Specific Mechanical Power Assessment in Patients With Acute Respiratory Distress Syndrome
Condition: Ventilation, Mechanical
MeSH terms: Respiratory Distress Syndrome; Respiratory Distress Syndrome, Newborn; Acute Lung Injury
Study type: Observational [Patient Registry]

Summary: 
      In ARDS patients, mechanical ventilation should minimize ventilator-induced lung injury. The
      mechanical power which is the energy per unit time released to the respiratory system
      according to the applied tidal volume, PEEP, respiratory rate, and flow should reflect the
      ventilator-induced lung injury
    

Detailed description: 
      Mechanical ventilation is an essential tool for the treatment of patients with acute
      respiratory distress syndrome (ARDS); however, as other strategies, it is not free of
      complications. Inadequate ventilation may have a negative impact on the lung that may
      eventually cause the development of multiple organ failure and death. This process is known
      as ventilator-induced lung injury (VILI). From a clinical perspective, one of the most
      important objectives of ARDS treatment is to avoid or mitigate the development of VILI, not
      only to preserve pulmonary integrity, but also to reduce mortality.

      Ventilator-induced lung injury results from the interaction between the mechanical load
      applied to the lung and its capacity to tolerate it. Factors such as tidal volume (Vt),
      plateau pressure (PPlat), lung strain or insufflation pressure (ΔP), inspiratory flow rate
      (VI), respiratory rate (RR), excessive inspiratory effort, high levels of FiO2 and high
      levels of positive end-expiratory pressure (PEEP), have been directly involved in damage
      mechanism. With an integrating and rheological idea, the concept of mechanical power tries to
      encompass the majority of these factors within a measurable unit in joules per minute, as the
      expression of power applied on a repetitive basis on the respiratory system in ARDS. Although
      the concept of MP holds promise for preventing the risk of VILI, its utility has not been
      proven in clinical practice until now. The main value of MP over the rest of commonly used
      variables for the monitoring of patients with ARDS is that it includes flow on injury
      mechanism (kinetic energy), accepting that an inverse relationship exists between this
      mechanism and the capacity of alveoli to adapt to change during the ventilation cycle (strain
      rate), as well as it embodies the concept of process repeatability (respiratory rate), though
      not of its duration. This begs the question whether we should consider its value at the
      moment of defining a mechanical ventilation strategy. The main disadvantage of its
      application is that MP conceives the respiratory system in an integrated manner and not
      related to or standardized with the ventilable lung portion, that is ultimately the one who
      has to withstand the ventilatory load; in other words, the same MP may have different
      consequences depending on the baby lung size or its equivalent, the severity of ARDS.

      The objective of this study is to evaluate the influence of the ventilable lung size on VILI
      mechanisms in patients suffering from ARDS treated with protective ventilation with similar
      MP.
    

Intervention name(s): Evaluation of CT images
Intervention type(s): Other
Intervention description(s): A helicoidal CT scanner will be used (Aquilion CXL, Toshiba, Japan), with AIDR 3D technique (Adaptive Iterative Dose Reduction 3D) in order to minimize exposure to X-rays. Two complete thorax CT scans will be performed, one of them in expiratory pause (PEEP) and the other in inspiratory pause (PPlat). Esophageal pressure shall be measured (FluxMed GrT, Argentina) and transpulmonary pressure will be calculated at the end of inspiration (Ppl-insp) and expiration (Ppl-exp).
Other intervention name(s): Evaluation of transpulmonary pressures
Observational model: Cohort
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        patients consecutively admitted with ARDS, as defined according to the Berlin expert
        consensus
      
Keywords: ARDS; Mechanical power