One of the immortal sayings in Aeromedical Retrieval medicine is “We’re a Flying ICU!” or “We bring the ICU to the patient!” . These slogans are supported by the fact that one of the defining characteristics of an aeromedical critical care transport/ retrieval team is the ability to initiate and maintain invasive mechanical ventilation support for the really sick patients. In order to provide this, the essential piece of transport equipment is the transport ventilator!
In my aeromedical service, Royal Flying Doctor Service, Queensland section, we have been using the Oxylog 3000 model for close to a decade now. Before it, we used the Oxylog 2000 and before that the Oxylog 1000! So it is now a good time I thought, to review the whole transport ventilator topic as the current Oxylog 3000 is starting to show its age. Like computers, technology changes , improves in capability but also pricing and medical equipment is no different. You are either looking for something that is lighter, cheaper and does the same job or something that adds major new capabilities to the job you want done. In Australia, in many city and rural emergency departments, and in the majority of aeromedical services, the Oxylog transport ventilators have been the work horse for over 20 years. They are simple to use, generally reliable and affordable.
In recent years, I have noticed a trend in ICU to trial non invasive ventilation and respiratory support that doesnt require a tracheal tube or even a face mask anymore. This has increasingly been reflected in aeromedical retrieval with greater use of non invasive ventilation such as CPAP and BiPAP and the transport ventilators have changed to allow these modalities. Most recently especially in paediatric critical care, high flow nasal oxygen systems have been trialled in conditions like bronchiolitis and pneumonia and shown to be safe and sometimes as effective as traditional approaches. So I think the next transport ventilator I want to use, should have this option of providing humidified high flow nasal oxygen therapy.
So here’s my shopping list for a new transport ventilator:
- It should do everything that the older current Oxylog 3000+ does ( SIMV, PCV, CPAP, PS)
- It should do something that the Oxylog 3000+ doesnt do ( HiFlow Nasal, operate without compressed gas supply)
- Same price or cheaper!
- Same weight or lighter!
- Same battery life or greater!
So did you know on the market currently there are broadly two types of transport ventilator available? They can be classed as turbine driven or pneumatic driven. Pneumatic ventilators rely upon a pressurised gas supply to operate. i.e no gas supply , no operation at all. Turbine ventilators use an internal turbine to generate their own pressurised gas supply i.e they can run on room air technically. Guess which is cheaper to make ? Yes the pneumatic ventilators. Guess which performs as close to modern sophisticated ICU ventilators as possible. Yes the turbine ventilators. Now lets be clear about something. Transport ventilators are no replacement for modern sophisticated ICU ventilators. They just dont perform as well as a machine costing a $100000 or so. The current most expensive transport ventilator the Hamilton T1 is $54000 approx. whilst the Oxylog 3000 brand new will set you back $20000 odd bucks.
So how does one choose? Has anyone done an actual comparison of these two categories of transport ventilators? I havent but I found some Frenchmen who have!
Here’s there conclusion but its worth reading the whole open access article!
In conclusion, the performance of transport ventilators is heterogeneous in VT delivery and during spontaneous ventilation. Some of the transport ventilators tested, particularly turbine ventilators, show good performance comparable to those of ICU ventilators suggesting that they could improve the safety of the critically ill patients during transport. These results suggest that turbine powered transport ventilators allow for better performance. Other studies should be performed in order to show the real clinical benefits in patients and to assess the ergonomics of these devices.
What about my current Oxylog 3000? How did it do? It had the longest tested battery life! thats gotta be a good thing! But its performance in triggering and pressure control modes was not so great compared with the turbine driven ventilators. Surprisingly it did better at tidal volume of 300ml than the Hamilton T1 which is marketed as a superior transport ventilator for paediatric patients! In fact its compared well with newer ventilators! The Hamilton T1 overall did better but its heavier, costs more and has a problem with tidal volumes of 300ml, at least in this bench study. IN actual aeromedical transport work it is used as the current preferred PICU ventilator in my region and I have not heard of any issues with performance. It does however offer highflow nasal support which is a major advantage over the Oxylog 3000 and it is turbine driven so can operate even if oxygen supply is not available. This has been an issue on a couple of occasions during aeromedical transfer of patients on CPAP/BiPAP and using the Oxylog 3000, when the oxygen consumption has been so high that the supply on aircraft was exhausted and the Oxylog could no longer operate!
What do other services use? I know some use the Oxylog series, others use the Medumat ventilator, whilst others the Elise. Overseas there is a whole range of transport ventilators like the Univent. I am not familiar witb the American transport ventilators but found a useful article that reviewed them recently here:
Notably a huge variation in performance was described so it pays to study these data offered to make informed choices when you go shopping for transport ventilators!
So hopefully this short article on transport ventilators and comparisons available will give you some food for thought on your next shopping trip for retrieval medicine gear!