Cross-sectional, Observational, Prospective and Analytical Study:MECHANICAL POWER DAY (MPDay)

Introduction and justification:

Over the last few years the investigators have witnessed an important technological developement in the field of mechanical ventilation. Along with the technological advances, the better understanding of the respiratory physiopathology has shown that mechanical ventilation "per se" can lead to deleterious effects.

In this context, the search for those variables which are responsible for the developing of ventilator-induced lung injury (VILI) has become an important goal in this field. In fact, the investigators are witnessing the nearly exponential increase in the publication of studies that have tried to associate the different parameters that intervene in mechanical ventilation with the injury to the lung structure.

Recently the new concept of "mechanical power" has been proposed. It refers to the amount of energy per minute that is transferred to the lung by the ventilator. The generation of this form of energy would include both parameters that were previously proposed to be possible causes for lung damage and new parameters that had not been taken into account until now, such as the flow rate or the respiratory rate, without forgetting the individual characteristics of each ventilated subject.

12J/min has been stablished experimentally as the energy threshold from where changes in the lung that can lead to VILI begin to appear. Nevertheless, the true issue would be to get to know the best way to normalize the mechanical power value. However, it seems reasonable to think that the values of energy originating VILI in experimental animal models and in humans are different.

Nowadays, in spite of the wide range of monitoring systems that the investigators have, the investigators still don´t know the real mechanical power that the investigators are transmitting to our patients. The different research teams that have deepened into the subject have seen themselves forced to infer their results from retrospective data and from very selected samples of patients immersed in different studies. As one of the first steps in the way of a better understanding of the impact of "mechanical power", the investigators believe it is justified to develope a descriptive and observational study to get to know the real mechanical power value the investigators ventilate our patients in the ICU with.

Objective and hypothesis:

Clinical guides and recommendations aimed at improving ventilation basing on the characteristics of the different pathologies in order to minimize VILI do exist, but the fact remains that the threshold of mechanical power in mechanical ventilation is still unkown.

The main hypothesis of the present study is that the mechanical power received by the patients who need mechanical ventilation in the intensive care unis is greater tan the threshold that has been established by experimental models.

Moreover, the investigators think that mechanical power varies considerably depending on the current and previous pathology of the patient and the days on mechanical ventilation.

Resting on the previous hypothesis, the main objective of the current study is:

• Know the value of the mechanical power in the patient connected to mechanical ventilation, in a volume control model.

This value will be calculated from electronically provided data using the simplified formula by Gattinonni et. Al.

Secondary objectives are:

• Analyze the epidemiology of different modalities in ventilatory, not just VC, on the basis of the collected variables.
• To assess if the transmitted mechanical power varies depending on the pathology, on the days on mechanical ventilation or on the reason that leads to the need for mechanical ventilation.
• In case of a ventilatory mode which allows spontaneus breathing, the investigators can see the variability of the plateau pressure and if the investigators can infer its value in the calculation of mechanical power.
• To know the driving pressure and the ventilatory ratio of ventiled patients.
• To establish differences among the main analysed parameters depending on the type of critical carea area studied.

Design and methodology:

Cross-sectional, observational, prospective and analytical study. The variables of the study will be collected on a fixed date as agreed with the participating ICU. These variables will be registered during the period of time between 8 am to 15 pm on the 21st of November 2019, in order to adjust to the normal working routine at an intensive care unit.

Sample selection:

All patients that are hospitalised in a critical care unit and on mechanical ventilation on the 21st of November 2019.

Inclusion criteria:

All the patients hospitalised in a crital care unit who are on invasive mechanical ventilation, whatever the cause.