Topic 2 - Fluid Therapy And Transfusion Medicine Flashcards
What is the equation for Calculated Osmolalilty?
= 2 (Na+) + BUN mmol/L + Glucose mmol/L
What is the difference between effective and ineffective osmoles?
Effective osmoles cannot cross cell membranes and are excluded from intracellular fluid (e.g. sodium). Ineffective osmoles can cross cell membrane and are unable to contribute to the osmotic pressure gradient (e.g. urea and glucose when insulin is present).
What is the 60-40-20 rule?
60% BW is water, 40% BW is intracellular fluid, 20% extracellular fluid (broken down into interstitial and plasma)
Traditional Starling’s Forces equation
J(v) = K (fc) [P capillary - P interstitium] - omega (pi capillary - pi interstitium)
The difference between the hydrostatic pressure in the capillary and the interstitial space less the difference between the oncotic pressure in the capillary and the interstitial space.
What is the glycocalyx?
It is a gel matrix layer, made of glycoproteins and proteoglycans that covers the endothelium of all blood vessels. This layer varies with different organs.
What are the functions of the endothelial glycocalyx?
- Modulates inflammation, anti-inflammatory
- Modulates haemostasis, anti-coagulant
- Modulates shear stress
- Modulates transcapillary fluid flux (modified Starling’s equation)
Common causes of destruction of the glycocalyx
- Hypervolaemia
- Rapid administration of crystalloids
- Hyperglycaemia
- Surgery/trauma
- Ischaemic or reperfusion
- Cytokines (sepsis)
What are the six perfusion parameters?
- Pale mucous membranes
- Prolonged CRT
- Tachycardia
- Low amplitude femoral pulses
- Cool extremities
- Obtundation
What is the signs of interstitial fluid volume dehydration?
- Decreased skin turgor, elasticity
- Dry/tacky mucous membranes
- Decreased tear film
What is the delivery of oxygen equation?
DO2 = CO x CaO2 [(1.36xHCT x SaO2) + PaO2 x 0.003]
How do mitochondria make energy? Equation
O2 + Glu -> CO2 + 36 ATP
How much isotonic crystalloids is left in intravascular space after 30min?
1/4 amount
What are the hormones that regulate Na balance?
Angiotensin II, aldosterone, catecholamines, atrial natriuretic peptide
What are the hormones that regular water balance?
Vasopressin (ADH), atrial natriuretic peptide (ANP)
Draw and describe the renin angiotensin aldosterone system
Draw as required
What is the main hormone that regulates water balance?
Vasopressin (ADH) - produced in the hypothalamus, released into circulation at the level of posterior pituitary gland
What is ADH stimulated by?
Hyper osmolarity, sensed by hypothalamus, hypovolaemia, hypotension, SNS, Angiotensin II
What is the most common cause of hyponatraemia?
Loss of intravascular volume, compensatory mechanism to try and a result of ADH release. Note: cortisol inhibits ADH. Therefore Addison’s patients are hyponatraemic
What is central pontine myelinosis? Related to hypo or hypernatraemia?
Commonly caused by hyponatraemia corrected too quickly — when the myelin sheath pulls away from the nerve. Signs start to appear in 2-3 days.
How quickly should chronic hyponatraemia be corrected? ( mEq/L/hr)
0.5mEq/L/hr
