Overview
This study assesses changes in physiological variables, aiming to determine whether a reduction in the mechanical power delivered by artificial ventilation while maintaining constant peep levels generates a reduction in the Bohrs dead space in patients with moderate to severe acute respiratory distress syndrome (ARDS). Commonly used ventilatory strategies aimed at reducing mechanical power will be applied sequentially to assess their impact. Data obtained from volumetric capnography will be recorded after each ventilatory strategy is applied.
Description
Invasive mechanical ventilation is the cornerstone of the management of patients with Acute Respiratory Distress Syndrome. However, studies have shown that increasing tidal volume and driving pressure leads to negatives outcomes. It has also been observed that an increase in the physiologic dead space is associated with significantly higher mortality. We designed this study to assess these physiological variables, aiming to determine whether the reduction in the mechanical power delivered by artificial ventilation generates a decrease of the Bohrs dead space in patients with moderate to severe ARDS. Therefore, this observational study will describe the effect that mechanical power has on Bohr's dead space and its subcomponents in mechanically ventilated patients with ARDS. Commonly used ventilatory strategies aimed at reducing mechanical power will be applied sequentially to assess their effects. Data obtained from volumetric capnography will be recorded after each ventilatory procedure is implemented. This observational study will be performed in the Intensive Care Unit of a University Hospital.
Protocol design: The protocol will start recording the data during baseline protective ventilation. After 30 minutes of data recording, we studied four levels of setting in mechanical ventilation. Each level will last 30 minutes.
We will analyze the last 20 breaths of each step of the protocol and calculate the average value to obtain the result of dead space and all its variables by volumetric capnography. Respiratory, hemodynamic, and arterial blood gas analysis will also be recorded.
Eligibility
Inclusion Criteria:
- Age older than 18 years
- The requirement of invasive mechanical ventilation for more than 4 hours and less than 72 hours
- Severe hypoxemia (PAFI < 200) secondary to ARDS
Exclusion Criteria:
- Heart failure stage IV
- Chronic obstructive pulmonary disease (COPD) on home oxygen
- Bronchopulmonary fistula
- Hypovolemic Shock with active hemorrhage
- Gastrointestinal bleeding
- Oesophageal Varices
- Nasopharynx surgery, recent oesophageal or gastric surgery
- Massive Pulmonary Thromboembolism
- Catastrophic respiratory failure requiring urgent extracorporeal life support
- Respiratory acidosis. Hydrogen potential (pH) is less than 7.20 and PaCO2 higher than 60 mmHg at baseline.