How torso tilt and ventilator PEEP affect lung opening in ARDS

Impact of Trunk Inclination on Lung Mechanics According to PEEP and Reruitability

This study will see if tilting the patient's torso and changing PEEP helps open more lung and improve breathing mechanics in adults with moderate to severe ARDS on a ventilator.

Quick facts

• Study type: Observational
• Enrollment: 40 (estimated)
• Ages: 18 Years and up
• Sex: All
• Sponsor: Zhongda Hospital (Academic / other)
• Locations: 3 sites (Nanjing, Jiangsu and 2 other locations)
• Trial ID: NCT07504731 on ClinicalTrials.gov

What this trial studies

This multicenter physiological observational study measures how changing trunk inclination interacts with positive end-expiratory pressure (PEEP) and lung recruitability in intubated adults with moderate-to-severe ARDS. Participants undergo standardized lung recruitment maneuvers and decremental PEEP steps while respiratory mechanics and regional aeration are monitored using bedside tools such as electrical impedance tomography and conventional ventilator measurements. Investigators compare effects of different head-of-bed inclinations on end-expiratory transpulmonary pressure, recruitment of previously collapsed units, and signs of overdistension. The protocol is performed at tertiary hospitals in China and enrolls sedated, mechanically ventilated patients who meet the Berlin criteria for moderate-to-severe ARDS.

Who should consider this trial

Good fit: Intubated adults (≥18 years) with moderate-to-severe ARDS (PaO2/FiO2 ≤ 200 mmHg) under continuous sedation, without contraindications to recruitment maneuvers or trunk inclination, would be appropriate candidates.

Not a fit: Patients who are hemodynamically unstable, pregnant, have bronchopleural fistula, intra-abdominal hypertension, pure COPD exacerbation, cannot accommodate EIT monitoring, or who are not mechanically ventilated are unlikely to benefit from this protocol.

Why it matters

Potential benefit: If successful, this work could help tailor bedside positioning and PEEP to open more lung while avoiding overdistension, potentially improving oxygenation and reducing ventilator-induced lung injury.

How similar studies have performed: Head-up positioning is proven to reduce ventilator-associated pneumonia and anesthesia studies show increased lung volume with tilt, but in ARDS the net effect on recruitment versus overdistension is uncertain, making the combination of trunk inclination with tailored PEEP/recruitment a relatively novel physiologic approach.

Eligibility criteria

Inclusion Criteria:

* Intubated moderate and severe ARDS according to the Berlin definition (PaO2/FiO2 ratio \<= 200 mmHg)
* Under continuous sedation with or without paralysis

Exclusion Criteria:

* Age \<18 years
* Bronchopleural fistula
* Pure COPD exacerbation
* Contraindication to EIT monitoring (e.g. burns, pacemaker, thoracic wounds limiting electrode belt placement)
* Hemodynamic instability (Systolic BP \< 75 mmHg or MAP \< 60 mmHg despite vasopressors and/or heart rate \< 55 bpm)
* Contraindications to mobilization (e.g., intracranial hypertension, spinal cord injury)
* Intra-abdominal hypotension (IAP≥12mmHg)
* Pregnancy
* Attending physician deems the transient application of high airway pressures to be unsafe

Where this trial is running

Nanjing, Jiangsu and 2 other locations

• Zhongda Hospital, Southeast University — Nanjing, Jiangsu, China (Recruiting)
• The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital — Jinan, Shandong, China (Recruiting)
• West China Hospital of Sichuan University — Chengdu, Sichuan, China (Not_yet_recruiting)

Study contacts

• Study coordinator: Fengmei Guo, M.D

Conditions Acute Respiratory Distress Syndrome; trunk inclination; lung mechanics; positive end-expiratory pressure; lung recruitability