Fluids

Question 1

What do you need to when you are asked to prescribe some fluids?

Answer 1

1. History
   a. How much have they been eating/drinking over past few days?
   b. Clinical monitoring- fluid balance chart
   c. Weight
2. Vital parameters
   a. Temperature
   b. BP
   C. RR
   d. Pulse
   e. Cap refill
   Trend over the past few days
3. Check lab results
   a. FBC
   b. U&e
   c. Creatinine
4. Any extra sources of fluid loss?
   e.g stomas, drains, nausea or vomiting and output from this.
   Basically figure out any extra losses over maintanese

Question 2

What are the two main fluid compartments?

Answer 2

Intracellular (70%) and extracellular (30%)

Question 3

What is the extracellular fluid divide into?

Answer 3

Interstitial and Intravascular

Question 4

What is starlings hypothesis?

Answer 4

Fluid movement due to filtration across the wall of a capillary is dependent on the balance between the hydrostatic pressure gradient and oncotic pressure gradient across the capillary.

Question 5

What is the component of intracellular fluid?

Answer 5

High potassium concentration

Low sodium concentration

Intracellular solute concentrations remain more or less constant

Question 6

What is extracellular fluid concentration?

Answer 6

High sodium concentration

Low potassium concentration

Question 7

What is the maintenance requirements in an average healthy adult with no extra losses?

Answer 7

2 to 2.5l of fluid per day

e.g 1.5l to replace losses in urine and 500-800 ml in insensible losses

Question 8

What is the routine maintenance of fluids, electrolytes and glucose per day?

Answer 8

25-30ml/kg/day of water

1mmol/kg/day each of sodium, chloride and potassium

50-100 g/day of glucose to limit starvation ketosis

Question 9

How much urine does a health person lose?

Answer 9

1ml/kg/hour

so 1.5 to 2.5l a day

Question 10

In fluid replacement, what should you aim for a minimum urine output?

Answer 10

0.5ml/kg/hour

Question 11

Sweating results in loss of…

Answer 11

sodium

Question 12

Diarrhoea/increased stoma output are sources of loss of

Answer 12

sodium, potassium and bicarbonate

Question 13

Vomiting may lead to loss of

Answer 13

potassium, chloride and hydrogen ions

Question 14

Electrolytes in sodium chloride 0.9%

Answer 14

Na: 154
Cl: 154
K+: Nil
Lactate: nil
Calcium: nil
glucose: nil

Question 15

Electrolytes in glucose 5%

Answer 15

All nil

except 50g/litre glucose

Question 16

Electrolytes in hartmann (sodium lactate)

Answer 16

Na: 131
CL: 131
K: 5
Lactate: 29
Ca: 2
Glucose: nil

Question 17

Electrolytes in NaCL 0.18% &Glucose 4%

Answer 17

Na: 30
Cl: 30
K: nil
lactate: nil
calcium: nil
Glucose: 40g/litre

Question 18

Electrolytes in gelofusine

Answer 18

Na: 154
Cl: 12
K: nil
lactate: nil
calcium: nil
glucose: nil

Question 19

If someone is hypovolaemic, why might their BP be normal?

Answer 19

Compensation secondary to peripheral vasoconstriction (may show increase cap refill time).

Check orthostatic BP (when hypotension is absent, there may be dramatic drop inbox on standing and is a sensitive and early indicator of volume loss)

Question 20

What are the benefits of crystalloids?

Answer 20

Cheap and effective solutions

Do not cause adverse immunological reactions

Question 21

What can crystalloids be used for?

Answer 21

Maintenance and replacement fluids

Question 22

How are crystalloids classed as?

Answer 22

Hypotonic- lowers serum osmolality and are not commonly used e.g. NaCL 0.45%

Hypertonic- increase plasma tonicity and draw fluid out of cells e.g. NaCL 3%, mannitol

Isotonic- fluid stays almost entirely within extracellular compartment e.g. NaCL 0.9%

Question 23

How much does sodium chloride 0.9% distribute in each fluid compartment?

Answer 23

100% within extracellular fluid

25% will go in intravascular
75% is in interstitial fluid

Question 24

How does glucose 5% distribute in each fluid department?

Answer 24

2/3 in intracellular fluid
1/3 goes to extracellular fluid
(only 80ml of 1000 would go into intravascular space- that is why it is not commonly used for resus in blood loss)

Question 25

Examples of colloids

Answer 25

Blood Dextran Gelatin Human albumin

Question 26

Drawbacks of colloid

Answer 26

Higher cost | Risk of anaphylactoid and anaphylaxis

Question 27

What is the colloid distribution in fluid compartments?

Answer 27

1000ml of human albumin compartment | 100% stays in intravscular compartment

Question 28

What to use- colloids vs crystalloid in resus?

Answer 28

Crystalloids cause initial expansion within vessels then redistribute. SR has shown no difference between the use of colloid and crystalloid. However, from practice use, crystalloids are more available and cheaper so use them first. Nice guidelines: Use crystalloid containing Na+ in the range of 131-154 (so sodium chloride 0.9%) Human albumin solution 4-5% can be considered for fluid resuscitation only in patients with severe sepsis. Note: human albumin solution 20% should not be used as it is hyperoncotic and rapid administration in fluid resuscitation scenarios can lead to rapid volume expansion and cardiac failure.

Question 29

What is distributive shock?

Answer 29

1. Results in relative hypovolaemia Causes include: sepsis, anaphylaxis and neurogenic shock

Question 30

What is hypovolaemic shock?

Answer 30

Most common form | Causes include haemorrhage, burns or any cause of substantial fluid loss

Question 31

How is shock severity graded?

Answer 31

1-4

Question 32

What is shock severity 1?

Answer 32

15%- 750ml volume lost Mild resting tachy, slight delayed cap refill at 3 seconds (10% volume loss)

Question 33

What is shock severity 2?

Answer 33

15-30% loss 750-1000ml Cool peripheries, tachycardia, decrease pulse pressure, delayed cap refill (5 seconds) May have catecholamine driven increase in diastolic BP and some anxiety

Question 34

What is shock severity 3?

Answer 34

30-40% 1500-2000ml Marked tachycardia and tachypnoea, decreased systolic BP Very narrow pulse pressure, oliguria, low volume pulse, postural drop of 20-30mmHg and confusion/agitation

Question 35

What is shock severity 4?

Answer 35

40-50% 2000-2500ml Low GCS or unconscious, minimal or no urine output Thready pulse, very tachycardiac, very low BP, cold skin

Question 36

What are the signs that a patient may need urgent fluid resus?

Answer 36

Systolic blood pressure less than 100 mmHg Heart rate is more than 90 beats per minute Capillary refill time more than 2 seconds or peripheries are cold to touch Respiratory rate more than 20 breaths per minute National Early Warning Score (NEWS2) is 5 or more Passive leg raising suggests fluid responsiveness

Question 37

What is the passive leg raise for?

Answer 37

thought to mimic the administration of a fluid bolus by redirecting blood from the lower limbs to the heart (i.e. increased pre-load). This auto-transfusion of blood has been shown to increase cardiac output in patients' who are fluid depleted. Therefore, the test is used to predict which patients are most likely to respond to administration of a fluid bolus. One minute after performing the PLR manoeuvre the patient's heart rate, blood pressure and stroke volume variance should be checked. After returning the patient to their original position, their observations should return to baseline pre-test values.

Question 38

Sodium chloride 0.9% in large volumes may result in...

Answer 38

Hypercholaraemic acidosis

Question 39

What is the rate for IV fluid resus

Answer 39

500ml of a crystalloid solution in the range of 130-154 mmol/l (e.g. sodium chloride 0.9%) administered over less than 15 min Any resus fluid are IN ADDITION to calculated maintenance fluid requirements

Question 40

What types of fluid regimen are there?

Answer 40

resus maintenance replacement

Question 41

What are the complications of fluid overload?

Answer 41

1. Dilutional hyponatraemia- treat with fluid restriction | 2. Pulmonary oedema:

Question 42

How to treat fluid overload?

Answer 42

Stop intravenous fluids: this is essential to avoid further deterioration. Furosemide: can be given as a bolus or infusion. It causes a diuresis and venodilation. Sublingual nitrate: causes a reduction in preload, the effects of which can be seen within five minutes. Intravenous nitrate: provides an excellent and titratable pre- and after-load reduction. BP monitoring is essential with this intervention, as hypotension is an indication to stop the infusion. Continuous positive airway pressure ventilation: has been shown to improve gas exchange by recruiting collapsed alveoli and redistributing excess fluid into the interstitial and intravascular compartments. It reduces pre- and after-load although this measure is usually only carried out by critical or coronary care units.

Question 43

What should you consider when picking a fluid? 4D's

Answer 43

1. Correct drug? 2. Correct dose and rate of administration? 3. Duration and review date documented? 4. De-escalation- when to STOP parental fluid prescription been document?