Real-Time Effort Driven Ventilator Management: A Pilot Study

Abstract

Objectives: Mechanical ventilation of patients with acute respiratory distress syndrome should balance lung and diaphragm protective principles, which may be difficult to achieve in routine clinical practice. Through a Phase I clinical trial, we sought to determine whether a computerized decision support-based protocol (real-time effort-driven ventilator management) is feasible to implement, results in improved acceptance for lung and diaphragm protective ventilation, and improves clinical outcomes over historical controls.

Design: Interventional nonblinded pilot study.

Setting: PICU.

Patients: Mechanically ventilated children with acute respiratory distress syndrome.

Interventions: A computerized decision support tool was tested which prioritized lung-protective management of peak inspiratory pressure-positive end-expiratory pressure, positive end-expiratory pressure/FIO2, and ventilatory rate. Esophageal manometry was used to maintain patient effort in a physiologic range. Protocol acceptance was reported, and enrolled patients were matched 4:1 with respect to age, initial oxygenation index, and percentage of immune compromise to historical control patients for outcome analysis.

Measurements and main results: Thirty-two patients were included. Acceptance of protocol recommendations was over 75%. One-hundred twenty-eight matched historical controls were used for analysis. Compared with historical controls, patients treated with real-time effort-driven ventilator management received lower peak inspiratory pressure-positive end-expiratory pressure and tidal volume, and higher positive end-expiratory pressure when FIO2 was greater than 0.60. Real-time effort-driven ventilator management was associated with 6 more ventilator-free days, shorter duration until the first spontaneous breathing trial and 3 fewer days on mechanical ventilation among survivors (all p ≤ 0.05) in comparison with historical controls, while maintaining no difference in the rate of reintubation.

Conclusions: A computerized decision support-based protocol prioritizing lung-protective ventilation balanced with reduction of controlled ventilation to maintain physiologic levels of patient effort can be implemented and may be associated with shorter duration of ventilation.

Figures

Figure 1:

Flow chart for study protocol. Acute and weaning phase are separated by the vertical dotted line. Effort of breathing (EOB) guided weaning while on pressure support (PS) ventilation occurs after failing the first spontaneous breathing trial (SBT).

Figure 2:

Run chart for REDvent CDS showing the per patient percent acceptance (blue) and cumulative percent acceptance (red) over the course of the pilot study. Iterative adjustments were made based on clinician feed-back throughout and shown as the vertical blue dashed-lines with corresponding numbers: (1) porting the CDS from an Microsoft Access to a web-based version (2) modification of the rules that incorporate effort of breathing (3) adjustments to the upper limit of respiratory rate when air trapping is present (4) incorporating adjustments for inhaled nitric oxide when a clinician decides to use it. Near the end of the study, per patient acceptance was above 90%.

Figure 3:

Ventilation parameters for REDvent (red), historical controls (blue), and N( ) as a function of time. For each subject, study day, and parameter, the median value was used. On day 1, ΔP is lower in REDvent with similar trends maintained through study day 4. Exhaled tidal volume per kg is significantly less on day 0 and also maintains significance through study day 4. * Indicates significance for a Mann-Whitney-U test, P

Figure 4:

FiO2 as a function of PEEP between REDvent (red) and historical controls (blue) over the entire course of mechanical ventilation. As FiO2 was increased, PEEP increased at a greater rate in the REDvent group particularly when FiO2 was > 0.6.