Air Collective Forum

ARDS (medical respiratory protocol) Q&A to doctors

Medical professionals please scroll down to see unanswered questions. Everyone please hit the blue reply button to ask questions.

How quickly do you need a ventilator available when someone starts ARDS?

Depends on the grade- from minutes to hours and days.

Could a CPAP or “BiPAP” device be used or adjusted to perform as a ventilator for ARDS cases, even if e.g. in short term?

NIV can be used limited for light and early conditions

What are the tolerances for ARDS treatments in an individual patient, for variables like how accurate the tidal volume is, flow rate, humidity etc.

In my opinion 5% is admissible

Are applicable face-masks & intubation tubes for ventilators available for ventilators, or should these also be manufactured?

Yes, the masks are commercially available. The price is far beyond 100 USD. 2 types-ventilated and non ventilated. If ventilated there is parameter of the holes which should be calculated by the ventilator software to fix air loses.

Is the required Oxygen supply sufficiently available in hospitals, or is this also to be solved?

Yes, they have it.

I saw your email comment: “Domestic use devices are also certified. They can be used as NIV but the use is limited according to the last WHO clinical therapy instructions” Thanks for that. So to help me understand and make this actionable, what’s your direction to us on which models are going to be fastest to address need? Domestic or clinical? Or is that just not a relevant factor if we are prioritising speed?

In WHO recommendations is written that NIV is not exluded but limited for COVID ARDS …Забележка 4: Насоките за неинвазивната вентилация (NIV) не дават препоръки относно употребата при хипоксемична дихателна недостатъчност (с изключение на кардиогенен белодробен оток и следоперативна дихателна недостатъчност) или пандемична вирусна инфекция (отнасяща се до изследвания за ТОРС и пандемичен грип) (5). Рисковете включват отложена интубация, големи приливни обеми и нанасящо щети транспулмонарно налягане. Ограничените данни предполагат висок процент на неуспех при пациенти с други вирусни инфекции като MERS-CoV, които получават НИВ (45).
Забележка 5: Пациентите, получаващи пробна НИВ, трябва да бъдат в контролирана обстановка и за тях да се грижи опитен персонал, способен да извърши ендотрахеална интубация, в случай че пациентът остро се влоши или не се подобри след кратко изпитване (около 1 час). Пациентите с хемодинамична нестабилност, полиорганна недостатъчност или нарушен психичен статус вероятно не трябва да получават НИВ вместо други възможности като инвазивна вентилация.

So, it is better to have NIV than nothing and clinical ventilators are ultimative device from this kind. Actually the hardware is probably the same. But withouth doubt both classes of devices should be certified.

I sent my idea about the design: "My idea is for pressure controlled ventilator but the adjusting of the volume of ventilated air can be done by supplying cyclically air from fixed volume chamber by a piston with variuous move. The change in the delivered volume can be controlled by the stroke of the piston in each phase, and the pressure control can be controlled by the speed of the piston so different pressure values can be achieved in different phases /like BiPAP/. The measuring of the volume in each cycle can be done by compairing start and end positio of the piston.

In this way the need of measuring the volume by flow is avoided."

So, the Rado`s design fits to my vision. It is essentially to have the possibility ti control the Volume /Vt/ during tje inspiration and the dynamically the pressure /rise time, plateau pressure etc/ in every moment in periods like 50-100 ms in my opinion. If the hardware allows this the different modes can be delivered by the software.

But in any case at some moment we need also the opinion of colleagues from the ICU. This is not my specialty and I just “translate” fixed medical protocols and terms to be understandable for technicians.


Unanswered questions

(To answer, highlight the question, then click the reply button)

Is there any particular ventilator(s) or systems that are the ideal reference in this ARDS situation?

Are there any Bulgarian manufacturers of ventilators that you can recommend?

Does anyone have stock of older “lower tech” ventilators, which could be easier to replicate?

Can this be used in the clinical setting: a doctor’s solution for multiple patients on 1 machine with adjustment for each patient: https://youtu.be/eSVbwWANqRI

Are there any other similar systems or equipment in a hospital that could have useful spare parts?

  1. A ventilator that can be used for a prolonged period of time would need to have the ability to adjust Peak End Expiratory Pressure (PEEP). As the patient deteriorates, the level of PEEP is often increased.

  2. In developed economies the likely standard would be that circuit used with the ventilator would need to be humidified. So a ventilator must cope with that.

  3. It would be useful to have the ability to have warning systems (alarms for excessive pressure etc)

  4. All other measurement systems could be attached distal to the endotracheal (for example if you integrate a measurement device that integrates flow with a infrared gas analyser, many important measurements pertaining to flow could be made.

Finally, in terms of cheap prototype “cheap”, rudimentary, and robust ventilators, I really like the oxylog 1000. Simple and indestructible and powered by the gas pressure! Here is a link:

https://www.draeger.com/en_sea/Hospital/Products/Ventilation-and-Respiratory-Monitoring/Emergency-and-Transport-Ventilation/Oxylog-1000

Thanks
Pratik

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