Inspiratory Effort-Targeted Pressure Support Ventilation (IT-PSV) Trial

Pressure-support ventilation (PSV) is widely used in the intensive care unit (ICU). The successful implementation of PSV depends on matching the patient's inspiratory effort with the ventilator support. Traditionally, pressure support levels are set according to tidal volume (VT) and respiratory rate (RR). However, previous studies have shown that over-assistance under PSV is not uncommon based on this setting strategy. Pressure muscle index (PMI) is an inspiratory effort monitoring, which can be easily obtained on the ventilator screen at the bedside.

Aim:

The aim is to determine whether an inspiratory effort-targeted pressure support setting strategy, compared to the traditional approach, can improve clinical outcomes in adult participants undergoing PSV.

Design:

This is a two-arm cluster randomized trial in 18 clusters randomized 1:1 to pressure support setting by a PMI-targeted strategy or a traditional VT/RR-targeted strategy.

Population:

Patients with acute hypoxic respiratory failure who have been intubated within seven days and undergoing PSV within 24 hours will be enrolled.

Intervention:

During the study, a general standard of care for mechanical ventilation will be followed, including the transition of control modes to PSV, the principle PSV settings (trigger, cycle-off, fraction of inspired oxygen, and positive end-expiratory pressure), rescue backup of controlled ventilation, performance of spontaneous breathing trial, and weaning and extubation.

In the VT/RR-targeted group, the pressure support is adjusted to obtain a VT between 6 and 8 ml/kg predicted body weight and RR between 20 and 35 breaths/min.

In the PMI-targeted group, the pressure support is adjusted according to the PMI between 0 and 2 cmH2O.

During the study period in the two groups, pressure support adjustment will be performed at least twice daily.

The intervention will be implemented over 24 months.

Training:

After randomization, a four-week comprehensive training program will be conducted for all staff in the participating ICUs before the formal start of the trial.

Outcomes:

The primary outcome is the ventilator free day during 28 days. Secondary outcomes include total duration of mechanical ventilation, the time before the first spontaneous breathing trial, weaning time, frequency of prolonged and failed weaning, frequency of mechanical ventilation longer than 21 days, length of stay in the ICU and hospital, ICU mortality, hospital mortality, and 28-day mortality.

Study sites:

The study will be conducted in 18 ICUs in university-affiliated hospitals in three provinces in China: Beijing, Tianjin, and Hebei.

Mechanically ventilated patients, who are admitted to the ICU with acute hypoxic respiratory failure, will be consecutively screened daily at 08:00-10:00 morning rounds.

Inclusion criteria

• PSV initiated during the last 24 hours;
• Mechanical ventilation expected to be required for at least 24-48 h by responsible physicians;
• The partial pressure of oxygen in arterial blood (PaO2)/inspired oxygen fraction (FiO2) ≤ 300 mmHg (measuring at clinical FiO2 and positive end-expiratory pressure PEEP);
• No sedation or stable sedation with Richmond Agitation Sedation Scale (RASS) of -2 to +1 or Riker's Sedation-Agitation Scale (SAS) of 3 to 4.

Exclusion criteria

included:

• Age younger than 18 years old;
• Initiation of PSV before ICU admission;
• Duration of mechanical ventilation longer than 7 days before enrollment;
• History of neuromuscular diseases;
• Clinical suspicion of increased intracranial pressure;
• Extracorporeal support;
• Moribund conditions;
• Refusal by the ICU physicians or the patient.