Variable Pressure Support - Variable Pressure Support

Variable Pressure Support

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Mimic Natural Breathing

By generating random changes in inspiratory pressure, Variable Pressure Support (Variable PS) mimics the subtle variability of normal breathing. Improved pulmonary function and a reduced risk of ventilator-associated lung injury (VALI) are the main potential effects of this gentle variation. Patients feel more comfortable and there are fewer adjustments to the ventilator settings.

Proven facts: improved outcome with Variable PS

  • More homogenous ventilation, surfactant production and pulmonary perfusion without negative hemodynamic effects of elevated intrathoracic pressures.
    1, 2, 3, 4    
  • More natural breathing with improved patient ventilation synchrony. 5, 6, 7  

Variable Pressure Support: How does it work?

Watch the video to learn how Variable Pressure Support works.

Use the chance – the idea of randomized Variable PS

Breathing is a cyclic activity with variable inspiratory and exspiratory phases. It is almost impossible to observe two spontaneous breaths with exactly the same characteristics. This variability of spontaneous breathing is called “noise”.

Controlled mechanical pressure support ventilation is even characterized by fixed support level. To provide a more physiological respiratory pattern and to improve outcome, the option of Variable PS mimics noise of the nature. It generates random variation values in pressure support levels and then applies those values to the pressure support delivered to the patient. Finally, biologically variable ventilation or “noisy pressure support” seems to improve oxygenation and lung function.

Variation of ventilation follows a random function

The addition of noise (random changes) to a monotonously treated nonlinear biological system, such as the lung, induces stochastic resonance that contributes to the recruitment of collapsed alveoli and atelectasis in the lung segments. This random variation is based on the variability according to Gaussian normal distribution.

Gaussian Normal Distribution


You would like to get more information about what Gaussian normal distribution means?

The Variable PS as a derivation of Gaussian normal distribution

The level of Variable PS breaths follows a random function according to a Gaussian distribution. Regardless of the patient’s spontaneous breathing effort, Variable PS therefore induces tidal volume variation. The variation is performed for every single breath. To make it easier for the user, the variability in Variable PS can be set directly in percent: “Press. Var. %”. Settings for “PEEP” and “∆PS” remain the same.

You can compare effects on the Gauss equation and the ventilation curve by setting the variability on 25%, 50%, or 100%. Click on the download links below to make the differences visible.

What customers say about Variable PS

“Variable Pressure Support ventilation could improve lung mechanics and thus unload the respiratory muscles at the same support level.”

Referring to a case report by Dr. Tommaso Mauri, Milan, Italy 2

Improving lung mechanics with Variable PS

This case demonstrates the distribution of ventilation pre and post initiation of Variable PS. It becomes visible by using the Dräger PulmoVista® 500 that helps optimize and individualize lung ventilation.

PulmoVista Screen Initial

Ventilation distribution during pressure support ventilation

  • Reduced ventilation in upper left quadrant (ROI 2) becomes visible
  • Uneven ventilation distribution
PulmoVista Screen after 10-minutes

Patient 10 min after the start of Variable PS

  • More homogeneous distribution of ventilation
  • Increase of ventilation towards ROI 2

The positive effects of improved ventilation during Variable PS

Long-Term Ventilation with variable

Optimized treatment with Variable PS

This case of the German University Hospital in Dresden deals with a 73-year-old man who had to be ventilated after a fall from 12 feet height. With variable pressure support it was possible to cover a wide range of ventilation pressures by optimizing the gas exchange and increasing patient comfort levels.

Get the full case

Clinical evidence on Variable Pressure Support shows that:

  • In the very short term, noisy pressure support ventilation (PSV) proved safe and feasible in patients with acute hypoxemic respiratory failure. Compared to conventional PSV, noisy PSV increased the variability of tidal volumes, and was associated with improved patient-ventilator synchrony, at comparable levels of gas exchange. 5
  • Variable ventilation offers a new physiological approach to lung recruitment without the negative hemodynamic effects from markedly elevated intrathoracic pressures. 2
Literature List Variable PS
Literature List Variable-PS

Clinical studies, cases and reviews

Get more information about Variable PS here in our download section

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1 Naik BI, Lynch C, Durbin CG. Variability in Mechanical Ventilation: What's All the Noise About? Respir Care. 2015;60(8):1203-10

2 Mauri T, Lazzeri M, Bronco A, et al. Effects of Variable Pressure Support Ventilation on Regional Homogeneity and Aeration. Am J Respir Crit Care Med. 2017 1;195(5):e27-e28

3 Gama de Abreu M, Spieth PM, Pelosi P, et al.: Noisy pressure support ventilation: a pilot study on a new assisted ventilation mode in experimental lung injury. Crit Care Med 2008; 36: 818–27

4 Arold SP, Suki B, Alencar AM et al. Variable ventilation induces endogenous surfactant release in normal guinea pigs. Am J Physiol Lung Cell Mol Physiol. 2003;285(2):L370-5.

5 Spieth PM, Güldner A, Huhle R, et al.: Short-term effects of noisy pressure support ventilation in patients with acute hypoxemic respiratory failure. Crit Care 2013; 17: R261

6 Morawiec E, Kindler F, Schmidt M. Comparative Effects of Variable Pressure Support, Neurally Adjusted Ventilatory Assist (NAVA) and Proportional Assist Ventilation (PAV) on the Variability of the Breathing Pattern and on Patient Ventilator Interaction Am J Respir Crit Care Med.. 2015;191:A3163

7 Vassilakopoulos T, Zakynthinos S. When mechanical ventilation mimics nature.
Crit Care Med. 2008 36(3):1009-11.