Medical & Laboratory | {{writeDate('2020-11-22T16:00:00Z')}}

Compact fans in breathing aids

Loss of breath during sleep, also known as sleep apnea, affects many people over 40 years of age. A proven form of therapy supports the body’s own respiratory reflexes through the controlled injection of air into the lungs. A highly dynamic centrifugal compact fan now supports breathing through the controlled supply of fresh air.

Compact fans in breathing aids

The lightweight, efficient small fan is also well suited for long battery operation, for example for a mobile sleep therapy device. Other applications in medical technology include mechanical intensive care ventilation, mucus secretion mobilization and mobile air filter technology, e.g. respiratory protection devices. The reliability of medical devices and their components is particularly important. Particularly when using apnea machines at home or as a ventilator in the intensive care unit, quiet operation is also important. If, for example, a ventilator is used during sleep, such a device must be located close to the user and must not interfere with healthy sleep due to operating noises.  The RVE45 fan is able to meet these requirements.


Fig 1. The RVE 45 offers highly available, efficient and quiet air delivery.

How does mechanical ventilation work?

The technology behind it is easy to understand: Air pressure generated by the fan inflates the lungs and thus supports breathing. But the trick is in the details: The application requires highly dynamic fan operation, meaning very rapid changes in speed. However, smooth running in dynamic operation is not easy to implement. The biological properties of breathing demand swift and smooth control of the airflow and pressure. For example, it is often necessary to generate a high “blowing pressure” for a short time at the beginning of the inhalation sequence. This pressure raises the flaccid soft palate and allows air to enter the windpipe. However, this “initial high air pressure” may only be applied very briefly and it must rise quickly, but not abruptly, in order to give the palate the necessary time to clear the windpipe.

After opening the soft palate, the pressure must be quickly reduced to the inhalation level prescribed by the doctor and sustained at this level. To match the patient’s respiration, the supporting flow rate and pressure must be constantly adjusted. In order to exhale, the pressure must then drop quickly again, but not abruptly, in order to allow unhindered exhalation. For the breathing dynamics, approximately 200 ms control time is typical with volume flows around 150 l/min and pressure fluctuations from 400 Pa to 2,000 Pa. The pressure should be kept as low as possible and never exceed 3,500 Pa to avoid lung damage.

On the other hand, the adjustable high volume flow rate is important in order to be able to reliably compensate for leaks, e.g. in the respiratory mask due to poor fit or in the case of bearded wearers. In order to regulate the necessary variation in volume flow and pressure in practice, the speed of the centrifugal fan must therefore be quickly increased or decreased. 


Compact fans in breathing aids

Fig 2. Example of a breathing aid

by ebm‑papst Mulfingen GmbH & Co KG

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