Fluids

Question 1

Reasons for fluids

Answer 1

Maintenance
Resuscitation
Replacement

Question 2

General key considerations before initiating fluids

Answer 2

What is the aim?
What is the weight and size of the patient?
Are there any co-morbidities present that are important to consider, such as heart failure or chronic kidney disease?
What is their underlying reason for admission*?
What were their most recent electrolytes?

Question 3

Why is it important to give large volumes of fluids to septic patients

Answer 3

In patients who are septic, the tight junctions between the capillary endothelial cells break down and vascular permeability increases. As a result, increasing hydrostatic pressures and reducing oncotic pressure lead to fluid leaving the vasculature and entering the tissue.

It is often therefore necessary to give relatively large volumes of intravenous fluid to maintain the intra-vascular volume, even though the total body water may be high. Close monitoring of the fluid balance will be required.

Question 4

What does insensible losses of fluids refer to

Answer 4

Losses from non-urine sources in unwell patients who may be febrile, tachypnoeic or having increased bowel output

Question 5

Signs of dehydration

Answer 5

Dry mucous membranes and reduced skin turgor

Decreasing urine output

Orthostatic hypotension

Late stages - increased cap refill, tachycardia, low blood pressure

Question 6

Signs of fluid overload

Answer 6

Raised JVP
Peripheral or sacral oedema
Pulmonary oedema

Question 7

Daily requirements for fluids and electrolytes

Answer 7

Water:25 mL/kg/day

Na+: 1 mmol/kg/day

K+: 1 mmol/kg/day

Glucose: 50g/day

Question 8

Uses of crystalloids

Answer 8

Neither crystalloids or colloids are superior in replenishing intravascular volume for resus purposes

Crystalloids are used more commonly in acute setting, in theatres and for maintenance fluids

Question 9

Definition of reduced urine output

Answer 9

<0.5ml/kg/hr

Question 10

Factors to consider in replacing ongoing fluid losses

Answer 10

Any third-space losses? 
Any diuresis? 
Tachypnoeic or febrile? 
Is the patient passing more stool than usual(or high stoma output?)? 
Losing electrolyte-rich fluid?

Question 11

What does third-space fluid losses refer to?

Answer 11

Refers to fluid losses into spaces that are not visible, such as the bowel lumen(in bowel obstruction) or the retroperitoneum(as in pancreatitis)