Body fluid compartments + IV FLUID PRESCRIBING/STAT/MAINTENANCE in adults/children/neonates Flashcards
Let’s discuss the bodily fluid compartments
What percentage of body weight is water and what are the two (broad) compartments where water is stored known as?
In women, 50% of the body weight is water
In men, 60% of the body weight is water
This percentage of body weight is split between, intracellular fluid and extracellular fluid
How is the water divided in the intracellular and extracellular fluid compartements in men and women?
50% of body weight in females is water.
- 2/3rds body weight is divided into intracellular fluid (ICF)
- 1/3rd body weight is divided into extracelluar fluid (ECF)
For men, body fluid compartments can be remembered using the 60-40-20 rule.
60% of body weight in males is water
- 2/3rds body weight is divided into intracellular fluid (ICF)
- 1/3rd body weight is divided into extracelluar fluid (ECF)
Intravenous fluid can be divided into crystalloids and colloids. They distribute differently throughout our fluid compartments of the body.
What is the difference in particle size between crysalloids and colloids? Give exmaples of both
- Crystalloids: solutions of small molecules in water (e.g. sodium chloride, Hartmann’s, dextrose) (Hartmanns and sodium chloride are isotonic, dextrose is hypotonic)
- Colloids: solutions of larger organic molecules (e.g. albumin, Gelofusine)
Why are colloids used left often than crystalloid solutions?
Give an example of when you would use a colloid eg albumin?
- Colloids are used less often than crystalloid solutions as they carry a risk of anaphylaxis (and more expensive) and research has shown that crystalloids are superior in initial fluid resuscitation. (in reality few examples of condition where you would give HAS (human albumin solution) – eg if carrying out an ascitic drain)
In principles, what bodily fluid compartments do colloids remain in when given to a patient?
In principles, colloids remain in the intra-vascular space - TO LARGE TO PENETRATE THROUGH THE COMPARTMENTS
Intravenous fluid can be divided into crystalloids and colloids. They distribute differently throughout our fluid compartments of the body.
Just as colloids and crystalloids can distribute differently throughout our fluid compartments of the body, the different crystalloids can distribute differently
What compartments do the crystalloids below go into:
- Saline?
- Dextrose?
Saline is distributed in the extracellular fluid (made up of interstitial (aka extravascular) and intravascular fluid)
Dextrose is distributed betweeen intracellular and extracellular fluid compartments - not as useful because it goes intracellular
Patients require a daily intake of fluids and therefore you need to know the maintenance fluids intake required
What is the maintenance fluids required for:
- Water
- Electrolytes (Na+/K+/Cl-)
- Glucose
- Adults
- Water (crystalloids) give 25-30ml/kg/day (cardiac problems 20-25ml/kg/day)
- Electrolytes – roughly 1 mmol/kg/day of potassium, sodium and chloride (so 50kg person generally needs about 50mmols/day)
- Glucose – roughly 50-100g/day (therefore 5% dextrose which is 5g/100mls – if you gave 1 litre of glucose at 5% dextrose that would be 50g dextrose)
The initial assessment involves assessing the patient’s likely fluid and electrolyte needs from their history, clinical examination and available clinical monitoring (e.g. vital signs, fluid balance). Your clinical examination and review of available clinical monitoring should be performed using the ABCDE approach, with a focus on the patient’s fluid status.
- What crystalloid is usually given as a bolus?
- What crystalloid is usually given as maintenance fluid? - when may this not be given
Usuaully saline is given as the bolus fluid
- Adequate electrolytes are provided by 1L of 0.9% saline and 2L of 5% dextrose per day – 1 salty and 2 sweet
- 1L saline 0.9% + 20mml KCl (over 8 hours)
- 1L dextrose 5% + 20mmol KCl (over 8 hours)
- 1L dextrose 5% + 20mmol potassium chloride (over 8 hours)
- Hartmanns is useful to be given as maintenance fluid as it is the most physiologically similar to plasma
- As it contains a little potassium, don’t give if they are hyperkalaemic.
As discussed during Michael Murphey’s biochemistry tutorial- the Na+/K+ ATPase pump maintains the difference in Na+ gradient held between the extracellular & intracellular compartment. This pump means if you lose or gain Na+ (and by extension water), you lose it from the ECF (specificially the intravascular compartment first)
What are the initial signs of dehydration?
After trying to compensate for the loss of ions causing dehydration here, what body compartment would lose fluid next?
. Hence our initial dehydration symptoms i.e. hypotension - due to fluid being lost from the intravascular compartment (of the extracellular fluid)
, once compensation is maxed- you then lose fluid from the extravascular compartment, which is MUCH bigger- at this point we then get our extravascular symptoms
What are the signs of extravascular fluid loss?
Drying of mucous membranes
Skin turgor
Tachycardia
Hypotension
Elevated JVP
What are the sink holes we need to be aware of when assuming somebody is dehydrated due to their extravascular depletion sympotms?
- Dry Mouth. Not usually helpful. One of the first things a paramedic will do, is give therapeutic oxygen. Irrespective of the oxygen route i.e. mask/ nasal cannula. The mouth will become dried out as a consequence. Secondary, there is a vast proportion of patients who are on anti-cholinergics i.e. amitriptyline, tolterodine
- Skin turgor. Again, can be helpful but is not of much use in the elderly or those who have became ill with associated weight loss i.e. cancer because “of course their skin is gonna look saggy”
- Heart Rate- Can be of use however many patients are now on B blockers or other rate limiting cardiac drugs so their heart may not be allowed to reach a state of clinical tachycardia
- BP. Exceptionally useful.
- JVP. Again, Exceptionally useful if performed properly.
Assess whether the patient is hypovolaemic (fluid input equals fluid output)
What are different indications that a patient may require urgent fluid resuscitation?
(BP, HR, Cap refill, RR, NEWS, other test)
- systolic blood pressure is less than 100 mmHg
- heart rate is more than 90 beats per minute
- capillary refill time is more than 2 seconds or peripheries are cold to touch
- respiratory rate is more than 20 breaths per minute
- National Early Warning Score (NEWS) is 5
- Passive leg raising, increase *
Clinical examination should include an assessment of the patient’s fluid status:
- pulse, blood pressure, capillary refill and jugular venous pressure
- presence of pulmonary or peripheral oedema
- presence of postural hypotension*
Clinical monitoring should include current status and trends in:
- NEWS
- fluid balance charts
- weight.
What is seen in postural hypotension / a straight leg raise in somebody with lack of haemodynamic control due to dehydration?
There is a well-known overlapping relationship between postural hypotension and the positive straight leg raise test. In a normal situation, we can assess lack of haemodynamic control by doing a postural hypotension test and seeing a reactivate postural drop of 20/10. However in patients who are unable to do this test (i.e. an 86, year old delirious woman) this test is unable to performed. Instead of doing this, we can do the straight leg raise test. In these patients, if we lie them flat and suddenly bring their legs to a 45 angle°, a ‘positive’ patient will have an increase in their BP of 20/10 due to the increase venous return.
- In a healthy patient with stable haemodynamics, we are unlikely to see this change so use this test as an alternative to the postural hypotension test in the ‘old, delirious patient’
IV FLUID MAINTENANCE - 4th year stuff What is the type of fluid and what range is the sodium in this fluid that is given as a bolus and as maintenance fluids to patients who require IV fluid therapy?
Initially use isotonic crystalloids that contain sodium in range 131 - 154 mmol/litre * Saline is an example of an isotonic crystalloid fluid
IV FLUID MAINTENANCE - ADULTS What is the initial bolus of fluid given to an adult who requires fluids and over how long? When does this change?
* Give 500ml bolus of fluid to an adult over 15 minutess * If heart failure, give 250 ml bolus of fluid over 15 minutes
- What is phosphate required for in the body?
- What phosphate blood level should we aim to maintain a patient at?
- What are signs of hypogphosphateaemia?
- How is phosphate lost?
- Phosphate is required for the cell membrane and enzyme regulation, ATP, 23,DPG (oxygen release from haemoglobin)
- We should aim to maintain blood phosphate levels at >/=0.8mmol/l
- Signs of hyphophosphataemia include low energy supply and poor release of oxygen to muscles and muscle weakness
Phosphate is lost via the kidneys and increased use of ATP
