IV Fluids Flashcards
What different mechanisms of movement between fluid compartments exist?
Electrochemical gradients, hydrostatic pressure, osmotic forces, oncotic pressure, primary and secondary AT
What is the equation for calculating oxygen delivery to tissues?
CO x Hb conc x 1.34(mls O2/g Hb) x O2 sats % (0-1.00)
What is the unit of DO2 (oxygen delivery to tissues)?
mls O2/min
What is the unit for Hb?
g/litre
What makes a solution hypotonic and hypertonic?
Amount of Sodium present
Hypotonic is when there is little sodium
Hypertonic is when there is too much sodium
Why is it dangerous to give fluid that is hypotonic?
hypotonic hyponatraemia causing intracerebral osmotic shift and cerebral oedema
How many grams of glucose do you require every day?
50-100g
What is the breakdown of fluid in the body?
2/3 is intracellular
1/3 is extracellular broken down into interstitial and intravascular
Comparing intracellular and extracellular compartments, which has higher sodium? potassium? calcium? magnesium? chloride? phosphate?
sodium - higher extracellularly potassium - high intracellularly calcium - higher extracellularly Magnesium - high intracellularly Chloride - high extracellularly Phosphate - higher intracellularly
What are the 3 layers of blood vessels called and made of?
Tunica intima - endothelium single cell lining supported by basement membrane and CT
Tunica media - muscular layer
Tunica adventitia - CT
Which layer of the blood vessels differs depending on the blood vessel type?
Tunica media as muscular layer only present in bigger vessels and not present in capillaries
What is the pathophysiology of oedema occuring?
Causes leakage through the blood barrier (tunica intima) as well as larger molecules and cells leaking
Is serum sodium and potassium a good indicator of total body?
Serum Na is good indicator but serum K is not
Difference between crystalloids and colloids?
Crystalloids have smaller particles and can therefore pass through semipermeable membranes whereas colloids have larger particles and therefore largely remain within the intravascular system
What can an excess of NaCl fluid cause?
Hyperchloraemic acidosis
What should you never add to Hartmanns solution
Any additional electrolytes
What happens to solute concentration when osmolality decreases?
Decreased conc making it more watery
What happens when glucose 5% is administered
It is metabolised very quickly by the body leaving water which can distribute across all departement
What situation would you administer colloid instead of crystalloids?
When you want a higher sodium concentration administration
Name the principle natural colloid that can be given IV? potential risk?
Human albumin infusion wither 4.5% or 20%
Risk of transmitting infection
What are the indications for administration of human albumin?
Low serum albumin in haemodynamically unstable patient Large volume paracentesis for ascites Spontaneous bacterial peritonitis Hepatorenal syndrome Therapeutic plasma exchange
2 artificial colloids that can be administered and their associated side effects?
Gelatin - anaphylaxis, coagulation effects
Dextrans - highly branched polysaccharide, coagnulation defects, anaphylaxis, coats RBC so can cause interference to cross matching, precipitate an AKI
What 2 reasons is Dextrans primarily used for?
Microsurgery
VTE prophylaxis
What is the definition of hyponatraemia and what are the categories of causes?
An Na less than 135 mmol/l
Can be hypotonic hyponatraemia, isotonic hyponatraemia, hypertonic hyponatraemia
Which 8 categories of people do the norma IV fluid prescribing recommendations not apply to?
Those under 16 Pregnant Renal or liver failure Diabetes Burns traumatic brain injury Those who need inotropes Those on intensive monitoring
5 Rs in fluid prescribing?
Resuss Routine Replacement Redistribution Reassess
How often are fluid plans reassessed?
Usually every 24 hours unless long term and stable can be more infrequent
If they are on resus or replacement therapy then may need more frequent monitoring
What are the 4 types of shock and which 2 do not require fluid resuscitation?
Cardiogenic, distributive, obstructive or hypovolaemic
Cardiogenic shock and obstructive shock do not require fluid resuscitation
In resus what volume of fluid bolus are given and up to what total volume before senior help needs to be called?
give 500ml bolus’
Up to 20ml/kg or max of 2000ml
What fluid should be given as a resus bolus?
crystalloid like saline na 130-154 over 15 minutes
When do you consider albumin in fluid resus?
When there is severe sepsis
Why is maintenance therapy given? what 3 parts of maintenance therapy are there?
to account for insensible losses from the skin, respiratory, stools and UO
Need water, electrolytes, glucose
Fasting times for elective surgery?
6 hours food
4 hours breast milk
2 hours fluids
1 hour clear fluids in children
Give some examples of where ongoing losses can occur?
Vomiting and diarrhoea NG tube Stoma sites - ileal, colostomy, jejunal fistula urinary losses Biliary drainage Bleeding Sweating, fever, dehydration
What issues can cause problems with redistribution of fluids?
Sepsis Gross oedema Hypo or hypernatraemia Liver, renal or cardiac failure Post operative fluid retention Malnourished or refeeding issues
What is the stress response, what happens when it is activated and why can it lead to fluid overload and hyponatraemia?
Stress response is the hormonal and metabolic changes that follow injury or trauma
Causes increase in pituitary hormones to be released and SNS activation
ADH release causes increased water reabsorbtion
More chance for fluid retention overload and hyponatraemia
excess vomiting or NG loss causes what type of electrolyte deficiency and go on to create what systemic state? management invovles what?
Hypochloraemic
Hypokalaemic
Metabolic alkalosis
Need KCl
Gastric fluid contains what amounts of what electrolytes?
K 14 mmol/l
Cl 140mmol/l
H+ 60-80mmol/l
Na 20-60 mmol/l
Biliary drainage loss would see what electrolytes predominantly and how much of them?
HCO3 30mmol/l
Na 145 mmol/l
K 5mmol/l
Cl 105 mmol/l
if the cause of ongoing losses was due to excess urinary losses, what electrolytes would you be particularly worried about?
Na
K
Monitor serum electrolytes closely
Main difference in electrolyte loss between vomiting and diarrhoea?
Vomiting has high Cl ions
Diarrhoea has a high HCO3 content
What questions is it important to ask about in a history of fluid status assessment?
Any vomiting or diarrhoea? Any diuresis? Any bleeding? Any sweating, rigors, temperatures? Are they thirsty? Any headaches? Any light headedness of standing? Are they fasting?
What can you do on examination to assess someones fluid status?
CRT BP HR mucus membranes JVP UO - catheter Fluid balance chart Daily weights Postural changes in BP and HR RR Any oedema present for fluid overload
What happens to UO after surgery and why?
Decreases due to stress response
3 lab investigations to assess fluid status?
U&E
FBC
urinary sodium
When should you do extra monitoring for urinary Na in patients on IV fluids?
If they have high volume GI losses
When do you need to monitor Cl in IV fluid admin? How often?
When the patient is receiving over 120mmol/l of chloride ions in their fluids - NaCl 0.9%
Risk of developing hyperchloraemic acidosis
Measure daily
How do you combat the fact fluid balance charts dont account for insensible losses?
Add 500mls to fluid balance in order to account for insensible losses and therefore calculate euvolaemia
Losing 1kg in weight is equivalent to how much water loss?
1 litre
Define the frank starling law?
SV will increase as EDV increases
reaches a point where SV starts to decrease as EDV increases further past a point
Where are pressures measured inside the heart?
Atrias as without any obstruction the EDV pressure accurately reflects that of the ventricle
What external location are cardiac pressures usually measured from? How is this done?
Usually a central venous catheter is inserted into the SVC or the right atrium along with the tip and transducer
Central venous pressure accurately reflects right ventricle end diastolic pressure
How can you measure the left atrial pressure indirectly?
Through the pulmonary capillary wedge pressure
Balloon into the pulmonary artery
What types of heart problems can cause a raised LAP and therefore right ventricular end diastolic pressure increase
Mitral stenosis Mitral regurgitation Aortic stenosis Aortic regurgitation Pulmonary hypertension
benefit of using CVP over pulmonary capillary wedge pressure?
CVP allows a constant measure of pressure whereas PCWP allows snap shots
How does a low of high CVP affect your decision as to whether to administer a fluid bolus?
High CVP means they are unlikely to respond to fluids
Low CVP means they are more likely to respond
How does CVP change as you administer fluids to a hypovolaemic patient?
Initially CVP does not change but HR decreases and BP increases
As patient becomes normovolaemic, CVP will start to rise and normalise
How does CVP change as you administer fluids to a hypervolaemic patient?
Abrupt and sustained rise in CVP
What are arterial lines used for?
Close BP monitoring
Draw blood easier and send off blood tests
What can be seen on an arterial line waveform that indicates a hypovolaemic state?
Venous returns falls cyclically with respiration
Beat to beat changes in SV and pre-load are cause
Swinging trace
What methods are available to monitor cardiac pump function?
Echo
Doppler
Transpulmonary dilution with temperature or lithium
Blood Pressure Curve Analysis
