Fluids

Question 1

IV fluids can be categorised into 2 major groups.

Name these groups

Answer 1

Crystalloids: solutions of small molecules in water (e.g. sodium chloride, Hartmann’s, dextrose)

Colloids: solutions of larger organic molecules (e.g. albumin, Gelofusine)

Question 2

Give an example of a Crystalloids IV fluid

Answer 2

Hartmann’s

Dextrose

Normal saline (sodium chloride)

Question 3

Give an example of a Colloid IV fluid

Answer 3

Albumin

Gelofusine

Question 4

Why are colloids are used less often than crystalloid solution

Answer 4

Colloids carry a risk of anaphylaxis and research has shown that crystalloids are superior in initial fluid resuscitation

Question 5

What two types of fluids are used for resuscitation

Answer 5

Normal saline (sodium chloride 0.9%)

Hartmann’s solution

Question 6

Fill in the blanks on which fluids are which

Answer 6

Question 7

What fluid types are isotonic

Answer 7

Isotonic means it has similar concentration of dissolved particles as blood

Normal Saline (sodium chloride 0.9%)

Hartmann’s solution

Question 8

What fluid types are hypotonic

Answer 8

Hypotonic have a lower concentration of dissolved solutes than blood

Sodium chloride 0.18% + Glucose 4%

5% Dextrose

Question 9

When prescribing IV fluids, remember the 5 Rs.

What are the 5 “Rs”

Answer 9

Resuscitation

Routine maintenance

Replacement

Redistribution

Reassessment

Question 10

If you’ve performed your initial assessment and things aren’t looking great and you decide to prescribe some resuscitation fluids.

What is the initial fluid bolus you will prescribe

Answer 10

Initial 500 ml bolus of a crystalloid solution (e.g NaCl 0.9%/Hartmann’s solution) over less than 15 minutes.

Question 11

After administering the initial 500 ml fluid bolus you should reassess. If the patient still has clinical evidence of ongoing hypovolaemia

What is your next step

Answer 11

Further 250-500 ml bolus of a crystalloid solution e.g NaCl 0.9%/Hartmann’s solution

Question 12

You can keep giving patients fluid resusitation if there is ongoing clinical evidence up until how many mls?

Answer 12

Until you’ve given a total of 2000 ml of fluid.

At that point seek expert help

Question 13

In what patient groups should you apply a more cautious approach to fluid resuscitation

Answer 13

If patients with complex medical comorbidities (e.g. heart failure, renal failure)

and/or

elderly

Question 14

What fluid bolus should be given when you have cautious approach to fluid resuscitation i.e. if the patient has complex medical comorbidities (e.g. heart failure, renal failure) and/or are elderly

Answer 14

Fluid boluses 250ml rather than 500ml

i.e. initial fluid bolus will be 250ml of a crystalloid solution (e.g NaCl 0.9%/Hartmann’s solution) over less than 15 minutes.

Question 15

What are the daily maintenance fluid requirements

Answer 15

25-30 ml/kg/day of water

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

50-100 g/day of glucose to limit starvation ketosis (however note this will not address the patient’s nutritional needs)

Question 16

In which patients groups should we use a more cautious approach to fluid prescribing (e.g. 20-25 ml/kg/day)

Answer 16

Elderly patients

Patients with renal impairment or cardiac failure

Malnourished patients at risk of refeeding syndrome

Question 17

When are Nasogastric fluids or enteral feeding preferable in terms of maintenance needs

Answer 17

When maintenance needs are more than 3 days

Question 18

Name some of the sources that can cause ongoing fuid or electrolyte loss

Answer 18

Vomiting/NG tube loss

Diarrhoea

Stoma output loss (colostomy, ileostomy)

Biliary drainage loss

Blood loss (e.g. malaena/haematemesis)

Sweating/fever/dehydration (reduced or absent oral intake)

Urinary loss (e.g. diabetes insipidus/post-AKI polyuria)

Question 19

There are two fluids spaces in the body. Intracellular and extracellular space.

Which space contains the most of the total body fluids

Answer 19

Intracellular (2/3)

Question 20

There are two fluids spaces in the body. Intracellular and extracellular space.

The extracellular space can be subdivided further into 3 compartments. Name them

Answer 20

Intravascular space (inside blood vessels)

Interstitial space – the functional tissue space between and around cells

The “third space”

Question 21

What is the third space, extracellular space

Answer 21

Refers to areas of the body that do not normally contain fluid and where fluid collection is not functional or desirable e.g. peritoneal cavity (forming ascites), plerual cavity (forming pleural effusions)

Also refers to non-functional and excessive collection of fluid in the intersitital space resulting in oedema

Question 22

Name some incidences in which patients require a specific fluid restriction

Answer 22

Heart failure

Renal failure

Hyponatraemia

Question 23

In patients that require fluid restriction. What is the total fluid intake capped at

Answer 23

1.5 L per day

Question 24

Define the term insensible fluid loss

Answer 24

refers to fluid output that is difficult to measure, such as through respiration (breathed out), in stools, through burns and from swea

Question 25

Name some of the signs of hypovolaemia (inadequate fluid)

Answer 25

Hypotension (systolic < 100 mmHg)

Tachycardia (heart rate > 90)

Capillary refill time > 2 seconds

Cold peripheries

Raised respiratory rate

Dry mucous membranes

Reduced skin turgor

Reduced urine output

Sunken eyes

Reduced body weight from baseline

Feeling thirsty

Question 26

Name some of the signs of fluid overload

Answer 26

Peripheral oedema (check the ankles and sacral area)

Pulmonary oedema (shortness of breath, reduced oxygen saturation, raised respiratory rate and bibasal crackles)

Raised JVP

Increased body weight from baseline (regular weights are an important way of monitoring fluid balance)

Question 27

What signs will a patient with third spacing have

Answer 27

Signs of hypovolaemia (e.g., hypotension, tachycardia and prolonged capillary refill time) as they have low level of fluid in the intravascular space

AND

Signs of fluid overload (e.g., oedema and ascites) as they have excessive fluid in other areas (such as the interstitial space or peritoneal cavity)

Question 28

Name the 3 main indications for IV fluids

Answer 28

Resuscitation (e.g., sepsis or hypotension)

Replacement (e.g., vomiting and diarrhoea)

Maintenance (e.g., nil by mouth due to bowel obstruction)

Generally, IV fluids should be avoided if the patient can adequately meet their fluid requirements with oral fluids.

Question 29

Name a potential adverse effect if you give a patient a lot of nomal saline (0.9% sodium chloride)

Answer 29

Hypernatraemia - high sodium

Normal 0.9% saline has a concentration of sodium of 154 mmols/L (a lot more than the normal l blood concentration of 135-145 mmols/L). When you use normal saline, you are adding a lot of sodium into the system, significantly increasing the risk of hypernatraemia.

Risk of causing metabolic acidosis - as adding so much chloride

Question 30

Name a potential adverse effect if you give a patient a lot of 5% dextrose

Answer 30

Hyponatraemia - low sodium

Oedema

Question 31

The rate of potassium infusion should not exceed

Answer 31

10mmol/hour

As there is a risk of inducing an arrhythmia or cardiac arrest

Question 32

If you need give a higher rate of potassium infusion (under expert supervision).

What provisions must you put in place

Answer 32

Cardiac monitoring throughout

The IV fluid through a central line (rather than a peripheral cannula).

Question 33

What is defined as a low urine output

Answer 33

< 0.5 ml/Kg/hr