The New Year ushered in desires for change, feelings of hope and the determination to uplift South Africa. Along with it came a number greater than 18 000 for new Covid-19 cases. The first surge now lies in the shadow of the second. In the Old Year, I left you with a question, a graph and principles to consider.
May the New Year be one which lends itself to a new perspective on the pragmatic use of oxygen amongst healthcare professionals.
For example, I learned, practised and taught that a low flow oxygen device was a device that used oxygen below a flow of 15l/min. Anything higher, was regarded as a high flow device. This inherently was based on the premise that most patients’ inspiratory demands were above 15l/min for both their Peak Inspiratory Flow and Inspiratory Minute Ventilation. But now I know that this approach over simplified the concept. Yet it made bedside medicine easier on thought. Clinical practice was simple: attach a patient to a device that improved their oxygen saturation, monitor for complications, discover the cause and address it with therapeutic interventions. Along came the Covid-19 pandemic but the clinical approach remained unchanged. This marriage gave birth to the Oxygen Problem.
Many healthcare professionals will argue that the clinical approach cannot be unchanged and that the solutions lie with increasing oxygen stores, improving oxygen supply systems (reticulation) and upscaling the number of oxygen devices. It may be so, but I wish to depict the problem mathematically:
The Oxygen Problem:
In the past: Oxygen supply > Oxygen demand
Currently: Oxygen supply < Oxygen demand
Oxygen supply = f(manufacturing capacity, logistics, reticulation, procurement, finances etc) + Δ( oxygen inventory)
Oxygen supply controllable factors: manufacturing capacity, logistics, reticulation, procurement, finances etc)
Oxygen demand = f(patient numbers x clinical approach)
Clinical approach= f(patient oxygen deficit, available oxygen device(s), complications, cause, therapeutic intervention)
Oxygen demand controllable factors: available oxygen devices
On the supply side, there are many interventions which can help, but few of them can be resolved quickly. This is managed by government, corporate companies and institutions. On the demand side more efficient oxygen devices must be made and healthcare professionals should apply efficient oxygen use. Thus the solution to the Oxygen Problem is a responsibility carried by everyone.
“Now bear with me, as I take you back to The Oxygen Dilemma”
“Levels of oxygen therapy can be divided into two groups. That being low flow and high flow oxygen devices. The differentiation between the two: the oxygen flow rate in relation to the patient’s Peak Inspiratory Flow and Inspiratory Minute Ventilation. By definition, a low flow device does not meet the entire requirement of the patient’s inspiratory demand. Thus room air will be entrained to make up for the volume unaccounted for by the device. The resulting consequence will be dilution of the oxygen percentage. Yet a high flow device will meet the entire inspiratory demand. Hence no additional room air will be entrained ” .
With this in mind; when an oxygen device is used, the healthcare professional should begin to ask:
- How much oxygen is truly enough to maintain an appropriate blood-oxygen level?
- Does the oxygen flow need to meet the entire inspiratory demand?
- How much oxygen is wasted when using the device?
Answers to these questions are not simple. And often there is a balanced relationship between all three. But at the bedside there are worthy tools which may lead to the answers:
- An oxygen saturation monitor.
- Clinical assessment of the work of breathing and simply asking the patient how does their work of breathing feel after the device is applied.
- A new perspective on the pragmatic use of oxygen.
Thus, has oxygen use been inefficient during the fight against Covid-19? I leave you with this question, two graphs and some principles that may influence choice: effectiveness, efficiency, availability, limitation and emotion.
Until next time, have a blessed New Year.
- Agarwal R, Gupta D. What are high-flow and low-flow oxygen delivery systems? 2005 Oct;36(10):2066-7; author reply 2067. doi: 10.1161/01.str.0000185387.51425.f9. PMID: 16192461.
- Toy, B. (2020, December 20). The Oxygen Dilemma. Retrieved January 3, 2021, from UMOYA | Innovation in the air: https://umoya.org.za/