Measuring breathing drive and effort at different pressure support levels after major abdominal surgery
Assessment of Respiratory Drive and Inspiratory Effort Across Pressure Support Levels in Patients After Major Abdominal Surgery
This project will test whether changing pressure support levels can reveal under- or over-assistance of breathing in adults on ventilators after major abdominal surgery.
Quick facts
| Phase | Not applicable |
|---|---|
| Study type | Interventional |
| Enrollment | 40 (estimated) |
| Ages | 18 Years and up |
| Sex | All |
| Sponsor | Mahidol University Academic / other |
| Locations | 1 site (Bangkok, Bangkoknoi) |
| Trial ID | NCT07199881 on ClinicalTrials.gov |
What this trial studies
This is a physiological, bedside observational protocol performed in adult surgical ICU patients who remain invasively ventilated after major abdominal operations. Investigators will apply a stepwise pressure support ventilation (PSV) adjustment protocol and record noninvasive indices of respiratory drive and effort, including P0.1 (airway occlusion pressure at 100 ms), Pocc (maximum negative occlusion pressure), and the pressure muscle index (PMI). The study will quantify how patients adapt to increases and decreases in PSV and identify patterns consistent with under-assistance or over-assistance. Results are intended to inform practical PSV titration strategies that could reduce ventilator-related complications and improve clinical outcomes.
Who should consider this trial
Good fit: Adults (≥18 years) in the surgical ICU after recent major intra‑abdominal surgery who are invasively ventilated in PSV for more than 48 hours and are clinically stable without planned extubation within 6 hours are ideal candidates.
Not a fit: Patients with neuromuscular respiratory disease, hemodynamic instability requiring escalating vasopressors, those not receiving PSV, or those unable to tolerate short-term PSV adjustments are unlikely to benefit from this protocol.
Why it matters
Potential benefit: If successful, the results could help clinicians set pressure support more accurately to avoid under- or over-assistance and potentially reduce ventilator-related complications.
How similar studies have performed: Prior physiological studies have used P0.1, Pocc and related indices to characterize respiratory drive and effort, but few large clinical trials have demonstrated clear outcome benefits from routine PSV titration based on these measures.
Eligibility criteria
Show full inclusion / exclusion criteria
Inclusion Criteria: * Adult patients (≥18 years) admitted to the surgical ICU * Recent major abdominal surgery (intra-peritoneal operation without primary thoracic involvement, including luminal resection and/or resection of a gastrointestinal solid organ) requiring postoperative ICU care * Receiving invasive mechanical ventilation in pressure support ventilation (PSV) mode at the time of enrollment * Duration of invasive mechanical ventilation \>48 hours * Clinically stable, with no plan for extubation within 6 hours of study enrollment, defined by all of the following: Respiratory rate \<35 breaths/min, SpO₂ ≥90%, Heart rate \<140 bpm, No visible accessory muscle use, Hemodynamically stable without escalation of vasopressor support during the past hour, Able to tolerate short-term adjustments in PSV level as per protocol Exclusion Criteria: * Known neuromuscular disease affecting respiratory muscle function * Hemodynamic instability requiring escalation of vasopressor support * Severe hypoxemic respiratory failure requiring Positive End-Expiratory Pressure (PEEP) \>10 cmH₂O or FiO₂ \>60% * Deep sedation (Richmond Agitation-Sedation Scale \[RASS\] score \< -3) or ongoing neuromuscular blockade * History of chronic obstructive pulmonary disease (COPD) or other obstructive lung disease
Where this trial is running
Bangkok, Bangkoknoi
- Faculty of Medicine, Siriraj Hospital, Mahidol University — Bangkok, Bangkoknoi, Thailand (Recruiting)
Study contacts
- Principal investigator: Nuanprae Kitisin — Department of Anesthesiology, Faculty of Medicine, Siriraj Hospital, Mahidol University
- Study coordinator: Nuanprae Kitisin, MD
- Email: nuanprae.kit@mahidol.ac.th
- Phone: +66896767706
How to participate
- Review the eligibility criteria above with your treating physician.
- Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
- Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.