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The first answer to this question Mason This year’s theme is: Heart, Heart. Knowing ourselves, our heart and our lifestyle allows us to improve our condition by minimizing the risk of cardiovascular disease.
Prevention is the first step to heart health! Among the pillars of cardiovascular disease prevention we find a series of actions specifically aimed at mitigating all modifiable risk factors:
What steps can be taken to reduce the risk of cardiovascular disease?
The concept of non-invasive mechanical ventilation (NIV) refers to the ability to provide ventilation support through the patient’s upper airway using a mask or other device.
This technique is different from those that bypass the airway by placing an endotracheal tube, laryngeal mask, or tracheotomy and is therefore considered invasive.
Lung ventilators are complex devices that can provide different modes of ventilation to patients. Even the application of positive airway pressure (CPAP), if implemented using a mechanical ventilator, inevitably involves machine/patient interactions at different stages of the breathing act.
From mechanical ventilation to continuous positive airway pressure
This machine/patient interaction is very useful in complex ventilation methods, but may not be the case in simple modes like CPAP from an overall performance perspective.- This is easy to understand if we consider, for example, the need to activate an inhalation trigger or to enter the exhalation phase.
The trigger represents the communication system between the patient and the ventilator, and if the ventilator detects this signal, it starts the inspiratory phase or the expiratory phase. Therefore, it is a useful tool to synchronize the ventilator cycle according to the patient’s requirements. The inspiratory trigger signal is the signal that starts the inspiratory phase, while the expiratory trigger signal is the signal that starts the expiratory phase.
Applying positive pressure to the airways using a lung ventilator inevitably involves additional work of breathing by the patient (to reach the triggering threshold, allowing the opening and closing of the inspiratory and expiratory valves).
In CPAP mode
The machine doesn’t have to recognize at every moment what stage of breathing behavior we are in, but this inevitably happens because of the way ventilators are designed and constructed.
Another problem that can occur with the ventilator in CPAP mode is that if the patient has a high ventilation demand, a high inspiratory flow rate (acute patients), the device cannot immediately adapt the patient’s mixture flow: it is a delay and therefore a change in the flow delivery, which can cause a pressure drop in the airways during inspiration.
Compared to traditional ventilators, there are simpler devices on the market that are designed only to administer CPAP and do not have the trigger cycle issue.
At this point, we are only covering situations where non-invasive ventilatory support is provided through the use of a mask or helmet, and therefore not situations where so-called “high-flow systems with nasal cannulae” (HFNC) are used.
- These HFNC systems do not produce true Cpap but only provide a PEP effect (positive end expiratory pressure) that does not exceed
- s 5 cmH20 and therefore does not cover most respiratory diseases, especially those in the acute phase. High flow system with venturi type generator
- A Venturi system is a system that accelerates the flow of gas by forcing it into a tapered tube. As the tube contracts, the velocity of the gas increases and the pressure decreases, creating a partial vacuum.
When the gas leaves the confinement, its pressure increases again to the ambient or pipeline level
- So if we make a window outside the duct, low air pressure will be created in this very narrow section, and the surrounding air will be sucked into the duct through the pressure gradient (from highest pressure to lowest pressure).
- The end result at the duct outlet is a mixture of the gas present inside the duct (e.g. oxygen) and the ambient air: the flow rate and flow rate (volume per unit time) of this mixture is very high. High. High.
In this system using oxygen as the source gas, Air is introduced inside the “Venturi meter” and ambient air is sucked in from the outside in a gradient, the FiO2 (fraction of inspired oxygen) delivered to the patient depends directly on the resulting gas mixture. , which in turn depends on the amount of ambient air entering the duct through the window.
If a high FiO2 is required (thus a high concentration of oxygen in the overall gas), the window for the return of ambient air will have to be closed, which will result in a lower overall mixture flow to the patient, and vice versa, if a low FiO2 is required (thus a lower concentration of oxygen), the window for the intake of ambient air will be very open, resulting in a high volume of mixture flowing to the patient.
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