The goal of this quasi-experimental study is to investigate how different body positions, performed through Automatic Lateralization Therapy, affect respiratory drive, ventilation, and pulmonary aeration in critically ill adult patients under mechanical ventilation. The main questions this study aims to answer are:
* Does Automatic Lateralization Therapy, modify respiratory drive, as measured by P0.1, estimated Pmus, and sEMG of the diaphragm and parasternal muscles? * Is there an association between respiratory drive, ventilation, and pulmonary aeration measured by Electrical Impedance Tomography (EIT) in different body positions promoted by Automatic Lateralization Therapy ?
Does combining Automatic Lateralization Therapy, with Flow Bias improve physiological and functional outcomes compared to Automatic Lateralization Therapy, without Flow Bias?
Participants will:
* Be positioned in different lateralization strategies using Automatic Lateralization Therapy, while under mechanical ventilation; * Have respiratory parameters and ventilation images assessed by EIT and sEMG;
Participate only during their ICU stay, with no need for additional visits after discharge.
Patients of both sexes will be included;
Aged ≥ 18 years;
BMI 18-35 kg/m²;
Under invasive mechanical ventilation via orotracheal tube for ≥ 24 hours and expected to remain on mechanical ventilatory support for at least 48 hours;
Patients presenting medical restrictions to body repositioning, or to the use of EIT or sEMG;
Those in therapeutic failure;
Individuals with spinal cord injury, brain injury, or stroke with a history of functional loss and respiratory impairment prior to hospitalization;
Neurological diseases affecting respiratory myoelectric conduction;
Crossover
Automatic Lateralization Therapy
Other interventionDuring this phase of analysis and intervention related to lateral positioning, patients will be maintained on a Multicare bed (LINET) and subjected to personalized lateral positioning based on the morphofunctional pattern detected by electrical impedance tomography. This positioning will be performed using automatic lateralization therapy, programmed for unilateral or bilateral application, continuously alternating between angles of 0°, 15°, and 30°, maintained for 20 minutes at each position. The procedure will be conducted in two sequences, with the second sequence combined with the Flow Bias intervention. At each angle, data will be collected on hemodynamic monitoring, respiratory drive, respiratory mechanics, regional distribution of ventilation and aeration, and gas exchange.
Supine Positioning
Other interventionDuring this analysis phase, patients will be positioned on a Multicare bed (LINET) in the dorsal decubitus position with the head of the bed elevated to 30°. Data will be collected on hemodynamic monitoring, respiratory drive, respiratory mechanics, degree of lung involvement, regional distribution of ventilation and aeration, and gas exchange.
Respiratory drive parameters: Surface electromyography (sEMG)
The respiratory drive parameter will be assessed using surface electromyographic (sEMG) activity of the respiratory muscles, including the diaphragm and parasternal intercostals, expressed in microvolts (µV) (Silva Junior et al., 2023). Data are given in: • µV: Microvolts Measurements will be performed during the first and last 5 minutes of each body angulation. Unilateral: 140 minutes \| Bilateral: 370 minutes. Following the sequence: Semi-seated 30°/20 minutes, Supine 0°/5 minutes, 15°/20 minutes, 30°/20 minutes, 15°/20 minutes, Supine 0°/5 minutes, and Semi-seated 30°/20 minutes, totaling 70 minutes per sequence plus 60 minutes of washout between sequences. This results in 140 minutes for patients undergoing Unilateral Lateralization Therapy and 370 minutes for patients undergoing Bilateral Lateralization Therapy.
Respiratory drive parameter: P0.1 (airway occlusion pressure during the first 100 ms of the inspiratory effort)
The respiratory drive parameter will be assessed by P0.1(airway occlusion pressure during the first 100ms of the inspiratory effort,cmH₂O).P0.1 is the drop in airway pressure within 100 ms after the onset of inspiration and is considered a reliable, fast, and feasible bedside marker.The following values are considered: Normal: 1.5-3.5 cmH₂O; Low: \<1.0 cmH₂O(hypostimulated); High:\>4.0 cmH₂O (hyperstimulated)(CHEN et al.,2023). Data are given in: cmH₂O: centimeters of water Measurements will be performed during the first and last 5 minutes of each body angulation. Unilateral: 140 minutes \| Bilateral: 370 minutes. Following the sequence: Semi-seated 30°/20 minutes, Supine 0°/5 minutes, 15°/20 minutes, 30°/20 minutes, 15°/20 minutes, Supine 0°/5 minutes, and Semi-seated 30°/20 minutes, totaling 70 minutes per sequence plus 60 minutes of washout between sequences. This results in 140 minutes for patients undergoing Unilateral Lateralization Therapy and 370 minutes Bilateral.
Respiratory drive parameters: Pmus (estimated inspiratory muscle pressure)
The respiratory drive will be assessed using Pmus (estimated inspiratory muscle pressure). Pmus is derived from the airway pressure drop during a brief inspiratory occlusion and reflects inspiratory effort. Reference ranges: Pmus \< 5 cmH₂O indicates over-assistance/low drive; Pmus ≤ 10 cmH₂O represents the diaphragmatic protection zone; Pmus \> 13-15 cmH₂O indicates excessive effort (Dianti, Bertoni ;Goligher, 2020). Data are given in: •cmH₂O: centimeters of water Measurements will be performed during the first and last 5 minutes of each body angulation. Unilateral: 140 minutes \| Bilateral: 370 minutes. Following the sequence: Semi-seated 30°/20 minutes, Supine 0°/5 minutes, 15°/20 minutes, 30°/20 minutes, 15°/20 minutes, Supine 0°/5 minutes, and Semi-seated 30°/20 minutes, totaling 70 minutes per sequence plus 60 minutes of washout between sequences. This results in 140 minutes for patients undergoing Unilateral Lateralization Therapy and 370 minutes for patients undergoing Bilateral
Pulmonary ventilation: Ventilation Impedance Change (ΔZ)
ΔZ will be quantified using electrical impedance tomography (EIT). ΔZ represents the sum of impedance changes of all pixels within a predefined region of interest (ROI), corresponding to regional tidal ventilation. ROIs will include right anterior, left anterior, right posterior, and left posterior lung regions, and will also be categorized as dependent or non-dependent lung areas. Data will be expressed in arbitrary units (a.u.). Measurements will be performed during the first and last 5 minutes of each body angulation. Unilateral: 140 minutes \| Bilateral: 370 minutes. Following the sequence: Semi-seated 30°/20 minutes, Supine 0°/5 minutes, 15°/20 minutes, 30°/20 minutes, 15°/20 minutes, Supine 0°/5 minutes, and Semi-seated 30°/20 minutes, totaling 70 minutes per sequence plus 60 minutes of washout between sequences. This results in 140 minutes for patients undergoing Unilateral Lateralization Therapy and 370 minutes for patients undergoing Bilateral Lateralization Therapy.
Mechanical response associated with respiratory drive: Diaphragmatic excursion
Diaphragmatic excursion will be assessed by ultrasonography using a convex transducer placed along the right mid-clavicular line, using the liver as an acoustic window. The procedure follows established ICU protocols and can be performed without ventilator disconnection. In this study, ventilation will remain connected, and diaphragmatic excursion will be quantified in millimeters (mm) (Santana et al., 2020). Data are given in: mm: Millimeters. Measurements will be performed during the first and last 5 minutes of each body angulation. Unilateral: 140 minutes \| Bilateral: 370 minutes. Following the sequence: Semi-seated 30°/20 minutes, Supine 0°/5 minutes, 15°/20 minutes, 30°/20 minutes, 15°/20 minutes, Supine 0°/5 minutes, and Semi-seated 30°/20 minutes, totaling 70 minutes per sequence plus 60 minutes of washout between sequences. This results in 140 minutes for patients undergoing Unilateral Lateralization Therapy and 370 minutes for patients undergoing Bilateral.
Mechanical response related to respiratory effort and lung stress: Dynamic transpulmonary driving pressure
Dynamic transpulmonary driving pressure (cmH₂O) will assess the mechanical response to respiratory effort and lung stress. It is derived from the same expiratory occlusion maneuver used for Pmus, applying a correction formula to isolate lung distension. This provides a non-invasive measure of dynamic lung stress during ventilation. Recent studies have targeted values between 15 and 20 cmH₂O (Dianti et al., 2022). Data are given in: cmH₂O: centimeters of water Measurements will be performed during the first and last 5 minutes of each body angulation. Unilateral: 140 minutes \| Bilateral: 370 minutes. Following the sequence: Semi-seated 30°/20 minutes, Supine 0°/5 minutes, 15°/20 minutes, 30°/20 minutes, 15°/20 minutes, Supine 0°/5 minutes, and Semi-seated 30°/20 minutes, totaling 70 minutes per sequence plus 60 minutes of washout between sequences. This results in 140 minutes for patients undergoing Unilateral Lateralization Therapy and 370 minutes for patients undergoing Bilateral.
Driving Pressure (cmH₂O)
Driving pressure will be assessed using ventilator-derived parameters during mechanical ventilation to estimate lung stress under different body angulations and lateralization strategies. Driving pressure will be calculated as the difference between plateau pressure (Pplat) and positive end-expiratory pressure (PEEP), according to the formula: Driving Pressure = Pplat - PEEP. Data will be expressed in: cmH₂O (centimeters of water). Measurements will be performed during the first and last 5 minutes of each body angulation. Unilateral: 140 minutes \| Bilateral: 370 minutes. Following the sequence: Semi-seated 30°/20 minutes, Supine 0°/5 minutes, 15°/20 minutes, 30°/20 minutes, 15°/20 minutes, Supine 0°/5 minutes, and Semi-seated 30°/20 minutes, totaling 70 minutes per sequence plus 60 minutes of washout between sequences. This results in 140 minutes for patients undergoing Unilateral Lateralization Therapy and 370 minutes for patients undergoing Bilateral Lateralization Therapy.
Respiratory System Compliance (mL/cmH₂O)
Respiratory system compliance will be evaluated using ventilator-derived parameters to assess lung distensibility during different body angulations and lateralization strategies under mechanical ventilation. Respiratory system compliance will be calculated as the ratio between tidal volume (VT) and driving pressure, according to the formula: Compliance = VT/ (plateau press - PEEP). Data will be expressed in: cmH₂O (centimeters of water). Measurements will be performed during the first and last 5 minutes of each body angulation. Unilateral: 140 minutes \| Bilateral: 370 minutes. Following the sequence: Semi-seated 30°/20 minutes, Supine 0°/5 minutes, 15°/20 minutes, 30°/20 minutes, 15°/20 minutes, Supine 0°/5 minutes, and Semi-seated 30°/20 minutes, totaling 70 minutes per sequence plus 60 minutes of washout between sequences. This results in 140 minutes for patients undergoing Unilateral Lateralization Therapy and 370 minutes for patients undergoing Bilateral Lateralization Therapy.
Clinical Severity - SAPS 3 (Baseline)
Baseline clinical severity will be assessed using the Simplified Acute Physiology Score 3 (SAPS 3). This score provides a standardized measure of acute illness severity based on physiological, laboratory, and clinical variables collected within the first hours of ICU admission. SAPS 3 generates a total score typically ranging from 0 to 217, with higher scores indicating greater severity and higher predicted mortality risk (Salluh; Soares, 2014). The score will be recorded once before any intervention and used solely for sample characterization and stratification.
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University of Pernambuco
Lead sponsor
Universidade Federal de Pernambuco
Collaborator
Fundação de Amparo à Ciência e Tecnologia de Pernambuco
Collaborator
Conselho Nacional de Desenvolvimento Científico e Tecnológico
Collaborator
