Pressure Muscle Index and Threshold of Over-assistance During Pressure Support Ventilation (PUMA)

PressUre-Muscle-index to Identify Patient's Desired Tidal Volume and the Threshold of Over-Assistance During Pressure Support Ventilation

Pressure support ventilation (PSV) is used to assist the breathing of the intubated patient with some pressure from the ventilator. This support aims at avoiding excessive inspiratory effort, while ensuring a certain degree of training of the patient's inspiratory muscle. Avoiding both minimal and excessive assistance is thus important for the optimal care of the intubated patient ensuring a lung and diaphragm protective ventilation with the goal to liberate the patient from the ventilator as soon as possible.

Recently pressure-muscle-index (PMI), an index of inspiratory effort easy to be measured on the ventilator screen, has been proposed to avoid excessive assistance in PSV. This will be the first prospective study testing the effects of setting pressure support based on PMI to avoid excessive assistance on patients recovering from acute lung injury (acute hypoxemic respiratory failure).

Study Overview

• Status: Recruiting
• Conditions: Acute Hypoxemic Respiratory Failure
• Intervention / Treatment: Other: Measuring Respiratory Mechanics; Other: Randomized Pressure Support

Detailed Description

First, for each patient enrolled the investigators will perform 1 inspiratory and 3 expiratory occlusions separated at least by 30 seconds at clinical PSV to measure respiratory mechanics (plateau pressure [Pplat] and respiratory system compliance [Crs] and elastance [Ers]) and inspiratory effort and drive (Pocc, P0.1, PMI) and Vt expressed in ml/Kg of predicted body weight.

Second, if PMI≥0 at baseline, the investigators will set Pressure Support (PS) so that positive end-expiratory pressure (PEEP) +PS (i.e. Peak pressure [Ppeak]) equals Pplat measured at baseline, in order to make PMI=0. If PMI<0 at baseline, the investigators will set PS so that PEEP+PS equals Pplat measured at baseline, then the investigators will perform an inspiratory occlusion and repeat the procedure until PMI=0. The PS level at which PMI=0 (PSPMI=0) and the corresponding breathing pattern (tial volume [Vt] and respiratory rate [RR]) will be used as reference for the study protocol. After 5 minutes at PSPMI=0 the investigators will perform 3 inspiratory and 3 expiratory occlusions separated at least by 30 seconds.

Third, each patient will undergo 3 steps of PS above (+2, +4, +6 cmH2O) and 3 below (-2, -4, -6 cmH2O) PSPMI=0 in a randomized order. Steps will be randomized using a simple sequence written within envelopes opened blindly by the investigators. Each step will last 5 minutes or less if poorly tolerated (see tolerance rules below). At the end of each step the investigators will perform 1 inspiratory occlusion and 3 expiratory occlusions. Each of the expiratory occlusion will be separated by 30 seconds in order to restore the patient's breathing pattern. The investigators will resume a 3-minutes clinical PS in between each step to minimize changes in PaCO2. If not yet comprised by the study steps each patient will undergo an adjunctive 5 minutes step at PS 0 (zero) cmH2O.

The study protocol will last approximately 60 minutes. The patient will be continuously monitored by a physician and a respiratory therapist.

At the end of the study, if different from clinically set PS, the investigators will propose clinicians to adjust the PS to target PMI>0 and a lung and diaphragm protective ventilation strategy following current literature. Data about PS setting at the end of the study will be recorded in the case report form.

Tolerance rules:

Protocol will be stopped if: heart rate >140 beats/min; increase in respiratory rate by 50% or more if not explained by ineffective effort; hypotension [systolic blood pressure <90 mmHg] or hypertension [systolic blood pressure >180 mmHg]; peripheral arterial oxygen saturation <90% for 5 minutes; excessive use of accessory respiratory muscles, diaphoresis, agitation, and the appearance of major abdominal or thoracic paradoxical movements. If apnea would appear at high PS levels (as described as overassistance), the PS will be decreased to the next lower level. PS will be set to not exceed a Ppeak of 30 cmH2O or a Vt of 12 mL/kg of predicted bodyweight

• Study Type: Observational
• Enrollment (Estimated): 20

Contacts and Locations

• Study Contact: Name: Laurent Brochard, MD, PhD; Phone Number: 4168645686; Email: laurent.brochard@unityhealth.to

Study Locations

• Canada
  • Ontario
    • Toronto, Ontario, Canada, M5B 1W8
      • Recruiting
      • St. Michael's Hospital
      • Contact: Laurent Brochard, MD; Email: laurent.brochard@unityhealth.to

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

The Study population will include patients mechanically ventilated in the St. Michael's Intensive Care Unit. Patients who are younger than 18 years of age will be excluded from this study on the basis that the ICUs at St. Michael's Hospital are intended for adults; individuals aged less than 18 years are rarely, if ever, admitted.

Description

Inclusion Criteria:

• >18 y.o.
• Invasively ventilated in Intensive Care Unit.
• Diagnosed with acute hypoxemic respiratory failure (P/F<300 mmHg).
• Breathing on pressure support ventilation.

Exclusion Criteria:

• <18 y.o.
• Contraindication for Electrical Impedence Tomography monitoring (e.g. pacemaker, burns, or - wounds limiting electrode placement).
• Severe and previously diagnosed neurological and neuromuscular disease.
• Psychomotor agitation (Sedation Agitation Scale > 4).

Study Plan

How is the study designed?

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Inspiratory Occlusion	To investigate the role of the inspiratory occlusion as a diagnostic tool to understand the patient's desired tidal volume and minute ventilation in Pressure Support Ventilation (PSV),	60 minutes
Pressure Muscle Index (PMI)	To investigate the role of a PMI>0 strategy to avoid over-assistance in Pressure Support Ventilation	60 minutes

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Pendelluft	To investigate the relationship between "active" and "passive" pendelluft measured over different levels of assistance in PSV.	60 minutes
Lung and Diaphragm Protective Ventilation	To measure indexes proposed by current literature to target a lung and diaphragm protective ventilation strategy with both inspiratory and expiratory occlusions in PSV, while applying a PMI>0 strategy.	60 minutes

Collaborators and Investigators

• Sponsor: Unity Health Toronto
• Investigators: Principal Investigator: Laurent Brochard, Unity Health Toronto - St. Michael's Hospital

Study record dates

Study Major Dates

• Study Start (Actual): October 4, 2024
• Primary Completion (Estimated): February 28, 2026
• Study Completion (Estimated): February 28, 2026

Study Registration Dates

• First Submitted: July 2, 2024
• First Submitted That Met QC Criteria: July 2, 2024
• First Posted (Actual): July 10, 2024

Study Record Updates

• Last Update Posted (Estimated): May 20, 2025
• Last Update Submitted That Met QC Criteria: May 15, 2025
• Last Verified: August 1, 2024

More Information

Terms related to this study

• Keywords: Intensive Care Unit; Mechanical Ventilation; Pressure Support Ventilation; Pendelluft
• Additional Relevant MeSH Terms: Respiratory Tract Diseases; Respiration Disorders; Respiratory Insufficiency
• Other Study ID Numbers: 24-105

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No