Pressure Release Ventilation Compared to Lung Protective Ventilation in Moderate and Severe ARDS

Koot Ahmad60 enrolled

Overview

This study compares two different ways of providing mechanical ventilation to patients with moderate to severe acute respiratory distress syndrome (ARDS), a serious condition in which the lungs become inflamed and make it difficult to breathe and maintain normal oxygen levels. Patients are randomly assigned to receive either airway pressure release ventilation (APRV) or conventional low-tidal-volume ventilation (LTV). The study compares the two ventilation strategies in terms of successful removal from the ventilator, time needed on mechanical ventilation, improvement in blood oxygen levels, length of stay in the intensive care unit and hospital, and complications such as the need for reintubation, barotrauma, and death. The aim is to determine whether APRV provides better outcomes than conventional low-tidal-volume ventilation in patients with moderate to severe ARDS.

Acute respiratory distress syndrome (ARDS) is a severe form of acute respiratory failure characterized by impaired oxygenation and bilateral pulmonary abnormalities. Mechanical ventilation is a cornerstone of supportive treatment for patients with moderate to severe ARDS. This prospective randomized controlled study compares airway pressure release ventilation (APRV) with conventional low-tidal-volume ventilation (LTV) in patients with moderate to severe ARDS. Eligible patients are randomly allocated in a 1:1 ratio to receive either APRV or LTV according to a predefined ventilation protocol. In the LTV group, ventilation is provided using a lung-protective strategy with tidal volumes targeted according to predicted body weight and limitation of plateau pressure. In the APRV group, ventilation is delivered using two airway pressure levels with prolonged high-pressure periods and brief release periods. APRV settings are individualized according to oxygenation, ventilation, respiratory mechanics, clinical response, and hemodynamic tolerance. Release tidal volume, minute ventilation, and respiratory-system compliance are monitored during APRV. Patients in both groups undergo daily assessment for readiness for ventilator weaning. Once predefined weaning criteria are met, patients undergo a standardized spontaneous breathing trial using the same procedure in both groups. Patients who successfully complete the trial are assessed for extubation according to predefined clinical criteria. The primary outcome is successful extubation, defined as liberation from invasive mechanical ventilation without the need for reintubation within 72 hours after extubation. Secondary outcomes include time to successful extubation, duration of mechanical ventilation, change in the PaO₂/FiO₂ ratio during the first 7 days, ICU length of stay, and hospital length of stay. Safety outcomes include all-cause mortality and barotrauma.

Interventions

Arm 1 Intervention Name: Low-Tidal-Volume Ventilation (LTV)BEHAVIORAL

For LTV Participants received conventional low-tidal-volume mechanical ventilation using a tidal volume of 4-8 mL/kg predicted body weight, with plateau pressure maintained below 30 cmH₂O. Ventilator settings were adjusted according to oxygenation, ventilation, respiratory mechanics, and hemodynamic status. FiO₂ and PEEP were adjusted to maintain the predefined oxygenation target. Patients underwent the standardized weaning and spontaneous breathing trial protocol used in both study groups. For APRV Participants received airway pressure release ventilation using two airway pressure levels (P-high and P-low), prolonged T-high, and brief T-low periods. P-high was initially set at 20-30 cmH₂O and P-low at 5 cmH₂O. T-high was initially set at 4-6 seconds and T-low at 0.6 seconds, with T-low subsequently adjusted according to the expiratory-flow waveform to limit excessive expiratory lung emptying and maintain end-expiratory lung volume. FiO₂ was adjusted to maintain SpO₂ at 88-95%. Rele

Eligibility

Sex: ALLMin age: 18 Years

Medical Language ↔ Plain English

Inclusion Criteria: 1. Adult patients aged 18 years or older. 2. Mechanically ventilated patients admitted to the Intensive Care Unit (ICU) at Banha University Hospital. 3. Patients diagnosed with moderate-to-severe acute respiratory distress syndrome (ARDS) according to the 2023 European Society of Intensive Care Medicine (ESICM) guidelines, characterized by (Matthay et al., 2024): 1. An acute predisposing risk factor (e.g., pneumonia, non-pulmonary infection, trauma, transfusion, aspiration, or shock), with pulmonary edema not primarily attributable to cardiogenic causes or fluid overload. 2. Acute onset or worsening of hypoxemic respiratory failure within one week of the onset of the predisposing risk factor or new/worsening respiratory symptoms. 3. Bilateral pulmonary opacities on chest radiography, computed tomography, or lung ultrasound that are not fully explained by pleural effusions, atelectasis, or pulmonary nodules/masses. 4. Moderate ARDS defined as a PaO₂/FiO₂ ratio \>100 to ≤200 mmHg (or SpO₂/FiO₂ ratio \>148 to ≤235 when SpO₂ \<97%) or severe ARDS defined as a PaO₂/FiO₂ ratio ≤100 mmHg (or SpO₂/FiO₂ ratio ≤148). Exclusion Criteria: 1. Patients younger than 18 years of age. 2. Pregnant women. 3. Patients with severe chronic heart failure (New York Heart Association Class III or IV). 4. Patients with uncontrolled shock requiring escalating doses of vasopressor support. 5. Patients with severe cardiac arrhythmias or active myocardial ischemia.

Outcomes

Primary Outcomes

Successful extubation

Liberation from invasive mechanical ventilation without the need for reintubation within 72 hours after extubation.

Time frame: From randomization until 72 hours after extubation

Secondary Outcomes

Time to successful extubation

Time from randomization to successful extubation among patients who achieved successful extubation, defined as liberation from invasive mechanical ventilation followed by at least 72 hours without reintubation.

Time frame: From randomization until successful extubation, hospital discharge, or death, whichever occurred first; assessed up to 30 days.

Change in PaO₂/FiO₂ ratio

Change in the PaO₂/FiO₂ ratio from baseline to 1, 3, and 7 days after initiation of the assigned ventilatory strategy (LTV or APRV).

Time frame: At baseline and 1, 3, and 7 days after initiation of the assigned ventilatory strategy.

ICU length of stay

Duration of stay in the intensive care unit, calculated from ICU admission until ICU discharge or death, whichever occurred first.

Time frame: From ICU admission until ICU discharge or death, whichever occurred first, assessed up to 30 days.

Hospital length of stay

Total duration of hospitalization, calculated from hospital admission until hospital discharge or death, whichever occurred first.

Time frame: From hospital admission until hospital discharge or death, whichever occurred first, assessed up to 30 days.