Stress Index in Pediatric Critical Illness: A Tool from Ventilator Graphics

Abstract

Background: Mechanical ventilation may result in ventilator-induced lung injury (VILI), primarily due to alveolar overdistension and tidal recruitment. The stress index, which is derived from the pressure-time curve during constantflow ventilation, functions as a non-invasive instrument for detecting these detrimental patterns. While it has been validated for adults, its use in pediatric patients has not been thoroughly investigated. Objective: The objective of this study is to assess the practicality and clinical significance of visually assessing the stress index among children with acute lung injury or ARDS who are on mechanical ventilation. Design: This was a prospective cohort study involving 50 pediatric patients receiving mechanical ventilation in a tertiary ICU. Intervention: During volume-controlled ventilation, a 5-second end-expiratory occlusion was conducted. Measurements: The stress index was visually assessed by examining the pressure-time curve displayed on the ventilator and categorized as linear, downward concavity (suggesting tidal recruitment), or upward concavity (indicating overdistension). Ventilator settings and clinical outcomes were documented. Results: The visual assessment revealed that 60% of patients had a linear curve, 20% had downward concavity, and 20% had upward concavity. The overall mortality rate was 68%. Patients exhibiting upward concavity showed significantly higher peak inspiratory pressure, driving pressure, plateau pressure, and oxygenation index (p<0.05). Logistic regression analysis identified peak inspiratory pressure, mean airway pressure, plateau pressure, as well as driving pressure as key predictors of poor outcomes in those with upward concavity. Conclusion: The visual assessment of the stress index is a straightforward and feasible tool for pediatric critical care. An upward concavity pattern, which indicates overdistension, correlates with poorer ventilator parameters and clinical outcomes. Utilizing this visual assessment could assist in implementing lung-protective ventilation strategies and minimizing barotrauma in children.