User manual

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6. Using the patient simulator and breathing simulators in the

area of ventilation technology

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Theoreticalintroduction

Artificial lung ventilation is used as a technology substituting spontaneous breathing

in case of the patient’s respiration failure. It is a rather old method, currently rather

widespread and very frequently used. So far, many different types of ventilators have been

constructed, and many different ventilation methods have been developed, respecting the

patient’s breathing efforts, and minimizing adverse effects of artificial lung ventilation, yet

the mortality of patients suffering from breathing failure is still too high - around 40 %. In

patients with combined complications, mortality reaches an even higher percentage. For

example, occurrence of haematological complications increases mortality of patients caused

by respiration failure to up to 60 %. Using standard ventilator regimens and methods without

any changes and modifications does not succeed in further reductions of mortality in case of

respiration failure. The modifications and approaches include everything - from minor (at first

sight) changes and additions, all the way to substantial changes in approaching ventilation and

the development and change of the entire ventilation modes. There is a common goal in all

these modifications: to minimize the negative influence of artificial lung ventilation on the

ventilated patient.

A majority of the currently used artificial lung ventilation regimens can be marked by

summarizing term “positive-pressure ventilation”. Despite its nearly exclusive use in the

clinical practice, this is the less suitable type of ventilation, when the lung is subject to

pressure inversion compared to the normal state in spontaneous breathing. During inspirium,

spontaneous ventilation creates a negative pressure in the lungs towards their surrounding,

which causes the flow of gas from the surrounding atmosphere into the lungs. On the

contrary, during inspirium in the positive-pressure artificial lung ventilation, the pressure

generated by the ventilator, affecting the beginning of the airways and thus also the entire

respiration system, is greater than the atmospheric pressure. The positive pressure, among

other things, has negative influence on the circulation system as well as on the lungs as such.

During expirium, the pressure balance between spontaneous and artificial breathing is also

inverted. The said pressure inversion causes the “non-physiological character” of the positive-

pressure ventilation modes, which leads to the lung distress caused by the “treatment”