3.4 A focus on maths in clinical practice

Intravenous (IV) saline is used to replenish fluids or to deliver medications to patients. Normally the saline solution used is 0.9% (w/v) NaCl.

  1. Why is this concentration of saline used?
  2. What is the molar concentration of 0.9% (w/v) NaCl?
    (The molecular weight of NaCl is 58.44 g mol–1.)
  3. What is the osmolarity of 0.9% (w/v) NaCl?
    (Osmolarity refers to the molar concentration of particles of solute per litre of solution.)
  4. If you needed to infuse 1 l of 0.9% (w/v) NaCl over 8 hours, what is the required flow rate in ml h–1?


Maths in Clinical Practice

Yangama Jokwiro is a registered general nurse with extensive experience. He has worked in a variety of clinical settings but now focuses on teaching undergraduate nursing students. Watch an interview with Yangama to find out the answers to the questions above and learn how critical quantitative literacy is for clinicians to be able to effectively treat, monitor and care for their patients. Also learn how Yangama instils this literacy in his students!

Side Bar – Concentrations can be expressed as percentage weight per volume (e.g. 0.9% (w/v) NaCl). What this really means is the grams of solute in 100 ml of solution. That is, the percentage concentration tells us the parts of solute by mass per 100 parts by volume of solution. (see Chapter 7 Solutions and concentrations)

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