Assessment of Respiratory Drive and Inspiratory Effort Across Pressure Support Levels in Patients After Major Abdominal Surgery

NCT07199881 | Recruiting

• 1 other identifier: PSV-SICU_SIRIRAJ
• Study Type: interventional
• Target: 40
• Locations: 1 country
• Sites: 1

Brief Summary

This physiological observational study will assess respiratory drive and inspiratory effort across varying levels of pressure support ventilation (PSV) in adult surgical ICU (SICU) patients after major abdominal surgery. By using non-invasive bedside indices (airway occlusion pressure at 100 ms after the onset of inspiration \[P0.1\], maximum negative occlusion pressure \[Pocc\], and pressure muscle index \[PMI\]), we aim to quantify how patients adapt to changes in ventilatory support and determine patterns of under- and over-assistance. Findings may inform optimal titration of PSV to reduce complications and improve clinical outcomes.

Conditions

Inspiratory Effort; Mechanical Ventilation; Major Abdominal Surgeries

Keywords

Pressure support ventilation; respiratory drive; inspiratory effort; mechanical ventilation; Major Abdominal Surgery

Outcome Measures

Primary Outcomes (1)

• Respiratory drive and inspiratory effort across pressure support levels

  Respiratory drive and inspiratory effort will be assessed using airway occlusion pressure at 0.1 seconds (P0.1), maximum negative inspiratory occlusion pressure (Pocc), and the pressure muscle index (PMI). These indices are measured non-invasively via ventilator maneuvers during standardized stepwise adjustments of pressure support ventilation (baseline, ±3 cmH₂O, ±6 cmH₂O, return to baseline). The mean of three repeated measurements at each step will be analyzed.

  Baseline and during protocol sessions, up to 3 days after enrollment

Secondary Outcomes (5)

• Incidence of ventilatory response patterns during PSV

  Baseline and during protocol sessions, up to 3 days after enrollment

• Duration of mechanical ventilation after protocol

  Within 48 hours after extubation

• Reintubation or non-invasive ventilation use

  48 hours after extubation

• ICU length of stay

  Through ICU stay, an average of 7-21 days

• Hospital discharge disposition

  Through hospital stay, an average of 14-60 days

Study Arms (1)

Single Cohort (Postoperative SICU patients on PSV >48h)

EXPERIMENTAL

Adult patients admitted to the surgical ICU after major abdominal surgery who remain on pressure support ventilation (PSV) for more than 48 hours. Each participant will undergo a standardized stepwise protocol of PSV adjustment (baseline, -6 cmH₂O, -3 cmH₂O, +3 cmH₂O, +6 cmH₂O, return to baseline). At each step, a 2-minute stabilization is followed by repeated measurements of respiratory drive and inspiratory effort indices (P0.1, Pocc, PMI) and ventilatory parameters.

Procedure: Stepwise PSV adjustment protocol

Interventions

Stepwise PSV adjustment protocol PROCEDURE

Patients will undergo standardized stepwise PSV changes (baseline, ±3 cmH₂O, ±6 cmH₂O, return to baseline), with 2-minute stabilization and repeated measurements of ventilatory parameters.

Single Cohort (Postoperative SICU patients on PSV >48h)

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• 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

You may not qualify if:

• 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

Sponsors & Collaborators

• Mahidol University: lead
• Siriraj Hospital: collaborator

Study Sites (1)

Faculty of Medicine, Siriraj Hospital, Mahidol University

Bangkok, Bangkoknoi, 10700, Thailand

RECRUITING

Related Publications (6)

• He Q, Lai Z, Peng S, Lin S, Mo G, Zhao X, Wang Z. Postoperative pulmonary complications after major abdominal surgery in elderly patients and its association with patient-controlled analgesia. BMC Geriatr. 2024 Sep 10;24(1):751. doi: 10.1186/s12877-024-05337-y.

  PMID: 39256677 RESULT

• Miskovic A, Lumb AB. Postoperative pulmonary complications. Br J Anaesth. 2017 Mar 1;118(3):317-334. doi: 10.1093/bja/aex002.

  PMID: 28186222 RESULT

• Courtney A, Clymo J, Dorudi Y, Moonesinghe SR, Dorudi S. Scoping review: The terminology used to describe major abdominal surgical procedures. World J Surg. 2024 Mar;48(3):574-584. doi: 10.1002/wjs.12084. Epub 2024 Feb 11.

  PMID: 38342951 RESULT

• Docci M, Foti G, Brochard L, Bellani G. Pressure support, patient effort and tidal volume: a conceptual model for a non linear interaction. Crit Care. 2024 Nov 6;28(1):358. doi: 10.1186/s13054-024-05144-2.

  PMID: 39506755 RESULT

• Al-Bassam W, Parikh T, Neto AS, Idrees Y, Kubicki MA, Hodgson CL, Subramaniam A, Reddy MP, Gullapalli N, Michel C, Matthewman MC, Naughton J, Pereira J, Shehabi Y, Bellomo R. Pressure support ventilation in intensive care patients receiving prolonged invasive ventilation. Crit Care Resusc. 2023 Oct 18;23(4):394-402. doi: 10.51893/2021.4.OA4. eCollection 2021 Dec 6.

  PMID: 38046681 RESULT

• van Oosten JP, Akoumianaki E, Jonkman AH. Monitoring respiratory muscles effort during mechanical ventilation. Curr Opin Crit Care. 2025 Feb 1;31(1):12-20. doi: 10.1097/MCC.0000000000001229. Epub 2024 Nov 14.

  PMID: 39560150 RESULT

Study Officials

• Nuanprae Kitisin

  Department of Anesthesiology, Faculty of Medicine, Siriraj Hospital, Mahidol University

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Nuanprae Kitisin, MD

CONTACT

+66896767706; nuanprae.kit@mahidol.ac.th

Nattaya Raykateeraroj, MD

CONTACT

+66993519963; nuanprae.kit@mahidol.ac.th

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: DIAGNOSTIC
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: September 10, 2025
• First Posted: September 30, 2025
• Study Start: October 31, 2025
• Primary Completion (Estimated): September 30, 2026
• Study Completion (Estimated): September 30, 2027
• Last Updated: November 18, 2025

Record last verified: 2025-11

Data Sharing

• IPD Sharing: Will not share

Locations

TH (1)