Fluid and Nutrition Management Flashcards
In the average person, what percentage weight does water contribute?
60%
In the average person, what percentage body weight is Intracellular Fluid?
40%
In the average person, what percentage body weight is Extracellular Fluid?
20%
How can the Extracellular Compartment be further divided?
Intravascular (5%)
Extravascular/Interstitial (15%)
How may fluid cross compartments?
Osmosis which depends on a solute gradient
Filtration which is the result of a hydrostatic pressure gradient
Describe generally the electrolyte balance of the intracellular compartment
Low sodium
High Potassium
Describe generally the electrolyte balance of the extracellular compartment
High sodium
Low potassium
Compare the protein balances of the interstitial and the intravascular compartments of the extracellular compartment
Interstitial fluid has a very low protein balance
What fluid(s) should be considered when trying to fill the intravascular compartment rapidly? Why?
Plasma Substitute or Blood
These fluids have a high colloid osmotic pressure and remain in the intravascular space in contrast to a crystalloid solution such as Hartmann’s which will distribute over the entire extracellular compartment, thus less would remain in the intravascular compartment
What are the routes from which fluid is lost?
Which are termed ‘insensible losses’
Kidney
GI tract
Skin
Respiratory Tract
Skin and Resp tract are insensible
Describe how many mL of fluid, mmol of Na+ and mmol of K+ are lost via the Kidney for a normal person in a 24 hour period.
2000mL
80-130mmol of Na+
60mmol of K+
How many mL of fluid are lost each day via the faeces?
300mL
How many mL of fluid are lost each day insensibly?
400mL
Describe how surgery effects fluid loss
Surgery causes a stress response which leads to the release of ADH, catecholamines and activation of the RAAS, which results in oliguria and water retention.
Describe the importance of assessing the patients state of hydration in spite of oliguria
Patient may be euvolaemic, unnecessary administration of fluids mat expand the blood volume and reduce haematocrit, overexpand the interstitial space, resulting in oedema and a salt load that the patient cannot excrete
Explain the effect of surgery on potassium levels. Explain the basis for the recommendation that supplementary potassium may not be necessary in the first 48 hours post surgery or trauma
Potassium is released by damaged tissues, and may be further increased by blood transfusion (each unit of blood contains ~20mmol/L of potassium). If renal perfusion is poor and urine output sparse, the potassium will not be excreted and instead accumulates. This leads to hyperkalaemia and causes life-threatening arrhythmias.
Unless they have a disorder affecting gastric emptying, up until what time mark can elective surgery patients continue clear fluids
2 hours
Can a patients take carbohydrate drinks pre-operatively?
Yes, in fact, pre-op carbohydrate drinks around 2-3 hours before surgery can reduce anxiety and post-operative nausea and vomiting
Describe a fluid regimen for a patient undergoing normal fluid loss
3L of 0.4% dextrose/0.18% saline with 20mmol/L of potassium added to each litre of fluid.
How should a patient be monitored whilst on a fluid regimen?
Regular clinical assessment
Measurement of fluid losses
Daily weights
Regular blood samples
Describe what fluids are described as special losses
Nasogastric aspirates
Losses of fistulas
Diarrhoea
Stomas
As a rough guide, how would you manage the loss of gastric fluid?
Replace with equal volume of normal saline with extra potassium supplements
As a rough guide, how would you manage losses from diarrhoea, ileostomy, small bowel fistulas and ileus?
Hartmanns solution
Describe some signs of fluid deficit
Thirst Dry mucous membranes Loss of skin turgor Tachycardia Postural hypotension Low JVP
These suggest a loss of between 5% and 15%
