Fluids

Question 1

Recommended daily fluid intake average adult male

Answer 1

~3.7 litres

Question 2

Recommended daily fluid intake average adult female

Answer 2

~2.7 litres

Question 3

Common causes of hypovolaemia

Answer 3

1) GI losses
2) Haemorrhage
3) Endocrine disturbance (adrenal insufficiency, diabetes insipidus, SIADH)
4) Renal disturbance
5) Fever

Question 4

Equation for daily fluid intake needs

Answer 4

30-40mL/kg/day

Question 5

Average fluid loss per day

Answer 5

1600mL (500ml in urine, 200ml in faeces, 900ml insensible)

Question 6

Common crystalloids

Answer 6

1) Normal saline
2) Compound sodium lactate (CSL, Hartmann’s)
3) 5% dextrose

+ 4% dextrose + 0.018% normal saline
+ 15-20% dextrose
+ Hypertonic saline

Question 7

Properties of normal saline

Answer 7

Contents: 154mmol sodium, 154mmol chloride
Total osmolarity: 308mosm/L
pH: 5.0

Question 8

Properties of CSL

Answer 8

Contents: 131mmol sodium, 111mmol chloride, 29mmol lactate, 5mmol potassium, 2mmol calcium
Total osmolarity: 279mosm/L
pH: 6.5

Question 9

Cons of normal saline

Answer 9

1) Hyperchloraemic metabolic acidosis (RF: >3-4L normal saline in 24hrs, renal impairment)
2) Hypernatraemia

Question 10

Cons of CSL

Answer 10

1) Cannot be mixed with some drugs (tazocin)
2) Caution in diabetes (gluconeogenic properties due to containing lactate)
3) Hyperkalaemia

Question 11

Pros of normal saline

Answer 11

1) Can mix with most drugs

Question 12

Pros of CSL

Answer 12

1) Lower risk hyperchloraemic metabolic acidosis

2) Can be used as a buffer to correct pH abnormalities

Question 13

Normal blood pH

Answer 13

7.35-7.45

Question 14

Pros/uses of 5% dextrose

Answer 14

1) T1DM fasting for theatre
2) Hypernatraemic patients
3) Short duration fasting (<24hrs)

Question 15

Cons of 5% dextrose

Answer 15

1) Not used for volume expansion (90% distributed into cells causing cellular swelling)
2) Hyponatraemia
3) Hypokalaemia
4) Pulmonary oedema
5) Cautious used in DM & HF

Question 16

Uses of 15-20% dextrose

Answer 16

1) Hypoglycaemia

Question 17

Common colloids

Answer 17

1) Albumin
2) Gelofusion
3) Hydroxyethel starch (HES)

Question 18

Use of colloids

Answer 18

To increase oncotic pressure
Effects: incr circulating volume, incr venous return, incr left ventricular end-diastolic pressure, incr cardio output, tissue perfusion & diuresis

Question 19

Oncotic pressure

Answer 19

Pressure of larger molecules that do not dissolve in water

Question 20

Osmotic pressure

Answer 20

Pressure of smaller molecules dissolved in water

Question 21

Properties of gelofusion

Answer 21

Contents: modified fluid gelatine
Timing: works over the 3-4hours after transfusion to draw water into the intravascular space

Question 22

Uses of gelofusion

Answer 22

Mostly in critical care situations

1) Haemorrrhage
2) Trauma
3) Dehydration

Question 23

Uses of HES

Answer 23

Most commonly used for shock (of various etiologies)

Question 24

Cons of HES

Answer 24

1) Caution in renal impairment
2) Allergic reaction
3) Coagulopathy (can halve the available FVIII resulting in prolonged APTT)

Question 25

Managing fasting patients (NBM >8hrs)

Answer 25

1) IV fluids (3x 8hrly bags normal saline or CSL)
2) UEC daily (for any pt fasting/ receiving IV fluids)
3) Fluid balance chart
4) Adjust fluid replacement to clinical picture (MORE if: incr losses ie drains/burns/diarrhoea/fevers/vomitting/tachypnoea, LESS if: hypothyroidism, oliguric renal failure, fluid overload, SIADH)

If fasting >24hrs: ensure K+ replacement (use CSL or addd 30mmol to 2x bags of normal saline)
If fasting >72hrs: notify dietician
If fasting >4 days: consider TPN

Question 26

Fluid resuscitation

Answer 26

Shock/severe hypovolaemia: 1-2L fluid bolus (normal saline or CSL), rate 15min/L 
Moderate hypovolaemia (moderate hypotension): fluid challenge (250mL bolus to see if hypoT fluid responsive). If fluid responsive: give further 250mL bolus then 1L 15min/hr bag then maintenance fluids (8-10hrly) 
Mild hypovolaemia/dehydration: 1L normal saline/CSL Q4H, then 1L Q6-8H, then maintenance

Caution: slow rates by 1.5 in elderly or patients with cardiac/renal/hepatic impairment

Question 27

Fluid review

Answer 27

1) Observations (esp HR & BP, if floridly overloaded RR & SpO2 may be affected)
2) Check daily weights
3) Fluid restriction? Adherence?
4) Fluid balance chart
5) Cap refill
6) Skin turgor
7) JVP
8) Mucous membranes
9) Lung auscultation (consider ECG or CXR if concerned)
10) Check for ascites
11) Check for peripheral oedema
12) Urine output (ask/ check IDC)

Question 28

Normal urine output

Answer 28

0.5-1mL/kg/hr

Question 29

Oliguria

Answer 29

<0.5mL/kg/hr

Question 30

Anuria

Answer 30

<100mL/day