Fluids and Fluid balance Flashcards
How can the anti diuretic hormone be affected when someone has had a major injury or surgery or severe illness?
Normal ADH - when BP is low RAS is activated - ADH is released alongside aldosterone, this acts to increase BP as blood vessels contact making them narrow. When someone is very unwell this mechanism can stop meaning there BP is now lower.
How can the Renin Angiotensin system be affected if someone has had, major injury, surgery or severe illness?
Activated by failing renal perfusion, an increase in aldosterone which increases sodium and water retention, - this can stop working.
What can decrease the need for fluid requirements?
Renal and Hepatic impairment
Cardiac failure
Head injury
What can increase fluid requirements?
Vomiting/diarrhoea
High output stoma
Fistula
Burns
When is fluid given?
To correct losses or maintain homeostasis
-Blood volume, fluid levels, organ perfusion and function.
-NBM
-Dehydration
-Excessive losses
-Heat stroke
-Excess diuretic use
What are the consequence of giving fluids wrong?
*Electrolyte imbalance
*Peripheral oedema
*Pulmonary oedema
*Renal impairment
*Acid/base disturbance
What are the signs and symptoms of dehydration?
Thirst, reduced skin elasticity, dry mucous membrane (eyes, mouth), decreased capillary refill time, altered consciousness, tachy, concentrated urine
You have a patient who has lost weight, a low BP, Rapid/shallow breathing wih a weak but rapid pulse, urine output is reduced and concentrated, skin is less elastic, very thirsty and has a high temperature? what is this due to?
Fluid Depletion
You have a patient who has gained weight, slightly raised blood pressure, has a moist cough, tachycardic, increased urine output, has oedema, what is the diagnosis?
Fluid overload
What are examples of Crystalloid fluids?
0.9% Sodium chlorine
5% Glucose
Dextrose-saline
Hartmann’s
What are the examples of Colloids?
Albumin
Dextran
Gelatin
What is a colloid fluid?
Dispersions of large organic molecules in a carrier solution
What is crystalloids fluids?
Solutions of small molecules in water, (ions Na and Cl) and/or glucose which is isotonic.
What type of fluid is sodium chloride 0.9%?
Crystalloid
Isotonic, and distributes into the whole extracellular space (Intravascular and interstitial space)
What type of fluid is 5% Glucose?
Crystalloid
Has some calorie content, distributes throughout the intravascular interstitial and intracellular compartments
-Glucose is primarily metabolised therefore does not cause plasma expansion
When isn’t a patient for plasma expansion?
If they have a big loss of fluids
What type of fluid is dextrose saline?
Crystalloid
Glucose and Sodium chloride
-Isotonic
Can have up to 3L over 24 hours
Not for long term use as it does not contain other electrolytes
If a patient is requiring fluids for longer than 24/48 hours what should be used?
Hartmann’s - balanced salt solution
Crystalloid
-Used in the critically ill patients
Where do colloid fluids stay?
Extracellular space
When is Albumin used?
Colloids
Shock: Burns, Haemorrhage, Surgical losses and Trauma
-Quick and short term use
What are synthetic colloids?
Dextrans - MW 7000 - it remains in circulation, is a long acting plasma expander
Gelatin Derivatives - Animal collagen
What are the advantages of Crystalloids?
-Maintain osmotic gradient
-Widely available
-Low risk of ADR’s
-Inexpensive
What are the advantages of colloids?
-Need less amounts of fluid, good for patients of FR
-Faster to give
-Longer half life
-Starches can reduce capillary leaks into interstitial space
-Lasts for 12 hours, can stick into insterstitial fluid for longer
What is the disadvantage of crystalloids?
-Poor in maintaining oncotic pressure
-Short half life
-Very cheap
