Lec 4-Aseptic

Question 1

The question

Answer 1

• You have been asked to prepare a solution containing
  
  • 67 mmol Na
  • 6 mmol K
  • 2 mmol Ca
  • 77 mmol Cl
• You have the following salts available- CaCl₂.H₂O, KCl, NaCl
• What quantity of each salt do you instruct your technician to inject into a bag of water for injection

Question 2

NaCl

Answer 2

• 67 mmol Na+
• From NaCl which in solution is Na+ Cl^-
• Weight of 67 mmol of NaCl
• Number of moles = Mass / MW
• Mass = N^o Moles x MW
• 67 x 58.44 (Na + Cl)
• =3.915g

Question 3

CaCl₂.2H₂O

Answer 3

• 2 mmol Ca
• From CaCl₂.2H₂O which in solution is Ca and 2 Cl and the water gets lost
• Weight of 2 mmol of CaCl₂.2H₂O (Not just CaCl₂)
• Mol = Mass/ MW
• 1 mol = 147.01g
• 2 x 147.01 mg = 0.294g

Question 4

What about Cl

Answer 4

• Does it need adding
• How much have you put in
  
  • 67 mmol with NaCl
  • 6 mmol with KCl
  • 4 mmol with 2 mmol of CaCl₂.2H₂O
• How much did you already add 77 mmol

Question 5

Mistakes

Answer 5

• The ward has reported the patient has had extreme discomfort while on the drip
• Your calculations are correct and the bag was clean

Question 6

Osmolarity

Answer 6

• The osmolarity of blood is approx 300 mmol/L
• The bag you released was 152 mmol/L
• mmol/L is the SI unit for osmolarity so should be used
• The Osmol is the molecular weight of a substance divided by the number of chemical species (ions or non-ionised) formed at dissolution
• Osmolarity (not osmolality) is measured in mmol/L or more commonly Osmol
• Examples NaCl 1 mmol/L = 2 mOsmol: glu1 mmol/L = 1mOsmol

Question 7

Osmolarity

Answer 7

• Blood contains 300 ions (or other components e.g. glucose) e.g. per L
• If it does not have 300 per litre, it obtains them
• This can cuase extreme pain as cells are forced to give up ions to the blood

Answer 8

Question 9

Another example

Answer 9

• Previously we saw every bag runs for 24hrs
• The bag volume changes
• What about the osmolarity (all the electrolytes stay the same) we would expect them to change, to keep the osmolarity the same
• May be the dextrose and amino acids are used to balance the bags. Actually dextrasor Aa don’t contribute greatly to osmolarity (they are only single ions)- this does not mean the quantity is insignificant
• Notice this bag- it is similar to 1 Ltr central but its 2 Lts

Question 10

Central vs Peripheral

Answer 10

• Upper limit for a peripheral IV is 900 mOsm/L
• Lower limit for any route 150 mOsm/L
• Central feeds are more tolerant because of the very fast dilution by blood. So you can exceed 900 mOsm/L
• Central line = higher risk of infection

Question 11

Your eyes have the same sensitivity to osmolarity as blood, calculate the concentration of NaCl required so your eyes don’t sting when you apply an eye wash. Make the assumption the solution is Ideal

Question 12

Common TPN problems

Answer 12

• Problem of balancing ions- getting the ions you want without too many of another type
• Problem of osmolarity- if it is not 300 mOsmol/L it could be painful
• Central or peripheral- advantage and disadvantage
• Solubility- it could crash out
• Your aware of the need for additive to be in specific ranges for PN to have an affect

Question 13

TPN prescribing process

Answer 13

1. The order
2. Pharmacist check
3. Technician input into computer
4. Worksheet produced (common name work order)
5. Label production
6. Prepare product
7. Storage
8. Release check (check to see if cracked)
9. Central line infusion
10. Administration by infusion pump