PT  - JOURNAL ARTICLE
AU  - Sun, Xiu-Mei
AU  - Chen, Guang-Qiang
AU  - Chen, Kai
AU  - Wang, Yu-Mei
AU  - He, Xuan
AU  - Huang, Hua-Wei
AU  - Luo, Xu-Ying
AU  - Wang, Chun-Mei
AU  - Shi, Zhong-Hua
AU  - Xu, Ming
AU  - Chen, Lu
AU  - Fan, Eddy
AU  - Zhou, Jian-Xin
TI  - Stress Index Can Be Accurately and Reliably Assessed by Visually Inspecting Ventilator Waveforms
AID  - 10.4187/respcare.06151
DP  - 2018 Sep 01
TA  - Respiratory Care
PG  - 1094--1101
VI  - 63
IP  - 9
4099  - http://rc.rcjournal.com/content/63/9/1094.short
4100  - http://rc.rcjournal.com/content/63/9/1094.full
AB  - 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.)