TY - JOUR T1 - Stress Index Can Be Accurately and Reliably Assessed by Visually Inspecting Ventilator Waveforms JF - Respiratory Care SP - 1094 LP - 1101 DO - 10.4187/respcare.06151 VL - 63 IS - 9 AU - Xiu-Mei Sun AU - Guang-Qiang Chen AU - Kai Chen AU - Yu-Mei Wang AU - Xuan He AU - Hua-Wei Huang AU - Xu-Ying Luo AU - Chun-Mei Wang AU - Zhong-Hua Shi AU - Ming Xu AU - Lu Chen AU - Eddy Fan AU - Jian-Xin Zhou Y1 - 2018/09/01 UR - http://rc.rcjournal.com/content/63/9/1094.abstract N2 - BACKGROUND: Stress index provides a noninvasive approach to detect injurious ventilation patterns and to personalize ventilator settings. Obtaining the stress index (SI), however, requires quantitatively analyzing the shape of pressure-time curve with dedicated instruments or a specific ventilator, which may encumber its clinical implementation. We hypothesized that the SI could be qualitatively determined through a visual inspection of ventilator waveforms.METHODS: Thirty-six adult subjects undergoing volume controlled ventilation without spontaneous breathing were enrolled. For each subject, 2 trained clinicians visually inspected the pressure-time curve directly from the ventilator screen. They then qualitatively categorized the shape of pressure-time curve as linear, a downward concavity, or an upward concavity at the bedside. We simultaneously recorded airway pressure and flow signals using a dedicated instrument. A quantitative off-line analysis was performed to calculate the SI using specific research software. This quantitative analysis of the SI served as the reference method for classifying the shape of the pressure-time curve (ie, linear, a downward concavity, or an upward concavity). We compared the SI categorized by visual inspection with that by the reference.RESULTS: We obtained 200 SI assessments of pressure-time curves, among which 125 (63%) were linear, 55 (27%) were a downward concavity, and 20 (10%) were an upward concavity as determined by the reference method. The overall accuracy of visual inspection and weighted kappa statistic (95% CI) was 93% (88–96%) and 0.88 (0.82–0.94), respectively. The sensitivity and specificity to distinguish a downward concavity from a linear shape were 91% and 98%, respectively. The respective sensitivity and specificity to distinguish an upward concavity from a linear shape were 95% and 95%.CONCLUSIONS: Visual inspection of the pressure-time curve on the ventilator screen is a simple and reliable approach to assess SI at the bedside. This simplification may facilitate the implementation of SI in clinical practice to personalize mechanical ventilation. (ClinicalTrials.gov registration NCT03096106.) ER -