• Xuan He, Xiu-Mei Sun, Guang-Qiang Chen, Yan-Lin Yang, Zhong-Hua Shi, Ming Xu, and Jian-Xin Zhou.
• Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, China.
• Respir Care. 2018 Feb 1; 63 (2): 169-176.

BackgroundThe dynamic occlusion test is used to guide balloon catheter placement during esophageal pressure (Pes) monitoring. We introduced a cardiac cycle locating method to attenuate the influence of cardiac artifacts on Pes measurement. The aim was to provide a reliable analytic algorithm for the occlusion test.MethodsEsophageal balloon catheters were placed in subjects receiving pressure support ventilation. During balloon position adjustment, end-expiratory occlusion was performed to induce 3 consecutive inspiratory efforts. Pes and airway pressure (Paw) data were collected for off-line analysis. For each occluded inspiratory effort, the change in Pes (ΔPes) was plotted against the change in Paw (ΔPaw), and the slope of the regression line was calculated. The ΔPes/ΔPaw ratio was also measured with the cardiac cycle locating method and peak-to-peak method. Bland-Altman analysis was used to assess the agreement between the ΔPes/ΔPaw ratio and the slope. We defined the occlusion test with all fitted slopes for the 3 inspiratory efforts within 0.8 to 1.2 to indicate optimal balloon position; otherwise, the position was deemed non-optimal. Using the slope as the reference, the diagnostic accuracy of the ΔPes/ΔPaw ratio in distinguishing the optimal and the non-optimal balloon position was analyzed.ResultsA total of 86 occlusion tests containing 258 inspiratory efforts were collected from 15 subjects. The median (interquartile range) slope of ΔPes versus ΔPaw plot was 0.85 (0.76, 0.91). Bias (lower and upper limit of agreement) of ΔPes/ΔPaw ratio measured by the cardiac cycle locating method and the peak-to-peak method was 0.02 (-0.13 to 0.16) and 0.06 (-0.18 to 0.31), respectively. Forty-five (52.3%) occlusion tests indicated optimal balloon positions. Compared to the peak-to-peak method, the cardiac cycle locating method was more specific in detecting the non-optimal position.ConclusionsThe cardiac cycle locating method provided reliable and precise measurement for the occlusion test. This method can accurately detect non-optimal balloon position during catheter adjustment.Copyright © 2018 by Daedalus Enterprises.

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