Fluids Flashcards
IV fluids can be categorised into 2 major groups.
Name these groups
Crystalloids: solutions of small molecules in water (e.g. sodium chloride, Hartmann’s, dextrose)
Colloids: solutions of larger organic molecules (e.g. albumin, Gelofusine)
Give an example of a Crystalloids IV fluid
Hartmann’s
Dextrose
Normal saline (sodium chloride)
Give an example of a Colloid IV fluid
Albumin
Gelofusine
Why are colloids are used less often than crystalloid solution
Colloids carry a risk of anaphylaxis and research has shown that crystalloids are superior in initial fluid resuscitation
What two types of fluids are used for resuscitation
Normal saline (sodium chloride 0.9%)
Hartmann’s solution
Fill in the blanks on which fluids are which
What fluid types are isotonic
Isotonic means it has similar concentration of dissolved particles as blood
Normal Saline (sodium chloride 0.9%)
Hartmann’s solution
What fluid types are hypotonic
Hypotonic have a lower concentration of dissolved solutes than blood
Sodium chloride 0.18% + Glucose 4%
5% Dextrose
When prescribing IV fluids, remember the 5 Rs.
What are the 5 “Rs”
Resuscitation
Routine maintenance
Replacement
Redistribution
Reassessment
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
Initial 500 ml bolus of a crystalloid solution (e.g NaCl 0.9%/Hartmann’s solution) over less than 15 minutes.
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
Further 250-500 ml bolus of a crystalloid solution e.g NaCl 0.9%/Hartmann’s solution
You can keep giving patients fluid resusitation if there is ongoing clinical evidence up until how many mls?
Until you’ve given a total of 2000 ml of fluid.
At that point seek expert help
In what patient groups should you apply a more cautious approach to fluid resuscitation
If patients with complex medical comorbidities (e.g. heart failure, renal failure)
and/or
elderly
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
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.
What are the daily maintenance fluid requirements
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)
In which patients groups should we use a more cautious approach to fluid prescribing (e.g. 20-25 ml/kg/day)
Elderly patients
Patients with renal impairment or cardiac failure
Malnourished patients at risk of refeeding syndrome
When are Nasogastric fluids or enteral feeding preferable in terms of maintenance needs
When maintenance needs are more than 3 days
Name some of the sources that can cause ongoing fuid or electrolyte loss
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)
There are two fluids spaces in the body. Intracellular and extracellular space.
Which space contains the most of the total body fluids
Intracellular (2/3)
There are two fluids spaces in the body. Intracellular and extracellular space.
The extracellular space can be subdivided further into 3 compartments. Name them
Intravascular space (inside blood vessels)
Interstitial space – the functional tissue space between and around cells
The “third space”
What is the third space, extracellular space
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
Name some incidences in which patients require a specific fluid restriction
Heart failure
Renal failure
Hyponatraemia
In patients that require fluid restriction. What is the total fluid intake capped at
1.5 L per day
Define the term insensible fluid loss
refers to fluid output that is difficult to measure, such as through respiration (breathed out), in stools, through burns and from swea
Name some of the signs of hypovolaemia (inadequate fluid)
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
Name some of the signs of fluid overload
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)
What signs will a patient with third spacing have
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)
Name the 3 main indications for IV fluids
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.
Name a potential adverse effect if you give a patient a lot of nomal saline (0.9% sodium chloride)
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
Name a potential adverse effect if you give a patient a lot of 5% dextrose
Hyponatraemia - low sodium
Oedema
The rate of potassium infusion should not exceed
10mmol/hour
As there is a risk of inducing an arrhythmia or cardiac arrest
If you need give a higher rate of potassium infusion (under expert supervision).
What provisions must you put in place
Cardiac monitoring throughout
The IV fluid through a central line (rather than a peripheral cannula).
What is defined as a low urine output
< 0.5 ml/Kg/hr
