rx 6 hourly to give 2 litres water,
how much sodium and 40mmol K?
Rx 6 hourly to give 2 litres water,
77mmol sodium and 40mmol K
Clear fluids and calorific drinks can safely be given until 2 hours before GA
If bowel prep given (and it isnt always) then fluid replacement will be required
People with diabetes will require variable rate insulin infusion (previously known as sliding scale)
- in the absence of any signs of fluid overload the default should be 1 litre in one hour, 1 litre in 2 hours, 1 litre in 4 hours then review
You are called to the receiving ward to write up more iv fluids for Mrs S age 65. She is currently nil by mouth and is now awaiting a second day for (delayed) endoscopy after a small nonhaemodynamically significant haematemesis.
Well with no other PMH; MEWS 0
Hb unchanged at 12.5. U+E all n range
How much and how fast?
6 hourly 500 ml bags
2:1 dextrose:saline 40-60 mmol K
500 ml 5% dextrose 6 hours 20 mmol KCl
500 ml 5% dextrose 6 hours
500 ml N saline 6 hours 20 mmol KCl
500 mls 5% dextrose
Patient with normal renal function with upset in normal water intake eg pre-operatively
Do not already have upset in water or electrolyte balance
Special circumstances need greater individualised care
1 L NaCL 0.9% - 4hrs
500 ml Dextrose 5 % - 4 hrs + 20mmol KCL
500 ml Dextrose 5 % - 4hrs
500 ml NaCL 0.9% - 4hrs + 20 mmol KCL
500 ml Dextrose 5% - 4hrs
500ml Dextrose 5 % + 20 mmol KCL -4hrs
Total in 24 hours = 3. 5 L
CHECK U/Es and Reassess
You are with your senior assessing a new admission. Mrs D aged 50 has Crohns Disease and has not been very well for 5 days.
She has been passing large volumes of liquid stool into her colostomy bag and has had a very poor oral intake of fluids.
Poor urine volumes
Mucous membranes dry, reduced skin turgour eyes sunken
CRT 4 secs
P 86 BP 105/70
Urea 17 creat 128
Senior says she is severely dehydrated and wants you to write up appropriate fluid
You are asked to see a 60 year old male who is 2 days post laparotomy who has stopped passing urine
Let’s consider if it was oliguria? dehydrated patient?
Mrs N 85 y resident nursing home
Less well for 1 week
Poor oral intake and intermittant diarrhoea
This morning, staff of nursing home difficulty waking her
Sleepy and confused
R # NOF 2008 hemi-arthroplasty
DH aspirin 75 mg
alendronate 70 mg weekly
GCS E3 M6 V4 looks very dry p 80 BP 120/70 T 37 O2 sats dehydrated patient?
Reduced skin turgor
No localising signs, no neck stiffness
Little else to find despite full examination of CVS, RS, GIS and CNS
Differential? dehydrated patient?
Vascular event? Head injury?
Infection – respiratory, UTI, GI source ?
Investigations – Na 165 mmol/L
Mr P 70 y day 2 post TURP dehydrated patient?
Increasingly confused and agitated
Called to see him
What goes through your mind?
Drug effect – new or withdrawal?
Hypoxic – PTE, pneumonia
Na 121 mmol/L dehydrated patient?
previous U+E pre-op N 141mmol/L